JP2001228755A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To well discriminate the kind of recording material by measuring glossiness of recording material by a gloss sensor, even when the accuracy of glossiness of a reference reflecting plate is not high. SOLUTION: When a print is started and a front end sensor detects the transportation of a recording paper, a gloss sensor unit is started by a timing generating circuit, and then the glossiness of the reference reflecting plate is measured. The glossiness data of the reference reflecting plate are set to Vr after A/D conversion, are divided by 2 in a division circuit, and a value Vr/2 is stored in a RAM as a reference glossiness Vc. Next, the glossiness of the recording paper is measured while choosing the time when the recording paper arrives at the reading part of the sensor unit. The glossiness data of the recording paper are set to Vm after A/D conversion, a relative value VS=Vm/Vc to the reference glossiness Vs is calculated in an arithmetic circuit. A comparator circuit compares Vs data with a threshold stored in a ROM, then the kind of recording paper is determined, and a suitable printing mode is set according to the kind of recording paper in a printer mode selector circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic system, and more particularly to measuring the glossiness of a recording material on which an image is printed and selecting an appropriate printing condition suitable for the type of the recording material. And an image forming apparatus.

[0002]

2. Description of the Related Art Generally, a color image forming apparatus requires control of image density. This color image forming apparatus includes a series of steps of forming a visible image (toner image) by charging, exposing, and developing a photosensitive drum as an image carrier, and transferring the visible image to an intermediate transfer belt. It is known that a color image is obtained by repeating a plurality of colors and finally re-transferring a superimposed image of a plurality of colors onto a recording sheet.

Hereinafter, a conventional color image forming apparatus will be described with reference to the accompanying drawings. FIG. 5 is a schematic view showing a conventional color image forming apparatus.

In this image forming apparatus, a photosensitive drum 100 as an image carrier, a roller charger 105, and a cleaner box 113 for storing waste toner are integrally formed as a cartridge, and are replaced when the number of prints reaches a specified number. A photosensitive drum cartridge L that is detachable from the main body of the image forming apparatus. Further, a toner storage unit and a developing unit for developing are integrated into a cartridge on the left side of the photosensitive drum cartridge L to complete the consumption of the stored toner. And a plurality of developing cartridges Dm, Dy, Dc, and Dk detachable from the apparatus main body. Each of the developing cartridges Dm to Dk is supported by a rotatable support having a rotating shaft 110, and a cartridge for developing is selected on the same cylinder around the rotating shaft 110.

[0005] Below the photosensitive drum cartridge L, an intermediate transfer belt (I) having a transfer function on which a toner image of each color formed on the photosensitive drum 100 is transferred for each color.
TB) 103 is disposed. An exposure device 107 including a laser diode 104 and the like is arranged above the apparatus. The exposure device 107 emits a laser beam by the laser diode 104 in response to the input of the image signal, deflects the emitted laser beam by the polygon mirror 106 that is rotated by a high-speed motor, and then exposes the laser beam through the lens 116 and the folding mirror 115. Irradiation is performed on the surface of the drum 100 to form an electrostatic latent image on the surface of the photosensitive drum 100.

The photosensitive drum 100 is formed by coating a photoconductor made of an organic photoconductor (OPC) on an outer peripheral surface of an aluminum cylinder having a diameter of 40 mm. AS instead of OPC
A photosensitive drum using i, CdS, Se, or the like may be used. The photosensitive drum 100 is rotationally driven in a direction indicated by an arrow in the drawing at a peripheral speed of 103 mm / sec by driving means (not shown).

To form an image, first, the photosensitive drum 10
0, the charging roller 105 is supplied with a DC voltage of -700 V, a frequency of 700 Hz, and a peak-to-peak voltage (Vpp).
A charging bias on which an AC voltage of 1500 V is superimposed is applied, and the surface of the photosensitive drum 100 is uniformly charged to approximately -700 V by the charging roller 105. And the exposure apparatus 10
7, a laser beam is irradiated as a first color in accordance with, for example, a magenta image pattern, and the potential of the laser beam irradiated portion on the surface of the photosensitive drum 100 is attenuated to about −100 V, so that the surface of the photosensitive drum 100 is magenta. Is formed.

In accordance with the formation of the latent image on the photosensitive drum 100, the magenta developing cartridge Dm is conveyed to a developing position facing the photosensitive drum 100 by rotation about the rotation shaft 110. The latent image moved to the developing position is developed by the developing cartridge Dm and is visualized as a magenta toner image. The obtained magenta toner image is formed by applying a voltage applied to the intermediate transfer belt 103 by a high-voltage power supply (not shown) to the photosensitive drum 10.
Due to the difference from the voltage of 0, the photosensitive drum 100 and the intermediate transfer belt 103 are transferred onto the surface of the intermediate transfer belt 103 at the primary transfer section facing the photosensitive drum 100.

By carrying out the above steps similarly for the three colors of cyan, yellow and black, a color image in which four magenta, cyan, yellow and black toner images are superimposed on the intermediate transfer belt 103 is obtained. can get. This color image is recorded on the recording paper 10 fed from the cassette 101 or the multi tray to the intermediate transfer belt 103.
The transfer roller 117 collectively transfers the intermediate transfer belt 103 and the transfer roller 117 onto the transfer roller 117 at a secondary transfer portion facing the transfer roller 117.

Recording paper 102 onto which four color toner images have been transferred
Is guided to the fixing device 119 by the conveyor belt 111, where the toner is melted and fixed to form a full-color print image, and then the face-up tray (image upward) 1
08 or face down tray (image downward) 109
Is discharged to

The toner remaining on the photosensitive drum 100 without being transferred is cleaned by a cleaning member in a cleaner box 113. The toner remaining on the intermediate transfer belt 103 without being transferred is transferred to a belt cleaner 11 provided with a known cleaning member such as a fur brush or a blade.
2 to be cleaned.

In the present image forming apparatus, prior to printing an image on the recording paper 102, a gloss sensor 140 for determining the type of the recording paper based on the glossiness of the surface is used to perform secondary transfer from the paper supply cassette 101. It is installed on the conveyance path of the recording paper to the unit. By detecting the type of recording paper by the gloss sensor 140, it is possible to perform optimal image formation in which the recording paper and the image are balanced in accordance with the glossiness of the recording paper,
In the HT, control is performed so that light is transmitted when an image is printed on a transparent original.

The gloss sensor 140 includes a light-emitting light source and two light-receiving elements, and first measures the gloss of a reference reflector disposed inside the image forming apparatus.
Next, when the recording paper is conveyed, the glossiness of the background of the recording paper is measured, a relative value to the previously measured glossiness of the reference reflector is calculated, and compared with a predetermined slice level,
The type of recording paper is determined.

This reference reflector is usually required to have a high-precision glossiness in order to distinguish OHT from high-gloss paper with little variation in sensitivity and mounting error of the gloss sensor and a small gloss difference.

[0015]

However, this reference reflector absorbs differences in sensitivity due to variations in the relative position of the lens and the like of the gloss sensor, mounting errors of the sensor, and glossiness between high gloss paper and OHT. In order to identify a recording sheet having a small difference in the degree, it is necessary that the precision of the glossiness is high.

In addition, when there is not much room in the mounting space for the gloss sensor, it is necessary to highly restrict the conveyance of the recording paper in order to maintain the detection distance between the sensor and the recording paper. When it comes into contact with the plate, abrasion occurs and the glossiness of the reference reflector is deteriorated. In addition, select a highly accurate glossy material required for the reference reflector,
Processing involves problems such as high cost and poor productivity.

Accordingly, an object of the present invention is to measure the glossiness of a recording material using a gloss sensor and determine the type of the recording material, even if the accuracy of the glossiness of the reference reflector used for the determination is not high. An object of the present invention is to provide an image forming apparatus capable of satisfactorily determining the type of a recording material.

[0018]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
Prior to printing an image on a recording material, the recording material is irradiated with light, and the specular component of light reflected from the recording material is detected and compared, thereby detecting the glossiness of the surface of the recording material. In an image forming apparatus provided with a gloss sensor, a reference reflector used to correct the sensitivity of the gloss sensor for deterioration of light quantity of the gloss sensor and dirt, and a correction unit for correcting a detection level of the reference reflector by the gloss sensor. Relativizing means for making the detection level of the recording material by the gloss sensor relative to the corrected detection level of the reference reflector; and a type of the recording material based on the result of the recording material detection by the relativized gloss sensor. And a printing unit that changes printing conditions for the recording material according to the determined type of the recording material.
In another aspect of the present invention, when it is difficult to determine the type of the recording material, or when the glossiness of the reference reflector decreases due to deterioration of the light emission amount of the gloss sensor, the reference reflection by the gloss sensor is performed. The means for correcting the plate detection level is changed.

[0019]

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

Embodiment 1 FIG. 1 is a block diagram showing a system for determining the type of recording material based on glossiness measurement in one embodiment of the present invention.

According to the present invention, the glossiness of a recording material is measured by a gloss sensor to determine the type of the recording material. Is distinguished well, and can be used for setting printing conditions according to the type of recording material. Since the mechanical configuration of the image forming apparatus of the present invention is basically the same as that of the conventional image forming apparatus shown in FIG. 5, the drawing of the image forming apparatus and the description of each part thereof are omitted.

In the present embodiment, the determination system includes a recording paper leading edge sensor 121, a gloss sensor unit 122, a timing generation circuit 125, a division circuit 128, an arithmetic circuit 129,
The configuration includes a comparison circuit 130, a determination circuit 132, and the like. When printing is started, the recording paper 120 is fed from a paper feed cassette or a multi-tray of the image forming apparatus, and the recording paper leading edge sensor 121 detects the leading edge of the fed and transported recording paper. The recording paper leading edge sensor 121 is disposed in front of the gloss sensor unit 122 and is used as a trigger for starting data sampling of the gloss sensor.
The gloss sensor unit 122 is installed on the conveyance of the recording paper from the paper supply unit to the secondary transfer unit in FIG.

The gloss sensor unit 122 includes the light emitting circuit 1
23, a light receiving circuit 124, a lens and a filter (not shown), and the like.
And irradiates the light with a regular reflection component of the reflected light.
4 and outputs an analog amount detection signal. The light emitting circuit 123 is mainly composed of an LED, and the light receiving circuit 124 is composed of a phototransistor. Gloss sensor unit 1
The reference reflection plate 13 is located at a measurement point of the recording paper 120 by the reference numeral 22.
The reference reflection plate 133 is used for correcting a detection error due to deterioration of an LED, contamination between optical axes, and the like.

The timing generation circuit 125 has an A / D conversion circuit 126 based on a signal from the recording paper leading edge sensor 121.
, A write signal to the RAM 127, and a read signal. The A / D conversion circuit 126 is a circuit that converts an analog signal from the gloss sensor unit 122 into a digital signal. The division circuit 128 is configured to always perform the division process on the gloss data of the reference reflection plate 133 by the same value to obtain a target reference glossiness. For example, the glossiness of the reference reflection plate 133 is set to 100%, the division calculation number is set to 2, and the target reference glossiness is set to 50%. The reference glossiness calculated by the division circuit 128 is temporarily stored in the RAM 127.

The arithmetic circuit 129 is a circuit for calculating the relative value of the gloss data of the recording paper with respect to the reference glossiness. The comparison circuit 130 outputs the output from the arithmetic circuit 129 to the ROM
This is for comparing the output (threshold) from the output 31.
The ROM 131 stores a threshold value for determining what kind of recording paper is. The determination circuit 132 determines A /
If the data of the D conversion circuit 126 is valid, the comparison circuit 130
Is invalidated, and if the data of the A / D conversion circuit is invalid, the data from the comparison circuit is adopted to make a final determination of the type of recording paper. Print mode selector 13
Reference numeral 4 denotes a circuit for setting print conditions according to the type of recording paper determined by the determination.

Next, the operation of the determination system of this embodiment will be described with reference to the flowchart of FIG. When printing is started, the process waits until the recording paper 120 is conveyed and detected by the recording paper leading edge sensor 121 in step S1.
In step S2, the recording paper 120 is detected by the leading end sensor 121.
Is detected, the timing generation circuit 1
25 activates the light emitting circuit 123 of the gloss sensor unit 122 by the signal D, and causes the LED of the light emitting circuit 123 to emit light. When the LED emits light, the light receiving circuit 124 receives the reflected light from the reference reflecting plate 133 and converts the analog detection signal from the light emitting circuit 123 into a digital signal by the A / D conversion circuit 126 according to the signal A from the timing generation circuit. Division circuit 128 as data Vr of the reference reflector
(S3). Reference reflector 1 in division circuit 128
The gloss data of 33 becomes 1/2, and the value Vr / 2 is stored as the reference glossiness Vc in the RAM 127 by the signal B (S4).

Next, the time when the recording paper 120 reaches the reading position of the gloss sensor unit 122 is estimated, and the gloss sensor unit 122 measures the gloss of the recording paper.
The gloss data of the recording paper is digitally converted by the A / D conversion circuit 126 by the signal A from the timing generation circuit 125, and is output to the arithmetic circuit 129 as Vm (S5). At this time, a signal C is generated from the timing generation circuit 125, the data of the reference glossiness Vc is read from the RAM 127, and output to the arithmetic circuit 129. In the arithmetic circuit 129,
Relative value V of recording paper glossiness Vm with respect to reference glossiness Vc
s = Vm / Vc is calculated, and the result Vs is output to the comparison circuit 130 (S6).

The comparison circuit 130 compares the input Vs data with the threshold value stored in the ROM 131 to determine the type of the recording paper 120. When the type of recording paper is determined, the determined recording paper type information is input to the printer mode selector circuit 134, and an appropriate print mode is set according to the type of recording paper (S7, S8).

In the present embodiment, the number of divisions calculated by the dividing circuit 128 is 2, but the greater the glossiness of the reference reflection plate with respect to the target reference glossiness Vc, the higher the accuracy in selecting the reference reflection plate. Can be rough.

Embodiment 2 FIG. 3 is a block diagram of a recording paper type judging system based on glossiness measurement in another embodiment of the present invention. In FIG.
The division circuit denoted by reference numeral 135 is an A / D conversion circuit 126
Is divided by the output from the CPU 136, and the result is output to the comparison circuit 130. The CPU 136 supplies the division number to the division circuit 135.

The ROM 131 stores a fraction for the reference reflector 133 for determining the initial calibration level Vc and a reference reflector for changing the calibration level again in order to investigate and select each recording sheet in detail. , Slice level data for determining the type of recording paper, and slice level data for checking the approximate type of recording paper. The RAM 127 is used to temporarily store the initial calibration level Vc. The comparison circuit 130 is for comparing the relative value of the calibration level with respect to the gloss level of the recording paper and the data supplied from the ROM 131.

Next, the operation of the determination system according to the present embodiment will be described with reference to FIG. When printing is started, step S1
Then, the glossiness Vr of the reference reflector 133 is read by the gloss sensor unit 122. The CPU 136 is connected to the ROM 13
The variable D1 for dividing Vr from 1 is read and sent to the division circuit 135. The division circuit 135 converts Vr to D
The output value Vc1 obtained by dividing by 1 is stored in the RAM 127 (S2). Next, the gloss sensor unit 122 reads the glossiness Vm of the recording paper 120. The CPU 136
Vc1 is read from the RAM 127 and divided by the dividing circuit 135.
Then, a relative value Vs = Vm / Vc1 of Vm with respect to Vc1 is calculated (S3).

The CPU 136 stores the relative value Vs and the ROM
The slice level for determining the type of recording paper stored in the storage 131 is compared to determine whether the type of recording paper can be determined (S4). If there is a sufficient margin above the slice level, the type of recording paper is determined. When the margin with the slice level is small, the CPU 136 outputs Vr
Is changed to D2, and Vc1 is changed to Vc2 (= V
r / D2). D2 is a number greater than D1. Along with this processing, the slice level for determining the type of recording paper is also multiplied by D2 / D1.

Next, the CPU 136 determines that Vr / D2 = Vc2
Is written into the RAM 127 (S5). Vm / Vc
2 = Vs2 is calculated and compared with the changed slice level of the recording paper type determination to determine whether the recording paper type is possible (S7, S8). If it can be determined, a parameter corresponding to the type of recording paper is set in the print mode selector 13.
4 and perform appropriate printing (S9, S10).
If it cannot be determined, the number of divisions is further changed, and the process is repeated until the determination becomes possible.

For example, when Vc is set to be 80% and the recording paper has a center value of 75% and the variation is ± 5%, and the recording paper has a center value of 85% and the variation is ± 5%, the slice of Vs is determined. When the level is set to 1, for example, when a recording paper having a glossiness of 75% is read, Vs = 75/80 = 0.9
37, the difference from slice level 1 is 0.06
3. When it is recognized that the determination of this difference is difficult, Vc
Is set to be 50%, the slice level is 1
× 80/50 = 1.6, and Vs = 75/50 = 1.
The difference from 5 is 0.1, which makes the judgment easy.

[0036]

As described above, according to the present invention,
By setting the glossiness of the reference reflector to a value larger than the actual target value and setting it to the target value by arithmetic processing when determining the type of recording material, the accuracy of the glossiness of the selected reference reflector can be roughly determined. Not only can the number of selection candidates be increased, but also the cost can be reduced. Further, in the determination of the recording material type, when the glossiness of the recording material is close to the slice level that is the determination criterion, the determination can be performed in detail by freely calculating the glossiness of the reference reflector. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a recording material type determination system based on glossiness measurement according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the determination system of FIG.

FIG. 3 is a block diagram illustrating a recording material type determination system based on glossiness measurement according to another embodiment of the present invention.

FIG. 4 is a flowchart illustrating the operation of the determination system in FIG. 3;

FIG. 5 is a schematic diagram illustrating a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 120 recording paper 121 recording paper leading edge sensor 122 gloss sensor unit 123 light emitting circuit 124 light receiving circuit 128 division circuit 129 arithmetic circuit 130 comparison circuit 132 determination circuit 133 reference reflector 134 print mode selector

Claims (2)

[Claims] 1. Prior to printing an image on a recording material,
By irradiating the recording material with light, by detecting and comparing the regular reflection component of the reflected light from the recording material, an image forming apparatus including a gloss sensor for detecting the glossiness of the surface of the recording material, Deterioration of the amount of light of the gloss sensor, a reference reflector used to correct the sensitivity to dirt, correction means for correcting the detection level of the reference reflector by the gloss sensor, and the detection level of the recording material by the gloss sensor. And a determining means for determining a type of the recording material based on a result of the relative gloss detection performed by the gloss sensor to determine the type of the recording material. An image forming apparatus, wherein printing conditions for a recording material are changed according to the determined type of the recording material. 2. It is difficult to determine the type of the recording material,
2. The image forming apparatus according to claim 1, wherein a unit for correcting the detection level of the reference reflector by the gloss sensor is changed when the glossiness of the reference reflector decreases due to deterioration of the light emission amount of the gloss sensor.