INTRODUCTION
Certainly attract attention of patrons. This LED sign board looks best in dimly light settings such as bars, night clubs and restaurants. The lighting technology in these menu displays is quite advanced. This LED sign board feature bright, equally distributed lighting so that even the center of the unit is bright. There are no hot and cold spots on any of these restaurant menu displays. Additionally, with these LED writing boards there is never any need to worry about light bulbs being blown. The technology on these menu signs uses diodes as the primary source of light.
PURPOSE OF THE PROJECT
The main purpose of signboard is communication, to convey information such that its receiver can make cognitive decisions based on the information provided. In general, signage can be classified into the following functions:
(a) Information: signs giving information about services and facilities, e.g., maps, directories, instructions for use, etc.
(b) Direction: signs leading to services, facilities, functional spaces and key areas, e.g., sign posts, directional arrows, etc.
(c) Identification: signs indicating services and facilities, e.g., room names & numbers, toilet signs, number of floors, etc.
(d) Safety and Regulatory: signs giving warning or safety instructions, e.g., warning signs, traffic signs, exit signs, rules & regulations.
OBJECTIVE OF THE PROJECT
This main objective of this work is to construct an electronics device that can be used to pass information to the public or passerby and outdate the use of Analogue or Traditional way of passing information on the street, Beer parlor and Restaurant using light emitting diodes.
SIGNIFICANCE OF THE PROJECT
The LED sign board is very slim and lightweight in design. LED light source, lower power consumption. Ultra slim & ultra light. Top designs for show window and guide board. This LED sign board is ideal for advertising or displaying purpose. The sign board allows you to display your advertising messages, product images at prominent places.
APPLICATIONS AND ADVANTAGES
This project can be used in public places as well as hospitals and private companies, schools, colleges and universities. Notice boards are particularly prevalent at universities. They are used by many sports groups and extracurricular groups and anything from local shops to official notices. Dormitory corridors, well-trafficked hallways, lobbies, and freestanding kiosks often have Notice boards attached to facilitate the posting of notices.
LIMITATION OF THE PROJECT
Presently almost all electronic notice boards are designed using wired system. One of the drawbacks of the design is the system is inflexible in term of placement, that is the information placed cannot changed easily and the wiring can be messy. It must be designed by professionals and not apprentices for normal operation.
PROJECT WORK ORGANISATION
The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows: Chapter one of this work is on the introduction to an electronics notice board using LED. In this chapter, the background, significance, objective limitation and problem of an electronics notice board using LED were discussed. Chapter two is on literature review of an electronics notice board using LED. In this chapter, all the literature pertaining to this work was reviewed. Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed. Chapter four is on testing analysis. All testing that result accurate functionality was analyzed. Chapter five is on conclusion, recommendation and references.
REVIEW
HISTORY OF ELECTRONIC SIGN POST ELECTRONIC MESSAGE DISPLAY SIGNS
We are all very fortunate to live in a society that places a premium value on Freedoms, and limits governmental intrusion upon those freedoms. Freedom of Speech is one of those essential freedoms, and one that is embodied within the Constitution that molds the rule of law governing this great nation. Many reputable organizations, like the U.S. Small Business Administration and the International Sign Association caution against sign regulations that interfere with the freedom of exercising commercial speech. The following information has been assembled by a coalition of manufacturers of electronic message display signs. We recognize the uncertainty surrounding the legality of certain sign regulations. We also respect the desire by communities to regulate signs, including electronic message display signs, and the need for responsible sign codes. Without engaging in debate over the legality of regulations affecting electronic message displays, the following materials are intended to develop a more sophisticated understanding of the current state of the technology, and to promote regulations that reflect the broad variations in the use of electronic message displays.
The History of ELECTRONIC MESSAGE DISPLAY SIGNS
In the day when signs were primarily painted, changing messages on a sign merely required painting over the existing message. More recently, signs with removable lettering made it possible to manually change the lettering on a sign to display a new message. Electrical changeable message signs followed the invention of the light bulb, and included light bulbs arranged in a pattern where, by lighting some light bulbs and not the others, letters and numerals could be spelled out. With the advent of solid-state circuitry in the early 1970s, electronic changeable message signs became possible. The first of these products were time and temperature displays and simple text message displays using incandescent lamps. These lamps were very inefficient. They used a great deal of power and had short life expectancies. During the energy crunch of the 1980s, it became necessary to find ways to reduce the power consumption of these displays. This need initially spawned a reflective technology. This technology typically consisted of a light-reflective material applied to a mechanical device, sometimes referred to as “flip disk” displays. Electrical impulses were applied to a grid of disks with reflective material on one side of the disk, and a contrasting finish on the other side. The electrical impulses would position each disk within the grid to either reveal or conceal the reflective portion of the device as required, to produce an image or spell out a message. These technologies were energy efficient, but due to the mechanical nature of the product, failures were an issue. Shortly after the introduction of the reflective products, new incandescent lamps emerged. The new “wedge base” Xenon gas-filled lamps featured many positive qualities. Compared to the larger incandescent lamps that had been used for several years, the wedge base lamps were very bright, required less power to operate and had much longer lifetimes. These smaller lamps allowed electronic display manufacturers to build displays that featured tighter resolutions, allowing users to create more ornate graphic images. Next in the evolution of the changeable message sign was the LED. LED (light emitting diode) technology had been used for changeable message displays since the mid 1970s. Originally, LEDs were available in three colors: red, green and amber, but were typically used for indoor systems because the light intensity was insufficient for outdoor applications and the durability of the diodes suffered in the changing temperatures and weather conditions. As technology improved, manufacturers were able to produce displays that had the intensity and long life required for outdoor use, but was limited in the viewing angle from which they could be effectively seen. Recently, breakthroughs in this field have made available high intensity LEDs in red, green, blue and amber. These LEDs have made it possible to produce displays bright enough for outdoor use with viewing angles that are equal to, or better than, other technologies currently available. They are energy-efficient, can be programmed and operated remotely, and require little maintenance. In addition, the computer software has evolved such that a broad range of visual effects can be used to display messages and images. The spacing of the LEDs can be manipulated to achieve near-television resolution. Earlier “flip disk” and incandescent technologies have become nearly obsolete as a result.
Types of Electronic Message Display Signs
Electronic message display sign been placed into two basic categories: manually changed and electronically-changed. The most common form of manually changed sign involves a background surface with horizontal channels. Letters and numerals are printed on individual plastic cards that are manually fitted into the channels on the sign face. A broad range of letter styles and colors are available. The manually-changed sign is relatively inexpensive and is somewhat versatile. Some discoloration has been experienced in the background surface materials with exposure to weather and the sun. Changing the message on such a sign is accomplished by having an employee or technician remove the existing plastic letter cards and replacing them with cards displaying the new message. Occasionally, such signs have been the subjects of vandals who steal the letters or, as a prank, re-arrange them to spell out undesirable messages. Over time, as letters are replaced with lettering styles that deviate in color or type style from the original set, such signs have had a tendency to take on a mix-and-match appearance. Electronic message signs are generally of two types: light emitting and light reflective. Current light emitting display technologies include LED and incandescent lamp. Light reflective displays typically consist of either a reflective material affixed to a mechanical device (like a “flip disk”) or a substance commonly referred to as electronic ink. Many of the above mentioned technologies have the capabilities to display monochromatic (single color) or multiple color images. Monochrome changeable message signs are typically used to display text messages. Multiple color displays are more common in applications where color logos or video is displayed.
Operational Capabilities of Electronic Signs
Electronic signs have evolved to the point of being capable of a broad range of operational capabilities. They are controlled via electronic communication. Text and graphic information is created on a computer using a software program. This software is typically a proprietary component that is supplied by the display manufacturer. These software programs determine the capabilities of the displays. The software is then loaded onto a computer that operates the sign. The computer may be installed within the sign itself, operated remotely from a nearby building, or even more remotely by a computer located miles away and connected to the sign with a telephone line modem or other remote communication technology. Since most of the software programs are proprietary, one can assume that each software program is slightly different. However, the capabilities that the program offers are all very similar. Changeable message sign manufacturers provide software that allows the end user to be as creative or as reserved as they like. The sign can be used to display static messages only, static messages changed by a computer-generated transition from one message to the next, moving text, animated graphics and, in some applications, television-quality video. Text messages or graphic images can simply appear and disappear from the display or they can be displayed using creative entry and exit effects and transitions. Example Oftentimes a display operator will choose to have a text message scroll onto the display and then “wipe-off” as if the frame has been turned like the page of a book. If a display has the capabilities to display graphics, logos or even video, it is common for the display operator to add motion to these images. Example: A display operator at a school may wish to create an animation where their school’s mascot charges across a football field and runs over the competing school’s mascot. Video-capable displays can operate much like a television. These displays can show live video, recorded video, graphics, logos, animations and text. All display capabilities are securely in the hands of the display operators. They are ultimately responsible for what type of, and how, information is displayed on their changeable message sign. Traffic Safety Considerations Electronic message displays (EMDs) are capable of a broad variation of operations, from fully-static to fully-animated. In exterior sign use, they are often placed where they are visible to oncoming traffic. Concerns are often raised as communities change their sign codes to expressly permit such signage about the traffic safety implications for signage with moving messages. These concerns are largely unfounded. EMDs have been in operation for many years. As is typical with many technological advances, the regulatory environment has been slow to respond to advances in the technology itself. In 1978, after many years of the use of electronic signs, Congress first passed legislation dealing with the use of illuminated variable message signs along the interstate and federal aid primary highway system. The Surface Transportation Assistance Act permitted electronic message display signs, subject to state law, provided each message remained fixed on the display surface but “which may be changed at reasonable intervals by electronic process or remote control,” and did not include “any flashing, intermittent or moving light or lights.” 23 U.S.C. § 131. In 1980, and in response to safety concerns over EMDs along highways, the Federal Highway Administration published a report titled “Safety and Environmental Design Considerations in the Use of Commercial Electronic Variable Message Signs.” This report was an exhaustive analysis of the safety implications of EMDs used along highways. The report highlights the inconclusive nature of safety studies that had occurred to that time, some concluding that roadside signs posed a traffic distraction, and others concluding that roadside signs do not cause traffic accidents. In view of the inevitable use of the technology in signage, the report made some sensible observations about traffic safety considerations for such signs:
1. Longitudinal location. The report recommended that spacing standards be adopted to avoid overloading the driver’s information processing capability. Unlike the standard for sign regulations in 1980, most communities today have spacing standards already integrated into their sign codes.
2. Lateral location. Often referred to as “setback,” the report initially recommended the common sense requirement that such signs be placed where the risk of colliding into the sign is eliminated. This was a legitimate concern, as such signs were being contemplated for use by highway departments themselves in the right-of-way. Private use of roadside signs is generally limited to locations outside the right-of-way, so this should not be a significant concern. The next issue addressed by the report was visibility. The report advocated the minimum setback feasible, stating that “standards for lateral location should reduce the time that drivers’ attention is diverted from road and traffic conditions. Generally this suggests that signs should be located and angled so as to reduce the need for a driver to turn his head to read them as he approaches and passes them.” This can best be handled by permitting such signs to be located at the property line, with no setback, and angled for view by oncoming traffic.
3. Operations: Duration of message on-time. The report states that the duration of the message on-time should be related to the length of the message, or in the case of messages displayed sequentially, the message element. For instance, based on state highway agency experience, “comprehension of a message displayed on a panel of three lines having a maximum of 20 characters per line is best when the on-time is 15 seconds. In contrast, the customary practice of signing which merely displays time and temperature is to have shorter on-times of 3 to 4 seconds.” Since this 1980 report, state highway agencies have adopted, for use on their own signs, informal standards of considerably shorter “on” time duration, with no apparent adverse effects on traffic safety. Federal legislation affecting billboard use of electronic signs requires only that messages be changed at “reasonable intervals.”1 Moreover, the U.S. Small Business Administration, in a report on its website reviewing safety information compiled since the 1980 report, has concluded that there is no adverse safety impact from the use of EMD signs. The most recent study was performed in 2003 by Tantala Consulting Engineers, available through the U.S. Sign Council at also concluding based on field studies that EMD signs do not adversely affect traffic safety. Many small businesses using one-line EMD displays are only capable of displaying a few characters at one time on the display, changing frequently, which takes virtually no time for a driver to absorb in short glances. These signs have likewise not proven to be a safety concern, despite many years of use.
4. Operations: Total information cycle. EMD signs can be used to display stand-alone messages, or messages that are broken into segments displayed sequentially to form a complete message. As to the sequential messages, the report recommended a minimum on-time for each message “calculated such that a motorist traveling the affected road at the 85th percentile speed would be able to read not more than one complete nor two partial messages in the time required to approach and pass the sign.”
5. Operations: Duration of message change interval and off-time. The report defines the message change interval as the portion of the complete information cycle commencing when message “one” falls below the threshold of legibility and ending when message “two” in a sequence first reaches the threshold of legibility. This is relevant when operations such as “fade off-fade on” are used, when the first message dissolves into the second message, or when the two messages move horizontally (traveling) or vertically (scrolling) to replace the first message with the second. Off-time, on the other hand, is a message change operation that involves the straightforward turning off of the first message, with a period of blank screen, before the second message is instantly turned on. The appropriate interval of message change may be affected by a variety of factors, and one standard does not fit all situations. Imagine, for instance, a bridge that serves two roadways, one with a speed limit of 30 mph and the other a highway with a speed limit of 60 mph. In a situation where the bridge is socked in by fog, an electronic sign on the approach to the bridge may be used to convey the message, “Fog ahead…on bridge…reduce speed…to 15 mph.” The driver on each roadway needs to see all the segments to the full message. The rate of changing each segment of the message needs to be different for each roadway. If the change rate were based only on the 60 mph speed, the sign on the slower roadway may appear too active. If the change rate were based only on the 30 mph speed, the result could be fatal to drivers on the highway. The report takes an extremely conservative approach as to message change interval, advising against the use of operations other than nearly instantaneous message changes. If such operations are permitted, the report suggests “that the figure commonly used as a measure of average glance duration, 0.3 second, be used here as a maximum permissible message change time limit.” The report further advocates minimizing off-time between messages, where static message changes are used, stating that “[a]s this interval of off-time is lengthened, the difficulty of maintaining the continuity of attention and comprehension is increased.” The conservative nature of the authors’ position is reflected both in the report, and in over twenty years of practice since the report was issued. The report cites studies indicating that, in some situations, the use of electronic operations had a beneficial effect on traffic safety, by creating a more visually-stimulating environment along an otherwise mind numbing segment of highway, helping to re-focus and sharpen the driver’s attention to his or her surroundings. In over twenty years of experience, with numerous electronic signs nationwide utilizing the various operational capabilities for message change, there has been no significant degradation to highway safety reported. Many electronic signs used by highway departments now use a mode of transition between messages or message segments, such as traveling or scrolling. Drivers are apparently capable of attaching primacy to the visual information most critical to the driving task, with sign messages taking a secondary role. The report further expresses its limited focus upon interstate and federal aid primary highways. Noting the stimulating visual environment created by full-animation signage in places like Times Square, Las Vegas and Toronto’s Eaton Centre, the authors of the report agreed that such signs added vitality and dimension to the urban core, but discouraged the use of animation alongside the highway. The report did not deal with the use of such signs, or their operational characteristics, on roadways between the extremes of the interstate highway and the urban core. In addition, animation has now been used on highway-oriented signs in many locations for years, with no reported adverse effect of traffic safety. In sum, the report acknowledged the appropriateness of full-animation electronic signs within the urban core, but recommended that full-animation not be used along interstate and primary highways. It took a conservative position on operations of such signs along highways, advocating static message change sequences only, with no more than 0.3 seconds of message change interval or “off-time” between messages. The message changes on sequential segmented messages should be displayed such that a motorist can see and read the entire chain of message segments in a single pass. Messages should be permitted to change at “reasonable intervals.” Such signs should have adequate spacing between signs, but be set back from the right of way as little as feasible. Since 1980, no new information has become available supporting a traffic safety concern about EMDs. They have been installed in highway locations, along city streets and in urban core settings, using all forms of operations: static, sequential messaging and full animation. Despite such widespread use, and the presence of environmental organizations generally adverse to sign displays, no credible studies have established a correlation between EMDs and degradation in traffic safety. An article in the Journal of Public Policy and Marketing in spring, 1997, arrived at the same conclusion. Professor Taylor, of Villanova University, analyzing this lack of data to support such a correlation, concluded that “there appears to be no reason to believe that changeable message signs represent a safety hazard.” From a safety standpoint, and based on the studies and practical experience that has been accumulated since the widespread use of EMDs, some conclusions can be reached: • In an urban core setting, where a sense of visual vitality and excitement is desirable, full-animation EMDs have been shown to be viable without degrading traffic safety.
• In an urban setting, such as along arterial streets, EMDs have been used with static messages changed by use of transitions such as traveling, scrolling, fading and dissolving, without any apparent impact on traffic safety. Quite likely, this can be attributed to the primacy of the navigation task, and the secondary nature of roadside signage.
• Along interstate and other limited access highways, the only significant traffic safety analysis recommends the use of static messages only, and the federal government permits message changes at “reasonable intervals.” Many highway departments change messages on their own signs every 1-2 seconds. The report further recommends that sequential messages be timed to ensure that the entire sequence of messages be displayed in the time it takes a car to travel from initial legibility to beyond the sign. In practice, and in the 20+ years since publication of this report, the operational characteristics of such signs have been expanded to include fading, dissolving, scrolling and traveling, without any apparent adverse effect on traffic safety.
Regulation of Electronic Signs Board
The history of the regulation of electronic signs has been largely marked by polar extremes in regulation. A number of zoning and sign codes have treated such signs as any other sign, with no special regulations. Others have attempted to prohibit their use in the entirety, largely out of concerns for traffic safety, and in some cases in the stated interest of aesthetics. For the reasons stated above, the traffic safety concerns have been largely unfounded. In decades of use and intense scrutiny, no definitive relationship between electronic signs and traffic accidents has been established. In fact, some studies have suggested that animated electronic signs may help keep the driver whose mind has begun to wander re-focused on the visual environment in and around the roadway. No studies support the notion that an electronic sign with a static display has a visual impact, from either a traffic safety or aesthetic impact, different from that of any other illuminated sign. Despite this, the fear of negative impact from potentially distracting signs has in the past motivated some communities to attempt to prohibit electronic signs altogether. Two common approaches have been to prohibit sign “animation” and the “intermittent illumination” of electronic signs. Both approaches have had their limitations. Electronic signs that are computer-controlled often have the capability to be displayed with a multitude of operational characteristics, many of which fall within the typical definition of “animation.” However, static display techniques are quite commonplace with electronic signs, and the cost of using electronics in relatively typical sign applications has become more affordable. The programming of an electronic sign to utilize static displays only is simple and straightforward, yet probably overkill in the legal and practical sense. Nonetheless, out of fear that the programming may be changed to animation after a sign is permitted and operational, some local regulators have attempted to take the position that LED and other electronic signs are prohibited altogether. This position is unsound. There is no legal basis to deny a static-display electronic sign, as it is legally indistinguishable from any other illuminated sign. We don’t prohibit car usage merely because the cars are designed so that they can exceed the speed limit; we issue a ticket to the driver if they do exceed the speed limit. Likewise, if a sign owner actually violates the zoning or sign code, the remedy is to cite them for the violation, not to presume that they will do so and refuse to issue permits at the outset. Moreover, most communities permit changing messages on signs displaying time and temperature, with no restrictions on timing. To apply a different standard to signs displaying commercial or noncommercial messages would be to regulate on the basis of the content of the sign, in violation of the First Amendment to the U.S. Constitution. The code technique of prohibiting “intermittent illumination” has its own limitations as it relates to electronic signs. The term “intermittent” suggests that the sign is illuminated at some times, and not illuminated at others. This is no basis to distinguish between an electronic sign and any other illuminated sign. Virtually all illuminated signs go through a cycle of illumination and non-illumination, as the sign is turned off during the day when illumination is not needed, or during the evening after business hours. If this were the standard, most sign owners would be guilty of a code violation on a daily basis. Other terminology may be used in sign codes, but the fact is that a regulation must be tailored to the evil it is designed to prevent. Community attitudes toward viewing digital images have changed nationwide, with personal computer use and exposure to electronic signs becoming widespread. People are simply accustomed to the exposure to such displays, more so than in years past. In some communities, there remains a concern about the potential that such signs may appear distracting, from a safety or aesthetic standpoint. Yet, static displays do not have this character, and even EMDs with moving text have not proven to have any negative impact. The real focus should be on the operations used for the change in message, and frame effects that accompany the message display. Many of these transition operations and frame effects are quite subtle, or otherwise acceptable from a community standpoint. It is now possible to define these operations, in the code itself, with sufficient specificity to be able to enforce the differences between what is acceptable and what is not. The critical regulatory factors in the display of electronic changeable message signs are: 1) Duration of message display, 2) Message transition, and 3) Frame effects. With the exception of those locations where full animation is acceptable, the safety studies indicate that messages should be permitted to change at “reasonable intervals.” Government users of signs have utilized 1-2 seconds on their own signs as a reasonable interval for message changes, and other communities permit very short display times or continuous scrolling on business signs without adverse effect. As a policy matter, some communities have elected to adopt longer duration periods, although to do so limits the potential benefits of using an electronic sign, particularly where messages are broken down into segments displayed sequentially on the sign. The message transitions and frame effects are probably the greater focus, from a sign code standpoint. It is during the message transition or frame effect that the eye is most likely drawn to the sign. What is acceptable is a matter of community attitude. Flashing is a frame effect that is prohibited in many communities, but other more subtle transitions can be accepted. It is relatively easy to define four basic levels of operational modes for message transitions that can be incorporated into a sign code:
Level 1 Static Display Only (messages changed with no transition)
Level 2 Static Display with “Fade” or “Dissolve” transitions, or similar subtle transitions and frame effects that do not have the appearance of moving text or images.
Level 3 Static Display with “Travel” or “Scrolling” transitions, or similar transitions and frame effects that have text or animated images that appear to move or change in size, or be revealed sequentially rather than all at once
Level 4 Full Animation, Flashing and Video There are, in fact, other operations recognized within the industry. However, in practice they can be equated in visual impact with “fade,” “dissolve,” “travel” or “scrolling,” based on their visual effect, or otherwise be considered full animation. Different transition operations may be acceptable in different locations. For example, communities like Las Vegas accept full animation as a community standard, whereas others accept full animation only in urban core locations where a sense of visual vitality and excitement is desirable. Some communities may desire not to have an area with such visual stimuli, and elect to prohibit animation everywhere. However, in such a community, fade or scrolling may be acceptable forms of message transitions for static displays. In the most conservative communities, static displays with no observable transition between messages may be the only acceptable course. The next decision point for a community seeking to regulate electronic signs is Procedural. Some signs may be acceptable always, while the community may determine that others are acceptable only in certain given circumstances. Alternatives to be considered for a sign code are as follows:
• Permit electronic signs “as a matter of right”.
• Permit electronic signs with certain transitions “as a matter of right” .
• Permit electronic signs, subject to a review procedure.
• Permit electronic signs, with certain transitions, subject to a review
Procedure.
• A hybrid of the above For instance, one community may find it acceptable to permit electronic signs, with full animation, as a matter of right. Other than a straightforward sign permit, no other review is required. In another community, the sign code structure may permit:
1) Static displays with no transitions as a matter of right,
2) Static displays using fade or dissolve transitions as a matter of right in certain commercial zoning districts,
3) Static displays using travel and scrolling transitions and animations in certain commercial districts, subject to approval of a special use permit, where the approving board can consider compatibility with surrounding land uses and attach conditions on the rate of message changes,
4) Fully-animated/video displays in the downtown commercial district only, subject to approval of a special use permit. The level of procedure involved should be tailored to the acceptance level of the community, and the resources available should public review be desired. In the following section, we have provided model code language that can be used, for reference, to incorporate into a community’s sign code. The model language suggests code scenarios based on each of the four levels of display transitions. It also provides alternative language, for some scenarios, to either incorporate a special review procedure or not. Of course, the model language must be tailored to a particular community’s sign code. Variation may be necessary, where, for instance, the special review procedure would be by the local planning commission, city council or design review board. With ease, the model code language can be modified to meet local conditions.
Definitions
ELECTRONIC MESSAGE DISPLAY – A sign capable of displaying words, symbols, figures or images that can be electronically or mechanically changed by remote or automatic means. Electronic Message Displays may be permitted [with the approval of a use permit] [in the zoning districts] subject to the following requirements:
a. Operational Limitations. Such displays shall contain static messages only, and shall not have movement, or the appearance or optical illusion of movement, of any part of the sign structure, design, or pictorial segment of the sign, including the movement or appearance of movement of any illumination or the flashing, scintillating or varying of light intensity.
b. Minimum Display Time. Each message on the sign must be displayed for a minimum of (insert reasonable interval) seconds.
c. Message Change Sequence. [Alternative 1: The change of messages must be accomplished immediately.] [Alternative 2: A minimum of 0.3 seconds of time with no message displayed shall be provided between each message displayed on the sign.]
Model Electronic Sign Code Provisions Level 2-Static Display (Fade/Dissolve Transitions)
DISSOLVE – a mode of message transition on an Electronic Message Display accomplished by varying the light intensity or pattern, where the first message gradually appears to dissipate and lose legibility simultaneously with the gradual appearance and legibility of the second message.
FADE – a mode of message transition on an Electronic Message Display accomplished by varying the light intensity, where the first message gradually reduces intensity to the point of not being legible and the subsequent message gradually increases intensity to the point of legibility.
FRAME – a complete, static display screen on an Electronic Message Display.
FRAME EFFECT – a visual effect on an Electronic Message Display applied to a single frame to attract the attention of viewers.
TRANSITION – a visual effect used on an Electronic Message Display to change from one message to another. Level 3-Static Display (Travel/Scroll Transitions and Animations).
SCROLL – a mode of message transition on an Electronic Message Display where the message appears to move vertically across the display surface.
TRANSITION – a visual effect used on an Electronic Message Display to change from one message to another.
TRAVEL – a mode of message transition on an Electronic Message Display where the message appears to move horizontally across the display surface.
DESIGN METHODOLOGY AND ANALYSIS
INTRODUCTION
This project is designed so as to realize an efficient, maintainable, and most importantly, affordable electronic re-programmable display system using dot matrix technology. The moving message display system is designed in modules, which involves the techniques of modularity. For simplicity, the suitability and compatibility of a stage to conform to the changing circuit parameters in other stages were considered. Another important step taken was early identification of hazards and the development of appropriate steps to isolate and control them in the design phase. The different section/modules that make up the whole system are shown below.
Block diagram of a Micro programmable moving message display system
showing its principle of operation.
THE POWER SUPPLY UNIT
The power supply unit is a system that supplies electrical or other types of energy to an output or group of loads. The power supply unit is a system that supplies voltage to all parts of a circuitry. There are basically two main types of power supplies – linear power supply and switched mode power supply. In this project, the linear power supply was used principally the linear power supply consists of four sections. Complete implementation. They include:
CONTROL UNIT
1. Transformation
2. Rectification 3.
Filtration
4. Regulation
A typical block diagram of the linear power supply unit is as shown below.
Block diagram of the power supply unit
THE TRANSFORMER
In this project, a 240/12V, 500MA based transformer is used based on the fact that the means supply is rated at 240V and the actual voltage required by the circuit components (micro – controller, line decoder LEDs etc.) is a regulated 5V However, a 7805 regulator is used which required a minimum of 8V. The back drop voltage from the regulator is 1.4v given a total of 9.4V. The 12V transformers are available. A current of 500mA is sufficient to drive all the circuit components.
THE RECTIFIER
A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification. Rectification can either be half wave or full wave.
Transformer rectifier filter regulator
Half – Wave Rectification
In half – wave rectification, either the positive or negative half of the AC wave is passed, while the half of the other is blocked.
Full – Wave Rectification
A full wave rectifier converts the whole of the input form if the inputs wave form to constant polarity at its output.
In this project, full wave bridge rectifier is used because it provides a better efficiency compared to half wave and bridge rectifier, because the transformer used not center tapped.
FILTER
Filters are electronic circuit which perform signal processing functions, specifically to remove unwanted frequency component from the signal to enhance wanted ones or both. They consist of a capacitor connected across the rectified output for the purpose of smoothening out the unwanted ripple in the output. The capacitors basically store charges temporarily and the stored charges are measured in farad, micro – farad and Pico-farad.
The Regulator
A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. It may use an electromechanical mechanism, or passive or active electronic component. Depending on the design, it may be used to regulate one or more AC or DC voltages. The voltage regulator used in this project is 78HC05 integrated circuit. It has three terminals and is capable of supplying 5+ 10% at 100Ma
Circuit symbol of a voltage regulator with pin out indicator Terminal 1 serves as the input. 2 serves as ground and 3 as the input terminal. The 7805 used takes 12V from the transformer and gives output of 5V± 0.2%.
Power Indicator
Diode D5 is a light emitting diode used as power on indicator. This glows once power is on. Resistor R1 is a circuit-limiting resistor, which helps to limit the amount of current flowing through the diode D5. The value of the limiting resistor is gotten by the expression.
Resistor R1 = (Vdc – Vd)
Imax
Where:
Vdc = the calculated dc voltage which is given by
Vdc = Vac √2
= 12* √2
Vdc = 16.97
Vd = Diode voltage drop = 1.7V
I2 = Maximum circuit rating of the LED (D5) = 20Ma
Value of the limiting resistor becomes
R1 = 16.07 - 1.7
20 * 10
R1 = 763.5Ω
Therefore for safety reasons, a value of 1000Ω or 1KΩ which is a little higher than 763.5Ω is used to take care of inconsistencies.
THE CONTROL UNIT
The control unit is made up of a single micro controller chip that can execute a user program, normally for the purpose of controlling the device; the transistors serve as switches and the line decoders.
ATMEL 89S52
The ATMEL 89S52 is a single chip micro-controller that has random access memory (RAM) and read only memory (ROM). It has instruction set and is compatible with any other MC51 controller family.
The RAM (Random Access Memory) – This consists of 128 byte arranged as four register bank, each containing 8 registers given the label R0 to R7.
The ROM (Read Only Memory) – The 89S52 has 8K bytes ROM. This portion of the 89S52 is made available for the storage of program written by the system designer. The operation of the 89S52 depends on the program. Serial Communication Ports/Pin Configuration- the 89S52 micro-controller is a 40 pin IC with basically four communication ports with pin 20 and 40 as ground and voltage supply respectively. The four communication ports are ports are port 0, port 1, port 2 and port 3. This is illustrated in the fig below.
Diagram of AT89S52
ALE/PROG:
Address latch enable output pulse latching the low byte of the address during accessory to external memory. ALE is emitted at a constant rate of 1/6 of the oscillator frequency for external timing or clocking purposes even when there are no accesses to external memory. This pin is also the program pulse input (PROG) during EPROM programming.
PSEN:
Program store Enable is the read strobe to external program memory. When the device is executing out of external program memory, PSEN is activated twice each machine cycle (except that two PSEN activation are skipped during access to external Data Memory). PSEN is not activated when the device is executing out the internal program memory.
EA/VPP:
When EA is held high, the CPU executes out of external program memory. Holding EA low forces the CPU to execute out of external memory regardless of the program counter value.
XTAL1: Input to the inventing oscillator amplifier.
XTAL2: Output from the inverting oscillator.
PORT 0: Port is an 8 bit drawn bi – directional port. As open drawn output port, it can sink eight LS TTL loads. Port ) pins that have 1s written to them float and in that state will function as high impedance inputs. Ports 0 is also the multiplexed lower – order and data bus during access program and data memory.
PORT 1: Port 1 is also 8 bit bi – directional I/O port with internal pull – ups. The port 1 output buffers can drive TTL inputs. Port 1 pins that have 1s written to them are pulled high by the internal pull – ups, and in that state can be used as inputs, ports 1 pins that are externally being pulled low will source current because of the internal pull – ups.
PORT 2: Port 2 is an 8 bit bi – directional I/O port with pull – ups. Port 2 emits the high order address byte during accesses to external memory that use 16 bit addresses.
PORT 3: Port 3 is an 8 bit bi – directional I/O port with internal pull ups.
VCC: Supply voltage.
VSS: Circuit grounded potential.
LATCHES
In this project the work of 74ALS573 is working as a master for chip selection its input is come from microcontroller and its output is used for chip selection its output is active low so as a low signal is applied on the pin1 of 74ALS573 latches it activated and get start working. When a pin 1 value is high then first 74ALS573 is disabled and other is enabled. Here D0, D1, D2, D3, D4, D5, D6 and D7 are the inputs of the 74ALS573 while Q0, Q1, Q2, Q3, Q4, Q5, Q6 and Q7 are its output. It should not be ON at every time. The 74ALS573 line Latches is a high performance memory decoding or data-routing IC that requires a very short propagation delay times. The 74ALS573 latches one of the seven lines depending on the conditions at the OE pin (output Enable).
LED dot matrix display
In a dot matrix display, multiple LEDs are wired together in rows and columns. This is done to minimize the number of pins required to drive them. For example, a 8×8 matrix of LEDs (shown below) would need 64 I/O pins, one for each LED pixel. By wiring all the anodes together in rows (R1 through R8), and cathodes in columns (C1 through C8), the required number of I/O pins is reduced to 16. Each LED is addressed by its row and column number. In the figure below, if R4 is pulled high and C3 is pulled low, the LED in fourth row and third column will be turned on. Characters can be displayed by fast scanning of either rows or columns.
Structure of a 8x8 LED dot matrix
The LED matrix used in this experiment is of size 5×7. We will learn how to display still characters in a standard 5×7 pixel format. The figure below shows which LEDs are to be turned on to display the English alphabet ‘A’. The 7 rows and 5 columns are controlled through the microcontroller pins. Now, let’s see in detail how it works. Suppose, we want to display the alphabet A. We will first select the column C1 (which means C1 is pulled low in this case), and deselect other columns by blocking their ground paths (one way of doing that is by pulling C2 through C5 pins to logic high). Now, the first column is active, and you need to turn on the LEDs in the rows R2 through R7 of this column, which can be done by applying forward bias voltages to these rows. Next, select the column C2 (and deselect all other columns), and apply forward bias to R1 and R5, and so on. Therefore, by scanning across the column quickly (> 100 times per second), and turning on the respective LEDs in each row of that column, the persistence of vision comes in to play, and we perceive the display image as still.
A standard 5x7 LED dot matrix display structure
The table below gives the logic levels to be applied to R1 through R7 for each of the columns in order to display the alphabet ‘A’.
Row values of each column for displaying the alphabet A
CONSTRUCTION AND OPERATION
Circuit Diagram of Electronics Sign Post
Power supply circuit diagram
CONSTRUCTION
The construction of the moving message display system was done in such a way that connections followed the circuit diagram. The LEDs were connected anode to anode and cathode to cathode in a 8 by 8 format so that the system can display 5 characters at a time, each comprising of 8 by 8 LEDs. Thus each letter is typified with 8 LEDs on the vertical axis and 8 LEDs on the horizontal axis. The connection of LEDs is interfaced with the micro controller and five line latches which control the display and movement of messages. The system’s internal circuit is connected in such a way that every unit except the transformer is mounted on the same circuit board. This was done to minimize the weight of the message display system. The casing is 12inches by 2 ft. and a total number of 320 LEDs were used in order to display five letters at a time. A reddish translucent glass was used in order to make the display visible.
List of components part |
RESISTOR |
CAPACITORS |
DOIDES |
TRANSISTORS |
TRANSFORMER |
SWITCH |
LEDs |
CRYSTAL OSCILLATOR |
REGULATOR |
DIODES
Diode is a non-linear semiconductor device that allows flow of current in one direction. A Diode is a two – terminal device and the two terminals are Anode and Cathode respectively. The following is the symbol of a Diode.
There are again a variety of components that come under the category of Diodes. They are PN Junction Diode, Light Emitting Diode (LED), Zener Diode, Schottky Diode, Photodiode and DIAC. Normal PN Diodes are often used in AC to DC Converter circuits. You might be familiar with LED or a Light Emitting Diode. It is a semiconductor device (or a PN Junction diode, to be more specific) that emits light when activated. A Zener Diode allows flow of current in both directions and is often used as a voltage stabilizer. Schottky Diode is similar to a regular PN Diode but with less forward current and hence is often used in fast switching circuits.
RESISTORS
A resistor is a two terminal electronic component that produces a voltage across its terminals that is proportional to the electric current passing through it in accordance to ohms law.
TRANSISTOR
This is a semi – conductor device commonly used to accomplish or switch electronic signals. A voltage or current applied to one pair of the transistor’s terminals changes the current following through another pair of terminals changes the current following through another pair of terminal. The transistor provides an amplification of signal.
LIGHT EMITTING DIODES (LEDs)
LEDs from the numbers on digital clock transmission from remote controls, light up watches, etc. They are tiny bulbs, but unlike ordinary incandescent bulb, they don’t filament that will burn off and they don’t get hot. They are illuminated solely by the movement of electron in a semi – conductor material and they last just as long as a standard transistor.
LINE LATCHES
Latches are collection of logical gates, which are arranged in a specific way so as to break down any combination of inputs to a set of terms that are all set to 0 apart from 1 term.
MICRO-CONTROLLER
This is a single programmable chip that is designed to control circuits that are interfaced with it. They usually consist of ports and other activation pins having specific functions. There are of various families including the 8086, 8088, 8951 series.
CAPACITOR
(Originally known as a condenser) is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The non-conducting dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, vacuums, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.
CRYSTAL OSCILATOR
is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency.[1][2][3] This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators,[1] but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.
Lm7805 Regulator
Power supply IC 7805
The KA78XX/KA78XXA series of three-terminal positive regulator are available in the TO-220/D-PAK package and with several fixed output voltages, making them useful in a wide range of applications. In the name of this IC the last two numbers indicate the regulated voltage which will be the output of this IC i.e. 7805 indicate that the regulated voltage in the output if this is 5 volts. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 1A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents.
Features
• Output Current up to 1A
• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V
• Thermal Overload Protection
• Short Circuit Protection
• Output Transistor Safe Operating Area Protection
Transformers
A transformer uses the principles of electromagnetism to change one A.C. voltage level to another. Faraday's work in the 19th century showed that a changing current in a conductor (e.g. a transformer primary winding) sets up a changing magnetic field around the conductor. If another conductor (secondary winding) is placed within this changing magnetic field a voltage will be induced into that winding.
Basic Transformer Operation.
Transformation Ratio.
Basic Transformer operation can be described by two formulae relating the transformation ratio to the turns ratio of the transformer windings.
· VP = the primary voltage.
· IP = the primary current.
· VS = the secondary voltage.
· IS = the secondary current.
· NP = the number of turns in the primary winding.
· NS = the number of turns in the secondary winding.
Volts per Turn.
A transformer with a primary winding of 1000 turns and a secondary winding of 100 turns has a turn’s ratio of 1000:100 or 10:1. Therefore 100 volts applied to the primary will produce a secondary voltage of 10 volts. Another way to consider transformer voltages is by volts/turn; if the 100 volts applied to the 1000 turn primary produces 100/1000 = 0.1 volts per turn, then each single turn on the 100 turn secondary winding will produce 0.1V so the total secondary voltage will be 100 × 0.1V = 10V. The same method can be used to find the values of voltage appearing across individual tapping’s of an autotransformer when the number of turns per tapping is known. Simply divide the total voltage across the whole winding by the total number of turns, and multiply this result by the number of turns in the particular tapping.
SWITCHES
A switch is an electrical device which is employed to interrupt the circuit, interrupting the current and to provide the current from one conductor to a different conductor. The switch works with ON and OFF mechanism. Switches are classified into four varieties like (SPST) single pole single throw, (SPDT) single pole double throw, (DPST) double pole single throw and (DPDT)double pole double throw.
When the lever is pushed upward, a conductive bridge is made between contacts a and b. When the lever is pushed downward, the conductive bridge is relocated to a position where current can flow between contact a and c.
SYSTEM SOFTWARE
Micro- controllers Program In this project, the program used is assembly language. Assembly language is a low key programming language that makes use of mnemonics or symbols to program the computer. This makes the assembly language user-friendly, since it is easier for a user to remember programming symbols which are far easier than complex machine codes. However, it employs a utility program that translates its symbols into a form that is readable by the computer’s machine. The assembly language is usually employed in the programming of computers, microprocessors, microcontrollers and even integrated circuits. They implement a symbolic representation of the numeric machine codes and other constants needed to program a particular CPU architecture. The utility program called the assembler is used translate assembly language into the target computer machine code. In this project however, the assembler used is the A51 Macro Assembler.
A51 MACRO ASSEMBLER
The A51 assembler is an Intel ASM51-compatible macro assembler for the 8051 family of microcontrollers. The A51 assembler translates symbolic assembly language mnemonics into reloadable object code where utmost speed, small code size, and hardware control are critical. The macro facility speeds development and conserves maintenance time, because common sequences need be developed only once. The assembler supports symbolic access to all features of the 8051 and is configurable for each 8051 derivative. The A51 assembler translates an assembler source file into a reloadable object module. If the DEBUG control is used, or if the “Include debugging information” option is checked, this object file will contain full symbolic information for debugging with the WinSim-51 debugger/simulator or an in-circuit emulator. The A51 assembler generates a list file, optionally with symbol table and cross references. The A51 assembler is fully compatible with Intel ASM51 assembly programs.
Assembling with A51
This chapter explains how to use the A51 assembler to assemble 8051 assembly source files and discusses the assembler controls that you may specify on the command line and within the source file. Using the controls described in this chapter, you can specify which operations are performed by A51. For example, you may direct the A51 assembler to: generate a listing file, produce cross reference information, and control the amount of information included in the object file. You may also conditionally assemble sections of code using the conditional assembly controls.
Running the Assembler
First the ASSEMBLER is invoked by selecting TRANSLATE, MAKE, or BUILD ALL from the Project menu in preview. The TRANSLATE command will assemble only the source file that is selected in the project window. The MAKE command will compile and link all changed files in the project. The BUILD ALL command will compile, assemble and link all of the files in the project. To invoke the Assembler, you enter A51 at the DOS prompt. The command line must contain the name of the 8051 assembly source file to be assembled as well as any required command-line controls. The format for the A51 assembler command line is: A51 source file controls… where source file is the name of the source program you want to assemble. The A51 assembler controls are used to direct the operation of the assembler. Refer to the “Assembler Controls” section later in this chapter for more information.
OPERATION
When the system is powered on, the powered supply unit provides the voltage (5V) necessary to power the micro controller, the LEDs and other circuit element. The micro – controller receives 5V from pin 1 with pin 20 grounded, begins to execute program from its internal memory. As a result of this, data signals are sent from the micro-controller port 2 to the input pins of the eight line latches and clock signals are sent to their clock input pin from port 3 of the micro-controller. At the same time, base biased signals are sent to the bases of the transistors from the micro-controller’s port 1. Immediately the line latches receives the clock signals from micro-controller, the latches transfers their data to other output pins, which are connected to the cathode of the LEDs. Also when the transistors receive their base bias currents from the micro controller they switch power to the LEDs, since they are wired to the anode of the LED array. At this time, LED will only grow if its anode is positive with respect to the cathode. Thus, by controlling the system sent to the decoders and transistors, the micro – controller controls LED which needs to be on/off for the device to achieve the display.
SYSTEM INTEGRATION
Usually before a system is developed, other subsystems are brought together in such a way as to achieve a singular purpose. In this piece of work, the case is not different. Subsystems were designed and integrated to each other. The hardware and the software are interwoven to realize a desired result. They must be compatible for there to be a smooth protocol or receiving and processing of the information.
TEST PLAN
To verify the functionality of various subsystems, a test plan is adopted. Here, we are using a module by module testing plan. This is necessary to ensure the smooth operation of the project work. The plan helps to detect any abnormality should there be any malfunctioning.
MODULE BY MODULE TESTING
POWER UNIT TESTING: This unit comprises the transformer, bridge rectifier, filtering capacitor and a voltage regulator. All electronic gadgets use a DC voltage source. In this work, TTL (Transistor Transistor Logic) was used, hence the need to use 5Volt source. The regulator 7805 stabilizes the DC voltage to +5V. At the end of the construction, the test was ok. This unit is very vital in any electronic circuit in that it supplies the required energy to each module.
MULTIPLEXERS AND LINE LATCHES: It operates on a principle of causing the output that corresponds to the binary input to go LOW. At each binary input, the output pins respond only if the enable pins are activated. Therefore its operation is dependent on the activation pins and the supply of the binary codes at the input pins.
PROCESSING UNIT TEST: This is tested based on its connection to other subsystems. It is the unit that establishes control over all other subsystems. The test has to include the software programs written to drive the hardware. More still, simulation software could be used to debug the program to verify its workability and compatibility to other modules.
CONTROL SYSTEM TESTING: The control is provided by a microcontroller based on the software program burned into it. It is expected to switch each lamp at appropriate time and also switch them OFF when it is desired. After the design, the software drives the hardware as expected and is working quite well.
USER MANUAL AND PRECAUTION
It is expected that the user must have read this manual before operating this system. Operation procedure:
1. Connect the mains plug to the mains.
2. Switch ON the system
3. Do not open the casing to avoid electric shock. For services, take to a registered service personnel.
4. Switch OFF the system when it is not in use.
RECOMMENDATION AND CONCLUSION
PROBLEMS ENCOUNTERED
In the course of carrying out this project, several problems were encountered First, sourcing for materials was pretty difficult as most of the circuit elements could not be found in neighboring markets. Traveling out town to get them was the only solution. Second, during the course of building, some components got damaged. Such damage could be allotted to over-heating during soldering, careless handling, environmental distortions and even incompetence of manufacturing. Third, due to wrong connection on one occasion, a fault arose, leading to the demand for trouble shooting which was time consuming and stressful. Fourth, due to my non conversance with this project, a lot of errors where registered in programming which had to be debugged for the program to run accurately.
RECOMMENDATIONS
The design of a micro-controller based electronics sign post system has characters showing five pages at a time. There is a great need for future design and implementations to cater for animations and symbols. Again, plasma display panels may be used in place of light emitting diodes to accommodate certain areas of our economy that may require large display board for advertisement. There is significant need for future design to include a universal serial bus of a serial interface that was used for the same purpose.
CONCLUSION
The digital electronic message display system has been modernized with sophisticated electronic devices, which center on the urgent needs in our advertising industry. They provide various applications in different aspects of our economy such as banks, airports, restaurants, superstores, institutions, entertainment, stock exchange market and directional venue guides. The light emitting diodes which constitute of the hardware system is mainly used to display alphanumeric characters and symbols in various systems such as digital clocks, microwave ovens, stereo tuners and calculators. The design of moving massage display systems have a single micro- controller chip which provides 8 kilobytes of flash, 256 of ram, 31 input/output lines, three 16 bit timer counters, six vector two-level interrupt architecture, full duplex serial port, on chip oscillator and clock that provides the necessary control and flexibility of display.
Below is the Video
Download Complete File both Circuit and Assembly Language Code Here
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