JP2003267589A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent incorrect detection of jamming by the influence of paper powder and the like by adjusting the quantity of light of a light emitting element of an optical sensor at an interval corresponding to the number of sheets of fed paper. <P>SOLUTION: A CPU 401 controls the dimming of a sensor M202 and a sensor N203 as a reflection-type optical paper detecting mechanism. In dimming the sensor M202 and the sensor N203, the dimming is performed through a sensor driver circuit 404. A counter 502 counts the number of sheets of fed paper in a paper feeding unit 201. A predetermined count value calculated on the basis of an endurance time and a premeasured amount of paper powder, is set in an ROM 504, the marking such as standing a flag is performed to inform the necessity of dimming both of the sensor M202 and the sensor N203 to the CPU 401, when the counter 502 reaches a value same as the set value, and the dimming is performed corresponding to stop sequence to adjust a light receiving level to a predetermined target value. <P>COPYRIGHT: (C)2003,JPO

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, and more particularly, to a light emitting element that emits light as a paper presence / absence detecting means in a paper transport path, and a light receiving element that receives light output from this light emitting element. And an image forming apparatus having an element.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, a photo interrupter, which is a mechanical detection method, is used as a paper detection means for a paper conveyance path. This photo interrupter has a movable plate between the light emitting element and the light receiving element in the photo coupler, and when the recording paper is not detected, the light from the light emitting element side can reach the light receiving element side without being blocked. , A constant voltage is output.

On the other hand, when detecting a recording sheet,
When the recording sheet hits the movable plate, the plate moves, and the light output from the light emitting side is blocked before reaching the light receiving side, so no output is output. The presence / absence of the recording paper can be determined by the presence / absence of both output voltages. However, immediately after the recording paper has passed, the plate tries to return to its original position by the force of the spring or the like. At this time, the plate returns to the original position while vibrating due to the recoil of the spring, so the output level vibrates near the presence / absence level of the paper, and it takes time to normally detect the presence or absence of paper. is there.

In order to perform paper feeding at high speed and accurately,
It is necessary to keep the paper interval constant, and for that purpose, it is necessary to judge the leading edge and the trailing edge of the recording paper. If there is chattering due to mechanical vibration of the photo interrupter described above, the trailing edge of the recording paper cannot be detected accurately. Optical paper detection means have been used to prevent this and detect the presence or absence of paper at high speed. Among the optical paper detecting means, the reflection type optical paper detecting means utilizes the fact that the output differs depending on the difference in the reflection intensity between the recording paper and the plate made of a material having a high reflectance. It is a detection means and a high-speed detection means.

In the optical paper detecting means, the light emitting element is
The more the current is passed, the higher the brightness becomes, and the large dynamic range depending on the presence / absence of the medium can be obtained, so that the reliability of the detection accuracy is improved. However, increasing the current value causes a reduction in life. Even in the case of a photo interrupter, it can be said that it is an optical type in that it uses a photo coupler, but it is equipped with a light emitting / receiving element within a short distance, and even a small amount of light is reliably detected by shielding with a black member that does not affect the reflection. it can.

On the other hand, in the optical paper detection means, since the medium itself to be shielded has a high transmittance and a high reflectance, it is required to secure a light amount that can be reliably discriminated. Therefore, when the amount of light is set to be low, it is advantageous for the life, but the dynamic range is narrowed, so that the degree of influence of the medium and the degree of influence of dirt become large, and there is a possibility of erroneous detection. Conventionally, as a countermeasure for this,
There is used means for adjusting the amount of light emitted from the optical paper detection means and keeping the output voltage constant when the main power of the apparatus is turned on or immediately after the copy job starts or ends.

[0007]

In the method of adjusting the characteristic deterioration of the reflection type optical detecting means during operation, only when the main power is turned on, the adjustment interval is increased in a high-speed machine with a large number of printed sheets. In some cases, it has passed and is insufficient. In other words, a large amount of printing is executed between the main power supply being turned on and the power being turned off until the next power is turned on. ,
It accumulates on the light emitting element or the light receiving element of the reflection type optical detecting means.

As a result, the accuracy of the sheet detection may be lowered, which may cause an erroneous jam detection. If a method that adjusts before and after a job is adopted, if the number of sheets printed in one job is very large, the paper dust generated during paper transport will also be reflected in the same way. It accumulates on the light emitting element or the light receiving element of the expression detecting means. As a result, the accuracy of detecting the paper may be reduced, which may cause an erroneous jam detection. Further, since all the optical paper detection mechanisms are adjusted at the timing, there is a problem that the adjustment takes time in a device having a plurality of optical paper detection mechanisms.

The present invention has been made in view of the above problems, and an object of the present invention is to adjust the light amount of the light emitting elements of the optical sensor at intervals according to the number of fed sheets, and An object of the present invention is to provide an image forming apparatus having an optical sensor that does not cause false detection of jam due to influence.

[0010]

SUMMARY OF THE INVENTION In order to achieve such an object, the present invention provides a conveying member and a conveying path for conveying a sheet, and the presence / absence of the sheet in the conveying path. In an image forming apparatus including an optical sensor having a light emitting element for detecting a light emission and a light receiving element, and a driver for changing the amount of emitted light of the optical sensor arranged in the conveyance path, a paper feed for feeding the paper. Section and a counter for counting the number of sheets fed from the sheet feeding section, and adjusts the amount of light emitted from the optical sensor according to whether the value of the counter reaches a predetermined value or not. It is characterized by

The invention described in claim 2 is the same as claim 1.
In the invention described in (3), the amount of light emitted from the optical sensor is adjusted when the sheet conveyance is stopped when the image forming apparatus self-maintains.

The invention described in claim 3 is the same as claim 1
In the invention described in (1), there are a plurality of the optical sensors, and the optical sensors are arranged in the paper feeding unit.

According to a fourth aspect of the present invention, there is provided a conveying member for conveying a sheet and a conveying path, an optical sensor having a light emitting element and a light receiving element for detecting the presence or absence of the sheet on the conveying path, and the conveying section. In an image forming apparatus equipped with a driver for changing the amount of light emitted from an optical sensor arranged on a road, a plurality of paper feed units for feeding the paper and a number of paper fed from the paper feed unit are set. When the optical sensor has a counter for counting and the optical sensor is provided on a common conveyance path in the paper feeding operation from the plurality of paper feeding units, the total value of the counters for each paper feeding unit is It is characterized in that the amount of light emitted from the optical sensor is adjusted according to whether or not the predetermined value is reached.

The invention described in claim 5 is the same as claim 1.
Alternatively, in the invention described in the paragraph 4, the optical sensor is characterized in that the light emitting element and the light receiving element are arranged adjacent to each other, and a reflection mechanism is installed on the opposite side.

The invention described in claim 6 is the same as claim 1.
Alternatively, in the invention described in (4), when the emitted light amount of the optical sensor is adjusted, the value of the counter corresponding to the optical sensor whose light amount is adjusted is reset.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a diagram showing an internal structure of a main body of an image forming apparatus to which the present invention is applied. This image forming apparatus is
A plurality of (34, 35, 36, 37) paper feed units (stages) equipped with a reflection type optical detection mechanism capable of adjusting the amount of emitted light as a means for determining the presence or absence of paper are arranged, and a large-capacity paper feed is performed. The device 15 may be attached. Also, the paper feeding unit 3
4, 35 can store only recording papers of relatively small size such as A4 size and B5 size, but the paper feed units 36, 37 can store large size of A3 size or B4 size to recording papers of A4, B5 size. Has become.

The image forming apparatus according to the present embodiment has a main body image output unit 10 for outputting a document image on a recording sheet, a main body image input unit 11 for reading the data of the original image, and an automatic main body image input unit 11 above the main body image input unit 11. The document feeder 12 is provided.

In the main body image input section 11, the light source 2 for scanning the original placed on the original table on the upper surface of the input section in the left-right direction in FIG.
Light is emitted from 1. The light is reflected by the document and an optical image is formed on the CCD 26 through the mirrors 22, 23, 24 and the lens 25. In the CCD 26, the formed image is converted into an electric signal and becomes digital image data. The image data is subjected to image conversion according to the user's request and stored in an image memory (not shown).

At the time of outputting an image, the main body image output section 10 calls the image data stored in the image memory, reconverts the digital signal into an analog signal, and the optical irradiating section 27 outputs the laser beam as an optical signal to the scanner 28. The photosensitive drum 31 is irradiated with light through the lens 29 and the mirror 30 and scans the photosensitive drum 31. As a result, an electrostatic latent image corresponding to the original image is formed on the photosensitive drum 31.

Next, the developing device 33 deposits toner on the electrostatic latent image and transfers it onto the recording paper conveyed inside the main body. At this time, the photosensitive drum 3 is charged by the chargers 38, 39 and 40.
A potential is formed on the photosensitive drum 1, and the photosensitive drum 31 and the recording paper are separated. Further, the fixing roller 32 fixes the toner on the recording paper. After that, the recording paper is discharged to the outside of the main body image output unit 10, and the post-processing device 14 performs post-processing such as stapling and binding according to the user's request.

When the number of copies reaches a predetermined number, the copy operation is temporarily stopped and self-maintenance is performed. The chargers 38, 39, 40 are configured to discharge from the wire to the photosensitive drum and the recording paper, and the discharge can be uneven due to dirt from the toner, so the number of sheets output from the main body image output unit 10 is counted. Then, when the number of sheets reaches the predetermined number, the self-maintenance for temporarily stopping the copying operation and cleaning the wire is required.

Next, the recording paper feeding system will be described.
FIG. 2 is an enlarged view of the paper feed unit (stage) of FIG. Paper feeder 3
6 includes a sheet feeding roller 204, a sheet feeding clutch 207, a pulling roller 205, a pulling clutch 206, a pickup solenoid 208, a pickup roller 20.
9 and a sensor M20 which is a reflection type optical paper detection mechanism
2. A paper feeding unit 201 including a sensor N203 is attached. A similar sheet feeding unit 211 is attached to the sheet feeding section 37.

At the time of paper feeding, first, a paper feeding motor outside the drawing is turned on. The paper feed clutch 207 repeats ON / OFF according to the paper feed timing signal sent from the controller, and transmits the power of the paper feed motor to the paper feed roller 204. At this time, the recording paper 210 is fed to the paper feed roller 20.
Each sheet is fed due to the difference in frictional force between the fourth and second sheets, and the sensor M202 detects the presence of the sheet. The pickup solenoid 208 is turned on when the sensor M202 is turned on, and the pickup roller 209 is raised.
Make sure that the second and subsequent sheets are not fed.

The paper feed clutch 207 is turned off at a constant timing by the detection signals of the sensor M202 and the sensor N203. Further, a sensor N203 is provided in front of the sensor M202 via the paper feed roller 204, and both sensors detect the timing at the time of continuous paper feed and at the same time are used as a detection device such as a paper jam.

When the feeding operation of the first sheet is completed, the pickup solenoid 208 is turned off, and the pickup roller 209 is lowered again to prepare for feeding the next sheet. When feeding the second and subsequent sheets, the sheet feeding clutch 207 is turned on again and the same operation is performed.

If a paper jam occurs in the paper feed section for some reason, it may stop with the leading edge of the paper between the sensor M202 and the sensor N203. If each of the sensor M202 and the sensor N203 has a counter, the counter of the sensor M becomes one more than the counter of the sensor N, and in the control of temporarily suspending the paper feeding operation at a certain number of times and performing light control, Since the two sensors dimming at different timings, the efficiency of the device deteriorates.

On the other hand, by providing only one counter in the paper feeding unit 201, the load on the CPU can be reduced, and the dimming of a plurality of sensors can be performed at the same timing, improving the efficiency of the apparatus. There is.

3 (a) and 3 (b) are cross-sectional structural views of the optical paper detection mechanism used in the present invention. FIG. 3 (a) is when there is no paper and FIG. 3 (b) is with paper. It is a block diagram at the time. The optical paper detection mechanism used in this embodiment is a reflection type sensor and uses a prism as the reflection plate, but the same applies when the reflection plate is a mirror. A light emitting element 302 and a light receiving element 303 are stacked on the sensor substrate 301,
The light emitting element 302 and the light receiving element 303 are covered with a cover 304.

A mirror or prism 305 is installed so as to face the sensor substrate 301, and when there is no paper in FIG. 3A, the light emitted from the light emitting element 302 is reflected by the prism 30.
5 is reflected, and the reflected light is detected by the light receiving element 303.
On the other hand, when the paper shown in FIG.
The light from the recording sheet 306 is blocked by the recording sheet 3 and
Since the reflectance of 06 is lower than that of the prism 305, the output of the light receiving element 303 becomes small, and the presence or absence of the recording paper can be determined by the difference in the received light intensity.

However, the light emitting element 302 and the light receiving element 303
When a current is applied to the device, the amount of light emission is weakened or the light receiving sensitivity is deteriorated depending on the amount of current and time. for that reason,
It is necessary to periodically adjust the current of the light emitting element to keep the output of the light receiving element 303 constant. In addition, since the output varies depending on the mechanical inclination at the time of attachment and the difference in sensitivity between the light emitting element 302 and the light receiving element 303, each optical system must make this adjustment.

FIG. 4 is a simplified diagram of the sensor driver circuit and CPU of the reflection type optical paper detection mechanism shown in FIGS. 3 (a) and 3 (b). LED which is a light emitting element from the CPU 401
8 bits or 16 bits corresponding to the emission intensity of 302
The digital value of is output. The digital value is converted into an analog voltage by the D / A converter 402, and a constant current for driving the LED 302 is output by the operational amplifier 407 to drive the LED 302 with a constant current.

Photodiode 303 which is a light receiving element
When the reflected light from the prism 305 is received, a current flows that is approximately proportional to the received light intensity. The operational amplifier 408 amplifies the output voltage in order to make the current flowing through the photodiode 303 constant. As a result, a large output change can be obtained even when the received light intensity change is small.

The output of the operational amplifier 408 is branched into the A / D converter 403 and the comparator 406. The comparator 406 compares the output voltage of the operational amplifier 408 with the reference voltage, and the output voltage is at the High level or the Lo level.
It is a binary value of w level. This binary output is the CPU 40
It is used only for determining whether there is paper or not at 1.

On the other hand, the output of the operational amplifier 408 provides the A / D
The voltage input to the converter 403 is 8 bits or 16 bits from the analog value in the A / D converter 403.
It is converted into a digital value of t and input to the CPU 401. As shown in FIG. 6, during the dimming sequence, the CPU 4
01 adjusts the output digital value so that the input digital value becomes a pre-stored dimming level.

That is, when the received light intensity decreases due to the life or paper dust, the output digital value is increased, and conversely, when the received light intensity after cleaning the paper dust etc. becomes greater than the previous time. , Decrease the output digital value. By repeating this control until it reaches a predetermined level, the output voltage of the reflection type optical paper detection mechanism is kept constant and a stable output can be obtained.

FIG. 5 is a block diagram of a control system for the reflection type optical paper detection mechanism according to the present invention. CP
U 401 is for controlling the operation of the clutch and pickup solenoid 510 in the paper feeding unit 201, the paper feeding motor 509 outside the paper feeding unit 201, and the dimming of the sensor M 202 and the sensor N 203 which are reflective optical paper detection mechanisms. Are in control.

During dimming of the sensor M202 and the sensor N203, as shown in FIG. 4, the sensor driver circuit 404 is used.
Light control is performed via the paper feed motor 509, clutch,
When the solenoid 510 or the like is driven, it is driven via the motor / clutch drive circuit 503. Paper feeding unit 201
In addition, although a plurality of sheet feeding units 211 and the like in FIG. 2 are arranged in parallel, the drawing is omitted here.

The counter 502 indicates the number of paper feeds of the paper feed unit 201 by turning on / off the clutch or solenoid 510.
The number of sheets fed is counted by the number of times F. The counter 502 may be previously arranged in the CPU 401 or may be provided outside. The counter value is stored in the non-volatile RAM 505, and the value can be rewritten or referred to as necessary.

The ROM 504 is set with a constant count value calculated from previously measured values of the endurance time and the amount of paper dust. When the counter 502 reaches the same value as the set value, both the sensor M202 and the sensor N203 are set. In order to inform the CPU that the light control is necessary, a flag is set, and marking is performed, and the light control is performed at the time of the stop sequence so that the light receiving level reaches a preset target value. The stop sequence is a process of stopping the copying operation and cleaning the wires of the chargers 38, 39 and 40 for discharging the photosensitive drum and the recording paper.

10A and 10B are graphs showing the input voltage Vin and the output voltage Vout for the reflection type optical paper detection mechanism. Here, Vi _max is the maximum value of the voltage that can be output by the circuit as shown in FIG. 4, Vo _h is a threshold value for the reflective optical paper detection mechanism to detect the presence or absence of recording paper, and Vo _M is a preset reflection value. It is an output set voltage value of the type optical paper detection mechanism.

When the device is shipped, the output voltage is equal to Vo _M at a point A0, and the input voltage is Via0. Figure 10
In (a), it is assumed that the device is used by a user and the state is lowered to A1 due to the influence of life, paper dust, and the like. At this time, if the amount of light emission is adjusted, the CPU 4 shown in FIG.
01 increases the input value by a predetermined input value Δ.
The value of Δ may be a constant value or a value calculated in consideration of the decrease in the output from A0 to A1.

However, if Δ is set to a fine value, it takes a long time to perform the adjustment. Therefore, it is desired that the value be an appropriate value in consideration of the adjustment time and accuracy. When the input is increased by Δ to become Via2, the output becomes Voa2, but since Vo _M > Voa2, the input voltage is increased again by Δ. By repeating this, if the output voltage is Vo _M or more (A4), the adjustment is finished and the input voltage is set to Via4.

On the other hand, as shown in FIG. 10B, even if the input voltage is Vi _max , if Vo _M > Vob6, the sensor is considered to have been attenuated by paper dust or has reached the end of its life. Notify users of cleaning or replacement.

FIG. 6 is a diagram showing a flow chart for dimming the reflection type optical paper detection mechanism during the stop sequence (self-maintenance) of the image forming apparatus. Here, the paper feeding unit 201 in FIG. 2 will be described. When the user starts copying (S1), first,
The paper feeding motor 509 is rotated (S2). Next, the paper feeding clutch 207 is turned on (S3), and the paper feeding roller 204
The paper is actually fed by rotating. At this time, the sensor M202 detects the conveyed paper and turns it on. The counter 502 increments the counter by 1 when the sheet feeding clutch 207 is turned on or when the sensor M202 is turned on (S4).

At this time, the counter value is compared with the set value for comparison (S5), and if it is determined that they are the same, the flag f (sensor M) is set to 1 for the corresponding sensor M202.
And At the same time, the sensor N2 attached to the paper feeding unit 36
Although 03 also makes the same judgment, since the same counter is used, it is not necessary to set a flag individually. After that, when it is determined by the detection signals of the sensor M202 and the sensor N203 that one recording sheet has been fed, the sheet feeding clutch is turned off (S7) to prepare for the next sheet feeding operation.

When the paper feeding operation for each sheet is completed, it is judged whether the stop sequence is entered (S8). If the stop sequence is not entered, it is judged whether the copy is completed (S14). The copy of S15 is completed. If the copy job is not completed in S14, the process returns to S3 again to perform the feeding operation of the next recording sheet.

If there is a request to enter the stop sequence in S8, the paper feeding operation is temporarily stopped (S9),
It is determined whether the flag f (sensor M) = 1 (S10). If the flag f (sensor M) = 1 is not set, only the stop sequence (S11) is performed. If the flag f (sensor M) = 1, the stop sequence (S11) is performed and adjustment is performed for both the sensor M202 and the sensor N203. An optical sequence (S12) is performed.

This dimming sequence will be described later in detail with reference to FIG. When the dimming sequence (S12) ends, the counter value of the counter 502 is reset,
The flag f (sensor M) is set to 0 (S13). When the stop sequence and the light control sequence are finished, it is judged whether or not the copy job is finished (S14), and then the above sequence is performed.

FIG. 7 is a diagram showing a flow chart at the time of adjustment used in the first embodiment of the present invention. This dimming sequence is for a case where a plurality of sensors attached to the same unit are dimmed. When a command to start dimming is issued (S21), the first sensor is selected (S21).
22), it is checked whether or not the sensor detects the paper (S23). When the paper is detected, the light receiving level becomes low and the light may be adjusted to the wrong value even if the light is adjusted. Therefore, the light is not adjusted and the process proceeds to the light adjustment of the next sensor (S
28). When there is no paper, the current A / D converter 403
The output AD value of is measured (S24) and compared with the target value (S25).

When the AD value and the target value are different, it is judged whether the DA value corresponding to the current LED current output from the D / A converter 402 is the maximum value that can be set (S26). If there is, the NG display is displayed to inform the user that the sensor cannot be adjusted, and the process proceeds to S28.

If the output DA value is not the maximum value that can be set, a value obtained by adding a constant value Δ to the current output DA value is output (S29), and the light receiving AD value is measured again (S2).
4). This control is repeated until the received light intensity AD value becomes the same as the target value, and when it becomes the same, it is checked whether there is a sensor to be dimmed next (S28), and if there is a sensor, that sensor is selected. Then (S30), the same dimming is performed. When the dimming of all the sensors is completed, the dimming sequence is ended (S31).

One counter 502 is associated with each of the paper feed units 201 and 211, and when each counter value reaches the set value, it is determined that the same number of recording sheets as the count value have passed. Flag all reflective optical paper detection mechanisms that This will be described with reference to FIG. 2. When the counter of the paper feeding unit 211 reaches the set value, a flag is set for the sensors M212 and N213.

On the other hand, when the counter of the paper feeding unit 201 reaches the set value, the sensor M202 and the sensor N203 are flagged, but the sensor N203 allows the recording paper to pass even when the paper is fed from the paper feeding unit 211. Therefore, it may be better to perform the adjusting means described in the second embodiment described later.

In the image forming apparatus of this embodiment, the dimming sequence as shown in FIG. 7 is performed to the all-optical detection mechanism even when the main power of the image forming apparatus is turned on and before and after each copy job. Be seen. At the same time, by resetting all counters of the optical detection mechanism, the initial detection voltage can be made constant at all times, the reliability of the first copy can be improved, and stable paper conveyance can be performed even during a large number of copies.

[Embodiment 2] The description of FIGS. 1 and 3 to 5 is omitted because it is the same as that of the first embodiment. In FIG. 2, when sheets are fed from the sheet feeding units 201 and 211, the recording sheets 210 and 220 pass through a sheet conveying path 221 that vertically penetrates both units. At this time, when the recording paper passes through both the paper feeding units 201 and 211 like the sensor N203, when the recording paper passes through, the paper feeding units 201 and 211
A value obtained by adding counters corresponding to both is used. This will be described in more detail below.

FIG. 8 is a schematic view of a sheet feeding section of an image forming apparatus having a plurality of reflection type optical sheet detecting mechanisms used in the second embodiment of the present invention, which is four sheet feeding stages 34, 35, 36 ,. 37 and sensors M202, N203, M212, N2 which are reflection type optical paper detection mechanisms attached to the paper feed stages 34, 36 and 37.
It is the figure which showed 13, M222, and N223. Paper feed stage 3
5 is omitted. Further, Table 1 is a table in which circles are attached to the passage of the recording paper when the paper is fed from the paper feed stages 34, 36 and 37 of the respective sensors in FIG.

[0057]

[Table 1]

The counter values of the counters attached to the paper feed stages 34, 36 and 37 are X, Y and Z, respectively. Sensors M212 and N21 attached to the lowermost paper feed stage 37
Since No. 3 is turned on / off only when the paper is fed from the paper feed stage 37, the number of times of ON / OFF is the same as X.

Sensors M202, N attached to the paper feed stage 36
Of the 203, the sensor M202 has the same number as the number of sheets fed from the sheet feed stage 36, and therefore has the same value as the counter value Y. The number of times the N sensor 203 is turned on / off is a value X + Y obtained by adding the count value X corresponding to the paper feed stage 37 and the count value Y corresponding to the paper feed stage 36.

Similarly, the sensor M22 attached to the paper feed stage 34
2 and N223, the ON / OFF count value of the sensor M222 is the count value Z of the paper feed stage 34, and the sensor N22
The ON / OFF count value of 3 is the paper feed stage 34, 36, 37.
Since all the count values of are added, X + Y +
It becomes Z. The same applies when a larger number of sensors are used.

FIG. 9 is a diagram showing a flow chart in the case of utilizing the counters of a plurality of sheet feeding stages by taking the sensor in the sheet feeding stage shown in FIG. 8 as an example. At this time, the case where the paper feed operation from the paper feed stage 36 is performed is taken as an example. The operations from S41 to S43 are S1 to S3 of FIG. 6 shown in the first embodiment.
Is the same as. In S44, the counter Y corresponding to the paper feed stage 36 is incremented by one. After that, a value obtained by adding the count value X corresponding to the paper feed stage 37 to the count value Y is calculated and compared with a value preset in the ROM 504 (S45).

When the counter addition value and the set value are the same, the flag f (sensor N203) is set to 1 for the sensor N203.
(S46). After that, sensor M202 and sensor N
When it is determined by the detection signal of 203 that one recording sheet has been fed, the sheet feeding clutch is turned off (S47),
Prepare for the next paper feed operation.

When the sheet feeding operation for each sheet is completed, it is judged whether the stop sequence is entered (S48). If the stop sequence is not entered, it is judged whether the copy is completed (S54). The copy of S55 is completed. If the copy job has not ended, S4 is executed again.
Then, the process returns to step 3, and the operation for feeding the next recording sheet is performed.

If there is a request to enter the stop sequence in S48, the paper feeding operation is temporarily stopped (S4
9), it is determined whether the flag f (sensor N203) = 1 (S50). Flag f (sensor N203) =
If not 1, only the stop sequence (S51) is performed. If the flag f (sensor N203) = 1, the stop sequence (S51) is performed and the dimming sequence (S52) is performed on the sensor N203.

This dimming sequence is the same as that described with reference to FIG. When the dimming sequence (S52) ends, the flag f (sensor N203) = 0 is set (S5).
3). When the stop sequence and the light control sequence are finished, it is judged whether or not the copy job is finished (S54), and then the above sequence is performed. The counter value is the sensor M202 or the sensors M212, N on the paper feeding unit 211.
Since it is also used for 213, it is not reset in S53. Therefore, when the counter addition value and the set value are compared in S45, the comparison value must be an integral multiple of the set value. Further, also in the case of the sensor N223, it can be considered in the same manner by setting the added value in S45 to X + Y + Z.

[Third Embodiment] FIG. 11 is a diagram showing a flow chart when light is adjusted during copying by the reflection type optical paper detection mechanism. When the user starts copying (S1),
First, the paper feeding motor 509 is rotated (S2). Next, the paper feed clutch 207 is turned on (S3), and the paper feed roller 204 is rotated to actually feed the paper. At this time, the sensor M202 detects the conveyed paper and turns it on. The counter 502 increments the counter by 1 when the sheet feeding clutch 207 is turned on or when the sensor M202 is turned on (S
4).

Thereafter, the pickup solenoid 208 is turned on (S5), and when it is determined by the detection signals of the sensor M202 and the sensor N203 that one sheet of recording paper has been fed, the paper feed clutch is turned off (S6). When the recording paper feeding operation is completed, the pickup solenoid 208 is turned off (S7) to prepare for the next paper feeding operation.

Further, the count value of the counter 502 and RO
A comparison with a value preset in M504 is performed (S8).
If the counter and the set value are different, it is determined whether the copy job is completed (S12). If the copy job is completed, the copy in S13 is completed. If the copy job has not ended, the process returns to S3 again, and the operation for feeding the next recording sheet is performed.

In S8, when the counter and the set value match, the paper feeding operation is temporarily stopped (S9), and the sensor M202 and the sensor N203 which are the reflection type optical paper detecting mechanism are executed by the light control sequence shown in FIG. The light emission amount of is adjusted (S10). When the light control sequence is completed, the count value is reset (S11), it is judged whether or not the copy job is completed (S12), and then the sequence described above is performed.

In the image forming apparatus of this embodiment, the dimming sequence as shown in FIG. 7 is performed on the all-optical detecting mechanism even when the main power of the image forming apparatus is turned on or before and after each copy job. Be seen. By resetting all the counters of the optical detection mechanism at the same time, it is possible to prevent the paper feeding operation from being stopped unnecessarily multiple times due to light adjustment during the copy job.
It is possible to carry a stable paper even during a large number of copies.

[Embodiment 4] FIG. 12 is a flowchart showing a case where counters of a plurality of paper feed stages are used by taking the sensor in the paper feed stage shown in FIG. 8 as an example. At this time, the case where the paper feed operation from the paper feed stage 36 is performed is taken as an example. The operation from S41 to S43 is the same as S1 to S3 of FIG. 6 shown in the first embodiment. In S44, the paper feed stage 36
The counter Y corresponding to is incremented by one. After that, S45 to S47 are S5 to S5 shown in FIG.
Since the same paper feeding operation as in S7 is performed, its description is omitted here.

Then, a value obtained by adding the count value X corresponding to the paper feed stage 37 to the count value Y is calculated and compared with a value preset in the ROM 504 (S48). If the counter addition value and the setting value are different, it is determined whether the copy job is completed (S51), and if it is completed, the copy in S52 is completed. If the copy job is not finished,
The process returns to S43 again, and the feeding operation of the next recording sheet is performed.

When the counter addition value and the set value match in S48, the paper feeding operation is temporarily stopped (S49),
According to the dimming sequence shown in FIG. 7, the light emission amount of the sensor N203 which is a reflection type optical paper detection mechanism is adjusted (S5).
0). When the dimming sequence ends, the third embodiment described above
Unlike the above, the count values of X and Y are measured by the sensors M212,
Since it is used in N213 and M202, it is not reset and it is judged whether the copy job is completed or not (S
51), and then the above sequence is performed. For this reason,
When comparing the count addition value and the set value in S48, the comparison value must be an integral multiple of the set value. Also in the case of the sensor N223, the addition value in S48 is X.
The same can be considered by setting + Y + Z.

[0074]

As described above, according to the present invention, it has a paper feed unit for feeding paper and a counter for counting the number of paper fed from the paper feed unit, and the value of the counter is predetermined. The amount of light emitted from the optical sensor is adjusted according to whether or not the value has been reached.Therefore, the amount of light emitted from the light emitting elements of the optical sensor is adjusted at intervals according to the number of sheets fed, and jams caused by paper dust, etc. It is possible to provide an image forming apparatus having an optical sensor that does not cause erroneous detection, and it is possible to always stably convey a sheet. Further, since it is not necessary to provide a counter for each optical sensor, the number of counters can be reduced and the load on the CPU can be reduced.

When there are a plurality of optical sensors used only for feeding paper from a certain paper feed stage, the light emission amount is adjusted at the same timing.

Further, since the light emission amount of the optical sensor is adjusted when the sheet conveyance is stopped when the image forming device self-maintains, the image forming device can be temporarily stopped only for adjusting the light emission amount of the optical sensor. Disappear. Then, the efficiency of the device is not lowered, and it is possible to prevent the user from feeling uncomfortable.

Further, according to the judgment as to whether or not the value of the counter reaches a predetermined value, when the paper conveyance is stopped in which the self-maintenance of the image forming apparatus is carried out, the light emission amount of the optical sensor is adjusted and the self-maintenance of the image forming apparatus is carried out. As a result, the amount of light emitted from the optical sensor is adjusted in accordance with the stop sequence that is performed with a fixed number of copies, such as cleaning the wires for high-voltage discharge during image formation, which reduces the efficiency of the image forming apparatus. Without doing so, it is possible to prevent the user from feeling uncomfortable.

Further, a plurality of paper feed units for feeding paper,
If the optical sensor has a counter for counting the number of sheets fed from the sheet feeding section and the optical sensor is provided on a common conveyance path in the sheet feeding operation from the plurality of sheet feeding sections, the sheet feeding section The amount of light emitted from the optical sensor is adjusted according to the judgment as to whether the total value of the counters for each set has reached a predetermined value, so a plurality of paper feed stages are automatically switched to perform a large number of copy jobs. Also in this case, an optical sensor having a large number of ON / OFF times is estimated and light is adjusted according to the total number of sheets, so that it is possible to perform stable high-speed stable paper conveyance without paper jams in all paper conveyance paths.

[Brief description of drawings]

FIG. 1 is an overall schematic view of an image forming apparatus using a reflection type optical paper detection mechanism of the present invention.

FIG. 2 is an enlarged view of a sheet feeding unit of the image forming apparatus using the reflection type optical paper detection mechanism of the present invention.

3A and 3B are internal configuration diagrams of a light emitting element, a light receiving element, and the like of the reflection type optical paper detection mechanism used in the present invention.

FIG. 4 is a drive circuit of a reflection type optical paper detection mechanism used in the present invention.

FIG. 5 is a block diagram of a reflective optical paper detection mechanism control circuit used in the present invention.

FIG. 6 is a diagram showing a flowchart used in the first embodiment of the present invention.

FIG. 7 is a diagram showing a flowchart at the time of adjustment used in Examples 1 and 2 of the present invention.

FIG. 8 is a schematic diagram of a sheet feeding unit of an image forming apparatus having a plurality of reflection type optical sheet detection mechanisms used in Example 2 of the present invention.

FIG. 9 is a diagram showing a flowchart used in Example 2 of the present invention.

10 (a) and 10 (b) are diagrams showing input / output characteristic curves during adjustment of the reflective optical paper detection mechanism used in the present invention.

FIG. 11 is a diagram showing a flowchart used in Example 3 of the present invention.

FIG. 12 is a diagram showing a flowchart used in Example 4 of the present invention.

[Description of Reference Signs] 10 main body image output unit 11 main body image input unit 12 automatic document feeder 14 post-processing device 15 large-capacity paper feeder 21 light sources 22, 23, 24, 30 mirrors 25, 29 lens 26 CCD 27 optical irradiation unit 28 Scanner 31 Photosensitive Drum 32 Fixing Roller 33 Developing Device 34, 35, 36, 37 Paper Feeding Section (Stage) 38, 39, 40 Charging Device 201, 211 Paper Feeding Unit 202, 212, 222 Reflective Optical Paper Detection Mechanism ( Sensor M) 203, 213, 223 Reflective optical paper detection mechanism (sensor N) 204, 214 Paper feed roller 205, 215 Extraction roller 206, 216 Extraction clutch 207, 217 Paper supply clutch 208, 218 Pickup solenoid 209, 219 Pickup Rollers 210, 220 Recording paper 221 Paper transport path 01 sensor substrate 302 light emitting element (LED) 303 light receiving element (photodiode) 304 cover 305 prism 306 recording paper 401 CPU, 402 D / A converter 403 A / D converter 404 sensor driver circuit 406 comparator 407, 408 operational amplifier 502 counter 503 motor , Clutch drive circuit 504 ROM 505 RAM

Continued front page    (72) Inventor Kunio Tsuruno             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Tetsuya Morita             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Masahiro Kurahashi             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Atsushi Nakagawa             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 3F048 AA01 AB01 BA14 CB03 CC01                       DB16 DB19 DC13 DC14

Claims (6)

[Claims] 1. A transport member and a transport path for transporting a sheet,
An image forming apparatus comprising: an optical sensor having a light emitting element and a light receiving element for detecting the presence / absence of paper on the conveyance path; and a driver for changing the amount of light emitted by the optical sensor arranged on the conveyance path. A paper feed section for feeding paper,
A counter is provided for counting the number of sheets fed from the sheet feeder, and the amount of light emitted from the optical sensor is adjusted according to whether or not the value of the counter reaches a predetermined value. Image forming apparatus. 2. The amount of light emitted from the optical sensor is adjusted by
The image forming apparatus according to claim 1, wherein the image forming apparatus is carried out when a sheet conveyance is stopped in which self-maintenance of the image forming apparatus is carried out. 3. The image forming apparatus according to claim 1, wherein there are a plurality of the optical sensors, and the optical sensors are arranged in the paper feeding unit. 4. A transport member and a transport path for transporting a sheet,
An image forming apparatus comprising: an optical sensor having a light emitting element and a light receiving element for detecting the presence / absence of paper on the conveyance path; and a driver for changing the amount of light emitted by the optical sensor arranged on the conveyance path. The optical sensor has a plurality of sheet feeding units for feeding sheets and a counter for counting the number of sheets fed from the sheet feeding units, and the optical sensor is common in the sheet feeding operation from the plurality of sheet feeding units. When it is provided on the conveyance path, the amount of light emitted from the optical sensor is adjusted in accordance with the determination as to whether the total value of the counters for each of the sheet feeding units has reached a predetermined value. Image forming apparatus. 5. The image forming apparatus according to claim 1, wherein the optical sensor has the light emitting element and the light receiving element arranged adjacent to each other, and a reflection mechanism is provided on the opposite side. apparatus. 6. The image forming apparatus according to claim 1, wherein when the amount of light emitted from the optical sensor is adjusted, the value of a counter corresponding to the optical sensor whose light amount has been adjusted is reset. .