JP2001088980A - Method for detecting overlap feed and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the wrong detection of overlap feed and single feed caused by the change of the temperature or contamination of a light emitting element and a light receiving element. SOLUTION: On the basis of the output voltage value from a light receiver 40b for detecting the non-transmitted light reaching the light receiver 40b without being transmitted by a transfer paper 50, the output voltage from the light receiver 40b in the detection of the transmitted light transmitted by the transfer paper 50, or the reference value for this output voltage value is corrected, and the presence of double feed is detected on the basis of the correction result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming method and an image forming apparatus using the same, such as a copying machine, a facsimile, a printer, and the like. The present invention relates to an image forming method and an image forming apparatus for detecting presence / absence.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a transfer sheet as a recording member discharged one by one from a sheet feeding device such as a sheet feeding cassette or a sheet feeding tray is directed to an image forming section. It is known that the sheet is conveyed and a visible image such as a toner image is transferred onto the transfer paper by the image forming unit. In this type of image forming apparatus, it is difficult to separate transfer papers due to electrostatic force or entanglement of paper fibers, and so-called multi-feeding in which a plurality of transfer papers are discharged and conveyed from a paper feeder in an overlapping state. May occur. When such a double feed occurs, a paper transport roller, a photosensitive drum for forming an electrostatic latent image before development, a transfer roller for transferring a transfer image onto a transfer sheet, and a fixing roller for fixing the transfer image on the transfer sheet. The transfer paper wraps around the fixing roller, etc., causing jams,
Various problems such as the interposition of blank paper between printout papers occur.

Therefore, conventionally, light emitted from a light emitting body is irradiated on a transfer paper in a paper conveying path, and the amount of transmitted light transmitted through the transfer paper is detected by the light emitting body, and based on the amount, the paper is detected. 2. Description of the Related Art An image forming apparatus including a double feed detecting unit for detecting the presence or absence of a double feed in a conveyance path is known. Since the amount of transmitted light transmitted through a plurality of transfer papers is smaller than that transmitted through a single transfer paper, the double feed detecting means uses an output voltage value from a photoreceptor for detecting the amount of transmitted light and a predetermined value. By comparing with a set reference value, the presence or absence of double feed is detected. By providing such a double feed detecting means, it is possible to cause the apparatus to perform an operation for avoiding the various problems described above in response to the occurrence of the double feed.

[0004]

Generally, since a luminous body has a temperature characteristic in its luminous performance, the luminous quantity changes with the temperature change. Further, since the photoreceptor also has a temperature characteristic in its light receiving property, the output voltage value based on the amount of received light is changed according to the temperature change. Further, the light-emitting body and the light-receiving body change the light emission amount and the output voltage value according to the change in the amount of adhered dirt. As a result, in the above-described double feed detecting means, the output voltage value from the photoreceptor for detecting the transmitted light changes with the change in the temperature of the light-emitting body or the photoreceptor or the amount of dirt. As a result, the output voltage value of the transmitted light that has passed through one sheet of transfer paper exceeds or falls below the reference value, and a single feed (a state in which only one transfer sheet is being conveyed) is multi-feed. , Or conversely, so-called double-feed / single-feed erroneous detection in which double-feed is erroneously detected as single-feed.

In particular, when a relatively thin transfer paper is used, the output voltage value related to the transmitted light transmitted through one transfer paper and the output voltage value related to the transmitted light transmitted through two transfer papers Is smaller, the difference between the former output voltage value and the reference value is also set smaller. Therefore, the output voltage value easily exceeds or falls below the reference value due to the change in the temperature or the amount of dirt, and erroneous double-feed / single-feed detection is likely to occur.

The present invention has been made in view of the above background, and an object of the present invention is to reduce erroneous double-feed / single-feed detections caused by changes in the temperature and the amount of contamination of a light-emitting body and a light-receiving body. And an image forming apparatus.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a step of irradiating a luminous body with light toward a conveying path for a recording member in an image forming apparatus;
A photoreceptor that changes a signal output value in accordance with an amount of received light, detects transmitted light that is the light transmitted through the recording member in the transport path, and outputs a signal from the photoreceptor that detects the transmitted light Detecting a presence or absence of a double feed of a recording member in the transport path based on the value, wherein the light that has reached the photoreceptor without passing through the recording member. Based on the signal output value from the photoreceptor that detects transmitted light, correcting the signal output value from the photoreceptor that detects the transmitted light, and detecting the presence or absence of the double feed based on the correction result. It is a feature.

According to a second aspect of the present invention, there is provided a transport path for transporting a recording member, a light emitter for irradiating light toward the transport path, and a light receiver for changing a signal output value in accordance with the amount of received light. Image forming for detecting presence or absence of double feeding of a recording member in the transport path based on a signal output value from the photoreceptor for detecting transmitted light which is the light transmitted through the recording member in the transport path. A light-receiving device that detects the transmitted light based on a signal output value from the light-receiving body that detects non-transmitted light that is the light that has reached the light-receiving body without transmitting through the recording member. It is characterized in that the signal output value from the body is corrected and the presence or absence of the double feed is detected based on the correction result.

When the signal output value from the photoreceptor that detects non-transmitted light that does not pass through the recording member (hereinafter referred to as output value relating to non-transmitted light) changes, the temperature of the luminous body or the photoreceptor and the amount of dirt are changed. Has changed, and the signal output value from the photoreceptor that has detected the transmitted light in order to detect the presence or absence of double feed (hereinafter, referred to as an output value related to the transmitted light) also changes. In general, there is a correlation between the rate of change of the “output value related to non-transmitted light” and the rate of change of “output value related to transmitted light” due to the change in the temperature and the amount of dirt. Therefore, for example, the “output value related to the transmitted light” is calculated based on the “output value related to the non-transmitted light” and multiplied by the “output value related to the transmitted light”.
Is corrected based on the “output value related to the non-transmitted light”, it is possible to approach the value before the change. Therefore, in the invention according to claim 1 or 2, for example, the luminous body is formed between the time when the recording member traverses the optical path from the luminous body to the light receiving body and the time when the next recording member reaches the optical path. Irradiates the light to the light receiving body from the light receiving body to detect the non-transmitted light. Then, based on the “output value related to non-transmitted light”, the “output value related to transmitted light” is corrected. When corrected in this way, even if the “output value related to transmitted light” is changed with a change in the temperature or the amount of dirt of the light emitting body or the light receiving body, the “corrected value related to the transmitted light” is corrected so as to approach the value before the change. The presence or absence of double feed can be detected based on the “output value”.

According to a third aspect of the present invention, there is provided a transport path for transporting a recording member, a light emitter for irradiating light toward the transport path, and a light receiver for changing a signal output value in accordance with a received light amount. A signal output value from the photoreceptor that detects the transmitted light, which is the light transmitted through the recording member in the transport path, based on a comparison result between a preset reference value and a signal output value in the transport path. In an image forming apparatus that detects the presence or absence of double feeding of a recording member, based on a signal output value from the photoreceptor that detects non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member, A signal output value from the photoreceptor when the transmitted light is detected, or the reference value is corrected, and the presence or absence of the double feed is detected based on the comparison result related to the correction result. Is what you do.

In such an image forming apparatus that detects the presence or absence of double feeding based on the result of comparison between the "output value relating to transmitted light" and a reference value, the following is a description of double feeding / single feeding. An erroneous transmission detection occurs. That is, the “output value related to the transmitted light” that changes with a change in the temperature or the amount of dirt of the light emitting body or the light receiving body.
However, when the value exceeds or falls below the reference value due to the change (hereinafter referred to as exceeding the reference value), erroneous double feed / single feed detection occurs. In such a case, if the difference between the reference value and the “output value related to the transmitted light” after the change approaches the original value, the “related to the transmitted light related to the change It is possible to reduce the output value exceeding the reference value. As a method of making the difference between the reference value and the “output value of transmitted light” after the change close to the original value, there are a method of correcting the reference value and a method of correcting the “output value of transmitted light”. Conceivable. Among these methods, in the latter method, as in the invention of claim 1 or 2, the "output value related to non-transmitted light"
May be corrected on the basis of the above.
In the former method, for example, the rate of change is calculated based on the “output value related to non-transmitted light” and multiplied by a reference value, and the reference value is determined based on the “output value related to non-transmitted light”. Correction. Therefore, in this image forming apparatus, the reference value or the “output value related to the transmitted light” is corrected based on the “output value related to the non-transmitted light”.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the same amount of light as the transmitted light when transmitted through one of the recording members is transmitted to the photoreceptor or the additional second photoreceptor. Instead of correcting the reference value based on a signal output value from the photoreceptor for detecting the non-transmitted light, the photoreceptor or the second photodetector for detecting the light is detected at a predetermined timing.
The reference value is corrected to the same value as the signal output value from the photoreceptor.

In such an image forming apparatus that detects the presence or absence of double feeding based on the result of comparison between the "output value of transmitted light" and a reference value, the reference value is corrected as follows. If this is the case, erroneous double-feed / single-feed detections caused by changes in the temperature or dirt amount of the light-emitting or light-receiving body can be greatly reduced. That is, the "output value of the transmitted light" at the time of single transmission may be detected, and the reference value may be corrected to the same value as the detection result. However, in the transport path, since one recording member is fed alone or a plurality of recording members are fed multiple times,
It is not known how many recording members have passed through the obtained transmitted light. For this reason, if the reference value is simply corrected to the same value as the “output value related to the transmitted light”, the erroneous detection of the number of transmissions of the transmitted light to the recording member is performed, whereby the double feed / single feed error detection is performed. However, there is a possibility that a problem that the problem easily occurs. Specifically, for example, when the reference value has to be corrected so as to be the same value as the output value of the transmitted light transmitted through one recording member, the output of the transmitted light transmitted through a plurality of recording members is By correcting the reference value to the same value as the value, erroneous detection of double feed / single feed is rather likely to occur. Therefore, in this image forming apparatus, the same amount of light as that transmitted when passing through one recording member is detected at a predetermined timing by the photoreceptor or the additional second photoreceptor. Then, the reference value is corrected to the same value as the signal output value from the light receiving body or the second light receiving body that detects this light. When the reference value is corrected in this way, the double feed / transfer caused by erroneously determining the number of transmissions of the transmitted light to the recording member may be performed.
While avoiding erroneous single-transmission detection, it is possible to obtain substantially the same operation as in the case where the reference value is corrected to be the same as the “output value related to transmitted light” in single transmission. This makes it possible to more reliably reduce the occurrence of erroneous double-feed / single-feed detection as compared with the case where the reference value is corrected based on the “output value of non-transmitted light”.

According to a fifth aspect of the present invention, there is provided a transport path for transporting a recording member, a light emitter for irradiating the transport path with an amount of light corresponding to a value of a supplied current, And a current value changing means for changing the value of the current, and detecting the transmitted light which is the light transmitted through the recording member in the transport path. In an image forming apparatus for detecting the presence or absence of double feeding of a recording member in the transport path based on a signal output value, non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member is detected. The current value is changed by the current value changing means based on a signal output value from the photoreceptor.

In this image forming apparatus, the amount of irradiation of the illuminant is changed by changing the value of the current supplied to the illuminant based on the "output value relating to the non-transmitted light". Then, the signal output value from the photoreceptor is indirectly changed according to the change in the irradiation light amount. When the signal output value is indirectly changed in this way, even if the “output value related to non-transmitted light” is changed in accordance with the change in the temperature or the amount of dirt of the light-emitting or light-receiving body, Such an output value "can be calibrated to the original value. By performing such calibration, it is possible to greatly reduce the amount of change in the “output value related to transmitted light” that changes with the change in the temperature and the amount of dirt.

According to a sixth aspect of the present invention, there is provided a transport path for transporting a recording member, a luminous body for irradiating light toward the transport path, and a signal output according to a value of a supplied current and an amount of received light. A signal output value from the photoreceptor, comprising: a photoreceptor for changing the value; and current value changing means for changing the value of the current, and detecting transmitted light that is the light transmitted through the recording member in the transport path. An image forming apparatus that detects the presence or absence of double feeding of a recording member in the transport path based on the photodetector that detects non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member. The current value is changed by the current value changing means on the basis of the signal output value from.

In this image forming apparatus, even if the "output value relating to non-transmitted light" is changed in accordance with a change in the temperature or the amount of dirt of the light-emitting body or the light-receiving body, supply to the light-receiving body is performed by the current value changing means. By changing the current, the “output value related to the non-transmitted light” can be calibrated to the original value. By performing such calibration, it is possible to greatly reduce the amount of change in the “output value related to transmitted light” that changes with the change in the temperature and the amount of dirt.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described below. First, a basic configuration of the copying machine according to the present embodiment will be described. FIG. 1 is a schematic diagram showing a schematic configuration of a copying machine according to the present embodiment. In FIG. 1, when a power switch (not shown) is turned on and the copy start key 3 is pressed while the original 2 is set on the original mounting glass 1, the copy operation starts. In this copying operation, first, the two lamps 4 emitting the reading light 3 are driven by a drive system (not shown) together with the moving mirror 5 and the two reflectors 6 to start moving rightward in the drawing. The moving mirrors 7 and 8 are driven by a driving system (not shown), and start moving in the same direction at half the speed of the moving mirror 4.

The reading light 3 emitted from the two lamps 4 moves rightward in the drawing while irradiating the original 2 on the original mounting glass 1 directly or via two reflectors 6. Then, the light is sequentially reflected on the original 1 and the moving mirrors 5, 7 and 8, and transmitted through the lens 9. Further, the light enters the dichroic mirror 10 and is dispersed for each of the three primary colors. The blue light, green light, and red light obtained by this dispersion form a blue separation image, a green separation image, and a red separation image on the CCDs 11B, 11G, and 11R, respectively. CCD1
Each of 1B, 11G, and 11R outputs a signal of a voltage value according to the light amount of the formed decomposed image.

FIG. 2 is a block diagram showing a part of the scanning circuit of the copying machine according to this embodiment. In the figure, CCD
The minute output signals from 11B, 11G, and 11R are respectively amplified in the amplifying / A / D conversion circuits 12B, 12G, and 12R for each pixel, and then converted from an analog signal to, for example, an 8-bit digital signal. . These digital signals are respectively synchronized with the synchronization memories 15B, 15G, 1G so as to be synchronized with the clock signal 14 from the clock generation circuit 13.
5R is temporarily stored as an image signal. These blue, green, and green colors stored in the synchronous memories 15B, 15G, and 15R.
The red image signal is sent to the image processing unit 16 at a timing such that images of the same area can be combined.

The image processing unit 16 applies a known γ correction circuit, a masking processing circuit, and a UCR processing circuit to the transmitted blue, green, and red image signals.
Processing such as correction, color turbidity removal, undercolor removal correction, and black signal extraction is performed to obtain yellow, magenta, cyan, and black image signals. These yellow, magenta, cyan, and black (hereinafter, also referred to as each color)
The image signals of the density change circuits 17Y, 17M, 17C, 1
Send to 7K.

Density changing circuits 17Y, 17M, 17C, 1
7K receives a density reduction signal or a density increase signal from a control circuit (not shown) due to depression of the light density key 22 or the high density key 23 on the operation panel 21, and a color density change key (not shown) When a color density change signal is received from the control circuit due to being pressed, density change processing is performed on each color image signal.

Density changing circuits 17Y, 17M, 17C, 1
Each color image signal passing through 7K is sent to laser driver circuits 18Y, 18M, 18C and 18K. These laser driver circuits 18Y, 18M, 18C, 18
K indicates that the semiconductor laser 1 is subjected to time-modulation processing for each pixel according to the size of the received image signal of each color.
9Y, 19M, 19C and 19K are driven. By this driving, the semiconductor lasers 19Y, 19M, 19C, 19K
Laser beams 20Y, 20M, 20C, and 20K are emitted from the image forming units 33Y, 33M, 33C, and 33, which will be described later.
Sent to K.

Here, the four image forming units 33Y, 33Y in FIG.
33M, 33C and 33K, the configuration other than the color of the toner to be used is almost the same. Therefore, the configuration will be described below by taking the yellow image forming unit 33Y located on the rightmost side in the drawing as an example. In addition, regarding the structure of the other image forming units, the same reference numerals as those of the yellow image forming unit with the suffixes of M, C, and K are shown in the drawings as the corresponding members, and description thereof is omitted. .

In the yellow image forming section 33Y shown in FIG.
Polygon mirror 24Y rotationally driven by 5Y
Reflect on top. For the reflected laser beam 20Y,
An optical correction process is performed by an unillustrated f · θ lens so that the photosensitive drum 27Y, which is rotationally driven clockwise in the diagram by a not-illustrated drive system, can be scanned at the same speed as the rotational speed. The writing light 26Y modulated by the optical correction process scans the surface of the photosensitive drum 27Y in a direction orthogonal to the rotation direction.

An unillustrated B.C. is located approximately 11 [mm] upstream in the rotational direction from the optical writing start position on the photosensitive drum 27Y. D sensor photo sensor is installed,
When the writing light 26Y is detected in accordance with the rotation of the photosensitive drum 27Y, the light is sent to a control circuit (not shown). Transmit the D signal.

In FIG. 1, a charging device 28Y, a developing device 29Y, a static elimination lamp 30Y, a transfer electrode 31Y, a cleaning device 32Y, and the like are provided around the photosensitive drum 27Y to uniformly charge the surface. . The yellow image forming section 33Y includes these devices including the photosensitive drum 27Y, the above-described scanner motor 25Y, polygon mirror 24Y, f · θ lens, and B.Y. It is composed of a D sensor photo sensor and the like.

The surface of the photosensitive drum 27Y, which has moved to a position facing the charging device 28Y with the rotation, is uniformly charged by the charging device 28Y, and then moves to a position facing the polygon mirror 24Y. Then, the above-mentioned writing light 26Y is irradiated at the facing position, and thereby carries a yellow electrostatic latent image. When the yellow electrostatic latent image is moved to a developing position which is a position facing the developing device 29Y with the rotation of the photosensitive drum 27Y, the yellow toner moving from the developing device 29Y is adhered to the yellow electrostatic latent image. Is developed. The developing device 29Y that uses yellow toner as a developer is:
The yellow toner is attached to the yellow electrostatic latent image by a so-called magnetic blade method.

The surface of the photoreceptor drum 27Y on which the yellow toner image has been developed is discharged from the position of the yellow electrostatic latent image when passing through the position facing the charge removing lamp 30Y, and then is moved to the position facing the transfer electrode 31Y. To the transfer position.

A transfer bias is applied to the transfer electrode 31Y by a power source (not shown), and a transfer electric field is formed at the transfer position by a potential difference between the transfer electrode 31Y and the photosensitive drum 27Y.

The photosensitive drum 27Y moved to the transfer position
The upper yellow toner image is superimposed on the transfer paper 50 conveyed by a conveyance belt described later, and is transferred onto the transfer paper 50 by a synergistic effect of the pressing force between the photosensitive drum 27Y and the conveyance belt and the transfer electric field. Is done.

When the surface of the photosensitive drum 27Y that has passed the transfer position passes the position facing the cleaning device 32Y, residual toner that has not been transferred onto the transfer paper 50 is scraped off. Then, it again moves to a position facing the charging device 28Y and is uniformly charged.

On the lower side of the copying machine main body, a transport belt 36 stretched by a roller 34 and a drive roller 35 driven to rotate counterclockwise in the figure by a drive system (not shown).
Are arranged. The conveying belt 36, which rotates counterclockwise in the drawing together with the driving roller 35, has a rotation path of the image forming units 33Y, 33M, 33C, 33K of the respective colors.
The transfer paper 50 discharged from a paper feed cassette 42 described later is sequentially moved to these transfer positions. The image forming units 33Y, 33M, 33 of the respective colors are placed on the transfer paper 50 moving in this manner.
By C and 33K, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially superimposed and transferred, whereby a full-color image is formed. Then, the transfer paper 50 on which the full-color image is formed
Are the pressing roller 37a and the heating roller 3 in the fixing device 37.
7b, and is subjected to a fixing process of the full-color image, and then discharged outside the apparatus.

A pair of registration rollers 38, a paper detection device 39, a double feed detection device 40, a paper feed roller 41, a paper feed cassette 42, and the like are disposed on the right side of the transport belt 36.

In the paper feed cassette 42, a plurality of transfer papers 5
In the transfer paper 50, the paper feed roller 41 is in contact with the uppermost one of the transfer papers 50. When the paper feed roller 41 is rotated clockwise in the figure by a drive system (not shown), the transfer paper 50 located at the uppermost position is discharged from inside the paper feed cassette 42 toward between the rollers of the registration roller pair 38. It has become so.

Registration roller pair 38 and paper feed cassette 42
A paper detecting device 39 and a double feed detecting device 40 are disposed between the two.

A double feed detecting device 40 including a light emitting device 40a, a light receiving device 40b, a power supply (not shown), an amplifier circuit, and a control unit.
In, the transfer paper 50 discharged from the paper feed cassette 42 toward the registration roller pair 38 passes between the light emitting device 40a and the light receiving device 40b. When the transfer paper 50 enters the optical path of the light emitted from the light emitter 40a toward the light receiver 40b, the light passes through the transfer paper 50 and becomes transmitted light, and is then detected by the light receiver 40b. The amount of transmitted light decreases with an increase in the number of superposed transfer papers 50 entering the optical path, and the light receiver 40b increases the output voltage value with a decrease in the amount of transmitted light. The control unit of the double feed detection device 40 includes a light receiver 40b that detects transmitted light.
The double feed of the transfer paper 50 is detected based on the output voltage value from the printer. Specifically, the control unit includes a RAM (not shown)
A reference value for this output voltage value is stored in data storage means such as OM, and when the output voltage value from the light receiver 40b for detecting transmitted light exceeds this reference value, it is determined that double feed has occurred. to decide.

FIG. 3 is a circuit diagram showing a main circuit of the double feed detecting device 40. In FIG. 3, the light emitting device 40a and the light receiving device 40b are respectively supplied with +5 by a power source (not shown).
[V] is supplied. In the light emitter 40a, the supply of this voltage causes a current to flow to GND via the resistor R1 and the LED, which is a light emitter, thereby causing L to flow.
The ED emits light. On the other hand, in the light receiver 40b, the current flows through the following three paths.
That is, a path to GND via the collector and the emitter of the transistor T and the resistor R3, and G through the collector and the emitter of the resistor R2 and the phototransistor PT.
The current flows separately into a path leading to ND and a path leading to GND via the resistor R2, the base and the emitter of the transistor T. However, when the phototransistor PT does not receive any light, all the current that has passed through the resistor R2 due to the fact that no collector current flows in the phototransistor PT is used as the transistor T2.
Base current. Therefore, the emitter current of the transistor T becomes the maximum, and the signal emitted to the resistor R3 has the maximum voltage value. The phototransistor PT allows a collector current of a value corresponding to the amount of received light to flow. L
When light from the ED is received by the phototransistor PT and a collector current flows therein, the current flowing to the base of the transistor T decreases. Specifically, the base current value of the transistor T is a value obtained by subtracting the collector current value of the phototransistor PT from the value of the current flowing through the resistor R2. Therefore, as the amount of light received by the phototransistor PT increases, the base current value of the transistor T decreases. Then, as the base current value decreases, the collector current value of the transistor T decreases.
The voltage across the resistor R3 is output to the control unit 40c as a value proportional to the emitter current of the transistor T. As a result, as the amount of light received by the phototransistor PT increases, the output voltage value of the light receiver 40b decreases. However, the relationship between the amount of received light and the output voltage value is not directly proportional, and the ratio of the voltage change is small in the region where the amount of received light is relatively small, and the ratio of the voltage change is large in the region where the amount of received light is relatively large. .

In the copying machine according to the present embodiment, the photodetector 4 for detecting the transmitted light L2 transmitted through one transfer paper 50
The output voltage value which is the signal output value from 0b is, for example, 3.
The light emission amount of the LED is adjusted to be 48 [V]. Specifically, when a variable resistor (not shown) is operated by an operator, the supply voltage value from the power supply is slightly shifted from +5 [V], thereby adjusting the light emission amount of the LED. In the following description, the voltage gain of the light receiver 40b is set to 1 for convenience.

When the light receiver 40b detects the transmitted light L2 transmitted through one transfer sheet 50, an analog voltage of 3.48 [V] is input to the input terminal of the control unit 40c. The control unit 40c includes an A / D conversion circuit (not shown), converts an analog voltage input thereto into a digital signal, and determines an output voltage value from the light receiver 40b.

2 where the phototransistors PT overlap each other.
When the transmitted light transmitted through the transfer papers 50 is detected, the output voltage value from the light receiver 40b becomes, for example, 4.49 [V]. Therefore, the control unit 40c is an intermediate value between the output voltage value of 3.48 [V] for one transfer sheet and the output voltage value of 4.49 [V] for two transfer sheets. 0
[V] is stored in the data storage means as a reference value. If the output voltage value from the light receiver 40b exceeds this reference value, it is determined that "multiple feeding has occurred", the copying operation is interrupted, and a message "double feeding has occurred" is displayed on a display unit (not shown). Display a warning.

Similarly to the double feed detecting device 40, the light emitting device 39a
The paper detection device 39 including the power supply, the amplification circuit, and the control unit (not shown)
The transfer paper 50 discharged from inside 2 toward the pair of registration rollers 38 passes between the light emitting device 39a and the light receiving device 39b. When the transfer paper 50 enters the optical path from the light emitter 39a to the light receiver 39b, the light received by the light receiver 39b changes from non-transmission light to transmission light. As a result, the amount of light received by the light receiver 39b is significantly reduced, and the output voltage value from the light receiver 39b is greatly increased. The control unit of the paper detecting device 39 detects the leading end of the transfer paper 50 by such a large increase in the output voltage value.

When the paper detecting device 39 detects the leading end of the transfer paper 50, the paper feed roller 41 stops rotating after continuing the rotation for a predetermined time based on the detection result. With this suspension,
The transfer of the transfer paper 50 is stopped in a state where the leading end of the transfer paper 50 enters between the rollers of the registration roller pair 38.

The registration roller pair 38 is started to rotate by a drive system (not shown) at a timing when the transfer paper 50 and the yellow toner image on the photosensitive drum 27 can be overlapped at the transfer position of the yellow image forming section. The transfer paper 50 is discharged onto the conveyor belt 36.

In the above configuration, the lower side of the inside of the copying machine main body is described as follows: "in the paper feed cassette 42 → in the double feed detecting device 40 → in the paper detecting device 39 → in each image forming section → in the fixing device 37 → out of the machine. The transfer path of the transfer paper 50 is formed.

Next, the characteristic configuration of the copying machine according to this embodiment will be described. The double feed detecting device 40 is provided with the transfer paper 5
0 crosses the optical path from the light emitter 40a to the light receiver 40b and before the next transfer paper 50 reaches the optical path, the phototransistor P does not pass through the transfer paper 50 and
The non-transmitted light L1 that has reached T directly is detected by the light receiver 40b. On the other hand, the data storage means of the control unit 40c of the double feed detecting device 40 stores a standard voltage value output from the light receiver 40b which has detected the non-transmitted light L1 under a predetermined environment such as normal temperature and normal humidity. ing.

Based on the output voltage value (output value related to the non-transmitted light) from the light receiver 40b that detects the non-transmitted light L1, the control unit 40c outputs the output voltage value from the light receiver 40b that detects the transmitted light L2. (The output value of the transmitted light) is corrected, and when the correction result exceeds the reference value, it is determined that the double feed is performed. Specifically, the “output value related to non-transmitted light” is subtracted from the standard voltage value, and the amount of change of the “output value related to non-transmitted light” from the standard voltage value (hereinafter, referred to as a voltage shift amount) Is calculated.
The data storage unit stores a calculation formula for calculating a correction coefficient for “output value of transmitted light” based on the voltage shift amount. This calculation formula is obtained based on the relationship between the above-mentioned voltage shift amount obtained by a preliminary test and the rate of change of the “output value related to transmitted light”. When the voltage shift amount is zero, that is, L
When the temperature of the ED and the phototransistor and the amount of dirt do not change and the “output value of the transmitted light” is equal to the standard voltage value, the correction coefficient is 1. After calculating the amount of voltage shift, the control unit 40c calculates a correction coefficient using the amount of voltage shift and the above formula, and stores it in the data storage unit. Then, when the transmitted light is detected by the light receiver 40b, the light is corrected by multiplying by a correction coefficient storing the “output value of the transmitted light”. When corrected in this way, for example, even if the “output value related to the transmitted light” is changed with the change in the temperature or the amount of dirt of the LED or the phototransistor,
The difference between the corrected “output value of transmitted light” and the reference value can be made closer to the original value. As a result, it is possible to reduce the "output value of transmitted light" exceeding the reference value, which is caused by a change in the temperature or the amount of dirt of the LED or the phototransistor.

As described above, according to the copying machine of this embodiment, the LE
It is possible to reduce the "output value of transmitted light" exceeding the reference value caused by a change in the temperature of D or the phototransistor or the amount of dirt.
There is an excellent effect that single transmission error detection can be reduced.

In an image forming apparatus such as the copying machine of the present embodiment, which detects the presence or absence of double feeding based on the result of comparison between the "output value of transmitted light" and a reference value, If the difference between the “output value related to transmitted light” and the reference value is close to the original value, it is possible to reduce the “output value related to transmitted light” exceeding the reference value caused by the change in the temperature and the amount of dirt. be able to. As a method of bringing the difference between the “output value related to transmitted light” after the change and the reference value close to the original value, in addition to the method of correcting the “output value related to transmitted light” as described above, There is a method of correcting the value. Therefore, in the copying machine according to the present invention, the reference value may be corrected based on the “output value related to non-transmitted light”. Specifically, for example, the reference value may be shifted by the same amount as the shift amount of the “output value relating to the transmitted light” due to the change in the temperature or the amount of dirt.

In the present embodiment, the standard voltage value is subtracted from the “output value related to non-transmitted light” to calculate the voltage shift amount of the “output value related to non-transmitted light”. A copier in which the correction coefficient is calculated by using the correction coefficient and the "output value related to the transmitted light" is corrected by multiplication of the correction coefficient has been described. However, the correction method according to the present invention for the reference value or “output value related to transmitted light” is not limited to this method, and may be any correction method based on at least “output value related to non-transmitted light”. For example, a database in which the “output value related to non-transmitted light” and the correction value of the reference value or the “output value related to transmitted light” are stored in the data storage unit, and “data obtained from the light receiver 40b” The correction target may be specified based on the “output value related to non-transmitted light”, and the reference value or “output value related to transmitted light” may be corrected to the same value as the specified result. Further, for example, the change rate may be calculated by dividing the “output value related to non-transmitted light” by the standard voltage value, and multiplying this by the “output value related to transmitted light”.

Next, a description will be given of a copying machine of an embodiment in which a more characteristic configuration is added to the copying machine of the above embodiment.
FIG. 4 is a circuit diagram showing a main circuit of the double feed detecting device 40 in the copying machine of the present embodiment. As illustrated, the double feed detection device 40 includes a light emitting device 40a, a first light receiving device 40b,
0c, the second light receiver 40d and the ND filter 40
e. First light receiver 40b, second light receiver 40
Each of the elements d detects light from the light emitter 40a. The first light receiver 40b is a light receiver for double feed detection, and sends an “output value related to non-transmitted light” and an “output value related to transmitted light” to the controller 40c. The second light receiver 40d is a light receiver for correction, and detects the filter transmitted light L3 transmitted through the ND filter 40e. The ND filter 40e has the same light transmittance as the transfer paper 50, and the light amount of the filter transmitted light L3 is equal to the transmitted light L2 of one transfer paper 50.
Of light. For this reason, the second light receiving body 40d
This means that the same amount of transmitted light L3 as the transmitted light L2 of one transfer sheet 50 is detected. In the copying machine, the light transmitted through the filter L3 is transmitted through the ND filter 40e.
The device is devised so as not to be double transmitted light transmitted through the transfer paper 50 and the transfer paper 50. Specifically, for example, the light emitter 40a is disposed at a position where light can be irradiated both inside and outside the transfer path of the transfer paper 50, and the second light receiver 40d,
A device for disposing the ND filter 40e outside the transfer route, a device for disposing a plurality of reflecting mirrors, and preventing light to be received by the second photoreceptor 40d from passing through the transfer route are provided. I have.

The control unit 40c in the copying machine of this embodiment
Does not correct the “output value of transmitted light” based on the “output value of non-transmitted light”,
The reference value is corrected so that it becomes the same value as the output voltage value (output value related to the light transmitted through the filter) from the second light receiver 40d that detects No.3. When the reference value is corrected in this way, it is possible to avoid erroneous detection of double feed / single feed caused by erroneously determining the number of times of transmission of the transmitted light to the transfer paper 50 while avoiding erroneous detection.
It is possible to obtain substantially the same result as in the case where the reference value is corrected to be the same as the “output value relating to the transmitted light” at the time of single transmission. In this way, compared with the case where the reference value is corrected based on the “output value related to the non-transmitted light”,
The occurrence of erroneous single-transmission detection can be reliably reduced.

In this embodiment, as a method of obtaining a value substantially equal to the output value of the transmitted light transmitted through one sheet of transfer paper, the second photoreceptor 40d and the ND filter 40e are used.
Has been described so as to acquire the “output value related to the light transmitted through the filter”, but the value may be acquired as follows. That is, the movable filter capable of exhibiting light transmittance equivalent to that of the transfer paper 50 is
The light may be moved by moving the optical filter from 0a to the optical receiver 40b at a predetermined timing in the optical path, and the optical filter 40b detects the transmitted light transmitted through the mobile filter and transmitted by the optical filter. In addition, a second light emitting device capable of emitting the same amount of light as transmitted light transmitted through one transfer sheet is provided, and light emission of the first light emitting device for double feed detection is turned off and light emission of the second light emitting device is turned on. You may make it acquire by making it do.

Further, in the above embodiment and the present embodiment, the copying machine in which the "output value relating to the transmitted light" and the reference value are corrected has been described. Even if the current value supplied to the LED or the phototransistor PT is changed, the occurrence of erroneous double feed / single feed detection can be reduced. Specifically, for example, a D / A conversion circuit is provided in the control unit 40c, and the D / A conversion circuit is provided.
A current may be supplied from the A conversion circuit to the light-emitting device 40a or the light-receiving device 40b, and the value of the current supplied to the light-emitting device 40a or the light-receiving device 40b may be changed based on the “output value related to the non-transmitted light”. Good. With this configuration, even when the “output value related to the non-transmitted light” is changed according to the change in the temperature or the amount of dirt, the “output value related to the non-transmitted light” can be corrected to the original value. . As a result, it is possible to greatly reduce the amount of change in the “output value related to transmitted light” that changes with changes in temperature and the amount of dirt.

Also, a copying machine using a so-called one-component developer made of a toner has been described. However, an image forming apparatus using a two-component developer made of a toner and a magnetic carrier, and a wet image forming device made up of a toner and a liquid carrier are used. The present invention can be applied to a device.

Further, the copying machine for directly transferring the toner image on the photosensitive drum 27 onto the transfer paper 50 has been described.
The present invention is also applicable to an image forming apparatus that performs transfer via an intermediate transfer member such as an intermediate transfer belt.

Also, a copying machine having only one sheet feed cassette 42 as a recording member supply device has been described.
The present invention is also applicable to an image forming apparatus including a plurality of supply devices. However, in such an image forming apparatus, it is desirable to dispose the LED and the phototransistor PT at a position where transmitted light of all recording members supplied from each supply device can be detected. By arranging in this way, it is possible to detect the presence or absence of double feeding for all the recording members supplied from each supply device.

[0058]

According to the first or second aspect of the present invention, even if the "output value relating to the transmitted light" is changed in accordance with the change in the temperature of the light-emitting body or the light-receiving body or the amount of dirt, the value before the change remains unchanged. Since the presence / absence of double feed is detected based on the “output value related to transmitted light” corrected so as to be close to each other, it is possible to reduce double feed / single feed erroneous detection caused by a change in the temperature or the amount of dirt. effective.

According to the third aspect of the present invention, it is possible to reduce the "output value of transmitted light" exceeding the reference value, which is caused by a change in the temperature or the amount of dirt of the light emitting body or the light receiving body.
There is an excellent effect that double feed / single feed erroneous detection caused by the change can be reduced.

According to the fourth aspect of the present invention, the reference value is set to "non-transmitted light" while avoiding erroneous detection of double feed / single feed caused by erroneously determining the number of transmissions of transmitted light to the recording member. Output value according to "
There is an excellent effect that the occurrence of double feed / single feed erroneous detection can be reliably reduced.

According to the fifth or sixth aspect of the present invention, even if the temperature or the amount of dirt of the light emitting body or the light receiving body is changed, the amount of change of the “output value related to transmitted light” which changes with the change is greatly increased. Therefore, there is an excellent effect that erroneous detection of double feed / single feed caused by a change in the temperature or the amount of dirt can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a copying machine according to an embodiment.

FIG. 2 is a block diagram showing a part of a scanning circuit of the copying machine.

FIG. 3 is a schematic diagram showing a configuration of a main part of a double feed detecting device of the copying machine together with peripheral devices.

FIG. 4 is a circuit diagram showing a main part circuit of the double feed detecting device in the copying machine of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Original mounting glass 2 Original 3 Copy start key 4 Lamp 5 Moving mirror 6 Reflector 7, 8 Moving mirror 9 Lens 10 Dichroic mirror 11 CCD 12 Amplification / A / D conversion circuit 13 Clock generation circuit 14 Clock signal 15 Synchronous memory 16 Image Processing unit 17 Density changing circuit 18 Laser driver circuit 19 Semiconductor laser 20 Laser light 21 Operation panel 22 Thin density key 23 High density key 24 Polygon mirror 25 Scanner motor 26 Writing light 27 Photoconductor drum 28 Charging device 29 Developing device 30 Static elimination lamp 31 Transfer electrode 32 Cleaning device 33 Image forming unit 34 Roller 35 Drive roller 36 Conveying belt 37 Fixing device 38 Registration roller pair 39 Paper detector 40 Double feed detector 40a Light emitter (light emitter) 40b Photodetector (Phototransistor mounted as photoreceptor) 40c Control unit 40d Second photoreceiver 40e ND filter 50 Transfer paper

Claims (6)

[Claims] A light-emitting element for irradiating a light toward a recording member transport path in the image forming apparatus; and a light-receiving element for changing a signal output value in accordance with an amount of received light. A step of detecting transmitted light that is the light transmitted through the member, and a step of detecting the presence or absence of double feeding of the recording member in the conveyance path based on a signal output value from the photoreceptor that detects the transmitted light. Wherein the transmitted light is detected based on a signal output value from the photoreceptor that detects non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member. A double feed detection method, comprising correcting a signal output value from the photoreceptor to be detected, and detecting the presence or absence of the double feed based on a correction result. 2. A transport path for transporting a recording member, a light emitter for irradiating light toward the transport path, and a photoreceptor for changing a signal output value in accordance with an amount of received light. An image forming apparatus that detects the presence or absence of double feeding of a recording member in the transport path, based on a signal output value from the light receiving body that detects the transmitted light that is the light transmitted through the recording member, A signal output from the photoreceptor when the transmitted light is detected based on a signal output value from the photoreceptor that detects the non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member. An image forming apparatus that corrects a value and detects the presence or absence of the double feed based on a correction result. 3. A transport path for transporting a recording member, a light emitter for irradiating light toward the transport path, and a photoreceptor for changing a signal output value in accordance with an amount of received light. The multi-feed of the recording member in the transport path is performed based on a comparison result between a signal output value from the photoreceptor that detects the transmitted light, which is the light transmitted through the recording member, and a preset reference value. In the image forming apparatus for detecting the presence or absence of, based on a signal output value from the photoreceptor that detects non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member,
A signal output value from the photoreceptor when detecting the transmitted light,
Alternatively, the image forming apparatus is characterized in that the reference value is corrected, and the presence or absence of the double feed is detected based on the comparison result of the correction result. 4. The image forming apparatus according to claim 3, wherein the same amount of light as the transmitted light when transmitted through one of the recording members is detected at a predetermined timing by the photoreceptor or the additional second photoreceptor. Instead of correcting the reference value based on the signal output value from the light receiving body detecting the non-transmitted light, the same value as the signal output value from the light receiving body or the second light receiving body detecting the light is used. An image forming apparatus for correcting the reference value. 5. A transport path for transporting a recording member, a luminous body for irradiating the transport path with an amount of light corresponding to a value of a supplied current, and a signal output value according to an amount of received light. A photoreceptor to be changed, and current value changing means for changing a value of the current, based on a signal output value from the photoreceptor for detecting transmitted light which is the light transmitted through a recording member in the transport path. In the image forming apparatus for detecting the presence or absence of double feeding of the recording member in the transport path, the image forming apparatus detects the non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member. An image forming apparatus, wherein the current value is changed by the current value changing means based on a signal output value. 6. A transport path for transporting a recording member, a luminous body for irradiating light toward the transport path, and a light receiving element for changing a signal output value according to a supplied current value and a received light amount. Body, and current value changing means for changing the value of the current, based on a signal output value from the photoreceptor for detecting transmitted light, which is the light transmitted through the recording member in the transport path. In an image forming apparatus for detecting the presence / absence of double feeding of a recording member in a conveyance path, a signal output value from the photoreceptor for detecting non-transmitted light that is the light that has reached the photoreceptor without passing through the recording member An image forming apparatus wherein the value of the current is changed by the current value changing means based on the following.