JPS6026365A - Image controller - Google Patents

Abstract

PURPOSE:To perform optimum control over the light and shade of a copy image easily and excellently according to an original surface by performing the control according to light and shade judgement results based upon reflected light detection outputs of an original image in a prescribed area and its preceding and following areas which are divided from the front end. CONSTITUTION:The reflected light detection output of a photodiode 1 for the original image is applied to a microcomputer 7 to make light and shade judgement by interruption, and the DC component of a development bias voltage passed through a high- voltage transformer 8 is controlled to adjust the light and shade of the copy image. The interruption of the computer 7 is controlled by an operational amplifier 11, transistor 12, etc., which detects the zero crossing of an AC power source 9. Then, the computer 7 judges the light and shade of the original in each area obtained by dividing the time from when reflected light from the front end of the original is detected to when the front end of the image appears on specific basis, and judgement results of an area before or after the divided area is added to obtain a light and shade judgement result. Thus, the optimum control over the copy image corresponding to the original surface is carried out with good reproducibility for a low-density character original and without fogging, etc., for a high-density character original.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic proper image recording forming apparatus such as a copying machine. Conventionally, to adjust the transferred image density of a copying machine to an appropriate amount, one has to adjust the volume VRi, etc. in the operation BIS as shown in Fig. 1, and then use the IfJL light lamp (not shown in Fig. 2). A
It was common practice to obtain an appropriate value by varying the lighting voltage of 1, but with this conventional method, several sheets of transfer paper were wasted in order to obtain an appropriate image. In many cases, the amount of transfer paper used increases beyond the required number.

The present invention has been made to eliminate this type of conventional drawback, and when an original is exposed, the reflected light in the direction of the original is detected by a photodetector element or the photoreceptor potential is detected by the potential H, and the output level is adjusted according to the output level. The purpose is to determine the density of the IJJI document and control the appropriate amount of developing bias voltage and exposure run voltage to obtain a proper density image.

FIG. 3 shows an embodiment of this J. In front of Inmitsu Lens IIJ, one optical sensor PH and seven odd diodes are installed to detect the intensity of reflected light from document glass PL. D is a photosensitive drum, and L is an original exposure lamp. Figure 4 shows the detection circuit. PH photodiode 1
Amplify the detection signal from operational amplifier 2, operational amplifier 3
The microcomputer 7 with a built-in gain adjustment L T A D converter inputs to the AD 1 input. The microcomputer 7 adjusts the ADI input level and the volume 5 described later
AD2 person level output boat determined by ◇
By outputting a pulse width modulated pulse from 1 and integrating it and inputting it to operational amplifier B, the output level of operational amplifier 6 is output in proportion to the nozzle width, and the developing bias DC component of high voltage transformer 8 is controlled. do. Reference numeral 9 denotes a transformer, and a full-wave rectifying jlflL operational amplifier 11 is used on the secondary side to detect AC zero cross. The zero cross pulse is input to the η<T1 interrupt terminal of the microcomputer 7,
By interrupt processing by K, the input of ADl is read by the program shown in FIG. 5, and the developing bias is controlled.

FIG. 5 will be explained. The relationship between each flag (indicated by FC) and the sequence is shown in Figure 8.0 First, when the copy button is pressed, the main motor starts rotating, and when the pre-rotation for drum removal and cleaning is completed, the optical system moves forward. The sensor S on the way forward starts the process and notifies the tip of the document p;R.
When there is an input (Step 1), start incrementing the 0NTO counter, which is the time it takes for the leading edge of the image to reach the developing operation.Step 2) The leading edge of the document is exposed to light according to the count-up value of the 0NTO counter, and then the latent image is developed. Measure the time until. Before starting development, a bias equal to the preset value FF plus AD2 is applied to prevent toner from adhering to the drum (step 0).

During that time, AD'l is sampled and added to the value of Σ1 (step 3), and when the above time elapses and the FG indicating that development is in progress is set (step 4), the value of Σ1 is set to 0N.
Divide by TO to calculate the average value of ADl and fine-tune volume 5
(Figure 3) and add this value to the input AD2 from N
Then step 5) H as shown in FIG. 6 of routine a.
The H level pulse width control @T in PWM is determined by the value of . 0NTO, 0NT1. CNT2 is INT
Increment the input input pulse gink.

Since 25<5LSB, the minimum is 0. This is because the maximum number is 510, and if this is divided into 3QLSB units, it can be divided into 18. Therefore, for each value of N←N÷30, Figure 4 o
By controlling the pulse width output to one boat by σ11, the C component can be changed as shown in FIG. 9. 1st by bias control constant pressure VB
As shown in figure 0, it varies from -50 to -600V, and this V
In order to control B, the pulse width output from the 01 output port of the microcomputer is controlled. The control) tl-charts are shown in FIGS. 6 and 7. Figure 7 shows the timer internal interrupt log 2 that starts when the power is turned on and starts when an interrupt is generated by your own time amplifier.
It is mu.

By the way, during the time period from when the image front end signal is input by the sensor S until the development starts, the force f) nl C
NT2 Kax Turtle. CN'r 1 and U
As shown in Figures 8 and 12, CNT 2 plays a role in distinguishing the sampling area for calculating and determining the bias output. The area is the flai control area (
n) and the area one before it (W-1) or after it (1-
1) is controlled by a value calculated from the average value of the input data from the photodetection sensor shown in FIG. 4 sampled during exposure of the original. Here, the bias control voltage V is calculated based on data that includes not only sampling of the control area (n) but also sampling of the area immediately before (tL-1) or after (W+1). Appropriate continuity in the developing bias value that is controlled in response to document density changes between control areas! This is because of the purpose of trying to make it happen. For ON'l'i, Σ1 is averaged in step 5), and for CNT2, Σ
2 (step 6) to determine the bias output.

By the way, since the photosensitive drum is a ◇PG drum and the primary fluorescent electricity is very strong, when the developing bias DC component is increased to the negative side, the amount of development decreases and the copied image becomes thin. Therefore, as shown in Figure 9, N
As the value of increases, that is, IQ + iA 9
As the density decreases, the negative value of the DC component of the developing bias becomes smaller and the amount of development increases to improve thinning.On the other hand, for documents with high density such as newspapers, the developing bias DC becomes smaller. The volume 5 shown in Fig. 4 is used to control the direction of eliminating fog in the copied image by increasing the component ~ 1. Volume 5 shown in Fig. 11 indicates that the EV characteristics of the drum have deteriorated to the drum. This is a means for appropriately correcting the DC component of the developing bias in order to obtain a proper copy image when one curve is changed to two curves.

In the present invention, the development bias is controlled by dividing the original document 4 scanning sections based on the time from the input signal from the document leading edge detection sensor until the leading edge of the image is developed, and calculating the sampling data. This method is not limited to the method described above, but for example, the scanning section may be divided into 7 minutes based on an appropriate predetermined scanning time width, or the scanning speed of the optical system may be changed depending on the magnification in a copying machine having a variable magnification function. Because of the difference, control such as dividing the scanning section based on a constant scanning distance becomes effective.Measure the potential on the dome 9Y4 immediately after exposure and use it as the above-mentioned According to the present invention, the World Bank can also perform and control the erudition's manuscript drawings.

The quality is good, and it is possible to obtain copied images without overlapping images such as those of newspapers, etc., saving the trouble of adjusting the conventional density adjustment bar, etc., and eliminating the wastage of transfer paper due to misprints, making it more efficient. Good G and Q refunctions are real.

[Brief explanation of drawings]

Figure 1 shows the operation section of the copying machine] Figure 2 is a conventional density adjustment circuit diagram, Figure 3 is a diagram illustrating the optical system, Figure 4 is a circuit for implementing the present invention, 5 to 7 are flowcharts of the present invention, FIG. 8 is a sequence timing chart, and FIG.
FIG. 10 is a diagram showing the relationship between the developing bias control voltage and the developing bias, FIG. 11 is a diagram showing the E-V characteristic of the drum, and FIG. 12 is a diagram showing the relationship between the bias control voltage and the original 4 sampling area. In the figure, 1 is a 7-point sensor. Applicant: Canon Co., Ltd.
et

Claims (1)

[Claims] It has means for detecting light and shade, and means for optimally controlling the multi-image forming process based on the density detection signal, and the control means detects a predetermined area or a predetermined area divided from a signal corresponding to the original image. An image control device characterized in that it determines the density of time and performs optimal control by taking into consideration the area or time before or after the minute νr'J.