JPH07187452A - Sheet conveyance device - Google Patents

Abstract

PURPOSE:To convey a sheet paper which has been stopped once at an exact timing regardless of the thickness of the sheet paper by controlling a driving amount with a driving means according to the thickness of the paper sheet detected by a sheet thickness detection means. CONSTITUTION:When a paper sheet P is conveyed and fed to a register roller 17 through a conveyance roller 31, the thickness of the paper sheet P is detected by a distance measuring sensor 33. Based on the measuring results, the time necessary to make the conveyance roller 31 stop after the paper sheet P is brought into contact with the register roller 17 is controlled. In the case of a thin paper sheet, for example, the time necessary to stop the conveyance roller 31 is controlled so as to be lengthened. In the case of a thick paper sheet, the time necessary to stop the conveyance roller 31 is controlled so as to be shortened. As a result, the force where the end of the paper sheet P works upon the register roller 17 is constant regardless of the thickness of the paper sheet, thus eliminating time lag of conveyance start, its advance and so on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for conveying a sheet cut into a predetermined size to a predetermined position, for example, a sheet conveying apparatus for conveying a sheet of paper to an image forming position.

[0002]

2. Description of the Related Art Conventionally, according to an image recording apparatus, a sheet-shaped recording sheet is conveyed to a recording position, a recording image is formed on the sheet, and then the sheet is ejected to the outside of the apparatus. For example, a copying apparatus in which an image of an original is directly formed on a recording medium, the image on the recording medium is transferred to a sheet-shaped conveyed sheet, and the sheet after the transfer is discharged to the outside of the apparatus through a fixing step. Etc.

In the copying apparatus, a document is placed at a predetermined position, that is, an exposure position which is a document reading position, and the document at the exposure position is projected on a recording medium. In this case, in order to save the trouble of manually placing the sheet original at the exposure position, the sheet original is placed on the original placing tray, and the sheet original on the original placing tray is moved to the exposure position. There is a copying machine equipped with an automatic document feeder that automatically conveys.

Further, in addition to feeding the sheet original, according to the image forming apparatus, in order to transfer an image formed on a photoconductor, which is a recording medium, in particular, a toner image onto a sheet of paper,
A sheet conveying device is provided for feeding the sheet paper to the transfer position. In this case, it is necessary to convey the sheet of paper to the transfer position with the image formed on the photoconductor and the leading edge of the sheet of paper aligned. Therefore, the sheet of paper is fed from the paper feeding device, the leading end of the registration roller arranged before the temporary transfer is stopped, and the timing control is performed so that the leading end of the image formation on the photoconductor coincides with the leading end of the sheet at the transfer position. The conveyance is started by the registration rollers. Thus, the image (toner image) formed on the sheet of paper on the photoconductor can be transferred to a desired position.

An example of this is shown in FIG. In the figure, for example, the sheet paper accommodated in the paper feed cassette (16-1) detachably provided in the main body of the copying apparatus is fed by the rotation of the paper feed roller (16-2). One sheet is fed by the pair of feeding rollers 31 which is a feeding means arranged in front of (16-2). This paper sheet is conveyed to the registration roller (17) arranged in front of the transfer position facing the photoconductor. The registration roller (17) is not rotating and stops the leading edge of the conveyed sheet of paper. At this time, the leading edge of the sheet of paper is inserted into the registration roller (17), and the sheet of paper is slightly curved so that the registration roller (17) can be accurately conveyed without slipping when the conveyance is started. The sheet is bent and the repulsive force for restoring the original shape of the bent sheet paper is used to prevent delay of the sheet paper (P) at the start of conveyance and conveyance error. In this case, since the leading edge of the sheet of paper is stopped by the registration roller (17) whose rotation is stopped, some skew feeding of the sheet is corrected at this position,
There is also an effect that the leading edge of the sheet of paper is aligned by the registration roller (17). The registration roller (17) constitutes a conveying means for temporarily stopping the sheet.

[0006]

Conventionally, the amount of bending of the sheet paper temporarily stopped by the registration rollers is controlled to be constant. In other words, the leading edge of the conveyed sheet of paper is detected by the sheet detecting unit in front of the registration roller, and from this detection time, the time when the leading edge of the sheet of paper comes into contact with the registration roller is further estimated, and the predetermined deflection is formed. The feeding by the feeding roller is stopped. Therefore, the deflection of the sheet of paper is kept constant.

Therefore, in order to make the amount of deflection constant, the drive of the feeding roller is stopped after a fixed time from the time when the leading edge of the sheet of paper is detected by the detection means before the registration roller. Control for keeping the amount of deflection constant is proposed in, for example, Japanese Utility Model Publication No. 1-266664. In this system, the amount of deflection is directly detected, and the amount of deflection is controlled to be constant.

As described above, conventionally, the deflection amount of the sheet paper is usually controlled to be constant. However, the copying machine is not limited to the one specified as the sheet paper, but various sheet papers are used. That is, as the sheet paper, it is general that thick or thin sheets are mixedly used.

Therefore, the repulsive force of the bent sheet paper is determined by the stiffness of the sheet paper, that is, the thickness of the sheet paper. For example, if the sheet paper is thin, the repulsive force due to the deflection is weakened, the acting force applied to the registration roller is weak, and the conveyance start timing is delayed (delayed) without being accurately added when the registration roller starts rotating. There is a risk.

On the contrary, when the sheet paper is thick, the repulsive force due to the bending becomes strong, and the force exerted by the tip of the sheet paper between the registration rollers becomes strong, so that the registration rollers slip at the start of rotation of the registration rollers. The leading edge of the sheet may be advanced. Therefore, the timing at which the sheet of paper reaches the transfer position is advanced, and the transferred image on the paper is displaced. Further, in the state where the leading edge of the sheet of paper is aligned by the registration rollers, there is a considerable risk that the leading edge of the sheet partially slips and is obliquely fed.

In view of the above-mentioned problems, the present invention is a sheet conveying apparatus that can start conveying at a correct timing without delay or advance from the position where the leading edge of the sheet is stopped, regardless of the thickness of the sheet. The purpose is to provide.

Further, the present invention solves the above-mentioned problems by making the repulsive force acting between the registration rollers where the leading edge of the sheet of paper is stopped, for example, constant.

[0013]

A sheet conveying apparatus according to the present invention comprises a conveying means for temporarily stopping a sheet and starting conveyance at a necessary timing, and a feeding means for feeding the sheet to the conveying means. And a driving unit that drives the feeding unit and controls a driving amount of the feeding unit to bend the sheet by a predetermined amount when the leading end of the sheet is stopped by the feeding unit. A sheet thickness detecting means for detecting the thickness of the sheet fed by the feeding means, and a drive for controlling the driving amount by the driving means according to the sheet thickness detected by the sheet thickness detecting means And a quantity control means.

Further, the above-mentioned sheet thickness detecting means is composed of a distance measuring sensor to detect the thickness by the difference between the distance to the sheet surface and the distance to the reference surface, and the presence or absence of the conveyed sheet is detected. It also serves as a detecting means.

When the sheet thickness detected by the sheet thickness detecting means exceeds the allowable range, the drive amount control means performs drive control based on the average value of the sheet thickness detected in the past as a measurement abnormality, while If it is within the range, the drive control is performed based on the detected sheet thickness.

Further, since the sheet thickness detecting means is composed of a distance measuring sensor, the distance to the specified position is measured, and when the measured distance does not match the distance to the specified position, it is determined that there is a failure. Is self-diagnosed, and the drive amount control means controls the drive amount based on the detected sheet thickness based on the result of the self-diagnosis or selects the drive amount control based on the standard thickness of the sheet. .

[0017]

According to the apparatus of the present invention, the amount of deflection is controlled according to the thickness of the sheet. That is, when the sheet paper is thin, the amount of deflection is controlled to be larger than the thickness of normal sheet paper, so that the repulsive force is large. Therefore, the force applied by the leading edge of the sheet between the registration rollers and the like that constitute the conveying means is constant, that is, a repulsive force equivalent to that of a normal thickness acts,
Accurate transfer start can be performed without delaying the transfer start timing.

On the contrary, if the sheet is thick, the amount of conveyance of the sheet, that is, the amount of drive is controlled so that the amount of deflection is small, so that the repulsive force acting on the registration roller is equivalent to that of the sheet. become. That is, although the repulsive force is increased by the thicker amount, the repulsive force is suppressed by reducing the amount of deflection, and as a result, the repulsive force acting on the registration roller is held constant.

With the above operation, when the registration roller starts to rotate, the force acting on the registration roller is controlled to be constant irrespective of the thickness of the sheet paper. Will be resolved.

For the thickness detection of the sheet paper, a distance measuring sensor can be used to perform accurate detection. That is, since the thickness of the conveyed sheet of paper can be detected without being pressed against the conveyed sheet of paper, accurate detection can be performed and the presence / absence of the conveyed sheet of paper can be simultaneously detected. Therefore, it is not necessary to separately provide a sheet paper presence / absence detection unit.

Moreover, when the detected sheet thickness exceeds the allowable range. For example, when the detected thickness of the sheet is abnormal, defective conveyance occurs when the deflection amount of the sheet is controlled based on the measurement result. Therefore, when the allowable range is exceeded, the flexure amount is controlled based on the average value of the measured thicknesses in the past, so that the flexure amount control can always be performed in a normal state. For example, the paper feeding means,
Generally, sheets of the same thickness are set. Therefore, the sheet thickness is not significantly changed midway while the sheet is being fed from the sheet feeding means. Therefore, it can be said that it is appropriate to set a permissible range and, if the permissible range is exceeded, determine that the measurement is abnormal and perform control based on the past measured values.

By doing so, for example, when the measurement judged as abnormal occurs continuously, it is possible to judge that the thickness of the fed sheet is changed from the middle. This occurs when switching the paper feeding means or filling a sheet of paper halfway, but in this case, if the measured thicknesses are substantially the same in succession, the subsequent control is adjusted to that thickness. Can be controlled based on.

Further, if the sheet thickness detecting means measures the distance, the distance measurement can be performed normally by performing the distance measurement in advance before the paper feeding operation. You can self-diagnose whether or not. In other words, by measuring the distance to the specified position, if the measured distance is approximately the same as the distance to the specified position, it means that the device is operating normally. Can be diagnosed. By carrying out the processing as if the sheet thickness to be used is a standard thickness without performing distance measurement by this diagnosis, it is possible to execute the conveyance control in a state in which the same degree of inconvenience as in the past is eliminated.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a sheet feeding apparatus for cutting sheets of a predetermined size according to the present invention will be described below with reference to the drawings. Further, in the following embodiments, a copying apparatus will be described as an example of the recording apparatus, but the present invention is not limited to such an apparatus. That is, the present invention can be applied to all of the transporting devices that stop the temporary sheet of paper when the cut sheet is fed to the predetermined position and start the transport at the predetermined timing. In particular, the present invention can be applied to a conveyance device that feeds a sheet of paper on a loading tray to a transfer position in an image forming apparatus for processing a sheet, a document feeding device that feeds a sheet document to a reading position, and the like. Further, it is needless to say that the present invention can be applied not only to the image forming apparatus but also to a facsimile or the like in an apparatus for feeding one sheet of a transmission document to the reading position.

In FIG. 1, the copying apparatus is a copying apparatus main body 1
And a document processing unit, that is, a document recirculation device for sequentially transporting the document to the document exposure position and returning it to the original position after processing (hereinafter referred to as RD).
H) 35.

An optical system 2 for exposing a document image for image formation is arranged on the upper portion of the copying apparatus main body 1. The optical system 2 includes a copy lamp 3 including a halogen lamp, a plurality of mirrors 4 to 7, a zoom lens 8 and the like.
And have.

Below the optical system 2, a photosensitive member 9 having a photoconductive layer formed on the surface of a drum-shaped recording medium is rotatably arranged. Various devices for forming an image are arranged around the photoconductor 9. For example, the charging unit 10, the developing unit 11, the transfer unit 12, the peeling unit 13 which is a corona discharger for peeling constituting the peeling means of the present invention, the cleaning unit 14 for cleaning the toner and the like remaining on the surface of the photoconductor 9 and the removing unit. Electric appliances 15 and the like are arranged.

When forming an image, first, the surface of the photoreceptor 9 is uniformly charged to a predetermined potential by the charger 10, and then the original is irradiated by the optical system 2 to reflect the reflected light to the mirror and the lens. The image is projected on the surface of the photoconductor 9 via. As a result, an electrostatic latent image corresponding to the image of the original is formed on the photoconductor 9, and toner is attached to the developing unit 11 to make the latent image visible so that a toner image is formed. A sheet of paper, which is a transfer material, is fed from a paper feeding unit selected from a plurality of paper feeding units 16 for the toner image, and the registration roller 17 starts conveying the sheet of paper in synchronization with the rotation of the photoconductor 9. Electrostatic transfer is performed by the action of the transfer unit 12 on the sheet paper that is appropriately fed to the transfer position where the transfer unit 12 is arranged via the.

After that, the sheet of paper is electrostatically peeled from the photoconductor 9 by the action of the peeling device 13, and is fed to the fixing portion 19 via the suction conveyance means (conveyance belt) 18. The fixing unit 19 is composed of, for example, a heat roller whose side in contact with the toner image on the upper sheet is heated to at least a constant temperature by a heating source, and a pressure roller which presses the heat roller with an appropriate pressure. The toner image on the sheet is fixed by heating. This fixed sheet of paper on which an image has been formed is discharged onto a sorter 21 for aligning the sheets of paper connected to the discharge port 20 of the copying apparatus main body 1 in page order, and a sheet on which an image is formed. In order to form an image again on the opposite side or the same side, the sheet is carried out to the intermediate tray 22 provided at the lower part of the copying apparatus main body 1 via the switchback conveying section 23 or the ordinary conveying section 24.

On the intermediate tray 22, a placing table 25 for placing a sheet, a sheet feeding means 26 for feeding the sheet, and the sheet fed by the sheet feeding means are again fed to the registration roller 17 of the copying apparatus main body. A conveying means and a conveying path 27 for feeding the sheet are provided.

On the other hand, the optical system 2 transfers the image of the original to the photosensitive member 9
In addition to the RDH 35, the document placed on the document table 28 made of a transparent glass plate is optically scanned in order to project the image onto the document. Therefore, a first mirror base (not shown) composed of the lamp 3 and the mirror 4 and a second mirror base (not shown) composed of the mirrors 4 and 5 are moved in the arrow A direction,
The document on the document table 28 is optically scanned and sequentially projected onto the rotating photoconductor 9.

In addition to the image exposure on the original table 28, the optical system 2 also positions the first exposure section 29 and the second exposure section 30 for image exposure in response to the document being conveyed by the RDH 35. It is provided to be movable. That is,
A first exposure unit 29 and a second exposure unit 30 formed of a transparent plate are arranged side by side in order while the sheet original is being conveyed by the RDH 35. The optical system 2 is selectively fixed at positions corresponding to the first exposure unit 29 and the second exposure unit 30. Therefore, by fixing the first mirror base and the second mirror base at the positions shown in the figure, the image of the document conveyed on the first exposure unit 29 is projected onto the surface of the photoconductor 9. Further, the first mirror base and the second mirror base of the optical system 2 are connected to the second exposure unit 3
By moving it to 0 and fixing it at that position, the image on the opposite surface of the sheet original conveyed to the second exposure unit 30 is transferred to the photosensitive member 9.
Can be projected on.

In the copying apparatus having the above structure, the present invention particularly performs control for surely starting the sheet paper on the registration rollers 17. for that reason,
A conveyance roller 31 for feeding the sheet of paper to the registration roller 17 is arranged. By controlling the drive amount of the conveyance roller 31, the leading edge of the sheet of paper is moved to the registration roller 17
A predetermined amount of flexure is formed while being stopped.

The carrying roller 31 is arranged at a confluence portion of the sheet papers fed from the respective paper feed portions 16 and the intermediate tray 22, and the sheet paper fed to the confluence portion is passed to the registration roller 17. Transport.

FIG. 2 shows the details thereof and shows one of the sheet feeding units 16. The sheet feeding unit 16 is configured to, for example, a sheet feeding roller 16- that is disposed so as to face the sheet paper P in a sheet feeding cassette 16-1 that stores sheet paper.
By the rotation of 2, the topmost sheet of paper is fed. A rotary plate 16-3, on which sheet paper is placed in the cassette 16-1, is pushed up by the pressing means 16-4 on the copying machine main body side, and the uppermost sheet paper is fed to the paper feed roller 16-.
The sheet can be fed by pressing it against 2.

A carrying roller 31 for carrying the sheet paper to the registration roller 17 is arranged so as to face the fed sheet paper P. A rotation of a drive source (not shown) such as a motor is connected to the conveyance roller 31 via a clutch, and the rotation of the conveyance roller 31 is controlled by driving the clutch. The registration roller 17 is also connected to a motor similar to the above through a clutch to control the conveyance. On the way to the registration roller 17,
In particular, upper and lower guide plates 32 for guiding the sheet P to the space between the registration rollers 17 are arranged.

On the upper and lower guide plates 32, a distance measuring sensor 33 for detecting the thickness of the sheet P of the present invention is arranged. This distance measuring sensor 33
Is provided so as to detect the thickness of the sheet paper P immediately before the sheet paper P is fed to the registration roller 17, and the upper and lower guide plates 32 contact the lower guide plate side of the sheet paper P and the registration roller 17 It is provided to guide you to. In other words, the distance measuring sensor 33 has the lower guide 32-
The thickness of the sheet of paper P is detected by the difference between the distance of 2 and the distance of the conveyed sheet of paper P. The details will be described later.

With the above configuration, when the sheet P is fed and sent to the registration roller 17 via the conveying roller 31, the thickness of the sheet is detected (measured) by the distance measuring sensor 33. Based on the measurement result, the time from the contact of the sheet paper P with the registration roller 17 to the stop of the conveying roller 31 is controlled. For example, when the sheet paper is thin, the transport roller 31
When the sheet paper is thick, the time until the conveyance roller 31 is stopped is controlled to be short. Thus, the amount of deflection of the sheet paper is controlled according to the thickness.

Deflection amount control and distance measuring sensor 3
FIG. 3 shows a control system of a means for controlling the detection of the thickness of the sheet of paper by means of the control unit 3, and the control means is a master CPU 40 which is a microcomputer.
Composed of.

A slave CPU 41, which is a microcomputer for controlling the optical system 2 and the like, is also provided. The master CPU 40 receives signals from various program keys and sensors stored in advance in the ROM 42, stores necessary information by the signals in the RAM 43, and slaves when the document on the document table 28 is optically scanned. CPU41
A signal for instructing the first and second mirror bases to start moving in the A direction, and the first and second mirrors that have finished moving in the A direction.
It outputs a signal that returns the mirror base to the home position. In addition, the slave CPU 41 is the master C
According to a command from the PU 40, the first and second mirror bases are moved to the position of the first exposure unit 29 or the second exposure unit 30 shown in FIG. 1 and controlled to be fixed at the position.

Further, the master CPU 40 controls the supply and stop of supply of the voltage to the copy lamp 3 via the copy lamp lighting circuit 44, and adjusts the execution voltage level applied to the copy lamp 3. In this case, for example,
An image state formed on the photoconductor 9 (an image that serves as a reference during non-image formation is formed and an image state at this time) is detected by an image sensor 45 including a light emitting element and a light receiving element, and the detection signal is received. As a result, the master CPU 40 is
Necessary information is stored, and the voltage applied to the copy lamp 3 is controlled, and the charging potential is controlled by the charger 10 via the charging unit 46. Along with this control, various means for image formation (not shown) are controlled.

The slave CPU 41 follows the optical system 2 according to a program previously stored in the ROM 47.
The signal from the rotary encoder 49 for detecting the rotation speed of the motor 48 for moving the first and second mirror bases, the signal from each position sensor (not shown), and the like are received, and the signal is transmitted via the driver circuit 50. Motor 48
Control the rotation speed of the
To output a conveyance start control signal for the registration rollers 17 for controlling the conveyance in time with the transfer position.

Further, the master CPU 40 receives a signal relating to the measurement from the distance measuring sensor 33 according to the present invention through the signal processing circuit 34-1, and conveys the sheet according to the thickness of the sheet P relating to the distance measurement. The clutch 51 for controlling the drive of the roller 31 is turned on and off via the driver 52.
FF control. Further, it also controls the clutch 53 for controlling the rotational drive of the registration roller 17 which starts the conveyance of the sheet paper P to the transfer position.

The distance measuring sensor 33 has a light emitting element 33-1 for measuring the distance. Therefore, the master CPU 40 drives the light emitting element 33-1 via the drive unit 34-2 at a predetermined timing in order to measure the distance of the distance measurement sensor 33, and the light receiving unit 33- of the distance measurement sensor 33 at this time. The signal output according to the light receiving state of No. 2 is received via the signal processing circuit 34-1, the distance to the conveyed sheet of paper is measured, and the thickness of the sheet of paper is calculated based on this.

The operation of the copying apparatus having the above structure will be described.

Therefore, a copy start switch (copy
Button 40), the CPU 40 receives the command and starts the copying operation. By the start of this copying operation, the paper feed roller 19-2 shown in FIG. 2 is driven, and the sheet paper P in the cassette is fed. The fed sheet paper P is
Registration roller 1 stopped via conveyance roller 31
It is sent to 7. The thickness of the sheet paper P is detected by the distance measurement sensor 33 performing distance measurement while the sheet paper is being guided to the registration rollers 17 by the guide plate 32. Then, in accordance with the thickness, the time T from the time when the leading edge of the sheet of paper comes into contact with the leading edge of the registration roller 17 to the time when the conveyance roller 31 is stopped is set. That is, the time T for controlling the drive amount by the transport roller 31 is set.

To set the time T, the CPU 40 configures an internal timer with the RAM 43. This set time T
Is set according to the thickness. This can be set using the results of experiments and the like. For example, sheet papers of various thicknesses are actually conveyed to the registration roller 17, and the conveyance state when the deflection amount at this time is variously changed is confirmed, and the optimum deflection amount is set to the thickness of each sheet. It is possible to create a table set according to the above, store it in ROM or RAM in advance, and refer to this table to set the time T for obtaining the amount of deflection according to the detected thickness.

FIG. 4 is a diagram showing the thickness (d) of the sheet P as a result and the amount of deflection (l) in an appropriate state, and FIG. 5 is a graph showing the thickness (d). 4 shows the drive time T corresponding to the sheet conveyance amount by the conveyance roller 31 for forming the deflection amount (1) of 4. A table having such characteristics may be stored in the ROM or the like. It should be noted that the amount of deflection of the sheet is shown as the amount of deflection that occurs between the registration roller 17 and the transport roller 31, as shown in FIG.

As described above, the conveyance roller 31 is continuously driven from the time when the sheet of paper P contacts the registration roller 17, so that the deflection is formed between the registration roller 17 and the conveyance roller 31. The amount of this deflection is controlled by the thickness of the conveyed sheet paper P, and when the predetermined amount of deflection is formed, the driving of the conveyance roller 31 is stopped by the OFF operation of the clutch 51. Then, when the registration roller 17 is started by the clutch 53 being turned on in synchronization with the transfer timing of the toner image formed on the photoconductor 9, the registration roller is caused by the amount of deflection formed according to the thickness of the sheet P. The repulsive force acting during 17 becomes constant, and accurate conveyance can be started.

Next, a specific example of distance measurement by the distance measuring sensor 33 of the present invention will be described in detail. This distance measuring sensor 33 is disclosed, for example, in "Sensor Technology", October 1992, Volume 12, No. 11 uses the “8-bit precision distance measuring sensor” described on pages 24 to 27. This distance measuring sensor is a PSD (Position Sensitive).
It is called a Deector sensor, which irradiates light from a light emitting element onto an object to be measured, and measures the distance by the incident position of the reflected light from the object to be measured on the sensor.

This distance measuring sensor will be briefly described. This is a kind of PIN type photodiode, and as shown in FIG. 7, the silicon chip has ap ⁻ layer on the front surface, an n ⁺ layer on the back surface, and an intermediate layer therebetween. It is composed of an i layer, and electrodes A, B and C as shown in the figure are provided on the respective layers on the front surface and the back surface. An equivalent circuit of the PSD sensor having the structure shown in FIG. 7 is shown in FIG.

In FIG. 8, by supplying the bias voltage VB to the terminal of the electrode C, the resistances R1 and R2 change at the position (spot position) of the light incident on the surface. For example, if light is incident on the midpoint (point d) between the electrodes A and B,
Although R1: R2 = 1: 1, the ratio of R1: R2 changes in proportion to the position of the incident light if the incident light deviates to one of the A and B electrodes. Now, assuming that the incident position of light is shifted to the B electrode side by x with respect to the center point d, and the length of the light receiving surface of the sensor (distance between A and B electrodes) is D, R1 + R2 = R0, R1 = R0 / 2 (1 + 2x / D) and R2 = R0 / 2 (1-2x / D).

Therefore, the current I extracted from the electrodes A and B in FIG. 8 is utilized by utilizing the above resistance change depending on the incident position (spot position) of the light on the light receiving surface of the PSD sensor.
1 and I2, and the current ratio I1 / I at this time
2 is, for example, proportional to the distance from the electrode B (inversely proportional to the distance from the electrode A). At this time, although the absolute values of the currents I1 and I2 change depending on the amount of light incident on the PSD sensor, since the incident position of light is proportional to the current ratio I1 / I2, the amount of light itself has no effect.

Therefore, in the relation of the current ratio I1 / I2, the position of the incident light on the light receiving surface on the PSD sensor can be specified, thus enabling accurate distance detection. In particular, when the current ratio becomes large, the incident light comes closer to the electrode A side of the PSD sensor, and conversely, when the current ratio becomes smaller, the electrode B side is irradiated with the incident light.

For example, as shown in FIG. 9, a light emitting element (infrared LED) 33 constituting the distance measuring sensor 33 of the present invention.
The light from -1 is applied to the object to be measured (the uppermost sheet document), and the reflected light is received by the light receiving section 33-2 of the PSD sensor that constitutes the distance measuring sensor 33 via the light receiving lens. The position x1 of the light receiving point (spot) at this time is obtained by x1 = A · f / L1 in the relationship shown in the figure. In the above formula, A is the center distance between the light projecting lens and the light receiving lens, L1 is the distance from the light projecting lens to the object to be measured, and f is the focal length of the light receiving lens. Therefore, the position x1 of the light receiving spot on the light receiving surface of the PSD sensor becomes smaller and the position moves to the position x2 as the distance to the object to be measured increases. On the contrary, when the position x1 of the light receiving spot becomes large, the distance to the object to be measured becomes short.

The point x on the light receiving surface of the PSD sensor is the current ratio I1 / I2 obtained from the electrodes A and B as described above.
Therefore, the distance D from the light emitting element 33-1 to the object to be measured, that is, the distance to the light receiving unit 33-1 of the distance measuring sensor 33 can be easily measured according to the above equation.

Therefore, in the present invention, as shown in FIG. 3, the currents I1 and I2 obtained from the PSD sensor, which is the distance measuring sensor 33, are converted into voltages V1 and V2 by the signal processing circuit 34-1, Input through the analog port input section of the master CPU 40. Here, the signal processing circuit 34-1 performs conversion processing as a voltage value equivalent to or equal to the obtained currents I1 and I2. Based on this voltage value, the master CPU 40 calculates a value corresponding to I1 / I2 to obtain the spot position (x) of the distance measuring sensor 20, and from this to the uppermost sheet document from the above equation for obtaining x. The distance L can be calculated.

Therefore, if necessary, the master CPU 4
0 outputs a signal for driving the driver 34-2 to cause the light emitting element 33-1 which is an infrared LED to emit light. Further, based on the output from the distance sensor 33, the thickness of the sheet P is obtained at the measured distance, and the above-mentioned transport roller 3 is obtained.
The drive time T of 1 can be controlled, and the amount of deflection of the sheet can be controlled according to the thickness of the sheet.

An actual example of sheet paper conveyance control according to the distance measurement of the distance measuring sensor 33 according to the present invention will be described below with reference to a flowchart.

(First Embodiment) FIG. 10 is a control flow for controlling the conveyance of a sheet of paper when copying is started by the copying apparatus, and shows the rough control.

First, the copy start switch (CSW)
When the copy start switch is operated by determining whether or not (N1) is operated, the paper feed roller 16-2 is driven (clutch ON) (N2). Then, before the sheet paper P in the paper feed cassette 16-1 is fed and the sheet paper is fed to the registration roller 17, the distance measurement sensor 33 guides the reference distance, that is, the sheet paper P from the sensor 33. The distance to the lower guide plate 32-2 is measured (N3).

The distance measurement by the distance measuring sensor 33 is performed by the CPU 40 driving the light emitting element 33-1.
The light is applied to the lower guide plate 32-2, and the reflected light is received by the light receiving unit 33-3. Therefore, the light emitting element 33-
By driving 1, the distance Lo from the distance sensor 33 to the uppermost part of the placed document can be measured. As described above, the master CPU 40 inputs the voltage V1 / V2 corresponding to I1 / I2 from the sensor 33 to measure the distance Lo to the lower guide plate 32-2 that is the object to be measured. it can. The measured distance Lo is stored in a desired area of the RAM 43, for example.

When this distance Lo is measured, the CPU 40
Determines the detection state of a sensor (not shown) that detects when the leading edge of the fed sheet paper P reaches the measurement position of the distance measurement sensor 33 (N4). This paper detection sensor can also be used as the distance measurement sensor 33. That is, the distance measuring sensor 33 is attached to the lower guide plate 32-
Even after the distance up to 2 is measured, it is driven periodically and the measured distance L
When it is detected that o has changed, for example, the measured distance L is shorter than the distance Lo to the guide plate 32-2, it can be detected that the sheet paper P is fed to the distance measurement sensor 33. Moreover, since the timing at which the sheet P reaches the distance measurement sensor 33 is a predetermined time after the time when the paper feed roller 19-2 and the transport roller 31 are driven, the sheet paper P is moved to the distance after the predetermined time. Measuring sensor 33
If it is not detected at, it can be treated as a jam. Therefore, the distance measuring sensor 33 can be used not only for distance measurement but also for sheet detection and jam detection.
There is no need to provide a special paper detection sensor.

Therefore, when the leading edge of the sheet of paper P is detected before the registration roller 17, the distance L from the distance measuring sensor 33 to the sheet of paper P is measured (N5) in the same manner as in step N3. . A schematic diagram in this measurement state is shown in FIG.

As described above, the distance measuring sensor 33 determines the distance Lo to the lower guide plate 32-2 and the distance L to the surface of the sheet P guided along the lower guide plate 32-2. Based on this, the thickness d of the conveying sheet paper P is obtained. That is, the thickness d is obtained by calculating the difference "Lo-L" in the measured distances (N6).

According to the thickness d, the registration roller 17
In order to control the amount of deflection of the sheet paper P in (3), the driving time T of the transport roller 31 is determined (N7). this is,
It is set under the conditions shown in FIGS. In this case, FIG.
As shown in, when the distance measuring sensor 33 is also used as the leading edge detecting sensor of the sheet of paper P, after ΔT time corresponding to the distance 1 from the position of the measured distance to the registration roller 17, the set time T is set. To start counting
After the counting, the driving of the transport roller 31 is stopped. The set time T may be set in consideration of the time ΔT, and the counting may be started from the time when the leading edge of the sheet P is detected by the sensor. This can be selected as needed.

The set time T is determined by the thickness d of the sheet P, but the counting of the time, that is, the timer utilizes a predetermined area of the RAM 43 and the CPU 40 is configured as an internal timer. To do. The details are self-explanatory and will not be described.

When the time T determined according to the thickness d of the sheet P is counted (N8), the driving of the conveying roller 31 is stopped. This is executed by turning off the clutch 51, and the amount of deflection according to the thickness d of the sheet P is formed in the state as shown in FIG.

Then, in accordance with the rotation of the photoconductor 9, the driving of the registration roller 17 is started at the timing when the leading edge of the image formation coincides with the leading edge of the sheet P. When the clutch 53 is turned on, the rotation of the drive motor is transmitted, the registration rollers 17 rotate, and the sheet of paper P
(N10) is started. At this time, the sheet paper P
Since the "deflection amount" according to the thickness d is controlled, a repulsive force corresponding to the deflection amount acts on the registration roller 17, and becomes constant, so that the registration roller 17 is reliably conveyed without being affected by slips or the like. It is started and fed to the transfer position at the timing coincident with the image forming front end of the photoconductor 9.

Since the control operation of the copying machine thereafter is not directly related to the present invention, the description thereof is omitted, but the control thereafter is performed in exactly the same manner as the conventional one. Also, the sheet paper P
For the multi-copy, the operation described above is restarted when the trailing edge of the sheet passes the position of the detection sensor.

Here, FIG. 12 shows a time chart of the driving time T of the conveying roller 31 which is determined to control the deflection amount of the sheet P. In the figure, the paper feed roller 16-2 and the transport roller 31 are started to drive, and the leading edge of the sheet P is set to the registration roller
From the timing when 7 is reached, the thickness d of the sheet paper
The drive time of the transport roller 31 is controlled in accordance with the above.

On the contrary, at the timing when the leading edge of the sheet certificate P reaches the registration roller 17, the conveying roller 31
Stop driving. Then, in accordance with the detected thickness d of the sheet paper, it is set as the time until the driving of the registration roller 17 is started, and the driving of the conveying roller 31 is started,
The driving of the registration rollers 17 may be started in synchronization with the timing of forming the deflection amount according to the thickness d of the sheet paper. FIG. 13 shows a time chart for controlling the amount of deflection at this time.

In the drive control of the transport roller 31 in FIG. 13, the drive start time of the registration roller 17 is determined when the copy control is started. Therefore, the time from when the leading edge of the sheet of paper P reaches the registration roller 17, that is, from the time when the leading edge of the sheet of paper is detected to the start of driving the registration roller 17, is constant. This time is a timing at which the leading edge of the sheet of paper P and the leading edge of the image formation are matched, and when a predetermined width (for example, 10 mm) from the leading edge of the sheet of paper P is desired to be the non-image area, a time corresponding to the predetermined width. If the conveyance of the sheet of paper is started earlier or vice versa, the image cannot be transferred onto the sheet of paper by a predetermined width from the leading edge of the image formation.

As described above, since the transport start time of the sheet P is determined from the timing when the leading edge of the sheet P reaches the registration roller 17, as shown in FIG. By restarting the driving of the conveyance roller 31 after the time corresponding to the subtraction of the time T,
A similar amount of deflection can be formed.

In particular, since the sheet paper P is also stationary during the period To in which the transport roller 31 and the registration roller 17 in FIG. 13 are stopped, the thickness of the sheet paper P is detected, so that the more accurate thickness can be obtained. Can detect. That is, when the sheet P is measured while being conveyed by the conveying roller 31, the sheet of paper is rough and the lower guide plate 32-
Although it may be possible to perform detection in a state in which the sheet F is slightly more floating than 2, the accurate thickness detection can be expected by measuring the distance using the stationary period To and detecting the thickness of the sheet P as described above. .

Therefore, if the distance measuring sensor 33 is not provided during the conveyance of the sheet P and the thickness is detected on the tray in the sheet feeding section, the thickness can be detected in a stationary state. . An example of this is shown in FIG.
The paper feed tray is used as a large-capacity paper feed tray arranged at the bottom of the paper feed unit in FIG. Here, the distance measuring sensor 33 is arranged to face the vicinity of the rear end portion of the paper feed tray 36 in the paper feed direction. The thickness of the sheet paper P is detected by first detecting the distance Lo to the uppermost portion of the tray 36 before the paper is fed by the paper feed roller 19-2.
Is measured. Then, the distance measurement is performed again at the timing when the trailing edge of the sheet when one sheet is fed by the operation of the sheet feed roller 19-2 passes the position of the distance measurement sensor 33. By obtaining the difference between the measured distance L at this time and the previously measured measured distance Lo, the thickness d of the fed sheet paper P can be detected. Since this detection is also performed while the sheet P is stationary, accurate detection can be performed in a stable state.

Further, as shown in FIG. 15, a member 37 for pressing down the sheet paper is provided on the uppermost part of the sheet paper P stacked on the tray 36, and the detection surface of the distance measuring sensor 33 of the member 37 is reflected. The thickness of the sheet of paper P to be fed can be similarly detected by the distance measuring sensor detecting the distance to the member 37 before and after feeding. In this case, erroneous detection in the floating state of the sheet due to disturbance such as the air flow of the sheet P can be eliminated.

On the other hand, as described above, the distance measuring sensor 33 provided on the tray 36 not only detects the thickness of the sheet paper, but also raises the sheet paper to the uppermost sheet paper within a predetermined range. It can be used not only as an upper limit detection sensor for performing the above, but also as the presence / absence detection of the sheet paper in the tray 36. That is, as shown in FIG.
The tray 36 is provided so as to be movable up and down, and is configured to always hold the uppermost portion of the sheet paper within a predetermined range by the normal rotation or the reverse rotation of the drive motor M. Therefore, the distance measuring sensor 33 always measures the distance to the top,
When the measurement result is equal to or longer than the distance within the above-mentioned determined range, the motor M can be driven in the ascending direction to raise the uppermost portion of the seat to the determined position.

For detecting the presence / absence of paper, the tray 3 is used.
An opening 38 is formed at the position of 6, and the distance measuring sensor 33 measures the distance to the bottom 39 of the storage box through the opening 38. At this measurement distance, it can be detected that there is no sheet of paper. This opening 38 is used for the distance measuring sensor 3
The light and the light emitted from the light emitting element No. 3 pass through and are reflected by the bottom 39 to reach the light receiving element. Therefore, the distance measuring sensor 33 can detect the presence or absence of the sheet of paper P, and can also be used as a detection sensor that always holds the uppermost sheet of paper P at a constant position when the uppermost sheet of paper is fed. , These detection sensors can be abolished and the cost can be reduced.

Further, as a method of stabilizing the detection of the thickness d of the sheet paper, it is possible to detect a plurality of times without deciding in one detection at the time of distance measurement, and to average the measured distances, The value stabilizes. That is, if the sheet thickness is uniquely determined, normal thickness detection cannot be performed if it is detected at the timing when the sheet of paper rises. However, by performing this detection a plurality of times for the same sheet paper, abnormal detection results are eliminated, and more accurate thickness detection can be performed.

The value to be detected in particular may be as large as possible, but it is sufficient to set the minimum number of times required to measure the amount of deflection by the registration roller 17. Regarding the averaging of this measurement result, not only the overall average is taken, but the maximum and minimum values of the measurement values may be cut and the rest values may be averaged, and the central value of the measured values may be used. It may be adopted.

(Embodiment 2) According to the above embodiment, the thickness of the sheet paper d fed to the registration roller 17 is detected every time it is fed, and the deflection amount control based on the thickness d is detected. It is carried out. In this case, when the paper feed cassette 16-1 or the paper feed tray 36 is used, as the sheet paper P stored in the cassette or tray, sheet papers having the same thickness are often stored.

Therefore, a plurality of past data of the thickness d measured each time the paper feeding operation is performed are stored, and an average value of the plurality of data is set as the reference thickness do. Thickness d of sheet paper fed as
When this is detected, the detected value is compared with the reference thickness do. If the comparison result is within a predetermined range, it is determined that the detection result is normal, and the measured thickness d is determined according to the measured thickness d. The amount of deflection is controlled. However, if it exceeds the predetermined range, it is determined that the measurement result is abnormal, and the measured value is ignored, and the deflection amount is controlled based on the reference thickness do.
By doing this, it is possible to eliminate large variations due to the detection of the thickness of a large amount of sheet paper stored at one time.
In addition, it is possible to prevent the control of the deflection amount due to a temporary false detection.

That is, when the sheet paper runs out, the sheet cassette is stored in the paper feed cassette or tray at a time, and the sheet paper bundle has the same thickness. Particularly, the packaging of the sheet paper is opened and stored as it is in a tray or the like. Therefore, when the sheet paper is continuously fed, the thickness thereof does not change greatly, and when the detection result shows a large change from the detected thickness d, it is treated as a detection abnormality. Yes, this prevents the formation of the wrong amount of deflection.

FIG. 16 is a flowchart showing the control example. The deflection amount control based on the sheet thickness detection will be described with reference to this figure.

When the copy start switch is operated,
The paper feed roller 16-2 operates and the transport roller 31
Are also driven (n1, n2). In this description, the transport device of FIG. 2 will be described.

Then, before the fed sheet paper P reaches the registration roller 17, the following is executed.
That is, the average value of the thickness d of the sheets fed so far is calculated as the reference value do (n3). For example, data up to the past five times of the sheet paper to which this data is fed are stored. The data is stored in the RAM 43 and 5
In order to store the previous data, old data is sequentially cleared.

After the calculation of the reference value do,
The sheet thickness d of N3 to N6 shown in (4) is measured (n
4) Do. The details are as described with reference to FIG. 10, and the description is omitted here.

When the thickness d of the fed sheet paper P is measured as described above, the thickness d and the reference value do
Is compared to determine whether or not the comparison result exceeds a predetermined range. That is, it is determined whether the difference (do-d) between the reference value do and the measured thickness d of the sheet P exceeds a predetermined thickness ± Do (n5). This predetermined thickness Do
As the above, it is preferable to set in consideration of the range of the measurement error of the distance measurement sensor 33, the variation of the sheet paper P used, and the like. That is, it can be processed as normal within the error range. For example, when the thickness of the sheet paper P used is about 80 μm, it may be set to about ± 5 μm.

Therefore, when the measurement result d is within the thickness Do within the predetermined range with respect to the reference value do, it is determined that the measurement result is normal, and the measurement thickness d is newly stored (n
6) is performed, and the oldest stored data is cleared.
Then, in order to form a deflection amount according to the measured thickness d, the drive roller driving duration T is set (n7). The setting is the same as the description in FIG.

When the difference (Δd) between the thickness d of the measurement result and the reference value do exceeds the thickness Do of the predetermined range,
Assuming that the measurement result is abnormal, the measured value is ignored, the reference value do is set as a normal value, and the driving time T of the transport roller is set to that value (n8).

When the time of the transport roller 31 is set, the time T is counted from the timing when the leading edge of the sheet P reaches the registration roller 17 (n
9), the transport roller 31 stops after the counting (n10)
To be done. Then, at the conveyance start timing (n11) of the registration rollers 17, the registration rollers 17 are driven and the sheet paper P is conveyed to the transfer position.

Therefore, since the leading edge of the sheet of paper is pressed by the registration roller 17 by an amount corresponding to the thickness d of the sheet of paper P, its acting force is kept constant regardless of the thickness, and the conveyance start is started. The timing can be constant.

The above control is a state in which sheets of the same thickness are continuously or intermittently fed, and when replacing or replenishing sheet sheets to be stored in a cassette or a tray, the past data is used. If it is used, it cannot cope when the thickness of the sheet paper is changed. Therefore, when replacing or replenishing the sheet paper, either remove the cassette,
In the case of a tray, since it descends to the lower part again, the past data is cleared by detecting this, and the data of the standard paper thickness dr is used as the initial value.

If the difference between the measured thickness d and the standard value dr is within a certain range, it is determined that the measurement result is normal.
The measured value is set as the initial value. Based on the initial value, subsequent thickness detection, comparison, and the like may be performed, and the thickness data may be sequentially accumulated in accordance with sheet feeding as the past amount and averaged to calculate the reference value do. In this case, in determining whether the difference Δd between the standard value dr and the measured value d when the paper is replaced is the thickness Do within a predetermined range, the thickness D is determined.
The range of o, including measurement error and the like, can be treated as a measurement abnormality if the difference from the usable sheet paper thickness is set as a constant range and the difference is larger than that.

In addition, when a sheet is placed on a tray or the like, there is a case where the upper portion of the previously stored sheet is replenished by supplementing it. If the replenished sheet paper and the previously stored sheet paper have the same thickness, it does not matter, but when the thickness changes, when the average value for the past is processed as the reference value do. When the thickness of the sheet paper after the replenishment is different, the measured thickness d is treated as an abnormality, and this data is not stored. Moreover, the deflection amount is controlled by the reference value do which is different from the measured thickness d.

To this end, in step n6, the number of times of processing as abnormal in comparison with the reference value do is counted each time. This count is cleared if it does not continue. If the count contents continue,
For example, in the case of three consecutive times, it is assumed that the thickness of the sheet paper has been changed in the middle, the data for the past is cleared, the measured thickness d is normal, and at the same time as the control of the deflection amount, The data of the thickness d is stored, and thereafter, the reference value do is calculated based on this data. If the measurement d processed as the above abnormality is not measured three times in succession, it is determined that the measurement is a temporary erroneous measurement, the contents of the counter for counting the number of times of abnormality processing are cleared, and the subsequent control is executed.

When a large number of paper feeding devices are provided, it is general that the paper feeding size of each paper feeding unit is fixed and used. Therefore, the sheet of each sheet feeding device having a constant thickness is used. Therefore, the data for the past is stored for each paper feeding device, and the data of the paper feeding device is read while the paper feeding device is switched.
The reference value do can be calculated and the abnormality of the measurement result can be determined. Therefore, the data unique to the selected sheet feeding device is accumulated, and the normal deflection amount control can be performed based on the data. Even in this case, it is desirable to store the data as described above when the sheet paper is replaced or replenished by replenishment.

Further, since the manual paper feed is used for copying a specific number of sheets in addition to the continuous use by the paper feed cassette or tray, it is conceivable that the thickness thereof is variously changed. In this case, it is better to perform averaging by accumulating data and not to control by this. That is, the measured thickness d often deviates largely from the average value do due to the past thickness, and for that reason, it is more effective to control based on the measurement result. In this case, as described in (Example 1), the thickness of the same sheet of paper is measured a plurality of times without determining the thickness by one measurement result, and the thickness d is determined by the average value thereof, If the control is performed by this, the effect is enhanced.

In any case, according to this embodiment, the thickness data d for the past is stored, the value averaged based on the stored data is set as the reference value, and this reference value is set. Based on this, it is determined whether or not the measurement result is abnormal, and it is possible to stabilize the control of the amount of deflection according to the thickness of the sheet paper. In other words, when used continuously (paper feed), it is likely that paper of the same thickness will be fed. If a measurement that is far from past data is performed during this paper feed, it will be treated as an error. However, stable control of the amount of deflection can be performed based on the reference value thickness do.

(Third Embodiment) In the first and second embodiments, the distance measuring sensor 33 is described as operating normally. Here, when the distance measuring sensor 33 is not operating normally, the thickness d cannot be measured, and the deflection amount is controlled with incorrect data.

In consideration of this point, the third embodiment makes a self-diagnosis of the distance measuring sensor 33 to determine whether or not to control the deflection amount by using the measurement result of the distance measuring sensor 33. It is in. That is, if the result of the self-diagnosis of the distance measuring sensor 33 is abnormal, the deflection amount control cannot be performed. However, since the paper feeding device and the transport system are not abnormal, the copy control can be executed. Therefore, if the abnormality is self-diagnosed, the deflection amount is controlled according to the thickness of the standard-use sheet paper. As a result, the transfer can be performed while maintaining a stable transfer for the time being.

FIG. 17 is a control flow showing an example thereof. That is, the self-diagnosis of the distance measuring sensor 33 is executed in the standby state of the copying machine before the copy start switch is operated. In the standby state of the copying machine, the distance measuring sensor 33 moves from the sensor position to the lower guide plate 32-
The distance L to 2 is measured (n20).

Here, the sensor 33 is fixed at a predetermined position, and the lower guide plate 32-2 is also unchanged. Therefore, the measurement distance L is measured as a constant distance. Therefore, when the copying apparatus is manufactured, the measured value is stored as the normal distance Lr in advance. Its normal distance Lr
By comparing (n21) with the measurement distance L, the distance measurement sensor 33 is assumed to be operating normally and the control shown in FIG.

However, the measured distance L is equal to the normal distance Lr.
If it is different from the above, a display (n23) indicating that the distance measuring sensor 33 is out of order is displayed.

The failure is only the distance measuring sensor 33, and it is not necessary to stop the copying operation, and the copying apparatus can be operated if the transfer system is not broken. Therefore, as the control of the amount of deflection, the thickness (80 μm) dr of standard paper that is frequently used is set, and the time T for forming the amount of deflection by this is set. This allows
The conveyance can be performed without any trouble by n26 to n28.

As described above, the description in each embodiment is about the conveyance control by the registration roller 17 for controlling the conveyance to the transfer position of the copying machine, but the invention is not limited to this, and the sheet is fed. The present invention can be applied to any of the transporting devices in which the sheet is temporarily stopped and a bend is formed during this stop to reliably start the transport. For example, when feeding an original document to the exposure position, the placed original document is pre-fed, and the document is temporarily held in this state, and the conveyance to the exposure position is started by a start command. If the timing of this conveyance is deviated, the image exposure on the photoconductor is deviated, and the image is transferred on the sheet as an image misregistration. For this reason, a slight bend is formed in the pre-fed original so that stable conveyance can be started. Even in such conveyance, the amount of deflection can be easily controlled by detecting the thickness of the document.

As shown in FIG. 14, the paper feed roller 16
It can also be used for those that form the deflection of sheet paper. That is, when the uppermost sheet is fed by the sheet feeding roller 16, if the registration roller 17 is arranged in front of the sheet, the sheet feeding control of the sheet feeding roller 16 and the driving of the carry amount are performed at the same time. You can do it.

Further, as the means for detecting the thickness d of the sheet paper, the distance measuring sensor 33 is used, but the thickness detecting device conventionally proposed can be used. For example, a conveyance roller that conveys the sheet of paper is provided so as to be movable up and down, and the thickness of the sheet of paper can be detected by detecting the position of the roller that moves up and down according to the thickness of the sheet of paper. Further, the sheet can be electrically connected to the conveying roller when the sheet passes, and the thickness can be electrically detected by the magnitude of the flowing current or the voltage value.

[0110]

According to the sheet conveying apparatus of the present invention, the amount of deflection is controlled according to the thickness of the sheet, so that the force exerted by the leading edge of the sheet on the roller for starting the conveyance causes the sheet thickness to change. Regardless of the constant force, the transfer can always be started in a constant state.

By using a distance measuring sensor as a means for detecting the thickness, the sensor can also be used to detect the presence / absence of the sheet, so that it is not necessary to provide a separate detecting sensor, and there are many merits for that. Come on.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a copying apparatus using a sheet conveying apparatus of the present invention.

FIG. 2 is a sectional view showing an example of a sheet conveying device according to the present invention.

FIG. 3 is a block diagram of a control system for performing sheet conveyance control and copy control according to the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the thickness of the sheet according to the present invention and the amount thereof.

FIG. 5 is a characteristic diagram showing the relationship of drive time according to the thickness of the sheet paper based on the relationship of FIG.

FIG. 6 is a schematic diagram showing a quantity state for the sheet paper according to FIGS. 4 and 5 above.

FIG. 7 is a cross-sectional structure diagram showing an example of a distance measuring sensor for detecting the thickness of the sheet of the present invention.

8 is an electrical equivalent circuit diagram of the sensor shown in FIG.

FIG. 9 is a view for explaining the principle of distance measurement for detecting the thickness of the sheet of the present invention.

FIG. 10 is a control flowchart showing an example of sheet conveyance control according to the present invention.

FIG. 11 is a schematic view showing a state of detecting the thickness of a sheet according to the present invention.

FIG. 12 is a time chart according to an example of sheet sheet conveyance driving according to the present invention.

FIG. 13 is a time chart according to another example of the sheet sheet conveyance driving example of the present invention.

14A and 14B show another example of sheet thickness detection by the distance measuring sensor according to the present invention, in which FIG. 14A is a diagram showing distance measurement before feeding, and FIG. The figure which shows the distance measurement in a state.

FIG. 15 is a diagram showing another example of sheet thickness detection by the distance measuring sensor of the present invention.

FIG. 16 is a control flowchart according to another embodiment for detecting the thickness of the sheet of the present invention.

FIG. 17 is a flowchart of conveyance control based on the thickness of sheet paper based on self-diagnosis by the distance measuring sensor according to the present invention.

[Explanation of symbols]

 17 Registration Roller (Conveying Means) 31 Conveying Rollers (Feeding Means) 33 Distance Measuring Center (Sheet Thickness Detecting Means) 40 CPU (Control Means) 43 RAM (Timer) P Sheet Paper

Claims (5)

[Claims] 1. A sheet conveying device comprising: a conveying unit configured to temporarily stop a sheet and start conveying the sheet at a necessary timing; and a sheet feeding unit that feeds the sheet to the conveying unit. Driving means for controlling the driving amount by the feeding means in order to bend the sheet by a predetermined amount when the leading edge of the sheet is stopped by the conveying means, and the sheet fed by the feeding means. And a drive amount control unit configured to control the drive amount by the drive unit according to the sheet thickness detected by the sheet thickness detection unit. Sheet transport device. 2. The sheet conveying apparatus according to claim 1, wherein the sheet thickness detecting means is composed of a distance measuring sensor and detects the thickness by a difference between the distance to the sheet surface and the distance to the reference surface. 3. The sheet conveying apparatus according to claim 1, wherein the sheet thickness detecting means also serves as a means for detecting the presence or absence of a conveyed sheet. 4. The drive amount control means controls the drive amount of the time drive means according to the thickness if the sheet thickness detected by the sheet thickness detection means is within the acceptable range, while the drive amount control means is within the acceptable range. 2. The sheet conveying apparatus according to claim 1, wherein when the deviation is out of the range, an average value of the past sheet thickness is set as a reference value, and the drive amount is controlled based on the reference value. 5. The sheet thickness detecting means comprises a distance measuring sensor, and the sensor measures the distance to a specified position. When the measured distance does not match the distance to the specified position, it is a failure. 3. A self-diagnosis is made, and the drive amount control means selects whether to perform control based on thickness detection or control based on standard thickness based on the diagnosis result. Sheet transport device.