Operating A Laser From Photocopier

[iceblu3710]

I took apart a photocopier and found a wonderful laser unit inside with collimating lenses and a 90deg mirror. This unit is begging to be turned into a little paper cutting or rastering laser but I have no idea how to interface with it.

The main drive IC is a custom job so I can not find any info on it. (Toshiba Louisiana 413A1) You can see the laser connected right above the IC with its POS, NEG and what I would assume is the PWM input from the IC. The brown box is a pot.

One thing of concern is lasers should be driven via a constant current source but this appears to be directly coupled to the power rails via a simple rheostat The negative leg of the laser diode does seem to go into the IC but without a datasheet I don't know where to start.

Anybody know how to go about using this unit?

 

[kak111]

Try to find schematics and service manual
for that photocopier.

There are shown , how the boards are connected.
And maybe more technical info for parts

KAK

 

[iceblu3710]

I have been looking for a service manual but everywhere I go all the websites want money for it. If you know where their is a copy for the Toshiba eStudio 3511 for free please let me know!

 

[betwixt]

Try looking for the data sheet for the IC, it might give clues as to the schematic and therefore how it operates. It is probably a Toshiba TA6020FN as marked on the PCB. In this kind of application it's likely the IC is designed to work in a very specific way and with spcified components around it so a data sheet may well give you full information on how to interface to the whole PCB.

Brian.

 

[FvM]

I'm not sure if a photocopier laser will actually cut paper. I know, that some DVD writer lasers can. To understand the laser diode operation requirements, you should also try to indentify the laser diode type. You can be sure that it's equipped with a monitor diode which is needed for the driver circuit to set the laser output power within the allowed range. If you know the specification, you can connect the diode to a different driver.

 

[iceblu3710]

@betwixt: Google shows no results for a TA6020FN and when searching for TA6020 I get hundreds of shitty chinese IC fishing websites and irrelevant things like wallets and forklifts.

@FvM: The laser diode is pressed and glued into a heat sink so I have no idea who manufactures it. I might end up just getting a 1W diode off eBay and a driver IC but I was hoping to at least play around with this one. Maybe I will hijack the diode and run it untill death...

 

[iceblu3710]

Well I got the laser diode removed from the housing but its markings are useless.

Laser Diode:
4BQA
0050

So not really ahead any. I have no idea the power of a standard laser printers laser but I would say its pretty low...

 

[betwixt]

The power would be very low, probably no more than one or two millwatts. In the printer all it has to do is project the image on to the toner drum and given that it's sharply focussed the power per area only has to be very small.

In general you will find they have 3 pins, one is usually bonded to the base and will be the common negative (ground) side, one will be the laser diode anode (+) side and the other will be the photo-sensor anode side. The 'lasing' will only happen over a very limited current range and exceeding the current will immediately fry the diode. The control IC will use the sensor output to regulate the laser diode current to keep it within range, regulate the light output by adjusting the current and of course provides the on/off control for actually projecting the raster on the drum. As far as I know, the laser power is not adjusted to produce gray levels, that is achieved by dithering the pixels.

Brian.