Posts Tagged ‘character LCD’

A short course on LCD controller Drivers

Friday, September 3rd, 2010

Character and Graphic LCD’s are supplied with an on-board Controller Driver. This is sometimes referred to as an IC (integrated circuit).

There are different manufactures of Controller Drivers such as Sitronix, Epson and Sunplus.

The Controller/Driver has three main functions.

1. RAM

  • This is the memory built into the controller driver that helps to drive the LCD.

2. Character Generator

  • This is a library that converts the customer’s data to letters, numbers and Punctuation marks.
  • The character generator is different for each language.
  • The SPLC7066U controller driver can supply up to 240 character fonts.

3. Liquid Crystal Driver

  • This drives each segment (dot)

The Sitronix C/D ST7066U has the ability to drive 640 segments. If you need to drive more than 640 segments, then you will need to add on an additional ‘segment driver’. The Sitronix version of the segment driver is the ST7063C and ST7065.

What is a segment?

A 16×1 character display can display one row of 16 characters. Each one of these ‘16’ characters is made up of ‘dots’ or segments. Each of these characters can be 5×8 (5 dots along the horizontal and 8 dots up and down). There are also characters that have 5×11 dots and 10×10 dots.

Below is a drawing of a 16×1 Character display that has a 5×8 character size.

Character Display

Each of the 5×8 character has 40 dots or segments (5 x 8 =40). Therefore a 16×1 character display has 16 characters with each character having 40 dots. This means that the 16×1 display has (16 [characters] x 40 [dots]) = 640 dots or segments.

One controller driver can handle all the functions of 640 segments. This is equivalent to a 16×1 character display, an 8×2 LCD or 8×1 Character display.

If you need a larger display such as a 16×2 or 20×2 you would add a segment driver such as the ST7063C. There is no need for another controller. Each display only needs one controller but can contain many additional segment drivers.

The segment driver does not have the ability to supply RAM and the character generator. The sole purpose of the segment driver is to drive the segments.

Below is a break down of how many controller drivers and segment drivers are needed for a character display. This is for monochrome LCD modules.

A 16×1 requires one ST7066.
A 16×2 requires one ST7066 and one ST7065 (segment driver)
A 20×2 requires one ST7066 and one ST7063 (segment driver)
A 16×4 requires one ST7066 and two ST7063 and one ST7065
A 20×4 requires one ST7066 and two ST7063’s.
A 40×2 requires one ST7066 and two ST7063’s.
A 40×4 requires one ST7066 and four ST7063’s.

The Focus Display standard offering of Alphanumeric and Numeric LCD Displays includes:
8 x 1 LCD Display, 8 x 2 LCD Display, 16 x 1 LCD Display, 16 x 2 LCD Display, 16 x 4 LCD Display, 20 x 2 LCD Display, 20 x 4 LCD Display, 24 x 2 LCD Display, 40 x 1 LCD Display, 40 x 2 LCD Display, 40 x 4 LCD Display,

Static displays, also called segment LCD or glass liquid crystal displays do not come with an on-board Controller Driver. The customer needs to supply the segment driver on their product.

The Focus Display standard offering of LCD modules includes:
LCD segment display, 7(seven) segment LCD display, 14(fourteen) segment LCD display, and 16 (sixteen) segment LCD displays.

Tags: , , , , , , ,
Posted in Displays | No Comments »

Safety Stock in Inventory

Saturday, July 17th, 2010

Is safety stock back in style?

Many suppliers do not want to carry excess inventory. It was not good business sense to tie up your cash and hope someone will come along and purchase your product. But this is changing.

The style is changing. Why?

  1. Lead times on segment displays, character and alphanumeric LCD’s have increased in the last few months. Customers (OEM’s) need inventory in a week or two, not 12 to 16 weeks after they place their purchase order.
  2. Many LCD suppliers are discontinuing their LCD displays. This is true for 16×1, 16×2, 20×2, 8×1, 8×2, 20×4 LCD displays. We receive calls for CCFL and EL backlights often. There is still a demand for 7 (seven) segment, 14(fourteen) segment, and 16(sixteen) segment static displays. It seems that many suppliers are scaling back on monochrome displays.
  3. Earning interest on cash in the bank is at an all time low.

Please call us if you need a replacement STN, FSTN or TN character LCD.

Tags: , , , , , , , , , , , , , , , , , , , ,
Posted in Displays, Inventory | No Comments »

Everything You Wanted to Know about Custom LCD Design but were Afraid to Ask

Sunday, July 4th, 2010

Well, maybe this is not the best title, but there are a few basics that are good to know before you move ahead on a custom LCD display.  This is true for all static, segment or glass displays such as 7 (seven), 14 (fourteen) and 16 (sixteen) segment displays. This is also true for all Character / numeric LCD modules.

Our goal is to recommend a standard display whenever possible; not a custom Liquid crystal display.  If this will not work, we are able to suggest alternatives.  Sometimes the customer needs a custom LCD with tooling to replace a module that has been discontinued.  Below are a few guidelines.

  1. If the customer pays for the tooling/ engineering (NRE), then the customer owns that LCD display. module In other words we cannot sell that display to any other customer without the permission of that customer.
  2. When the customer has approved the drawing of the display, we will then request samples. As a general rule, when the customer pays for the LCD tooling, we supply 5 samples at no cost.
  3. The cost of freight to bring in the custom lcd module samples is included in the tooling cost. This is for the first shipment only.
  4. The tooling fees for static, glass or segment displays are lower then for a character LCD module (alphanumeric LCD display module).
  5. The use of TN, STN or FSTN does not affect the tooling fee for the custom display, but this will affect the unit cost.

Here is a link showing the process for a custom display.

Tags: , , , ,
Posted in Displays | No Comments »

Changing Market Conditions in China may effect Pricing and Lead Time on LCD Modules

Monday, May 24th, 2010

Does “this quote is valid today only” sound like something you would hear from a salesman at the car dealership?

In the Liquid Crystal Display (LCD display module) industry we have enjoyed the luxury of honoring a customer’s quote for 30 days. In fact, if someone waited 45 days to place the PO, we would still honor the 30-day quote.

The cost of character, static and graphic monochrome LCD’s has not changed that much over the last few years.

This may be changing soon.

Why this drastic change in LCD display module prices? China is looking to increase minimum wage by as much as 20%. (see http://www.reuters.com/article/idUSTOE62F07R20100316).

The main concern I have is that the change in price could come very rapidly and with very little notice. End-users of our LCD modules need to be able to forecast their cost and profits for months in advance.

Could the price of LCD monochrome displays and custom lcd displays change every month or week and by a significant percentage as was the case of gas prices? Do you remember how businesses would charge a “fuel surcharge” onto your shipping cost as gas prices increased?

The impact that this could have is staggering.

Tags: , , , , , , ,
Posted in Displays, Pricing | No Comments »

To Drill or Not to Drill

Thursday, May 13th, 2010

I am not talking about off shore drilling of oil, but the drilling out of the mounting holes on a LCD module.

LCD’s with a PCB (printed circuit board) attached are called a chip on board. They come with two or four mounting holes to attach the LCD display module to the customer’s product. This is true for both a character LCD module and a monochrome Graphics display.

Mounting Holes on PCB

The standard diameter of this hole is 3.5mm. Sometimes a customer needs a larger hole to accommodate a larger screw.

The danger in drilling out the mounting hole to a larger diameter is that you stand a good chance of cutting a trace (see FAQ for trace). When this trace is cut, one of two things can happen.

  1. The connection between one part of the display will be severed from another part of the display. This may cause the backlight or the LCD module to stop functioning.
  2. The trace is now exposed to the environment and will allow moisture and other contaminants to come into contact with the copper. This may allow the display to continue working for some time and then after an extended period of time the LCD display module will fail. Or worse yet, become intermittent.

If you need the mounting holes to be larger, please contact us. We can redesign the PCB to accommodate any size of mounting hole that you require.

LCD display modules with a PCB (printed circuit board) attached are called a chip on board. They come with two or four mounting holes to attach the display to the customer’s product. This is true for both a character LCD module and a Graphic LCD display.

Tags: , , ,
Posted in Displays | No Comments »