JPH05322758A - Image processor - Google Patents

Abstract

PURPOSE:To provide an image processor of low cost capable of detecting the surface color of a photoreceptor drum and the density of a toner image on the photoreceptor drum. CONSTITUTION:An image processor is provided with a rotatable photoreceptor drum 31, a visible light emitting diode 2 arranged on one line and emitting the visible light to identify the surface color of the photoreceptor drum 31, an infrared light emitting diode 1 arranged on one line and emitting the infrared light to detect the density of a toner image on the photoreceptor drum 31, and a light receiving element 3 arranged on one line and receiving the visible light and the infrared light reflected from the photoreceptor drum 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus having a visible light emitting diode and an infrared light emitting diode for image control.

[0002]

2. Description of the Related Art A conventional image processing apparatus is a control system for optically reading the density of a toner image on a photoconductor drum of a copying machine and operating an exposure amount and a charging potential to maintain an optimum image limit. Have In addition, infrared light is used in consideration of ambient light to optically read the density of the toner image.

For example, in Japanese Examined Patent Publication No. 3-14186, a toner obtained by exposing a part of a photoconductor at the time of copying a reference target placed in the vicinity of a document table and developing it is developed.
In an electronic copying machine in which the image density of an image is detected by a photo-sensitive detector, the obtained detection signal is amplified by an amplifier circuit, and then supplied to a control circuit for controlling the image quality of copying. A photo-sensitive detector that detects the toner image of the get optically detects the state of the surface of the photoconductor that has not been exposed and developed for a short time at least at the start of copying, and amplifies the detection output so that it becomes constant. Disclosed is a method of adjusting the gain of a circuit for amplifying a toner image density detection signal in an electronic copying machine, which is characterized by controlling the gain of the circuit.

[0004]

On the other hand, the photosensitive member used in the image processing apparatus generally has different sensitivity characteristics, size, etc. depending on the model.

However, depending on the model, it is often the case that only the sensitivity characteristics differ because the surface color of the photoconductor differs even if the drum diameter and length are the same.

In addition, when a photoconductor is arranged, it is often the case that a photoconductor dedicated to another model is erroneously attached, and the color of the surface of the photoconductor drum is automatically read there. It will be convenient if you can put out the game. However, in general, the OPC photoconductor is highly transparent to infrared color, and it is necessary to read the color on the photoconductor drum surface with visible light in order to identify the surface color.

An object of the present invention is to provide a surface color of a photosensitive drum,
It is an object of the present invention to provide a low-cost image processing apparatus capable of detecting the density of a toner image on a photosensitive drum and obtaining an image of good quality.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a rotatable photosensitive drum and a visible light emitting diode which is arranged on one line and emits visible light to identify the surface color of the photosensitive drum. And an infrared light emitting diode which is arranged on one line and emits infrared light to detect the density of the toner image on the photoconductor drum, and a photosensitive body which is arranged on one line One light receiving element for receiving visible light and infrared light reflected from the drum, respectively.

[0009]

The visible light emitting diode emits light to identify the surface color of the photosensitive drum, and the infrared light emitting diode emits light to detect the density of the toner image on the photosensitive drum. The light receiving element receives visible light and infrared light reflected from the photosensitive drum, respectively. Therefore, the surface color of the photosensitive drum and the density of the toner image on the photosensitive drum can be reliably detected, and the image quality can be compensated based on the detection. Furthermore, since there is only one light receiving element, the installation location of the light receiving element can be reduced and the image processing apparatus can be manufactured at low cost.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic sectional view showing an embodiment of the configuration of the image processing apparatus of the present invention.

As shown in FIG.
Is a photoconductor drum 31, a cleaner unit 32, a charging unit 33, a blank lamp 34, a color developing tank 3
5, main developing tank 36, transfer charger 37, peeling charger 38, copy lamp 39, first mirror 40, second mirror 41, third mirror 42, fourth mirror 4
3, a fifth mirror 44, a sixth mirror 45, a CCD unit 46, a lens unit 47, a paper tray 48, a manual paper tray 49, a suction conveyance belt 50, a heat roller type fixing unit 51, a paper discharge roller pair 52, and The document table 53 is provided.

Cleaner unit 32, charging unit 3
3, blank lamp 34, color developing tank 35, main developing tank 36, transfer charger 37 and peeling charger 3
8 is arranged around the photosensitive drum 31 in accordance with a known mode.

Copying of the original image is performed as follows.

The original placed on the original table 53 is illuminated by the copy lamp 39, and the light reflected by the original image is reflected by the first mirror 40 and the second mirror 40 along the optical path indicated by the alternate long and short dash line in FIG. Mirror 41, third mirror 42, fourth
Mirror 43, fifth mirror 44 and sixth mirror 45
An electrostatic latent image is formed on the surface of the photoconductor drum 31 by exposing the original to the surface of the photoconductor drum 31 via the.

The electrostatic latent image formed on the surface of the photosensitive drum 31 is visualized as a toner image by the color developing tank 35 and the main developing tank 36.

Paper tray 48 or manual paper tray 49
The paper supplied from is conveyed to the transfer position between the photoconductor drum 31 and the transfer charger 37. At this transfer position, the toner image formed on the surface of the photoconductor drum 31 is transferred onto the sheet by the transfer charger 37.

The sheet on which the toner image is transferred is sent to the fixing unit 51 by the suction conveyor belt 50, and after the transferred image is fixed, it is ejected from the pair of ejection rollers 52. Thus, the copying of the original image is completed.

The structure of the optical sensor unit included in the image processing apparatus 30 will be described.

FIG. 1 is a view showing an optical sensor unit, that is, an infrared light emitting diode, a visible light emitting diode and a photo diode.

The infrared light emitting diode 1 and the visible light emitting diode 2 are arranged on the same line on the wiring board 12 arranged in the vicinity of the photosensitive drum 31. Between the light emitting diode 1 and the visible light emitting diode 2, reflected light is emitted from the infrared light emitting diode 1 and the visible light emitting diode 2, respectively, and reflected from the photosensitive drum 1. Photodiode as a light receiving element for receiving 11
The door 3 is provided.

FIG. 3 is a block diagram of a control circuit for controlling the operation of the visible light emitting diode and the infrared light emitting diode.

The infrared light emitting diode 1 and the visible light emitting diode 2 are turned on by the microcomputer 10 via the driver IC 13 at respective timings.

The reflected light 11 from the photosensitive drum 31 due to these lights is received by the photo diode 3, and the output from the photo diode 3 corresponding to the received reflected light 11 is amplified by the OP amplifier 9 to be supplied to the micro computer. -Ta 10
The analog port AN2 and the comparator 8 are input and compared with a predetermined reference value, and the comparison result is input to the input terminal CLK of the microcomputer 10.

Similarly, the output from the toner density sensor 4 for detecting the toner density in the developing tank is used for the microcomputer 1 as well.
It is detected by the analog port AN1 of 0. Then, as a result of the detection, it is judged whether or not the toner concentration is lower than a predetermined value, that is, whether or not it is an under toner, and if it is an under toner, the output TM of the microcomputer 10 is set to a high level. And the toner replenishment motor 5 via the motor drive circuit 6.
Is turned on to supply toner to the developing tank.

At this time, if it is desired to stop the motor drive urgently, the output TMI of the microcomputer 10 is set to a high level and supplied to the motor drive circuit to stop the motor. If the toner concentration is higher than a predetermined value, toner replenishment is blocked.

FIG. 4 shows the reflected light and the sensor output when the toner image (black) formed on the surface of the photosensitive drum 31 is irradiated by the visible light emitting diode 2 with respect to the surface color of the photosensitive drum 31. It is the figure shown.

The solid line represents the sensor output from the red photosensitive drum, and the dotted line represents the sensor output from the green photosensitive drum. When a red light emitting diode (635 nm) is used, there is a difference in sensor output between the red photosensitive drum and the green photosensitive drum as shown in the figure (complementary color relationship).

The reflectance of 100% on the surface of the drum means that the toner image is not formed. As the reflectance becomes smaller, the toner image changes from a halftone to a black solid image. Shows. If the image is solid black, the sensor output is naturally low, and the output is highest when the toner image is not formed. This phenomenon shows the same tendency when an infrared light emitting diode is used, but the S / N ratio is much better than that of visible light because it is strong against ambient light. Therefore, infrared light is suitable for detecting the toner density of about 50% and controlling the image quality.

On the other hand, the surface color of the photosensitive drum 31 is identified S /
In order to increase the N ratio, consider what is shown in FIG. That is, as shown in the same figure, the toner image (solid black, shaded portion in FIG. 5) may or may not be periodically formed on the photosensitive drum 31 in the rotation direction. FIG. 6 shows the output situation when the reflected light 11 is detected by the sensor 3. In the figure, the sawtooth solid line indicates the output (%) from the sensor 3 in the case of the red photoconductor drum and the sawtooth dotted line indicates the green photoconductor drum (the central straight line indicates the comparison level of the comparator 8). Indicates).

As is apparent from FIG. 4, there is a large difference in sensor output (%) between the red photoconductor drum and the green photoconductor drum even if the reflectance (%) on the drum surface is the same. The comparator 8 compares the two values with the intermediate value as a reference, and the output is compared with the input CLK of the microcomputer 10.
To enter.

In the microcomputer 10, if the pulse output synchronized with the cycle of the toner image on the photosensitive drum 31 is input, the red photosensitive drum, otherwise (high level or low level) red. Isn't it a photoconductor drum?
It can be regarded as a sensor abnormality, a circuit abnormality, or a disconnection of the signal harness system.

FIG. 7 shows a flow chart of the general operation relating to the infrared light emitting diode and the visible light emitting diode.

First, the output from the toner concentration sensor is read to determine whether the toner concentration is a predetermined value (7-
1) If the value is outside the predetermined value, the toner concentration is controlled (7-
2) Turn on the output TMI of the microcomputer 10 to prohibit toner supply.

If the toner density is within a predetermined value, the visible light emitting diode is turned on (light emission) (7-3), and a black solid toner image is periodically prepared using a blank lamp (7-). 4) The periodic pulse from the sensor output at this time is detected at the input CLK terminal of the microcomputer 10 (7-5).

If the pulse from the sensor output received at the input CLK terminal is not the pulse synchronized with the cycle of the toner image, it is not the red photoconductor drum, the sensor is abnormal, the circuit is abnormal, or the signal harness system is out of order. A judgment is made to stop the operation of the image processing apparatus and an alarm is displayed (7-6).

If OK, the visible light emitting diode is OF
Set to F (7-7), then turn on the infrared light emitting diode
Then, a halftone toner image is formed on the photosensitive drum 31 (7-8). This sensor output is input to the analog port AN2 and read (7-9), and the correction processing for compensating the image quality is performed according to the result (7-1).
0).

[0038]

The visible light emitting diode emits light to identify the surface color of the photosensitive drum, and the infrared light emitting diode emits light to detect the density of the toner image on the photosensitive drum. One light receiving element receives visible light and infrared light reflected from the photosensitive drum, respectively.

Therefore, the surface color of the photosensitive drum and the density of the toner image on the photosensitive drum can be reliably detected, and the image quality can be compensated based on the detection. Furthermore, since there is only one light receiving element, the installation location of the light receiving element can be reduced and the image processing apparatus can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical sensor unit of an embodiment of an image processing apparatus of the present invention.

FIG. 2 is a sectional view showing an embodiment of the configuration of the image processing apparatus of the present invention.

FIG. 3 is a block diagram of a control circuit that controls the operation of the optical sensor unit of FIG.

FIG. 4 is a diagram showing the relationship between the reflectance on the surface of the photosensitive drum and the sensor output.

FIG. 5 is a diagram illustrating a toner image pattern on the surface of a photosensitive drum.

FIG. 6 is a diagram showing an output situation when reflected light is detected by a sensor.

FIG. 7 is a flowchart of an operation relating to an infrared light emitting diode and a visible light emitting diode.

[Explanation of symbols]

 1 Infrared light emitting diode 2 Visible light emitting diode 3 Photodiode 31 Photoreceptor drum

Claims (5)

[Claims] 1. A rotatable photoconductor drum, a visible light emitting diode which is arranged on one line and emits visible light to identify the surface color of the photoconductor drum, and the one line. And an infrared light emitting diode that emits infrared light to detect the density of the toner image on the photosensitive drum, and the infrared light emitting diode arranged on the one line and reflected from the photosensitive drum. An image processing apparatus comprising: one light receiving element that receives the visible light and the infrared light that are received. 2. The image processing apparatus according to claim 1, wherein the toner image is formed on the photosensitive drum in a rotation direction of the photosensitive drum. 3. The image processing apparatus according to claim 1, further comprising a toner density sensor that detects the density of the toner in the developing tank. 4. When the toner density sensor detects that the toner density in the developing tank exceeds a predetermined value, the developing tank is prevented from supplying toner. The image processing device according to claim 3, wherein the image processing device is configured as follows. 5. The infrared light emitting diode is configured to emit infrared light when the surface color of the photosensitive drum has a prescribed value. 5. The image processing device according to any one of items 4 to 4.