HP-48 LCD
Photos by Marcos Navarro.
Can be used under the CC BY-SA 4.0 license.
Embedded Files
Area 1, Front Panel
Area 1, Front Panel
Here you can see parte of the front panel of the HP48 LCD.
At the right you can see the areas connected to the zebra rubber connector that connect the lcd to lines on the hp48 board. Some of those line goes to the CPU and some other go to the columns driver chips. There are two columns driver chips in the hp48.
Area 1, Back Panel
Area 1, Back Panel
Area 2, Front Panel
Area 2, Front Panel
Area 2, Back Panel
Area 2, Back Panel
Here you can see part of the back panel of the HP48 LCD.
This panel is not connected directly to the board, but rather receives signals from the front panel, to which it is connected through four groups of jumpers located in the corners of both panels. You can see some of these jumpers in the lower left part of this photo
Area 3, Front Panel
Area 3, Front Panel
Area 3, Back Panel
Area 3, Back Panel
(Model A)
(Model A)
Area 3, Back Panel
Area 3, Back Panel
(Model B)
(Model B)
Area 4, Back Panel
Area 4, Back Panel
Between areas 2 and 4, Front Panel
Between areas 2 and 4, Front Panel
Transmiting Anunciator, Front Panel
Transmiting Anunciator, Front Panel
(Model B)
(Model B)
Transmiting Anunciator. Back Panel
Transmiting Anunciator. Back Panel
(Model B)
(Model B)
These circles are the conductors that transmit the signals from the front panel to the back panel.
Here, a closer view
Here we can see part of the perimeter seal. Its function is to prevent the liquid crystal from coming out and keep the two panels glued together.
Here we can see part of the perimeter seal. Its function is to prevent the liquid crystal from coming out and keep the two panels glued together.
Here is a closer view of the perimeter seal.
Here is a closer view of the perimeter seal.
NOTES;
LCD screens consist of, among other things, two glass panels and two light polarizers.
Between the two glass panels there is a very thin layer of a special liquid named liquid crystal, that is sensitive to electric fields.
Lines are drawn on the panels using a almost transparent material. This material is very special, becouse it can conduct electricity.
A pixel of the display is a point where a line on the front panel is overlap to another line in the back panel. These lines never make contact, becouse they are separeted by the liquid crystal, but they look like that when you see the display from the front.
A pixel is activated by applying a electrical potential difference to the two lines passing over and under It. The electric field generated modifies the orientation of the layers of liquid crystal molecules found between the panels, reducing the amount of light that can pass through the polarizers.
This is a fascinating technology!
Thanks for reading.
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Copyright 2024 by Marcos Navarro
Last Update: 09/06/ 2024
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