JPS5948776A - Photosensor output correcting device - Google Patents

Abstract

PURPOSE:To perform optimum picture density control automatically by detecting the surface of a photosensitive drum where no toner is supplied by a photosensor prior to a copying process, and correcting the sensitivity of the photosensor according to the detected level. CONSTITUTION:The surface of the photosensitive drum 1 is detected by the photosensor 4 prior to the copying process and its output is read. A microcomputer 5 compares its output with a previously stored detection output to select one of transistors Q1-Qn-1 according to the drop in output level, and increases the load on a photodetecting element to perform output increase control over the element 3. In the copying process, another control system outputs a timing signal when a density pattern faces the sensor 4 and the sensor 4 detects the density of the surface of the drum 1. Its output is read in the computer 5 through an A/D converter 7 and compared with a reference density output value. The density control is carried out on the basis of the comparison result.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reflective photosensor that is disposed near a photosensitive drum of a copying machine and is composed of a light emitting element and a light receiving element, and particularly relates to an output correction device thereof.

In a copying machine that forms a toner image on a photoreceptor drum and transfers it to transfer paper, it is necessary to control the image contrast and black-and-white contrast to maintain standard values in order to obtain good image quality. be.

By the way, the image limit, black and white contrast, and last depend on the toner concentration in the developer, the developing bias level, the surface light lamp voltage, etc.

Therefore, these concentration controls, i.e., 1-so-2 degree control,
91 can be controlled by controlling the bias voltage t)ilJ, the forward lamp voltage, etc., but this secondary output can also be obtained from the above-mentioned sensor. L It's turning into a sea urchin.

However, since this photosensor is close to the photosensitive layer 1 + 1 nm and is located opposite m1, it is in a situation where the dirt J1 easily lands on the photo sensor due to the scattering. When toner adheres to the surface of the first sensor, the luminous intensity and the light receiving area (1) will be significantly reduced compared to the state in which no toner is attached.

If this happens, an error will occur in the detected υA suction force on the photoreceptor drum, and it will not be possible to perform an appropriate elevation of the sea level '+1ilJ'.

In the past, how did you consider this point?
One was the M6 mo for regular maintenance. In other words, the dirt on the photosensor is left as is until regular maintenance. However, in this case, it cannot be denied that the 7 ocent output just before regular maintenance is extremely unreliable.

Another method is to adjust the volume r, JU, i.e. manually 7
The output of Otosen's load resistance value is the M4 alignment one.
Ivy.

This method relies heavily on the user's intuition, and accurate output control cannot be expected.

Furthermore, Huo I Sen゛! 7' Dirt on the surface () IKf
A device that blows air to remove toner is also known.

However, this system has the disadvantage that the number of parts for the photoreceptor drum J1 is large, making the device complicated.

The present invention has been made to address the above-mentioned 11 defects in the past.
The purpose of this invention is to provide a first sensor output correction loading that is highly reliable and can withstand the density of 4'1≦ on the photoreceptor drum, regardless of the PC.

To this end, prior to the copying process, the first sensor detects whether or not toner is coming to the photoconductor drum, and corrects the IW sensitivity of the first sensor according to this detection level. The device d is configured to perform the following.

Embodiments of the present invention will be described below with reference to FIGS. 1, 2, and 3121.

First, FIG. 1 shows a photo processor output correction circuit according to the first embodiment.

In the figure, 1 is a photoreceptor drum, and near the surface of this photoreceptor drum 10 there is a photosensitive element consisting of a light emitting element (1-Bl') 2 and a light receiving element (7O)-transistor) 3. 4 arrives at 01 ff +, -C, this light receiving element 3 has a load resistance in series! (, ~■ are provided, and the selection of this load resistance 1(, ~R,, ,1
In this microcomputer 5, there is no toner attached to the light emitting element 2, the light receiving element 3K, and no toner is on the surface of the photoreceptor drum 1, so that the photoreceptor detection output when the reflectance is maximum is remembered.

7 is an A/1) converter which converts an analog voltage proportional to the amount of light received by the probe 3 into a digital signal and sends it to the microcomputer 5.

FIG. 3 shows the operation flow of such a control circuit.

Now, based on this flowchart, ε [system shown in Figure 1 (j
l+times I': The operation of S will be explained.

The present invention has a density pattern installed in front of the original cell 1 (contact glass, not shown, is provided on the north side).
I made one insect on the photosensitive R, E drum, and this? The photosensor detects this and replenishes toner according to the detection level, and currently changes the bias, exposure lamp voltage, high-voltage output, etc., so that a constant image is always obtained).

First, prior to the copying process, one side of the photosensitive drum that has been cleaned is horizontally 1. Read the output Voutl of f- (STEP 2).

Then, inside the microcontroller 5 described in h1f, this value of Voutl is compared with the photoconductor detection output described earlier 12, and depending on the low 1: -C progress 1f; / jista shout ~ Q/J-1 - Asasawashi-C, the load of the light receiving element 3 is 4' thick (-1 This light receiving element 30 output increase 1 bll (1141, l rj j is also noted (
S'rEJ'3. S'l'EP4) (T11, etc., the output voltage value (corresponding to the light reception) which has been reversed in advance by Bd) is It, and the load of the terminal 3 is It, and 1/transistor Q1
Choice 17 was ↑J. 17 In order to take advantage of the 1 output, transistors are selected such as 1 - Q, q, and the load on the photodetector 3 is increased.In this way, the photo sensor surface As for the presence of dirt, the initial state of the foot and the output of 1 novel are always maintained. Step 12: Next, the 4th step is started, and as shown in the figure, another control system sends the 4tl; /]-
The photo sensor 4 detects the food LL on the surface of the photoconductor drum, and this output signal ->3 Vout2 is sent to the microcomputer 5 via the converter 7 Read (S '1' E
P4). 1. 7. Based on the stiffness comparison results, at least one of the toner d anti, current bass f as, 1 renkou rung' east pressure, and high voltage output is compared with the standard tension output value of the density pattern. 2 f-Il, L city IJ, +11.

FIG. 2 shows an example of the song '-Ahm' of the photosensor output correction circuit.

In the first embodiment (not shown in Figure 1), the negative resistor fLI is connected in series to the light receiving element P3Q, but as in the second actual example shown in Figure 2, it is connected in series with the light emitting element 2. The connection may be made to perform the increase type ω11 of the emitted light with the same control as in the first embodiment.

The present invention follows the above JJli, and the photoreceptor tram 1hY.
The concentration rl + lI according to the detection of a degree Bata -77
Before carrying out the control, 1. Take a look at the cleaned photosensitive drum surface! 7. This thread removal iC
Since the output correction control of the 7 automatic sensors is performed on the i.
The effect of being able to automatically perform Hiroshi concentration control is impressive.

4. Figure Il] 1 tt+1 simple explanation 3
The figure is a flowchart of the operation.

1... Photosensitive drum, 2... Light emitting water droplets, 3... Light receiving element, 4... Photo sensor.

Figure 3

Claims (1)

[Claims] A reflective photosensor consisting of a light-emitting element and a light-receiving element is installed near the photoreceptor drum, and this photosensor reads the density pattern of the photoreceptor drum compared with a reference value, and various density controls are performed according to this detection level. In such a copying machine, prior to the copying process, the first sensor detects the photoreceptor drum on which no lubricant is mounted, and the sensitivity of the light-emitting element or light-receiving element of the photosensor is adjusted according to the detection level. A photosensor output correction device characterized in that it performs correction.