1、英文原文 Types of LCD Products - Glass or Modules The most fundamental decision to make is whether the display will have the drive circuitry attached (module), or not (glass only). There are advantages and disadvantages to each approach. When purchasing a Custom LCD Module, the basic electronic design w
2、ork will be done by the manufacturer. This obviously saves design time and reduces the manpower needed to bring a product to market. You can benefit from the experience we have gained during our previous designs to shorten the design cycle and deliver an optimized product. The major decisions you ne
3、ed to make are the interface type, with standard serial or parallel interfaces being the most common, and the type of integrated backlighting desired. The temperature range, viewing angle, viewing mode, and contrast will need to be considered, but those decisions are common to both approaches. A gla
4、ss only design puts the design burden on the end user. You will need to learn a great deal about LCDs in order to complete your design. Luckily, our website provides Application Information and Web Links to assist you in the search for the information you may need. The main reasons to buy just the L
5、CD glass are to reduce costs, and provide design flexibility. The total cost of the components necessary to build the drive circuitry is typically less than the cost of a pre-built module, and as long as you have space on your existing PC board, you wont have to pay for an extra PC board on which to
6、 mount the display, and have access to cost effective assembly and test. By doing a little homework, your design will work just as well as a module, and will allow the flexibility most designers need to adapt their design to ever changing demands. Types of LCD Images The LCD can contain character ic
7、ons, segments, graphic dot arrays, or any combination. Icons: By making a custom LCD, you can place images on the glass that specifically complement your produce, these are called Icons. These silhouettes can take the shape of any image you may need and count as one pixel or dot on the LCD. Segments
8、: Segments on an LCD display make up a larger character, such as a segment in a seven segment numeric character (displays 0-9), or a segment in a 14 segment alpha-numeric character (displays 0-9 & A-Z). Dot Arrays: These dot arrays can be made in almost any size and dot count. Examples would be char
9、acter displays that use a series of 5x7 dot arrays to create a string of alphanumeric characters, or the larger 320 x 240 graphic arrays that make images along with variable size alpha-numeric characters. Types of Liquid and Technology The type of technology used is determined by the specific perfor
10、mance requirements you set for the display that you are designing. Since several variations will do a fine job, the ultimate consideration is cost. So here is a quick breakdown of the technologies we offer. TN: Low production and NRE costs, poor viewing angle, average contrast. Coloration: Black on
11、Gray. Static preferred, but operates well up to a 32:1 Multiplex rate. LCD Glass favorite. STN: Medium production and NRE costs, average viewing angle, average contrast. Coloration Black on Green, or Dark Blue on Gray. Works well at high Multiplex rates. LCD Module favorite,high end LCD glass choice
12、. FSTN: Medium high production and NRE costs. Good viewing angle, excellent contrast. Coloration Black on White. Works well at high Multiplex rates. Higher end LCD Module favorite. Negative Image: This is an effect that reverses the image on the display and is only offered with transmissive displays
13、. The visual effect is to allow the backlight to define the pixels turned on (transparent), while the off pixels remain opaque. This configuration works best in moderate to low light conditions. Viewing Mode and Polarizers The viewing mode is controlled by the rear polarizer, and how much it does or
14、 does not reflect light. We offer three modes. Reflective: This type of polarizer gives the display the brightest appearance in high to moderate ambient light conditions, with the highest contrast ratio possible. Unfortunately, it will be difficult to read at night or under changing lightning condit
15、ions (think Game Boy). Transflective: (Favorite solution) If your display must be readable under a wide range of lighting conditions, you will generally want a transflective display so that it will look very good in the bright sunlight, but will also be back-lightable at twilight and at night. The t
16、radeoff with a transflective display is that it will not look as good as a reflective display during the day, and it will not look as good as a transmissive display at night. It will however enable you to have an acceptable compromise between the two, and provides a very acceptable appearance. Trans
17、missive: This display needs to have a working backlight, unless it gets its light from being a window type of device where the area behind the LCD has a light source room ambient light. Where it is in a contained display, the backlight may have a problem overpowering high ambient light. This type of
18、 display looks great for an indoor application, but is not very good in applications where power consumption is a problem and it needs a strong backlight. Remember, this choice of polarizer will not operate unless there is an active backlight. The polarizers are also affected by temperature, and a q
19、uality grade must be specified when choosing a polarizer. After you have determined your environmental temperature requirements, you then need to choose the polarizer grade. Here are your typical choices. Commercial Grade Polarizers: Displays which will be indoors, or mostly indoors, can use commerc
20、ial grade polarizers. These polarizers will hold up very well when used in most instrumentation, office and home products, and other applications where the products will be protected from high temperature, sunlight, and humidity. Industrial Grade Polarizers: For harsh environments, a polarizer speci
21、fically designed for outdoor, extremely humid conditions should be used. We call these polarizers industrial grade. Viewing Direction The viewing direction of a LCD part is defined as the angles above, below, left, and right of the point-of-view that is perpendicular to the center of the display. 6:
22、00 viewing direction has optimum contrast from below the perpendicular viewing plane (most popular). 12:00 viewing direction has optimum contrast from above the perpendicular viewing plane. 9:00 viewing direction has optimum contrast to the left side of the perpendicular viewing plane (uncommon). 3:
23、00 viewing direction has optimum contrast to right side of the perpendicular viewing plane (uncommon). Please keep in mind that viewing direction is less important for a direct drive display. As a general rule, the higher the multiplex rate, the more important the viewing direction becomes. Also, if
24、 your display is going to be viewed by a person wearing polarized sunglasses, you must specify this in the comment section to ensure that the display will not look blank to an observer wearing polarized sunglasses. However keep in mind that for quoting purposes, the price of the display will not cha
25、nge much (usually only a few cents) if you change your mind for the final viewing direction of the display. Environmental Considerations - Temperature Range The operating and storage temperature range of an LCD are important considerations, since operating outside of those ranges will result in a di
26、splay that is not readable (outside operational range) or permanently damage the LCD (outside storage range). The combination of the LCD fluid, polarizers, operational voltage, and multiplex rate determine the temperature range of the part. So instead of going through the different combinations of t
27、hese parameters, here are some general guidelines you can use when specifying the temperature range of your LCD, and manufacturer can then assist you in the process of selecting the correct fluid, polarizers, and voltage for your application. These values are typical operating temperature ranges. LC
28、D TN Glass / Static or Low Multiplex Rates: Standard Temp Range: -10C to +60C, Wide Temp Range: -40C to +80C, Specialized Temp range: down to -55C, or up to +110C LCD TN Modules / Multiplexed: Standard Temp Range: -0C to +50C, Wide Temp Range: -20C to +70C, Specialized Temp range: -40C to +90C LCD S
29、TN & FSTN Modules / Multiplexed: Standard Temp Range: 0C to +50C, Wide Temp Range: -20C to +70C, Specialized Temp range: -40C to +80C Another note to remember is the LCD Glass and Polarizers are not the only limiting factors in the temperature range of the LCDs. You also need to take into consideration the temperature limitations of the backlight and controller ICs that may be present along with the LCD.
