JPH0579515B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device such as a laser beam printer (LBP), and in particular, to a recording device such as a laser beam printer (LBP), etc., and in particular, a method for appropriately controlling the conveyance of recording material, for example, when a cut sheet of paper skews. This is what I did.

In recording devices such as this type of LBP, images can be recorded continuously on the photoreceptor, so the interval between feeding recording materials is kept to the minimum necessary to obtain the maximum number of recorded images with the minimum time loss. I can do things. Therefore, in such a recording device, there are problems such as problems in feeding the recording material, such as cut paper (sheets),
For example, when paper jams (so-called jams) occur, such as double feeding or skew feeding due to non-separation of multiple cut sheets, it is necessary to prevent the number of output prints per unit time, so-called throughput, from decreasing as much as possible. For example, when a jam occurs, it is usually necessary to immediately stop the recording operation of the apparatus and remove the jam, but even if a cut of paper skews, it does not necessarily mean that a jam will occur. That is, whether or not a jam is induced is determined by the degree of skew that has occurred, that is, the amount of skew, and the greater the amount of skew, the greater the possibility of inducing a jam. In particular, when a separation belt is used to separate the recording paper on which images have been transferred from the photoconductor, if the amount of skew is large, the recording paper will not be sufficiently caught on the separation belt, and the photoconductor and separation belt Jams are likely to occur during this period. On the other hand, if the amount of skew is below a certain level, even if it is not acceptable as an output image transferred to recording paper, it may not cause any problem in conveying the recording paper. However, in conventional recording apparatuses of this type, the skew of the conveyed recording paper is not particularly monitored, and regardless of the amount of skew, all the recording paper on which images have been transferred are processed in the same way, and the same paper is processed. If a jam is induced by skewing when the paper is housed in the storage section, the operation of the apparatus must be stopped each time the jam is removed, resulting in a reduction in throughput.

It is an object of the present invention to eliminate the above-mentioned conventional drawbacks, constantly monitor the occurrence of skewing of a conveyed recording material and the amount of skewing, and not only detect the skewing of the recording material but also detect the skewing of the recording material. If the occurrence frequency is high, it issues a warning, notifies the device of an abnormality, and stops the device's operation.Furthermore, it retries image formation of the same recorded information depending on the degree of skew.
It is an object of the present invention to provide a recording device that improves operability without interrupting the image forming operation.

That is, in the present invention, the amount of skew of the recording material being conveyed is detected, and if the amount of skew is less than a predetermined amount, it is assumed that the image formation on the recording material is normal, and the image formation on the recording material is determined to be normal. After the image formation, the recording material is accommodated in the first storage means, and recording information is generated next. On the other hand, if the amount of skew is larger than a predetermined amount, it is considered that the image formation on that recording material is defective, The conveying operation of the conveying means is continued to accommodate the recording material in the second storage means, and the same recorded information is automatically regenerated, and the image formation is redone on another recording material that is subsequently conveyed. The number of times the line occurs is counted, and if skew occurs a predetermined number of times, a warning is issued and the operation of the device is stopped.

The present invention will be described in detail below with reference to the drawings.

First, as an example of this type of recording apparatus suitable for implementing the present invention, the basic configuration of a laser beam printer LBP is schematically shown in FIG. In the illustrated configuration, a laser beam emitted from a laser oscillator 1 is made incident on an optical adjustment system composed of a lens 2, an A/O modulation element 3 that utilizes the well-known acousto-optic effect, and a lens 4. In addition, lens 2 is A/O
A laser beam is focused on a plug reflection surface generated in the modulation element 3, and a lens 4 restores the laser beam, which is diffracted and diverged from the plug reflection surface, into a parallel beam. Furthermore, when using an E/O modulation element that utilizes the well-known acousto-optic effect, the lenses 2 and 4 become unnecessary, and when the laser oscillator 1 is a gas laser or the like capable of current modulation, the above-mentioned The entire optical modulation system can be omitted.

Next, the laser beam consisting of the parallel light flux from the lens 4 is made incident on the beam expander 7 to expand the beam diameter of the parallel light flux, and then made incident on the polyhedral rotating mirror 8 . This polyhedral rotating mirror 8 is
It is attached to a rotating shaft supported by a high-precision bearing, for example, an air bearing, and is driven by a motor 9 such as a hysteresis synchronous motor or a CD servo motor to rotate at a constant speed, and horizontally deflected by the polyhedral rotating mirror 8. The laser beam is imaged to form a spot on the circumferential surface of the photosensitive drum 14 by an imaging lens 13 having f-θ characteristics. Therefore, in a general imaging lens, when the incident angle of a light ray is θ, for the position r on the image plane where the image is formed, for the focal length f of the imaging lens, r=f・tanθ (1) When the polyhedral rotating mirror 8 is rotated at a constant speed as in the illustrated example, the angle of incidence of the reflected laser beam on the imaging lens 13, shown as the deflected beam 52 in FIG. 2 described later, changes over time. Changes linearly. Therefore, the moving speed of the position of the imaged spot on the photosensitive drum 14, which is the image surface, changes non-linearly and is not constant. That is, the moving speed of the spot position where the angle of incidence increases increases. Therefore, when a laser beam is irradiated at regular time intervals to draw a line of imaging spots on the photosensitive drum 14, the spacing between the spots in the line of spots becomes wider at both ends than at the center. In order to avoid such development, the imaging lens 13 is designed to have the following characteristic: r=f·θ (2). The imaging lens 13 having such characteristics is called an f-θ lens. Furthermore, when a parallel beam of light is imaged into a spot by an imaging lens, the minimum diameter dmin of the spot is dmin=f・λ/A (3) where, f: focal point of the imaging lens Distance λ: Wavelength of light used A: Given by the entrance aperture of the imaging lens, and when f and λ are constant, A
The larger the spot diameter dmin, the smaller the spot diameter d min
is obtained. The beam expander 7 mentioned above is
It is used to provide such an effect. Therefore, if the required spot diameter d min can be obtained by the beam diameter of the laser oscillator, the beam expander 7 will be omitted.

As described above, the photosensitive drum 14 is irradiated with the deflected and modulated laser beam 52 shown in FIG. Output as hard copy. As an example of such an electrophotographic formation process, as described in Japanese Patent Publication No. 42-23910 filed by the applicant, the insulation of a photosensitive plate 14 whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer is disclosed. The surface of the layer is uniformly charged positively or negatively in advance by the first corona charger 16, and then the surface of the insulating layer to be charged is irradiated with the laser beam described above, and at the same time, the surface of the layer is charged by the AC corona discharger 17. After applying an alternating current corona discharge to form a pattern on the surface of the insulating layer due to the difference in surface potential that occurs according to the light and dark pattern of the laser beam, the entire surface of the insulator is exposed to the full exposure lamp 18. As a result, a high-contrast electrostatic latent image is formed on the surface of the insulating layer by uniform exposure, and the electrostatic latent image is further developed by a developing device 19 using a developer mainly composed of charged colored particles. The visible image is visualized and developed by developing it, and then the visible image is transferred by the transfer charger 22 to a sheet of paper pressed against the photosensitive drum 14 by the means described later, and then the transferred image is transferred by the fixing means described later. A fixed electrophotographic print image is obtained. After the transfer process is completed, the surface of the insulating layer described above is cleaned by the cleaning device 23 to remove remaining charged particles, so that the photosensitive plate 14 can be used repeatedly.

Further, as another example of the electrophotographic forming process, in the electrostatic latent image forming process described in Japanese Patent Publication No. 19748, also filed by the applicant,
Using a photosensitive plate whose basic components are a conductive support, a photoconductive layer, and an insulating layer, the surface of the insulating layer is uniformly positively or negatively charged in advance by a first corona discharge, and the photoconductive layer is Electrification with a polarity opposite to the above-mentioned charged polarity is captured at the interface between the insulating layer and the photoconductive layer, and then an alternating current corona discharge is applied to the above-mentioned surface to be charged to remove the charge on the surface of the insulating layer. After attenuation, a laser beam as an information signal is irradiated to form an electrostatic latent image on the surface of the insulating layer according to its brightness, but the subsequent development and fixing process is carried out in exactly the same manner as in the previous example. .

In the illustrated configuration, reference numeral 15 indicates a charger for pre-discharge, and reference numeral 16' indicates a pre-exposure lamp. make the characteristics of the photosensitive layer constant and uniform, and work together to erase residual potential from the preceding process that remains on the photosensitive drum 14 after cleaning by the cleaning device 23; This ensures that stable recorded images can be obtained at all times.

Further, in the electrophotographic formation process using the illustrated configuration, the following electrostatic latent image stabilization is performed as a means to always stably obtain a high quality recorded image. That is, 21 is an electrostatic electrometer for realizing such a means, and is adapted to measure the electrostatic potential in the light and dark areas of the photosensitive drum 14, that is, in the bright and dark areas scanned and exposed by the laser beam. Further, 20 is a carrier removal device,
This is to prevent the carrier immersed in the developer in the developing device 19 from adhering to the photosensitive drum 14 and the transfer paper, or from entering the cleaning device 23.

The structural arrangement of the optical system in the above-described configuration shown in FIG. 1 is three-dimensionally shown in FIG. Components having the same functions as those in FIG. 1 are indicated with the same symbols. In the configuration shown in the second figure, 51 is a beam detector consisting of a small entrance slit and a fast-response photoelectric conversion element, such as a PIN diode, and a laser beam deflected and swept by the polyhedral rotating mirror 8. 52 is detected, and the detection output signal determines the start timing of a modulation control signal for providing desired optical information on the photosensitive drum 14, as will be described later. In addition, in FIG. 2, the scanning direction of the laser beam is indicated by an arrow 53.

Next, regarding the conveyance of the transfer sheet, when the sheet 31 stacked on the sheet feeding stage 30 is sent out to the conveying path by the sheet feeding roller 32, a pair of registration rollers 33 is used to move the sheet 31 skewed during sheet feeding. In addition to correcting the edges, align the leading edges of the sheets. The sheet that has passed through the registration rollers 33 passes through a conveyance guide 34 that forms part of the conveyance path and comes into contact with the photosensitive drum 14, but a skew detection sensor 47 is disposed between them, and its detection output is Therefore, it is determined whether there is skew feeding during paper feeding. Next, the image on the photosensitive drum 14 is transferred onto a sheet of paper 31 by the transfer charger 22,
The transferred sheet 31 is separated from the photosensitive drum 14 by a separating means (not shown) and sent to a conveyor belt 39. A photo sensor 35 is disposed in the middle of the conveyor belt 39, and the presence or absence of a jam in the conveyance path from the paper feed roller 32 to the photosensitive drum 14 is detected based on the output of the photo sensor 35. Next, the sheet 31 is fed to a fixing device 40 by a conveyor belt 39, and the toner image on the sheet 31 is fused by the heat and pressure of the fixing device 40, thereby fixing it as a permanent image. The sheet 31 after fixing is fed to a conveyor belt 41 to a discharge roller 42.
A jam occurring between the photo sensors 35 and 36 is detected by the photo sensor 36 disposed in front of the photo sensor 2 and the photo sensor 35 described above. The sheets 31 that have been normally conveyed then pass through the paper ejection rollers 42 and are stacked on the first output tray 43.

Further, as will be described later, when the skew of the sheet is detected, the photo sensor 36 detects the skew of the sheet.
1 is detected, the paper ejection switching plate 44 is switched to the position shown by the broken line, and the skewed abnormal sheet is loaded onto the second output tray 46 via the paper ejection rollers 42 and 45. In addition, a photo sensor 37 is placed in front of the paper ejection roller 45 to ensure that unnecessary sheets, which cannot obtain an output image due to skew feeding, are transferred to the second paper.
It is detected that the paper is being transported toward the output tray 46.

Next, FIG. 3 shows an example of a schematic configuration of the above-mentioned skew detection section. In the illustrated skew detection device,
On the paper conveyance path, multiple sensors are arranged at intervals slightly narrower than the conveyance width in order to detect the leading edge of the sheet, and skew occurs by taking the difference in detection time between the two sensors. Determine whether or not. That is, when the sheet 31 is sent out by the paper feed roller 32, it passes through the paper guides 32-1 and 32-2, and is corrected by the registration roller 33 for skew, delay, etc. during paper feeding. Sent with . The sheet that the registration roller 33 has passed is placed in a guide 34.
While being guided between the
The guide 34 is provided with a sensor that detects the leading edge of the sheet. That is, the light emitting lamps 35a, 35b
The light-receiving photo sensors 47a and 47b constitute sensors A and B, and this combination of sensors A and B detects the amount of skew of the sheet. The output signal waveforms of such sensors A and B are shown in FIG.
By knowing the output time difference Δt of both sensors A and B in the signal waveform shown, it is possible to detect the skew amount Δd. , Δd=v×Δt.

Next, the laser beam printer LBP mentioned above
An example of the configuration of the control section is shown in FIG. In the illustrated configuration, 100 is a microprocessor that controls the operation of the LBP according to a program stored in a read-on memory ROM (not shown);
1, 102, 103 are photo sensors 47a, 47b, 36 in the configuration shown in the first diagram.
, and those photo sensors 1
The detection output signals from 01, 102, and 103 are compared with reference values by comparators 104, 105, and 106, respectively, and the results are sent to the microprocessor 1.
Enter 00. In addition, the microprocessor 10
0 to the switching circuit 107,
108 and 109, respectively, a paper feed roller clutch 110, a registration roller clutch 111,
output to the paper ejection switching solenoid 112, respectively.
The paper feed roller 32, registration roller 33, and paper discharge switching plate 44 are driven. Furthermore, the microprocessor 100 outputs the image write timing signal VTS to the page information output circuit 115, and the video signal VS from the page information output circuit 115 and the permission signal PS from the microprocessor 100 are sent to the AND gate 116. Enter that and gate 1
16 through an A/O driver 117 corresponding to block 5 in the configuration shown in the first diagram.
Similarly, it is input to an A/O modulator 116 corresponding to block 3 in the configuration shown in FIG. Further, a status code signal from the microprocessor 100 is passed through a decoder 113 to drive a display element 114.

FIG. 6 shows a timing chart of the control operation in the control section shown in FIG. 5 described above. As shown in the figure, when a print start is commanded, the paper feed clutch is turned on at time _{T1 with a delay of time τ1 ,} and after keeping the on state for time _Tf1 ,
It remains in the off state for a time T _f2 and feeds the topmost sheet (N=1). Below, in the same way, the time
N= ₂ , ₃ , ... sheets are fed to T 2 , T 3 , .... In addition, in order to convey the sheet fed in this way by forming a predetermined loop at the registration roller, the registration clutch is moved at a certain time.
After a time T _r1 has elapsed from T ₁ , the resist clutch is turned off for a time T _r2 to stop the conveyance, and then the resist clutch is turned on again to restart the conveyance.
Hereinafter, the same procedure will be applied to times T ₂ , T ₃ , . . . . On the other hand, after time _Tl has elapsed from time _T1 , page information is output from the page information output circuit 115, and each page n=1, 2,
... are written in sequence, and the leading edge of the sheet that has passed through the registration roller 33 is detected by photo sensors A and B, and when the output of each photo sensor A and B changes from a low level L to a high level H, respectively. Regarding the timing of , the elapsed time t _a from time T ₁ ,
When t _b is measured, the difference Δ between the elapsed times t _a and t _b corresponds to the amount of skew of the sheet.

Here, for convenience of explanation, when the time difference Δ≦2, the first level skew amount, when the time difference Δ is 2<Δ≦6, the second level skew amount, and when the time difference Δ≧7, the second level skew amount. Assuming three levels of skew amount, in the example of the timing chart shown in Figure 5, among the sequential sheets, N=2 and N=4 have a skew amount of the second level. Become. Therefore, N
=2 and N=4, that is, the second and fourth sheets are ejected and stored in a second output tray 46 that is separate from the first output tray 43 that absorbs normal output sheets. In order to do this, the output of the photo sensor 36 is changed from the low level L to the high level H only for the sheets N=2 and 4, and after a delay of a certain time τ ₂ , the paper ejection switching solenoid 112 is activated. Excite. On the other hand, by discharging sheets N=2 and 4 to the second output tray 46 in this way, the transfer information will be missing, so
The page information of =2 and n=4 is re-outputted and written on the photosensitive drum 14 again.

On the other hand, in the example of the timing chart shown in FIG. 6, for N=7 sheets, the time difference Δ=7
Therefore, as soon as the third level of skew is detected, the print start command is canceled, the device stops operating, and the jam is inspected and removed. Become.

Next, a detailed flowchart of the above-mentioned control operation is shown in FIG. In the illustrated flowchart, as described above, n is the number of pages of output information, N is the number of pages of sheets to be fed, k ₁ , k ₂ ,
Let k ₃ and k ₄ be constants, and i and j be counter variables.
Therefore, in the illustrated flowchart, first, in step 201, each necessary constant is set,
At step 202, the information data to be recorded is finished,
Alternatively, it is determined whether or not the state is a "stop" state in which there is no remaining amount of recording paper, and if not, the process moves to step 203. In step 203, the Nth page sheet is fed with N=1 at first, and then in step 204, the sheet is fed with N=1 at first.
Then, in steps 205 to 207, the registration rollers are sequentially controlled after paper feeding. Next, in step 208, the elapsed time t _a and t _b when the output from the photo sensors A and B changed from the low level L to the high level H is read, and then in step 209, both sensors A and B are read.
The output time difference Δ of B is calculated as an absolute value, and in subsequent steps 210 and 211, the calculation is performed according to the amount of time difference Δ, and if the skew amount is at the second level, step 215 is performed.
If the amount of skew is at the third level, the process moves to step 219.

If the amount of skew is at or below the first level in step 210, the counter variable i is reset in step 212, and then step 212 is reached.
At 213, the number of pages n of output information is incremented by 1,
Next, in step 214, the number N of fed pages is incremented by 1, and then the process returns to step 202 to repeat the above-described process.

However, in step 215 mentioned above, the second
The paper ejection switching solenoid 1 controls the paper ejection switching solenoid 1 to eject the sheet on which the skewed paper of the level amount is detected to the second output tray 46.
12, the process proceeds to step 216, where counter variables i and j are incremented by 1, and then, in step 217, constant _k3 and counter variable i are incremented.
It is determined whether skewing of the amount of the second level has occurred k ₃ times in a row or not. If it has exceeded k ₃ times, the process moves to step 218 and the device operation is The status is displayed as an abnormality, and at step 220, the operation of the device is stopped to eliminate the abnormality. If k ₃ times or less is found in step 217, the process moves to step 221, where the counter variable i is compared with a constant _k4 , and if j≦ _k4 , the process moves to step 213. , the step process described above is carried out, and if j>k ₄ , the step
The process moves to 218 and performs the process after displaying the status. Note that if the time difference Δ exceeds the constant _k2 in step 211, the process moves to step 219, and the third
As an abnormality in the operation of the device in which skewing of the amount of level occurs, a status display different from that in step 218 is displayed, and in step 220, the operation of the device is stopped in the same way as when a jam occurs. Carry out an inspection. In addition, by the treatment in step 221 described above,
By advancing only the paper feed page N, it is possible to repeatedly reproduce and transfer the output information of the same page n.

As is clear from the above description, according to the embodiment, in a recording device such as a laser beam printer, by classifying the skew detection level according to the amount of skew of a sheet, the first output for normal paper is detected. By combining the second output tray for waste paper, which is separate from the tray, skewed paper can be eliminated, and the throughput of the entire recording apparatus can be improved. Additionally, by checking the frequency at which skewed paper is ejected to the second output tray, that is, the cumulative number or the constant number of consecutively ejected sheets, it is possible to reliably determine whether there is an abnormality in the operation of the recording device. According to the present invention, even if the recording material is skewed, the operation of the apparatus is not stopped unnecessarily, so the operability is improved and the efficiency of the image forming operation can be prevented from decreasing. Furthermore, when skew occurs, the same recorded information is regenerated without any special operation, improving operability and preventing image loss.

Furthermore, since recording materials with defective image formation and recording materials with normal image formation are stored separately, skewed recording materials can be easily removed, improving operability. can. Additionally, when the number of times skewing occurs, which would cause image formation to be considered defective, reaches a predetermined value, a warning is issued and the device stops operating, so the user can be alerted to the fact that the device is in a state where skewing is likely to occur. You can notify service personnel, making it easier to maintain the device, and
It is possible to prevent wasteful recording operations and prevent wasteful consumption of recording materials.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing the configuration and arrangement of the recording apparatus of the present invention, FIG. 2 is a perspective view showing a partially enlarged view, and FIG. 3 is an enlarged view of the skew detection section. 4 is a waveform diagram showing the operation signal waveform of the skew detection section, FIG. 5 is a block diagram showing an example of the configuration of the control section, and FIG. 6 is a diagram showing the operation of the control section. The timing chart shown in FIG. 7 is a flow chart showing the operation of the control section. 1... Laser oscillator, 2, 4... Ends, 3...
...A/O modulation element, 5...A/O driver, 6...
... terminal, 7 ... beam expander, 8 ... polyhedral rotating mirror, 9 ... motor, 10 ... amplifier, 11
. . . Oscillator, 12 . ...Developing device, 20...Carrier removal device, 21...Electrostatic electrometer, 22...Transfer charger, 23...Cleaning device, 30...
Stage, 31... Sheet, 32... Paper feed roller, 32-1, 32-2... Paper guide, 33...
Registration roller, 34... Conveyance guide, 35, 3
6, 37...Photo sensor, 35a, 35b...
Light emitting lamp, 39, 41... Conveyor belt, 40...
...Fuser, 42, 45... Paper ejection roller, 43, 4
6... Output tray, 44... Paper ejection switching plate, 47...
... Oblique detection sensor, 51 ... Beam detector, 52
... Laser beam, 53 ... Arrow, 100 ... Microprocessor, 101-103 ... Photo sensor, 104-106 ... Comparator, 107
~109... Switching circuit, 110... Paper feed roller clutch, 111... Registration roller clutch, 112... Paper discharge switching solenoid, 113...
... Decoder, 114 ... Display element, 115 ... Page information output circuit, 116 ... AND gate, 1
17...A/O driver, 118...A/O modulator.

Claims (1)

[Scope of Claims] 1. A generating means for generating recording information; a conveying means for conveying a recording material; and an image forming means on the recording material conveyed by the conveying means based on the recording information generated by the generating means. an image forming means; first and second storage means for storing the recording material on which the image has been formed; a detection means for detecting the amount of skew of the recording material being conveyed by the conveyance means; and detection by the detection means. When the skew amount of the recording material is less than a predetermined amount, it is assumed that the image formation on the recording material is normal, and after the image formation on the recording material, the recording material is stored in the first storage means and the next step is carried out. generating recording information from the generating means; on the other hand, when the skew amount of the recording material is larger than the predetermined amount, it is determined that the image formation on the recording material is defective, and the conveying operation of the conveying means is continued; Transfer the recording material to the second
a control means for automatically generating the same recording information again from the generation means and redoing image formation on another recording material that is subsequently conveyed by the conveyance means; a counting means for counting the number of times image formation on a material is deemed to be defective; and a warning means for issuing a warning when the count value of the counting means reaches a predetermined value, the control means is configured to control the counting means. A recording device characterized in that the operation of the device is stopped when the count value of reaches a predetermined value.