How to find a tablet LCD suitable for test?

[apadana]

I have a Lenovo Ideapad Miix 310 whose 10.1'' LCD doesn't show anything but the backlight works. When I connect this tablet to an external monitor using HDMI, there is video output. Also, the ribbon cable seems to be healthy. So, I'm going to disconnect the ribbon cable from the internal LCD and temporarily connect it to another LCD to become quite certain if the original LCD is faulty.

But what LCDs can I use for test? Should any LCD that accept the ribbon cable of my tablet work (regardless of the size of the LCD, its part number, etc.)?

As far as I know, in laptops the LCDs are, in some sense, universal. For example, a 40 pin 14'' LCD can be used in many different laptops of different brands.

[mon2]

Re: How to find a tablet LCD suitable for test?

hi. the best suggestion is for you to take some clear pictures of the LCD so that we can review the part number on the display.

In general, you cannot just replace the display with a random choice. Most likely a tablet will be with the MIPI DSI interface. It is yet to be determined on the number of MIPI pairs. The pinout can be also custom to the vendor.

For MIPI DSI interface, small displays (iwatch / ipod) = 1 pair + 1 pair for clock.

As the screens get larger, the resolution increases and ipads for example will use 4 pairs for the data transfer + 1 pair for clock + backlight pins & ground / power.

Do not attempt a different display till you share the pictures of the LCD display with the part number / markings.

[apadana]

Re: How to find a tablet LCD suitable for test?

hi. the best suggestion is for you to take some clear pictures of the LCD so that we can review the part number on the display.

In general, you cannot just replace the display with a random choice. Most likely a tablet will be with the MIPI DSI interface. It is yet to be determined on the number of MIPI pairs. The pinout can be also custom to the vendor.

For MIPI DSI interface, small displays (iwatch / ipod) = 1 pair + 1 pair for clock.

As the screens get larger, the resolution increases and ipads for example will use 4 pairs for the data transfer + 1 pair for clock + backlight pins & ground / power.

Do not attempt a different display till you share the pictures of the LCD display with the part number / markings.

Thanks. It was helpful. The part number appears to be KD101N52 40NI B2. You may find two pictures in the attachments.

[apadana]

Re: How to find a tablet LCD suitable for test?

Does a "pair" here consists of 2 pins? I don't know what you mean by a "pair".

[mon2]

Re: How to find a tablet LCD suitable for test?

Yes. For each signal, there will be a pair (2 wires) to send out the information to the display.

This is due to the very high speed nature of the MIPI display interface. These are very high speed serial communication between the host CPU and the target display and very well could be 50Mhz to 1.2Ghz. Using single ended wiring like 3v3 swing is not suitable here for high speed data transfers.

For this reason, differential (LVDS) signals @ 1v2 or similar low voltage are used to send out the packets to the display. This is common to the MIPI DSI specification. The data lines increase to often 4 pairs = 8 wires to send data to the display + another pair (2 wires again) for the MIPI CLOCK. The receiving display understands MIPI DSI commands to initialize the X * Y screen size, refresh, starting / ending position of the display frame, etc. For this reason, it is important to pair the host CPU with the original or fully compatible MIPI DISPLAY.

I think you will be stuck (like most tablets) to source a valid compatible WITH the digitizer. The digitizer is the clear overlay that is glued ontop of the LCD display and will be the capacitive touch style. When you press on the touch panel, the X & Y locations will be sampled and returned to a touch sensor to alert the CPU of the position. Cheaper tablets use a resistive touch panel but very confident yours will be capacitive touch style.

Found many of the MIIX 310 displays + touch panel in a full replacement on Aliexpress. Just pick a good company you can work with and they will back you up.

In the meantime, can you count the number of contacts of the flex LCD cable on your display ? Unable to locate a datasheet for the display so far but it is a shot in the dark.

Some of the pins will be for the backlight. Ground. Power. The rest will be for the MIPI DSI display (likely 8 wires + clock pair = 10 wires) + capacitive touch controller interface - most likely I2C bus interface.