JPS6363449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the conveyance state of an image supporting sheet in an electrophotographic apparatus.

Conventionally, in electrophotographic apparatuses, the most common method for detecting the conveyance state of an image support sheet, such as a copy paper, is a time detection method. When the image support sheet is fed, the timer is started, and when the sheet is ejected, the timer is returned to the start state and restarted when the next sheet is fed, and when the timer elapses the set time, the timer is started again when the image support sheet is ejected. For example, there is a method in which transport is determined to be defective when this is not performed.

There is also a method of detecting on a sequence program. For example, in the case of a moving optical system, if there is no detection signal from an image support sheet detector provided near the transport path through which the image support sheet is scheduled to pass at the end of the exposure process, there is a method in which the transport is determined to be defective.

In addition to detecting the conveyance state of the image support sheet in the above-mentioned conveyance direction, detection of the conveyance state in a direction perpendicular to the conveyance direction or diagonal feeding may also be performed. The simplest method is to provide a detector at a position slightly deviated from the scheduled conveyance path and determine that conveyance is defective when an image sheet detection signal is generated from this detector. Furthermore, there is a method in which the image sheet is detected within a certain area and the detected amount is compared with a reference value.

The conventional time detection method described above has a drawback in that it is not possible to distinguish between a transport failure and a failure of the apparatus when the set time of the timer has elapsed due to a failure of the apparatus or the like. The conventional method of detecting on a sequence program does not have the disadvantages of the time detection method, but it is impossible to detect diagonal feed, and it is necessary to additionally install a detector for diagonal feed. If this is not possible, the detector itself may become an obstacle on the conveyance path, increasing the number of conveyance defects.

If multiple types of image support sheets can be conveyed, a detector corresponding to each type is required, and controlling the operation of the detector according to the type requires a complicated control device, which increases the risk of failure. The causes of this will increase.

The present invention eliminates the above-mentioned drawbacks of the conventional image sheet conveyance path, and provides an image that can detect conveyance defects in the sheet conveyance direction, sheet lateral deviation, diagonal feeding, and even sheet wrinkles and folds without causing any problems on the image sheet conveyance path. An object of the present invention is to provide an electrophotographic apparatus equipped with a support sheet conveyance state detection device.

Furthermore, the present invention provides an electrophotographic apparatus having functions such as safety processing when changing the conveyance route and a function of deducting usage fees when defective printed matter occurs by using an image support sheet conveyance state detection device. The purpose of

The details of the present invention will be explained based on embodiments shown in the drawings.

In FIG. 1, an original placed on an original platen 1 is moved and is sequentially illuminated by an exposure unit 3 including a light source 2, and the illumination light is emitted from mirrors 4, 5, 6, 7,
The light is projected onto the photosensitive drum 10 by an optical unit 9 including a lens 8 and the like, forming an electrostatic latent image on the photosensitive drum 10. The example shown in the figure shows a color electrophotographic apparatus that can color-separate image light after illuminating an original into three colors and form electrostatic latent images on three photosensitive drums for each separated color.

The electrostatic latent image on the photosensitive drum 10 is developed and visualized by a developing device 11 containing developers of individual colors according to the separated colors, and a sheet is conveyed from a paper feeder 12 by a transfer belt device 13. The developed images of each photosensitive drum 10 are sequentially superimposed and transferred onto the photosensitive drum 10.

The image supporting sheet after the transfer is fixed by the fixing unit 14, and then transferred to the paper ejection tray 1 by the paper ejection roller 15.
6 is discharged on top.

The paper feeding device 12 shown in the figure shows an example in which, for example, three types of paper feeding cassettes of different sizes are installed.

The exposure unit 3, optical unit 9, photosensitive drum 10, developing device 11, paper feeding device 12, transfer device 13, fixing unit 14, etc. are all based on a known copying system, so detailed explanations will be omitted.

Before the fixed image support sheet in the fixing unit 14 reaches the paper ejection roller 15, it is detected by the position detection device 18.
is detected and then ejected.

As shown in FIG. 2, the position detection device 18 is connected to a slit 20 provided in a guide plate 17 that guides an image support sheet 19, and is located approximately at the center of the slit on the side of the guide plate 17 opposite to the side through which the sheet 19 passes. It includes a position detecting section 21 arranged opposite to each other, for example, a condenser lens 22, a sensor 23 connected to the condensing lens 22, and a lamp 24 that illuminates the position detecting section 21 at the slit 20.

When the image supporting sheet 19 passes through the slit 20, the image supporting sheet 19 blocks the light beam emitted by the lamp 24, so that bright and dark areas are generated at both ends of the image supporting sheet 19. The light beams in bright and dark areas at both ends or one end are focused by a condenser lens 22 and sent to a sensor 23, and the level of the bright and dark areas is detected to determine the conveyance state. The sensor 23 may have a structure that has multi-point detection elements and can perform optical time-division detection, and the detection results may be digitally processed.

As shown in FIG. 3, the position detectors 18 can be provided one on each side of the image support sheet to detect the brightness and darkness of both ends individually, and furthermore, the condenser lens in FIG. 3 can be omitted. A lamp 24 as shown in FIG.
It is also possible to detect the position by providing sensors 23 and 23 at both ends of the image support sheet 19, respectively.

The operation of the device will be explained below.

Turn on the main switch of the electrophotographic device shown in Figure 1 to check the preheating of the fixing device, cleaning of the developing drum, and setting of the original platen, set the copy original on the original platen 1, select single color or full color, and select the size. Also, set the exposure amount using a prescribed dial, etc., and press the copy start button.

By pressing the copy start button, a sheet is started from the paper feeder 12 in synchronization with the rotation of the drum, and upon confirmation of paper feeding, the document table 1 is started.

The exposure unit 3 operates in synchronization with the movement of the document table 1, and a latent image is formed on the photosensitive drum 10. In the case of monochrome copying, one photosensitive drum is used, and in the case of full-color copying, all three drums 10 are used.

The photosensitive drum 10 is developed by a developing device 11 while rotating, and the developing powder is transferred by a transfer belt device 13 onto a sheet that is conveyed in synchronization with the rotation of the photosensitive drum.

In the case of monochrome copying, one transfer from the photosensitive drum is performed, but in the case of full-color copying, the developing powder from three photosensitive drums is sequentially superimposed and transferred onto the sheet.

After the transfer is completed, the image support sheet is transferred to the transfer belt device 13.
The image is separated from the image by the pick-off claw 25 and sent to the fixing unit 14.

In the fixing unit 14, for example, roller fixing is performed in the case of monochrome copying, and roller fixing and radiation fixing are performed in the case of full color copying.

The fixed image support sheet 19 is guided and conveyed by a guide plate 17, detected by a position detector 18, and discharged by a paper discharge roller 15.

In the detection method using a discrete circuit shown in FIG. 5, the brightness and darkness levels at both ends of the image support sheet 19 detected by the sensor 23 in the position detector 18 are sent as a continuous signal to the output separator 26 including a Schmidt circuit, and the output separation is performed. The signal is separated into a detection part (for example, high level...denoted as H) and a non-detection part (for example, low level...denoted as L) by the device 26,
The signal from the oscillator 27 is mixed with the gate circuit and output as an H part pulse and an L part pulse to a detection part counter 28 and a non-detection part counter 29, respectively.
separated and counted.

The counting results are compared with reference values 32 and 33 preset by a switch or ROM in a comparator 30 as a first comparison means and a comparator 31 as a second comparison means, respectively. This reference value is prepared for each size of sheet that can be fed by the paper feeding device 12. When the comparison result of the comparator 30 exceeds the allowable amount, a conveyance defect signal such as skew feed or wrinkles is output, and when the comparison result of the comparator 31 exceeds the allowable amount, a defect signal such as the feed position is too twisted is output. Sent out.

A controller 34 controls these sequence timings, the reset of the counters 28, 29, 35 at the time of copy start, and the like.

The control counter 35 counts the detection end time by the position detector 18 as a predetermined number of bits, and the output signal of the detection end time is transmitted to the controller 34 as one of the sequence signals.

The detection accuracy can be improved by repeating the above processing method multiple times within the sheet detectable time.

It is also possible to control the series of operations based on FIG. 5 by software by directly inputting the signal from the position detector 18 to a microprocessor, etc., and an example of its application is shown in FIG.

Memory addresses l, m, and n correspond to the detection portion counter 28, non-detection portion counter 29, and control counter 35 shown in FIG. Detector 18
The sending pulses are software controlled, but it is also possible to use the CPU's clock pulses, which requires some timing circuitry.

In FIG. 6, the read data from the sensor is input to the cleared memory addresses l, m, and n. The signals from the sensor are classified into H and L and stored as memories l and m, respectively. After the scan is completed, the contents of memories l and m are compared with pre-stored setting values l ₀ and m ₀ , and
When the memory l deviates from the predetermined range l ₀ +Δ>l>l ₀ −Δ, a signal such as diagonal feeding or wrinkles is output,
When the memory m deviates from the condition of a predetermined range m ₀ +Δ>m>m ₀ −Δ, a signal indicating that the feed position has been exceeded is outputted.

The detector 18 is desirably controlled by a sequence program in order to be able to simultaneously detect the conveying direction of the image supporting sheet, so that it can be used as a device for detecting the normal conveying state.

According to the present invention, an excellent effect has been obtained in that it is possible to detect not only the position of the image support sheet in the transport direction but also the position in the direction perpendicular to the transport direction without placing any burden on the transport path.

By providing a plurality of detection devices and installing one of them near the image support sheet supply device, it is possible to detect the sheet supply state of a conveying member such as a transfer belt device, thereby preventing the occurrence of defective copies. be able to.

If a plurality of detection devices are provided and are operatively connected to a conveyance defect correcting device provided on the conveyance path, defects during conveyance of the image supporting sheet can be immediately corrected. In addition, it is possible to output the defective copies as is without making any corrections to the conveyance, and to count the number of defective copies outputted as data.It is also possible to use the data to deduct defective copies from the copy total. It is.

Most simply, the device can be stopped at the same time as the conveyance defect is detected.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an example of a copying machine equipped with a detection device according to the present invention, FIG. 2 is an explanatory perspective view of the detection device according to the present invention, and FIGS. 3 and 4 are modifications of the present invention, respectively. FIG. 5 is an explanatory block diagram of an example of a circuit used in the present invention, and FIG. 6 is an explanatory block diagram of a detection method using the present invention. DESCRIPTION OF SYMBOLS 1... Original table, 3... Exposure unit, 9... Optical unit, 10... Photosensitive drum, 11... Developing device, 12... Paper feeding device, 13... Transfer belt device (conveyance device), 14... ...Fusing unit, 18...
...Position detection device, 19...Image support sheet, 24...
...Lamp, 23...Multi-point detection element (sensor).

Claims (1)

[Scope of Claims] 1. An image forming optical device and a charging/developing processing device that form an image of a document on a photoreceptor, a processing device, etc. that transfers and fixes the image on the photoreceptor to an image support sheet, and an image support sheet. In an electrophotographic apparatus, a position detecting device is provided in a part of an image supporting sheet conveying path, and the position detecting device includes a light source extending in a direction substantially perpendicular to the conveying direction of the sheet; A multi-point detection element is provided at a position facing the light source including both sides of the sheet with the sensor in between, and a device for digitally processing the optical time-division detection results by the detection element, the digital processing device being a first comparing means for comparing the number of bits in the portion where the image supporting sheet exists and a preset reference bit number; and a first comparing means for comparing the number of bits in the portion where the image supporting sheet exists and the number of bits in the portion where the sheet does not exist at at least one side edge of the sheet and the preset reference number of bits. and a second comparison means for performing a comparison, when the comparison value of the first comparison means exceeds the allowable amount, an output signal of skew feed or wrinkle is generated, and the comparison value of the second comparison means exceeds the allowable amount. An electrophotographic apparatus characterized in that an output signal exceeding the position is generated when the position exceeds the position. 2. The electrophotographic apparatus according to claim 1, wherein at least one of the position detection devices provided in the sheet conveyance path is provided at a position after passing through the fixing device.