Author Topic: Help,Can ordinary LEDs replace thin-film LEDs?  (Read 2073 times)

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Offline daisizhouTopic starter

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Help,Can ordinary LEDs replace thin-film LEDs?
« on: August 17, 2024, 03:45:43 am »
This is a ventilator.It is no longer used on patients.I usually use it to learn and practice the operation of the ventilator.

Due to the long time,Aging of the digital luminous film of the main display.I unpacked it,Found that there are 5 HV6506PJ drivers,
I guess 4 HV6506PJs should be used for the step display, and 1 HV6506PJ should be used for the 2 8-bit digital tubes in the center.
https://www.scribd.com/document/249426163/Manual-e100m-Serman-Rev-d-2202
104 pages


I hope to fix it cheaply.The original factory has stopped after-sales maintenance.
My plan is to use ordinary LEDs (chips) to replace each film, then make a PCB, install the LEDs on the PCB, and use them to replace the original display. The center will use the most easily available 8-bit digital tube to replace the original display.

I don't know if my idea is feasible.
If you have a better idea, I look forward to your help, thank you
« Last Edit: August 17, 2024, 07:57:13 am by daisizhou »
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Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #1 on: August 17, 2024, 08:13:07 am »
I don't know if this connection is possible, it looks like HVout and BPout are high voltages, I don't know if it's possible to connect a light-emitting LED here
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Offline MathWizard

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #2 on: August 17, 2024, 06:34:09 pm »
IDK the circuit, but for the chip it says it's 'a low-voltage serial to high-voltage parallel converter'. The output voltage is upto 80V in this datasheet. Yeah so that be a huge amount to drop just with resistors to some single LED. IDK about chip LED's or how many LED's could be put in series. If the HV was only 15V, then you could probably use some logic IC like a level-shifter to get back to the 5 or 12V you might have wanted to use for regular LED's.  Any idea if the chip's have a problem?

IDK about digital luminous film, what about getting more of that?
« Last Edit: August 17, 2024, 06:37:28 pm by MathWizard »
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #3 on: August 17, 2024, 10:26:15 pm »
IDK the circuit, but for the chip it says it's 'a low-voltage serial to high-voltage parallel converter'. The output voltage is upto 80V in this datasheet. Yeah so that be a huge amount to drop just with resistors to some single LED. IDK about chip LED's or how many LED's could be put in series. If the HV was only 15V, then you could probably use some logic IC like a level-shifter to get back to the 5 or 12V you might have wanted to use for regular LED's.  Any idea if the chip's have a problem?

IDK about digital luminous film, what about getting more of that?

This is the first time I have come across this type of display.It looks like a monochrome LCD screen, but on top of a plastic film.
In the picture below, you can vaguely see that only part of the LCD display is normal.This means the chip is functioning normally.
There is a 3-core flat wire in the lower right corner. I guess it may be connected to high voltage, similar to the backlight.
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Offline oPossum

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #4 on: August 17, 2024, 11:27:48 pm »
May be an EL display

https://en.wikipedia.org/wiki/Electroluminescent_display

Check the high voltage power supply. Should be about 100 volts. The display itself may be in serviceable condition.
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #5 on: August 17, 2024, 11:51:58 pm »
May be an EL display

https://en.wikipedia.org/wiki/Electroluminescent_display

Check the high voltage power supply. Should be about 100 volts. The display itself may be in serviceable condition.

It seems that the LCD display is almost incomplete.
Do you mean only repairing the high-voltage backlight power supply part?
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Offline oPossum

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #6 on: August 17, 2024, 11:57:03 pm »
I think the entire display is EL. Not an EL backlight behind a LCD. The high voltage drivers would not be needed for a LCD, but are needed and often used with EL displays.
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #7 on: August 18, 2024, 12:14:52 am »
Ok, if it's an EL display, can I change it to LED or other easier to implement methods?
Due to their age, many plastic films or coatings have aged or been damaged, resulting in incomplete displays
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Online Haenk

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #8 on: August 18, 2024, 08:33:37 am »
Ok, if it's an EL display, can I change it to LED or other easier to implement methods?
Due to their age, many plastic films or coatings have aged or been damaged, resulting in incomplete displays

"easier" seems impossible - you would need to a) create a whole new segmented display and b) maybe create a new driver circuit.
If you really need to have this running again, ignore the round segments and just create something for the 7-segments. Maybe use a LCD, and keep the original driver chip, just dropping the voltage might work (due to the little current required by LCD).

I assume this was a custom EL display, money obviously didn't matter. And the EL foils do fail, a lot. However, if all segments do no not work anymore, it might be the power supply after all - did you peek around checking voltages?
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #9 on: August 18, 2024, 08:57:01 am »
My initial plan was to replace each LCD progress bar with a glowing LED as shown in the following picture,The middle two use ready-made 8-bit digital display tubes.Now it seems that my plan will fail because EL's electrical performance is almost completely different from LED's.

I didn't check the high voltage part because the wiring connecting the high voltage has cracked and some conductive layers have started to peel off
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Offline Phil1977

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #10 on: August 18, 2024, 10:08:59 am »
Do you really want to solder and place over 140 LEDs there?

If yes, I´d try to find out if you can modify the supply voltages of the high voltage driver ICs to LED compatible levels.
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #11 on: August 18, 2024, 10:14:23 am »
If placing LEDs is feasible I will proceed with the plan.
I don't know if the electrical performance of EL is compatible if I change it to LED, because I am not familiar with EL components.

www.scribd.com/document/249426163/Manual-e100m-Serman-Rev-d-2202
Page 104 has the schematic diagram of the display part

thanks
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Offline Phil1977

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #12 on: August 18, 2024, 10:23:45 am »
I can't download the manual (registration required) but as I had a quick look over the datasheet pages, I wonder if it´s possible to reduce "V_pp" to let´s say 5V and connect LEDs to the outputs.

The max current of 0.5mA is not very much, but may be sufficient for a bright display. You could test it with a few wired LEDs that get patched to the headers.
 

Offline squadchannel

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #13 on: August 18, 2024, 10:34:10 am »
Schematic downloaded. Attached.
2343323-0

2343327-1

2343331-2

2343349-3

2343361-4

2343365-5

 :-+
« Last Edit: August 18, 2024, 10:44:58 am by squadchannel »
 

Offline squadchannel

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #14 on: August 18, 2024, 10:46:49 am »
with...
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #15 on: August 18, 2024, 10:52:36 am »
I can't download the manual (registration required) but as I had a quick look over the datasheet pages, I wonder if it´s possible to reduce "V_pp" to let´s say 5V and connect LEDs to the outputs.

The max current of 0.5mA is not very much, but may be sufficient for a bright display. You could test it with a few wired LEDs that get patched to the headers.

Do you want me to connect and test as shown below?
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Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #16 on: August 18, 2024, 10:53:29 am »
I appreciate your help, thanks :-+
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Offline Phil1977

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #17 on: August 18, 2024, 10:56:23 am »
I you could lift up pin 7 of IC U7, then you would disable the step-up-converter of the EL-driver and the output voltage VD should be slightly below 5V.

The EL-driver-ICs supply AC to the segments, but it seems it´s just the VD-voltage switched on/off. I can't see any reason this would harm the LEDs.

Does anyone see a reason not to try it? I hope the OP is aware that placing and routing >140LEDs according to a given schematics is quite a lot of work  :-\

Quote

Do you want me to connect and test as shown below?

No, don't connect the LED directly to the VD-supply of the device. I´d reduce the VD from 50V to 5V and then connect a few test LEDs to the outputs of the driver IC instead of the EL-display.

Sorry some edit was flawed. Now quotes and content should be okay again.
« Last Edit: August 18, 2024, 11:01:44 am by Phil1977 »
 

Offline squadchannel

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #18 on: August 18, 2024, 11:02:44 am »
I think everyone is mistaken.
From the video of it working below, I believe it is an LCD.


And HV6506PJ is an LCD driver.
I think it needs to be replaced by a shift register with a 32-pin output.
 
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Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #19 on: August 18, 2024, 11:07:59 am »
I you could lift up pin 7 of IC U7, then you would disable the step-up-converter of the EL-driver and the output voltage VD should be slightly below 5V.

The EL-driver-ICs supply AC to the segments, but it seems it´s just the VD-voltage switched on/off. I can't see any reason this would harm the LEDs.

Does anyone see a reason not to try it? I hope the OP is aware that placing and routing >140LEDs according to a given schematics is quite a lot of work  :-\

Quote

If you need a test I can do it.
140 LEDs using SMD 0603 packaged LEDs may be feasible,But the premise is that such a plan is feasible

Do you want me to connect and test as shown below?

No, don't connect the LED directly to the VD-supply of the device. I´d reduce the VD from 50V to 5V and then connect a few test LEDs to the outputs of the driver IC instead of the EL-display.

Sorry some edit was flawed. Now quotes and content should be okay again.
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Offline squadchannel

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #20 on: August 18, 2024, 11:09:57 am »
The datasheet for the HV6506PJ lists the high voltage supply current as 0.5 mA, which would be difficult to drive LEDs.
 

Offline Phil1977

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #21 on: August 18, 2024, 11:18:06 am »
0.5mA can be sufficient for non-multiplexed an efficient LEDs.

But you should definitely first clarify if it´s a LC- or EL-Display. If it´s LCD then current will be far too low.
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #22 on: August 18, 2024, 11:28:37 am »
0.5mA can be sufficient for non-multiplexed an efficient LEDs.

But you should definitely first clarify if it´s a LC- or EL-Display. If it´s LCD then current will be far too low.

It looks like an LCD display.I usually see glass LCD,This is the first time I have seen this kind of soft plastic film.
Due to the long time of use, the display effect is very bad.
Is there a better and more feasible upgrade solution?
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Offline squadchannel

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #23 on: August 18, 2024, 11:36:51 am »
It would be possible to make a custom board that would allow LEDs to be mounted to replace the LCD.
Can be connected with FFC cable.
VD power supply should be low voltage.

or can make a cheap FPC board with JLC.
 

Offline daisizhouTopic starter

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Re: Help,Can ordinary LEDs replace thin-film LEDs?
« Reply #24 on: August 18, 2024, 12:08:55 pm »
It would be possible to make a custom board that would allow LEDs to be mounted to replace the LCD.
Can be connected with FFC cable.
VD power supply should be low voltage.

or can make a cheap FPC board with JLC.
But I don't know how to connect the LED to HV6506PJ, because HV6506PJ was originally connected to the LCD.
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