JPH09244319A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum-jam detecting device capable of surely recognizing the toner image from a photosensitive drum base tube by comparing the signal from a detection sensor having a plurality of different spectral sensitivity in the wavelength range in the spectral reflection factor distribution of the toner to be used with the prescribed reference value for the operation. SOLUTION: A detection member 70 is provided on the downstream side of a transfer electrode in the rotational direction of a photosensitive drum, and is provided with a detection sensor having at least two different spectral sensitivity in the wavelength range in the spectral reflection factor distribution of the toner of one color or a plurality of colors to be used. A microprocessor 510 calculates the drum constant for each light emission source of the detection sensor, and calculates the reference value to recognize the tube level of the photosensitive drum from the drum constant. A comparison circuit 720 compares the signal from the detection sensor with the reference value, and a paper sheet jam judging part judges presence/absence of the paper jam by the operation based on the results of the comparison circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jam detecting method and a jam detecting device due to defective separation of recording paper from an image forming body provided in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine or a printer uniformly charges a surface of an image forming body (hereinafter referred to as a photosensitive drum) by a charger and then exposes the surface of the photosensitive drum with an image to expose the image. An electrical electrostatic latent image is formed. The electrostatic latent image is visualized by a developing device and becomes a toner image. The toner image formed on the surface of the photoconductor drum is transferred onto the recording paper, which is fed at the same timing, by using a transfer unit. The recording paper on which the toner image has been transferred is separated from the surface of the photosensitive drum, and the toner image transferred on the recording paper is fixed by a fixing device, and then the recording paper is ejected to the outside of the device.

In transferring the toner image formed on the surface of the photosensitive drum, the toner is transferred to the recording paper from the surface of the photosensitive drum by being charged with a polarity opposite to that of the toner by a transfer device discharging from the back. After the transfer, the high voltage AC voltage is applied from the recording paper to remove the electric charge, and the recording paper can be separated from the surface of the photosensitive drum. However, it is difficult to ensure transferability and separability, and particularly when the diameter of the photosensitive drum is large, for example, when the diameter is 100 mm, it is difficult to separate the recording paper from the surface of the photosensitive drum. The paper is conveyed while attached to the surface of the photoconductor drum, and paper jam (hereinafter referred to as jam) is likely to occur.

Therefore, a threshold value S is set in advance to a value between them based on the difference between the light receiving levels of the photosensitive drum and toner and the light receiving level of the recording paper, and the threshold value S and the light receiving output from the phototransistor are set. When the light receiving level is lower than the threshold value S, it is judged that the recording paper is not wrapped around the photosensitive drum or the toner when the light receiving level is lower than the threshold value S. When the light receiving level is equal to or higher than the threshold value S, Japanese Patent Laid-Open No. 6-56307 discloses that the image forming apparatus determines that the recording sheet is the recording sheet, determines that the recording sheet is wrapped, and automatically stops the image forming apparatus.

[0005]

However, since the above-described sensor system for detecting jammed drum winding has a high reflectance from a solid toner image formed with yellow toner when a yellow light source is adopted, such reflectance is high. Is only 1.5 times as high as the reflectance from the almost white recording paper, and the reflectance of the photosensitive drum is considerably high, so the detection range for distinguishing the almost white recording paper from the yellow solid toner is narrowed. However, there is a technical problem of false detection. If the toner patch level is adopted in the drum wrapping jam detection process, the reflection level from the toner image is not stable due to the forming conditions and the like, and there is a technical problem that a detection error occurs.

Further, in the image forming apparatus having the double-sided reversing device for reversing the recording paper, it is necessary to distinguish between the toner image and the raw tube of the photosensitive drum when detecting the drum winding jam at the time of printing on the back surface. . Even in such a case, there was the same technical problem as described above. There are technical problems that the toner image formed on the photoconductor drum and the recording paper cannot be distinguished at the time of the back surface printing, and that a jam cannot be detected due to the deviation of the recording paper at the time of the back surface printing.

A first object of the present invention is to provide a drum winding jam detecting device which can surely identify a toner image and a photoconductor drum element tube.

In view of the above technical problems, a second object of the present invention is to provide an image forming apparatus having a double-sided printing function, wherein the toner image formed on the photosensitive drum and the recording sheet are transferred at the time of back side printing. An object of the present invention is to provide an image forming apparatus that can be distinguished from existing toner images.

[0009]

SUMMARY OF THE INVENTION The above object is to eliminate the defect in the detection accuracy which occurs when a yellow light source is used as a sensor for detecting a jammed drum. Such a poor detection accuracy has a high reflectance from a solid toner image formed with a yellow toner. Therefore, such a reflectance is only 1.5 times the reflectance from a substantially white recording paper. This is because the reflectance is considerably high, and this is because the detection range for discriminating between almost white recording paper and yellow solid toner is narrow. This is achieved by the following configuration. Further, when the toner patch level is adopted for the drum winding jam detection processing, the reflection level from the toner image is not stable due to the forming conditions and the like, so the image forming apparatuses (1) to (4) below adopt the toner patch level. Absent.

(1) Developing means for developing the electrostatic latent image formed on the image forming body with color toner of one color or a plurality of colors to form a toner image, and transfer means for transferring the toner image onto recording paper. An image forming apparatus including: a separating unit that separates the recording paper from the image forming body; and a detecting unit that optically detects the recording paper wound around the image forming body due to a defective separation of the recording paper. The detection means includes a detection sensor section having a detection sensor having at least two different spectral sensitivities in the wavelength range of the spectral reflectance distribution of the toner of one color or a plurality of colors, and each light emission source of the detection sensor section. A drum constant determining means for calculating the drum constant of the image forming means, a threshold calculating means for calculating a threshold for identifying the tube level of the image forming body from the drum constant calculated by the drum constant determining means, and the detection sensor. And a paper jam determining unit that determines the presence or absence of a paper jam by performing a calculation process based on the result of each of the comparing units and a comparing unit that compares the signal from the reference value obtained from the threshold value calculating unit. A characteristic image forming apparatus. With the above configuration, the electrostatic latent image formed on the image forming body by the developing unit is developed by using color toner of one color or a plurality of colors to form a toner image, and the toner image is formed on the recording paper by the transfer unit. And the recording paper is separated from the image forming body by the separating means. Further, the detection means optically detects the recording paper wrapped around the image forming body due to the poor separation of the recording paper. The detection means has a detection sensor having at least two different spectral sensitivities in the wavelength region of the spectral reflectance distribution of the toner of one color or a plurality of colors used by the detection sensor section, and the comparison circuit section respectively It has a comparison circuit for comparing the signal from the detection sensor with a predetermined reference value, and further, the paper jam judging section performs arithmetic processing based on the result of each comparison circuit to judge the presence or absence of paper jam. As a result, the recording paper wrapped around the image forming body can be accurately detected.

(2) An exchange detecting means for detecting the exchange of the image forming body is provided, and the drum constant is determined by the drum constant determining means based on the detecting operation of the exchange detecting means.
The image forming apparatus according to (1), further comprising control means for causing the threshold value calculation means to calculate a threshold value for detecting jammed jams from the drum constant.

(3) A print number detection means for detecting whether or not the number of prints using the image forming body has reached a predetermined value is provided, and the drum constant is determined based on the detection operation of the print number detection means. The image forming apparatus according to (1), further comprising control means for determining a drum constant by means, and for causing the threshold value calculating means to calculate a threshold value for detecting a winding jam from the drum constant.

(4) An interlock switch signal or a drum constant is determined by the drum constant determining means by turning on the power or during a warming-up period of a predetermined time after the power is turned on, and a jam jam around the threshold calculating means is detected from the drum constant. The image forming apparatus according to (1), further including control means for calculating a threshold value.

According to the inventions (5) and thereafter, there is provided an image forming apparatus having a double-sided printing function, wherein the toner image formed on the image forming body and the toner image transferred on the recording paper can be discriminated at the time of back side printing. It is to solve the technical problem of being unable to do so.

(5) Developing means for developing the electrostatic latent image formed on the image forming body with color toner of one color or a plurality of colors to form a toner image, and transfer means for transferring the toner image onto recording paper. An image forming apparatus comprising: a separating unit that separates the recording paper from the image forming body; and a detecting unit that optically detects the recording paper wound around the image forming body due to a defective separation of the recording paper. A double-sided reversing device that reverses and conveys the recording paper to the transfer area of the image forming body is provided, and the detection means has at least two or more different spectral sensitivities in the wavelength region in the spectral reflectance distribution of the toner of one color or a plurality of colors. A detection sensor section having a detection sensor having, a yellow light emitting light source, and a blue light emitting light source are arranged so as to project light onto a non-image area of the image forming body, and receive reflected light from the non-image area. To the statue Arranged at an angle from the reflection axis of the formed body,
A drum constant determining means for calculating a drum constant for each of the light emitting sources, a threshold calculating means for calculating a threshold for discriminating the tube level of the image forming body from the drum constant calculated by the drum constant determining means, and the threshold calculating means. An image forming apparatus comprising: a control unit that detects a winding jam by comparing a threshold value obtained from the light receiving element with a detection level detected from the light receiving element.

(6) A movement mechanism for moving the detection sensor unit along the surface of the image forming body is provided, and movement control for moving the detection sensor in consideration of a binding margin and a white frame according to a recording size when printing on the back surface. The image forming apparatus according to (5), which is provided with a section.

With the above arrangement, the jam can be detected even if the recording paper is misaligned when printing on the back surface.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic configuration of an image forming apparatus according to the present embodiment will be described.

FIG. 1 is a sectional view showing a schematic structure of an image forming apparatus according to this embodiment, and FIG. 2 is a perspective view showing a moving mechanism of a detecting means 70.

The image forming apparatus according to the present embodiment is provided with a double-sided reversing device 300 and a recording paper feeding device 400 as options in the main body. The main body includes a process unit 100 and a lower main body 200. The configuration of each part will be described below.

The toner replenishing device 190 fixed to a part of the process unit 100 includes developing devices 150Y and 150Y.
Color toner and black toner are supplied to M, 150C, and 150K, respectively. Each new color toner is replenished from the outside to the toner replenishing device 190 from the opening / closing lid 191 configured to open a part of the process unit 100. The photoconductor drum 10 is rotatably driven by an axis at substantially the center of the process unit 100, and the charger 1 is provided along the circumferential surface of the photoconductor drum 10 from the upstream side of rotation.
40, four sets of developing devices 150 containing color developers of respective colors
Y, 150M, 150C, 150K, transfer roller 21
6. A cleaning device 160, which removes the residual toner adhering to the surface of the photosensitive drum 10 after transferring the image onto the recording paper P, is sequentially arranged. A recording paper P for detecting the recording paper P is provided between the transfer roller 216 and the cleaning device 160.
Detection member 70 is provided.

As shown in FIG. 2, the detecting member 70 is fixed to a rail 81 which is arranged in parallel with the driven roller 83 and the motor 82 on the surface of the photosensitive drum 10. Therefore, the microprocessor 510 is connected to the print controller 900.
The detection member 70 can be moved by driving the motor 82 based on the white frame length data received from (see FIG. 3) and the data indicating the length of the binding margin. The image forming apparatus having the center-based paper feeding system moves the detection member 70 in correspondence with the movement of the white frame and the binding margin in the axial direction according to the recording size. Further, the moving direction of the detection member 70 is adjusted depending on whether it is the left reference or the right reference.

The transfer roller 216 and the cleaning blade 161 are pressed against and released from the peripheral surface of the photosensitive drum 10. A pressure release mechanism for the transfer roller 216 and the cleaning blade 161 will be described.

Detecting means 70, 189 and 219 for detecting a jam-related conveyance abnormality related to the recording paper P are provided, and an abnormal situation is detected while the transfer roller 216 is pressed against the peripheral surface of the photosensitive drum 10. In this case, the task of abnormal stop of the drive system is performed by the program incorporated in the control circuit of the drive system. That is, when an abnormal situation is detected and the image forming program is switched to the abnormal stop task program, the main motor is turned off, the drive system of the apparatus is stopped, and the operation of the motor 59 is also temporarily stopped during image transfer. Be stopped.

After the main motor is turned off, the photosensitive drum 10 and others are kept stationary for a predetermined time, for example, 100 ms, then only the motor 59 is driven again, and the transfer roller 216 is restarted by restarting the rotation of the cam plate 30. Is released from the pressure contact with the peripheral surface of the photosensitive drum 10, and the rotation operation of the motor 59 is stopped by detecting the home position to keep the transfer roller 216 at a position retracted from the peripheral surface of the photosensitive drum 10. As a result, the photosensitive drum 10 can be safely moved and pulled out without any obstacle in the horizontal direction, and maintenance such as jam clearance can be performed.

The process unit 100 is provided with a manual paper feeder 2
70 is provided, and the manual paper feeding device 270 is provided with an insertion hole 271 into which the recording paper P3 is inserted and a detection member for detecting the recording paper P3 inserted into the insertion hole 271.
The leading end of the inserted recording paper P3 hits the built-in paper feed roller 272 and is stopped. The recording paper P3 is conveyed by the rotation of the paper feed roller 272, and is conveyed toward the registration roller 209 through the conveyance path 273. Manual paper feeder 2
70 is axially fixed to the process unit 100 and can be slightly moved outward. Further, a part of the outer member is supported by the shaft, and the insertion hole can be opened.

A paper feed cassette 203 containing a plurality of recording sheets P is detachably provided in the lower main body 200.
A half-moon-shaped paper feed roller 202 for feeding the recording paper P is provided on the paper feed cassette 203, and a push-up plate 204 for pushing the uppermost recording paper P against the separation claw 205 is provided in the paper feed cassette 203. ing. The recording paper P placed on the push-up plate 204 is constantly pushed upward by a spring (not shown), the leading end of the recording paper P is locked by the separation claw 205, and an electromagnetic clutch (not shown) is operated. The paper feed roller 202 is driven, and the topmost recording sheet P is separated by the separation claw 205 and is fed. The fed recording paper P is driven and conveyed by the intermediate paper feed roller 206 and guided to the registration roller 209. A registration shutter 215 that opens and closes the registration unit according to a control signal from the microprocessor 510 is provided on the downstream side of the registration roller 209 in the sheet feeding direction.
The detection member 219 is operated by the microprocessor 510, and the detection member 219 detects the recording paper P, so that the recording paper P directly enters the registration roller 209,
The registration shutter 215 stops. Further, a sensor 189 for detecting the transparency of the surface of the recording paper P is provided on the upstream side of the registration roller 209 in the paper feed. At that time, the detection member 1 rotatably and axially fixed to a part of the process unit 100.
89 The tip of the recording paper P hits a protrusion provided on a part of
After the detection member 189 is arranged at a predetermined position along the image forming surface of the recording paper P, the transparency of the image forming surface formed on the recording paper P is detected.

The recording paper P that has passed through the registration rollers 209
Is a transfer roller 21 that can be pressed and separated from the photosensitive drum 10.
The fixing device 22 is guided from the transfer roller 216 in six directions.
Transported to zero.

The fixing device 220 is a device for fixing the image transferred on the recording paper P, and comprises a fixing heating roller 221 and a pressure roller 222. The paper discharge roller 223 is the fixing device 2
The recording paper P is discharged from the sheet 20, and the discharged recording paper P is conveyed upward by the conveying roller 224. Transport roller 2
The recording paper P conveyed upward by 24 is ejected by a paper ejection roller 2 provided in a paper ejection passage formed in the process unit 100.
25, the recording surface is discharged downward onto the discharge tray 210 provided on almost the entire upper surface of the process unit 100. A paper discharge sensor 229 is provided in the paper discharge path of the fixing device 220. A transport path switching member is provided behind the paper discharge roller 223. Such a switching member is used for the paper ejection tray 2
Conveyor to face up to 10 and double-sided reversing device 300
It is possible to switch to a transport path for transporting to.

By the stepping motor 59 (see FIG. 3), driving force is respectively applied to the sheet feeding roller 202 and the intermediate sheet feeding roller 206 via a reduction mechanism (not shown) via a toothed pulley and an intermediate gear group. Transmitted. The paper feed roller 202 is intermittently driven by an electromagnetic clutch (not shown). On the other hand, the registration roller 209 and the intermediate sheet supply roller 206 are configured to be driven and rotated at all times.

As shown in FIG. 1, the process unit 100 occupies a space above the transfer roller 216 and forms the recording paper P.
It is located on the upstream side of the paper feed.

As described with reference to FIG. 1, the lower main body 200 is provided with a detection member 70 for detecting the density of the toner image formed on the photosensitive drum 10 or detecting the presence or absence (jam) of the recording paper wrapped around. is there.

The detection member 70 is a pair of a light emitting element and a light receiving element. When the lower main body 200 is attached to the main body 300, as shown in FIG. The light-receiving element reflects the reflected light of the surface of the photoconductor drum 10 which is located at, and faces the patch image formed on the non-image area or the image area of the drum side edge portion with a predetermined gap and is irradiated by the light-emitting element. By arranging so as to receive light, the photosensitive drum 1
It is relative to 0.

The double-sided reversing device 300 is a device for reversing the recording sheet to the transfer area of the photoconductor drum and conveying it, and is provided with a plurality of conveying rollers.

The above is the schematic mechanism of the image forming apparatus according to the present embodiment.

Next, a schematic structure of the engine controller used in the image forming apparatus according to the present embodiment will be described with reference to FIG.

FIG. 3 is a block diagram showing the main structure of the engine controller according to the present embodiment.

The engine controller 500 receives page data and print parameters from an external device such as a personal computer, and the writing device 230 described above is used.
And a scorotron charger 140 and a developing device 150Y, 1
The drive timings of the 50M, 150C, 150K, the transfer roller 216, and the cleaning device 160 are controlled, and the paper feeding device 400, the paper feeding cassette 203, and the manual paper feeding device 27 are controlled.
It controls the paper feed timing of recording paper from 0, and includes a microprocessor 510, an SRAM 520, and an RA.
An M530, a transfer cleaning drive system 550, a paper feed drive system 560 and the like. The configuration of each part will be described below.

The microprocessor 510 corresponds to the control means described in the claims, and executes the sequence program for executing the electrophotographic process from the SRAM 520 by using REGIST_PS which is an external signal as a trigger. Driver 552,562
Of the detection members 70, 189, 219,
The conveyance state of the recording paper is controlled based on the detection signal from 229, the purge processing corresponding to the recovery processing from the jammed state and the winding jam detection processing for detecting the winding jam due to the separation failure from the photosensitive drum 10 are executed. To do.

A detection member 70 is provided on the downstream side of the transfer electrode 217 with respect to the rotation direction of the photosensitive drum 10. The detection member 70 is, as described above, the photosensitive drum 10
A yellow light emitting diode and a blue light emitting diode which are installed so as to be able to irradiate the surface with light rays, and reflected light from the surface of the photoconductor drum 10 by the light rays from these light emitting diodes are provided at a certain angle θ. The phototransistor is installed so as to receive light. The light emitting diode emits light according to a light emission signal output from the microprocessor 510 at a predetermined timing, and the light beam irradiates the surface of the photoconductor drum 10. The phototransistor receives the reflected light of the irradiation light. Here, a paper such as recording paper has a large amount of light received by an object having a large amount of irregular reflection, and the surface of the photosensitive drum 10 has a large amount of regular reflection, and an object having a small amount of irregular reflection has a small amount of received light. Although the developed toner may remain on the surface of the photoconductor drum 10 and the reflected light from the toner may be received by the phototransistor, the light receiving level is substantially the same as that of the photoconductor drum 10. Becomes

The SRAM 520 has a warm-up process, a multi-color print process, a mono-color print process, a letter size print sequence, a postcard size print sequence, a first purge process, and a second purge process.
The programs corresponding to the paper feeding process including the purging process, the manual paper feeding process, and the double try sequence are written.

The RAM 530 stores parameters necessary for executing various print sequences.

The interlock detection circuit 540 corresponds to the replacement detection means and the print number detection means described in the claims, and the detection member 541 detects whether or not the process unit 100 is still attached with the protective cover. However, if it is detected that the protective cover is removed, the circuit determines whether the process unit 100 is old or new. Whether the process unit 100 is old or new is identified by, for example, the photosensitive drum 1
It is determined whether or not the fuse provided on the 0 axis 10A is blown. The unused process unit 100 is provided with an unblown fuse, and the microprocessor 510
When the unblown fuse is detected, the microprocessor 510 determines that the fuse is a new one, sequentially executes the monitoring items at several places, detects the protective cover at that time, and resets the life counter of the process unit 100. It is necessary to remove the protective cover of the process unit 100 before loading it in the lower main body 200. The surface of such a protective cover is formed of a white material or a material having a high reflectance or a material having a high diffuse reflectance, like the surface of the recording paper P. As a result, the microprocessor 510 causes the detection member 219 to operate.
Facilitate detection by.

The transfer cleaning drive system 550 controls the pressing / releasing state of the cleaning blade 161 and the transfer roller 216 to the photosensitive drum 10 in the various sequences described above, and is controlled by the gate circuit 570 and the motor driver 552. It will be. The transfer cleaning drive system 550 can change the speed and timing of the pressing / releasing operation between the cleaning blade 161 and the transfer roller 216 during continuous printing and other printing. The gate circuit 570 sends a SAVE signal and an ENABLE signal for controlling the driving state of the motor driver 552 to the motor driver 552 according to the print size and the print sequence. Further, the microprocessor 510 supplies two drive clocks CLOCKA and CLOCKB to the motor driver 552 from the internal clock. Therefore, the motor driver 552 rotates the motor 59 at a speed according to various sequences. Accordingly, the transfer / cleaning drive mechanism causes the transfer roller 216 and the cleaning blade 16 to move at a predetermined speed.
The pressure release operation of 1 is performed.

The paper feed drive system 560 controls the conveyance speed of the recording paper according to the print size, print mode, etc., and comprises a gate circuit 570 and a motor driver 562. The gate circuit 570 is used in common with the above-described transfer cleaning drive system.
10, a SAVE signal for controlling the driving state of the motor driver 562 in accordance with the control signal from the controller 10, an ENABLE signal, and clock signals CLOCKA and C for providing a driving timing.
LOCKB is sent to the motor driver 562. Therefore, the motor driver 562 rotates the motor 99 at a speed according to various sequences. As a result, the recording paper is fed at a speed according to various sequences.

Next, the operation for detecting the drum winding jam in the engine controller according to the present embodiment will be described with reference to FIGS.

FIG. 4 is a characteristic diagram of the spectral reflectance distribution of various toners used in the embodiment, FIG. 5 is a sectional view of the detecting member in the embodiment, and FIG. 6 is a comparison circuit of the embodiment. 7 is a circuit diagram of a part of the portion, and FIG. 7 is a reflection density ratio of the detection member in the embodiment.

The detecting means 700 comprises a detecting member 70, a comparing circuit section 720 and a paper jam judging section 730. The detection member 70 has a detection sensor having at least two different spectral sensitivities in the wavelength range of the spectral reflectance distribution of the toner of one color or a plurality of colors used. Further, the comparison circuit unit 720 has a comparison circuit for comparing the signals from the respective detection sensors with predetermined reference values. Further, the paper jam determination unit 730 is configured to perform arithmetic processing based on the results of the respective comparison circuits to determine the presence or absence of a paper jam.

The detection member 70 has a detection sensor, which will be described later, having at least two different spectral sensitivities in the wavelength region in the spectral reflectance distribution of the toner of one color or plural colors used. More specifically, in the embodiment, the first detection sensor is a sensor having a spectral sensitivity peak of about 580 nm,
The second detection sensor has a yellow LED light emitting portion, the peak of spectral sensitivity is about 760 nm, and the second detection sensor has a blue LED light emitting portion. These selections are made based on the information on the characteristics of the spectral reflectance distribution (FIG. 4) of the toner of one color or a plurality of colors used. That is, the first detection sensor has a low spectral sensitivity, and the reflectances of the spectral reflectance distributions of the cyan toner C and the magenta toner M are both low,
Furthermore, the LEDs used especially in the light emitting part are marketable. In addition, the second detection sensor has a low spectral reflectance in the spectral reflectance distribution of the yellow toner Y, and
Both the cyan toner C and the magenta toner M have a low reflectance in the spectral reflectance distribution, and L used especially in the light emitting portion.
The ED is marketable.

The comparison circuit section 720 is a comparison circuit which compares the signal from the detection sensor with a threshold value of a predetermined reference value. More specifically, in the embodiment, the comparison circuit unit compares the signal of the first detection sensor with a value (H) higher or lower than the first threshold (L). Similarly, the signal of the second detection sensor is higher (H) or lower (L) than the second threshold value.
It is a comparison circuit unit for comparing The information about the high value (H) or the low value (L) is used when the presence or absence of a paper jam of the photoconductor drum 10 is judged by a paper jam judgment circuit section described later. Further, the first threshold is the recording paper, the yellow toner Y,
Over with magenta toner M, cyan toner C, black toner B
It is set not to exceed K (FIG. 7 (A)). Further, the second threshold is the recording paper, the cyan toner C, the black toner BK.
Is set not to exceed. The same applies to the yellow toner Y and the magenta toner M (FIG. 7).
(B)).

Next, the paper jam judging circuit unit 730 is a circuit unit for judging the paper jam when the respective comparison values of the comparing circuit unit are both higher than the threshold value of the reference value. More specifically, in the embodiment, when the signal of the first detection sensor is higher than the first threshold value (H) and the signal of the second detection sensor is higher than the second threshold value (H), the photoconductor is A circuit unit that determines that the recording paper is jammed in the drum 10. When the signal of the first detection sensor is a value (H) higher than the first threshold and the signal of the second detection sensor is a value (L) lower than the second threshold, the signal of the first detection sensor is When the value (L) is lower than the first threshold value, the circuit unit determines that the recording paper does not jam on the photosensitive drum 10.

Here, the characteristic diagram of the spectral reflectance distribution of the yellow toner Y, the magenta toner M, the cyan toner C, and the black toner BK of the various toners used in FIG. 4 will be described. The horizontal axis represents wavelength and the vertical axis represents toner spectral reflectance. In the figure, the one-dot chain line shows the yellow toner Y, the solid line shows the magenta toner M, the dotted line shows the cyan toner C, and the solid line shows the black toner BK.

Next, FIG. 5 shows a sectional view of the detecting member. In FIG. 5A, two detection sensors are attached to one printed circuit board, and in FIG. 5B, the detection sensor of the light receiving portion which is shared with the two light receiving photosensors is attached to one printed circuit board. It is a thing. As shown in FIG.
The detection member 70 includes a first detection sensor 70A and a second detection sensor 70B, and a light emitting LED formed on the main body 71.
Light emitting diodes 72, 73 and light receiving photosensors 74, 75 are provided, and the light emitted from the light emitting LEDs 72, 73 is reflected on the surface of the photoconductor drum 10 respectively, and the light receiving photosensors 74, 75 are provided. It is configured to be incident. For the detection member, the emission LED 72 of the first detection sensor is a yellow LED and the emission LED 73 of the second detection sensor is a blue LED as the spectral sensitivity that is easily separated from the toner used. As for the spectral sensitivity distribution of the detection member, two detection sensors having different spectral sensitivity distributions of the detection member are selected by examining the spectral reflection distribution of the toner used on the photosensitive drum.

Further, as shown in FIG. 5B in another embodiment, the detecting member 870 has a light emitting LE on the main body 871.
D872, 873 and shared photosensor 874.

Next, FIG. 6 shows a part of the comparison circuit portion of the detection means in the embodiment. A detection circuit for processing a detection signal of the first detection sensor 70A to obtain a paper jam signal is shown. The light emitting LED 72 is connected in series with the resistor R1 in the forward direction between the power supply VCC and the ground, and the light receiving photosensor 75 that receives the reflection of the projection from the light emitting LED 72 is the power supply Vcc and the inverting input terminal of the operational amplifier 21. Is connected between and. A voltage obtained by dividing the power supply voltage Vcc by resistors R2 and R3 is applied to the non-inverting input terminal of the operational amplifier 21, and its output terminal is connected to the inverting input terminal by the resistor R4 and to the inverting input terminal of the comparator 22. Has been done. A voltage obtained by dividing the power supply voltage Vcc by the resistors R5 and R6 is input to the non-inverting input terminal of the comparator 22 as a predetermined reference voltage (threshold value) for comparison. This threshold value is set to a value such that the recording paper and each toner can be easily classified according to the spectral sensitivity of the toner used and the detection member used.

In this detection circuit, the photosensor 7 for receiving light is used.
When a large amount of reflected light is incident on 5, the photo sensor 7 for light emission
5 has a large emitter current, and this current is converted into a voltage and amplified by the operational amplifier 21. The output from the operational amplifier 21 decreases as the amount of light reflected by the photosensor 75 for light reception increases, and is input to the comparator 22 in the next stage. Then, in the comparator 22, when the output from the operational amplifier 21 to the inverting input terminal becomes lower than the reference voltage applied to the non-inverting input terminal, the output voltage becomes high level, and it is detected that the paper jam is detected. Shows.

The same applies to the second detection sensor 70B, and a description thereof will be omitted. In addition, in the second detection sensor, the second
The threshold L2 is set slightly above the value of cyan C.

Next, FIG. 7 shows the output signal of each detection sensor of the embodiment. FIG. 7A shows signals for the recording paper, the yellow toner Y, the magenta toner M, the cyan toner C, and the black toner BK of the first detection sensor 70A. More specifically, it shows the reflection density ratio of each toner used when the reflection density of the recording paper is 1.0. In the figure, L1 indicates a first threshold value of a predetermined reference value. The reflection from the yellow toner Y and the magenta toner M is considerably large and exceeds the first threshold value. Further, the cyan toner C has little reflection and does not exceed the first threshold value.

Similarly, FIG. 7B shows signals for the recording paper, the yellow toner Y, the magenta toner M, the cyan toner C and the black toner BK of the second detection sensor 70B. In the figure, L2 indicates a predetermined second threshold value. The yellow toner Y, the magenta toner M, the cyan toner C, and the black toner BK have little reflection and do not exceed the second threshold value.

FIG. 8 is a flow chart showing a threshold value determining operation used for detecting jammed drum jam. The flowchart described here explains the software constituting the drum constant determining means and the threshold determining means described in the claims.

A technique in which a single emission light source is used to detect a jam around a drum, the detection algorithm is complicated and inferior in reliability because there is no difference in the amount of light reflected from white recording paper and yellow solid toner. Problems were pointed out. In order to solve such a technical problem, in this embodiment, a yellow LED and a blue LED are used to improve the detection accuracy.

The threshold value for detecting the replacement of the unused photosensitive drum 10 is preferably determined from the amount of received light obtained from the reflected light from the yellow toner. When the microprocessor 510 detects the drum replacement by the algorithm described with reference to FIG. 10, it determines the yellow drum constant and the blue drum constant and writes them in the RAM 530. It is an essential condition that the detection member 70 is cleaned when determining the yellow drum constant and the blue drum constant when the drum is replaced. In the present embodiment, the process unit 1 is used.
The detection member 70 is cleaned in association with the replacement operation of 00. Further, the microprocessor 510 has 100
The yellow drum constant and the blue drum constant are updated every 0 prints. Here, the yellow drum constant = 0.7 × 0.8 ÷
It is calculated as the elementary tube level, and is calculated as blue drum constant = 0.6 × 0.8 ÷ element tube level, and the element tube level is the detection level from the detection member 70. The detection level from the detection member 70 is A / D converted with a maximum of 1.0, and the reflected light from the white recording paper is 0.
It is set to 8.

The microprocessor 510 turns on the development switching motor in the image forming apparatus 1 when the power is turned on. Next, the four developing units 150Y and 15 shown in FIG.
For 0M, 150C, and 150K, the development switching is moved to the home position, and the cam (not shown) is also moved to the home position. Next, the main motor of the image forming apparatus 1 is turned on, and after waiting for 15.2 seconds, the entire apparatus is operated. When the microprocessor 510 detects warming up (step 1), an image signal is input from another image output means (personal computer or the like).

Subsequently, the microprocessor 510 detects whether the photoconductor drum 10 is new or old and the number of prints (step 2).

The microprocessor 510 executes step 2
If it is determined that the process unit is unused, the yellow drum constant and the blue drum constant calculated from the above equation are determined (step 3), and the threshold value is determined based on the yellow drum constant and the blue drum constant. Is determined (step 4).

Here, the process of determining the threshold value from the determination of the drum constant will be described in detail. The microprocessor 510 emits light from a light emitting diode to measure the level of the raw tube of the photoconductor drum 10. The raw tube level is a level corresponding to the amount of reflection when toner or the like is not attached.

On the other hand, the microprocessor 510 determines that the number of prints is 1000 which is the predetermined number according to the determination in step 2.
If it is determined that the print is performed, the threshold is updated from the threshold = drum constant × element tube level as described above (step 5). In the present embodiment, the predetermined number is set to 1000 prints, and the threshold value is set again in response to deterioration over time. However, the present invention is not limited to this, and if the microprocessor 510 performs the above-mentioned threshold value resetting operation based on the detection output from the detection member 70 for each printing operation, damage to the photosensitive drum 10 in addition to deterioration over time, etc. It is possible to detect replacement due to the deterioration of the photosensitive drum 10 and determine replacement of the photosensitive drum 10.

The operation of discriminating between the old and new process units and the presence / absence of a protective cover in step 2 of FIG. 9 will be described with reference to FIG.

FIG. 9 shows a flow chart for discriminating between the old and new process units and the presence / absence of a protective cover. The flowchart described here explains the software constituting the replacement detection means and the print number detection means described in the claims.

The microprocessor 510 first checks the status of the new device and whether or not it is an unused photosensitive drum 10 (step 21). Here, the status of the new device indicates the number of prints. If the microprocessor 510 determines in step 21 that it is not the unused photoconductor drum 10, it returns to step 2 shown in FIG. 8 with the status of the new device.

The microprocessor 510 executes step 2
If it is judged that the status of the new device is not "00H" and it is an unused photoconductor drum 10 according to the judgment of 1, it is first checked whether the photoconductor drum 10 has a protection cover or not. Is started (step 22). When it is determined in step 22 that the protective cover is present, the microprocessor 510 determines that the photosensitive drum 1
Since the protective cover 337 is attached to 0 and the state is detected by the detection member 70, the image forming operation is stopped (step 23). On the other hand, if the microprocessor 510 determines in step 22 that the protective cover is not attached, it returns a code value indicating that the photosensitive drum is unused to step 2 shown in FIG.

The discrimination operation shown in FIG. 9 is executed during the warm-up period of a predetermined time from the power-on or the power-on of the interlock switch signal.

FIG. 10 is a flow chart showing a drum winding jam detection operation.

Subsequent to the threshold value determining operation described with reference to FIG. 8, the paper feed roller 202 is started and the recording paper P is started to be fed. When the recording paper P is conveyed, the recording paper P is detected,
The registration roller 209 conveys the image formed on the surface of the photoconductor drum 10 in the direction of the transfer roller 216 at the same timing. Next, from the leading edge of the recording paper P, the transfer roller 21
6 and the photoconductor drum 10 and the image is transferred. When the recording paper P passes through the image transfer section, the light emitting diode is turned on by the microprocessor 510 at the paper wrapping detection timing (step 11).

The microprocessor 510 includes the detecting member 7
If it is determined that the read level from 0 is within the range of 0.1 to 0.6, a P code is generated. Such a P code indicates the possibility of stains on the detection member 70.
If the microprocessor 510 determines that the reading level is being swung up or down, it generates an F code (step 12).

The microprocessor 510 includes the detecting member 7
If the error occurrence is not detected when reading from 0 (step 12), the winding jam determination operation is executed (step 13). Here, the microprocessor 510 is
The detection member 70 detects the reflected light from the photoconductor drum 10 by causing the yellow light emitting diode to emit light. Since the threshold level obtained from the yellow drum constant is used for such a determination operation, either the white recording paper or the yellow solid toner image is detected. Therefore, in order to distinguish between the white recording paper and the yellow solid toner image, the blue light emitting diode is caused to emit light, and the reflected light from the photosensitive drum 10 is detected by the detection member 70. A threshold level obtained from the blue drum constant is used for such a determination operation. Since such a detection process causes a large difference in the detection level between white and yellow, the recording paper can be detected without being confused with the solid yellow toner.

The microprocessor 510 detects the light reflected from the photosensitive drum 10 by the detecting operation and the determining operation.
The recording paper P is not attracted to the photoconductor drum 10 and the fixing device 22
When the recording sheet P is conveyed in the 0 direction and the recording sheet P is discharged by the discharge sensor 229, the image forming operation is stopped.

According to the above-described present embodiment, by providing the above-described configuration, the yellow solid toner image and the photoconductor drum 10 element tube can be surely identified, and the drum winding jam can be detected.

FIG. 11 is a flow chart showing in detail the comparison operation of step 13 shown in FIG.

Detection of paper jam by the color image forming apparatus according to the present invention will be described with reference to FIGS.
The operation of the first embodiment will be described with reference to the flowchart. Yellow toner Y, magenta toner M, cyan toner C, and black toner BK are independently provided on the photosensitive drums.
The case in which the residual remains will be described.

The concentration is measured by the first detection sensor 70A (step 131), and it is checked whether or not the measurement signal exceeds the first threshold value L1 (step 132).
If not, continue copying (step 13)
6). Next, if it exceeds, the second detection sensor 70B measures the concentration again (step 133), and the second threshold L
Check if it exceeds 2 (step 13)
4). If not, continue copying (step 1)
36). Next, if it exceeds, it is determined that there is a paper jam and the operation is stopped (step 135).

In the above embodiment, the photosensitive drum 10 is used.
The recording paper 6 is singly provided on the upper side, and the yellow toner Y, the magenta toner M, the cyan toner C, and
The case where the black toner BK is present has been described, but the same applies to the case where the black toner BK remains after being combined. For example, if half of the yellow toner Y and half of the cyan toner C remain, and if the recording paper is not jammed, assuming that the reflection density ratio of the yellow toner Y and the cyan toner C is proportionally divided in FIG. The first threshold L1 for the signal of the first detection sensor has a high value (H), and the second threshold L1 for the signal of the second detection sensor has a low value (L). As a result, it can be seen that there is no jam of recording paper.

In the embodiment, two detection sensors are used in the detection sensor section. However, the number of detection sensors is not limited to two, and three detection sensors may be used.

[0084]

As described above, according to the present invention, the jamming of the drum can be detected by surely discriminating the toner image and the photoconductor drum tube from each other by providing the above configuration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a perspective view showing a moving mechanism of detection means 70.

FIG. 3 is a block diagram showing a main configuration of an engine controller according to the present embodiment.

FIG. 4 is a characteristic diagram of spectral reflectance distributions of various toners used in the embodiment.

FIG. 5 is a sectional view of a detection member according to the embodiment.

FIG. 6 is a circuit diagram of a part of a comparison circuit unit of the embodiment.

FIG. 7 is a reflection density ratio of the detection member in the embodiment.

FIG. 8 is an operation flowchart of the embodiment.

FIG. 9 is a flowchart showing a threshold value determining operation used for detecting jammed drum winding.

FIG. 10 shows a flowchart for determining whether a process unit is old or new and whether or not a protective cover is provided.

FIG. 11 is a flowchart showing a drum winding jam detection operation.

[Explanation of symbols]

 10 photoconductor drum 70 detection member 81 rail 82 motor 83 driven roller 300 double-sided reversing device 510 microprocessor 520 SRAM 530 RAM 540 interlock detection circuit

Claims (6)

[Claims] 1. Developing means for developing an electrostatic latent image formed on an image forming body with color toner of one color or a plurality of colors to form a toner image, and transfer means for transferring the toner image onto a recording paper. An image forming apparatus comprising: a separating unit that separates the recording paper from the image forming body; and a detecting unit that optically detects the recording paper wound around the image forming body due to a defective separation of the recording paper, The detection unit has a detection sensor unit having a detection sensor having at least two different spectral sensitivities in the wavelength region of the spectral reflectance distribution of the toner of one color or a plurality of colors, and a drum constant for each light emitting light source of the detection sensor unit. From the detection sensor, a threshold value calculating means for calculating a threshold value for identifying the tube level of the image forming body from the drum constant calculated by the drum constant determining means, It is characterized by comprising a comparison unit for comparing the signal with a reference value obtained from the threshold value calculation means, and a paper jam determination unit for performing arithmetic processing based on the results of the respective comparison units to determine the presence or absence of a paper jam. Image forming apparatus. 2. A replacement detection means for detecting replacement of the image forming body is provided, and based on a detection operation of the replacement detection means,
The image forming apparatus according to claim 1, further comprising a control unit that determines the drum constant by the drum constant determination unit, and that causes the threshold value calculation unit to calculate a threshold value for detecting a winding jam from the drum constant. 3. A print number detecting means for detecting whether or not the number of prints using the image forming body has reached a predetermined value, and the drum constant determining means is based on the detecting operation of the print number detecting means. 2. The image forming apparatus according to claim 1, further comprising control means for determining a drum constant by means of the drum constant, and for causing the threshold value calculation means to calculate a threshold value for detecting a winding jam from the drum constant value. 4. A threshold value for determining a drum constant by the drum constant determination means by an interlock switch signal or by turning on the power source or during a warming-up period of a predetermined time after the power source is turned on, and detecting a jammed jam around the threshold value calculating means from the drum constant value. The image forming apparatus according to claim 1, further comprising control means for calculating 5. A developing means for developing an electrostatic latent image formed on an image forming body with color toner of one color or a plurality of colors to form a toner image, and a transfer means for transferring the toner image onto a recording paper. An image forming apparatus comprising: a separating unit that separates the recording paper from the image forming body; and a detecting unit that optically detects the recording paper wound around the image forming body due to a defective separation of the recording paper, A double-sided reversing device that reverses and conveys the recording paper to the transfer area of the image forming body is provided, and the detection unit has at least two different spectral sensitivities in the wavelength range in the spectral reflectance distribution of the toner of one color or a plurality of colors. A detection sensor unit having a detection sensor having, a yellow light emitting light source and a blue light emitting light source are arranged so as to project light onto a non-image area of the image forming body, and receive reflected light from the non-image area. The image forming body Of the drum constant determining means for calculating the drum constant of each of the light emitting sources and the threshold value for identifying the tube level of the image forming body from the drum constant calculated by the drum constant determining means. An image forming apparatus comprising: a threshold value calculating means; and a control means for detecting a winding jam by comparing a threshold value obtained from the threshold value calculating means with a detection level detected from the light receiving element. 6. A movement control unit which is provided with a moving mechanism that moves the detection sensor unit along the surface of the image forming body, and moves the detection sensor in consideration of a binding margin and a white frame according to a recording size when printing on the back surface. The image forming apparatus according to claim 5, further comprising: