How to adjust the density of Kyocera 1635 copier? Thanks! !

1. When the user manually adjusts the copy density, does the machine change the main charge, gate voltage, and developing bias voltage?

Testing process (the machine is Minolta digital copier Di351):

1. The default density options on the machine are: automatic density, text mode, initial density 0, enter maintenance mode to view The current gate voltage/development bias voltage are: -650V/-500V respectively; there is no adjustment option for the main charge, and the image stabilization system does not involve the main charge, so it should be a constant output;

2. Change the above items respectively The item is the default value at startup. If you check the gate voltage/developing bias output of the copier, there is no change, and the same is true when the user changes the density. It can be seen that when the user changes the density, the machine does not adjust the high-voltage output to achieve the purpose of changing the image density output.

So how does the machine control the concentration output? …

2. Image processing.

After the image is read and A/D converted, the image is reproduced through various corrections (such as black edges, gamma correction, etc.) and processing (binary, ternary). In digital machines, the level at the black and white boundary is defined as the "threshold level". For each individual pixel, it is either black or white, the level is either L or H, and the digital signal is either 0 or 1. The corresponding toner Only attached or not attached. When a digital machine performs image processing, such as trying to adjust in text mode, the machine should only perform binary processing accordingly. Adjusting the "threshold level" can achieve changes in density during image processing.

1. Non-black and white reproduction: Define the lowest level determined by the machine when reading the image as 0 and divide it into 64 density levels from bottom to top to 63 (the blackest level of 63 does not change ), if the threshold level takes an intermediate value, when trying to change the threshold level, the threshold level will also change accordingly, thereby achieving a change in image density.

2. Grayscale reproduction: If a 4*4 matrix is ??used to configure the threshold level in a pixel according to certain rules, a new D*** matrix is ??obtained, and then this matrix is ??used to perform binary processing on the image. value processing. A 4*4 matrix can obtain 16 gray levels. For example, a 16*16 matrix can achieve 256 gray levels. Of course, the illusion of the human eye is also used to make the image appear to have varying gray levels relative to the black areas.

3. Multi-valued processing: After A/D conversion, the digital signal input and output are transformed into a quadratic function relationship (curve). By changing the input concentration level, the curve used can be changed, thereby transforming the output. For signals, when the overall signal is shallow, the curve on the shallow side is used, and when it is dark, the curve on the dark side is used. In the process of writing based on this signal, combined with the length of the laser ON time and the power of a pixel, it can become a multi-valued writing [using the pulse width method to control the length of time the laser irradiates a pixel, using The power mode controls the irradiation power (brightness) of the laser to a pixel, thereby changing the potential difference of the pixel relative to the development bias, causing the amount of toner adhesion on a pixel to change, so that the concentration can also be changed according to the concentration adjustment requirements. To achieve the purpose of controlling the density of the output image]. Binary processing requires an 8*8 matrix to achieve 64 trial levels, while multi-valued processing can express 16 density levels per pixel, so the output dot pattern is more detailed.

It can be seen that when the user adjusts the copy density on the panel, the software solidified in the ROM of the digital copier performs image processing, threshold level adjustment, laser pulse width modulation and laser power output* **Working together to control the corresponding concentration level is not a single adjustment, but a comprehensive adjustment.

3. Automatic adjustment of the image stabilization system of digital copiers (a little biased, let’s write it down together)

1. Image reading adjustment

Digital copiers Most of them use fluorescent lamps. The amount of light gradually decreases with time of use, and the image density also becomes thicker. Therefore, the image stabilization system uses variable amplification technology.

A. The light conversion voltage value reflected by the new fluorescent lamp from the standard white board is used as the reference value;

B. After the fluorescent lamp ages, the light amount decreases, and the light conversion voltage value also decreases. Decrease;

C. When performing image processing, the difference between the above two voltages is used as the feedback value as the base to amplify and convert to the ideal value of the new glory lamp, thereby obtaining a clear and stable image. .

2. Gate pressure/development adjustment

A. Drum temperature correction: The thermistor detects the temperature change of the photosensitive drum and feeds it back to the CPU, and corrects the gate pressure/development according to the detected temperature. Bias voltage, compensates for changes in image density caused by drum temperature;

B. Drum aging correction: The drum rotation counter records the time when the photosensitive drum is opened and feeds it back to the CPU, corrects the development bias according to the recording time, and compensates for the photosensitive The sensitivity decreases due to drum aging and stabilizes the image output.

The second test process:

A. Turn on the machine in a cold state, check that the gate voltage/developing bias voltage is -650V/-500V respectively, and the customer copies data (continuously copies 900 times) Zhang, after waiting for a few days, I checked that the gate voltage/development bias has changed: -673V/-523V (the value is the same as the manual adjustment in maintenance mode).

B. Clear the drum component count. After restarting the machine, check that the gate voltage/developing bias voltage has dropped to -500V/-385V. Another Di351 machine of the same type cleared the count and copied 40,000 rear gates. The pressure/development bias voltage has increased to -696V/-523V.

4. Maintenance and adjustment

It is a very common phenomenon to use non-original consumables. Of course, I rarely use original consumables, and even use inferior consumables to deceive users. To temporarily obtain good image effects, many adjustments are made in maintenance mode to change the initial output voltage value of the machine. (Take Minolta Di351 as an example)

1. ID adjustment: There are seven adjustable levels. This adjustment will not change the gate pressure/developing bias. What is adjusted is that the copier adjusts the density when the user adjusts it. Base value for adjustment.

2. VG gate voltage adjustment: ***Five levels of adjustment, each level can adjust the gate voltage to -23V output. (Adjustment is very effective when black bars appear in the image, and there is no big change when the output image is normal)

3. F2 gate voltage/development bias (Vg/Vb) and current adjustment : There are four items to adjust the voltage and three items to adjust the current. The machine is good. This is a factory adjustment and has not been tested. Please test it again when you have the accessories.