JP2002091245A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an image forming apparatus as simple as possible and to reliably prevent toner from being wastefully consumed or the inside of the device from being soiled because of an error or the like by a user. SOLUTION: This device is equipped with a transfer paper selection button 64a for inputting the length dimension of transfer paper P1, a resist switch 28 for detecting the length dimension of the paper P1 fed to a photoreceptor drum 31, and a paper length comparing and discriminating part 61a for comparing the length L1 of the transfer paper detected by the switch 28 with the length L2 of the transfer paper inputted with the button 64a and discriminating which is longer, the length L1 or the length L2. When the length L1 is shorter than the length L2, the part 61a outputs an interruption control signal for preventing toner supply to a part on the drum 31 corresponding to the rear part from the trailing edge of the paper P1 to a development unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a facsimile or a printer.

[0002]

2. Description of the Related Art Generally, an image forming apparatus such as a copying machine, a facsimile, a printer, or the like, includes a photosensitive drum having a photoconductive substance applied to the surface of the drum, and a charge applied by applying a predetermined voltage to the surface of the photosensitive drum. A charging device for uniformly charging the photosensitive drum, an exposure device for forming an electrostatic latent image on the surface of the photosensitive drum by selectively exposing the surface of the photosensitive drum in accordance with the read image, and a charging device for the photosensitive drum. A developing device for developing an electrostatic latent image formed on the surface of the photosensitive drum by selectively attaching toner to the surface, and transferring the developed toner image on the photosensitive drum to the surface of the transfer paper A transfer device, a static eliminator for removing charges on the surface of the photosensitive drum, a cleaner for removing and cleaning toner remaining on the surface of the photosensitive drum, and fixing the toner image transferred on the transfer paper A fixing device because, taking out the transfer sheet from the paper feed cassette is constructed by a paper feed mechanism for feeding a transfer sheet to the discharge tray through the transfer device and the fixing device.

Such an image forming apparatus has a contact glass for placing a sheet to be transferred (hereinafter referred to as "document paper") disposed on an upper surface thereof, and a document such that a document screen faces the contact glass. By placing the paper, scanning is performed by light irradiation from below the contact glass, and the original screen is read by the reflected light.

Usually, when an original sheet is placed on the contact glass, a size sensor for detecting the sheet size of the original sheet is provided, and a transfer sheet of the size detected by the size sensor is provided in a dedicated paper cassette. And the toner image on the peripheral surface of the photosensitive drum is transferred to the transferred transfer paper. Therefore, the size of the original paper always matches the size of the transfer paper, and as a result, the image of the image due to the size mismatch between the two is always obtained. Inconveniences such as out of frame are avoided. However, the provision of such a size sensor is convenient for the user. On the other hand, various types of electrical equipment must be additionally provided in various places, and the manufacturing cost of the image forming apparatus increases. .

Therefore, in a popular model, the size of the transfer paper (A4 size, A3 size,
(B5 size and B4 size are four types in general.)
Is input, and an image forming process is performed in accordance with the input size. The production cost of such a popular model is considerably lower.

[0006]

Incidentally, in the image forming apparatus of the above-mentioned popular type, since a sensor for detecting the size of the transfer sheet is not provided, the user is required to set the size of the transfer sheet. May be entered incorrectly. Even if the user inputs a size larger than the transfer paper actually set, an image forming operation corresponding to the input size is performed. Unnecessary portions are supplied with excess toner, which not only increases running costs, but also causes repetition of the above-mentioned problems, resulting in significant contamination in the image forming apparatus and increased maintenance costs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been made as simple as possible. It is an object of the present invention to provide an image forming apparatus capable of reliably preventing the image forming apparatus from being consumed or contaminating the inside of the apparatus with the useless toner.

[0008]

According to the first aspect of the present invention,
After developing the electrostatic latent image of the original image formed by selectively exposing the surface of the photoconductor drum by supplying toner from a developing device, the toner image on the peripheral surface of the photoconductor drum is driven by the driving unit. In an image forming apparatus configured to transfer onto a transfer sheet sent from a transfer sheet stock unit, an input unit for inputting a size of the transfer sheet, and the transfer unit is driven toward the photosensitive drum while being driven. Transfer paper length detection means for detecting a length dimension of a certain transfer paper;
A sheet length comparing / determining means for comparing the detected transfer paper length detected by the transfer paper length detecting means with the input transfer paper length inputted by the input means to determine the length of the two; The comparison determining means is configured to interrupt the formation of the toner image on the photosensitive drum corresponding to the rear end position of the transfer sheet and thereafter toward the developing device when the detected transfer sheet length is shorter than the input transfer sheet length. Is output.

According to the present invention, when the paper length comparing / determining means determines that the detected transfer paper length is shorter than the input transfer paper length, the paper length comparison / determination means determines whether the detected transfer paper length is shorter than the input transfer paper length. A control signal for interrupting the formation of the toner image is output to the controller, thereby stopping the supply of the toner from the developing device to the surface of the photoconductor drum. The toner is not supplied to the portion after the rear end of the transfer paper within the toner supply range to the photosensitive drum determined by the input transfer paper length, so that wasteful consumption of toner is suppressed and running cost is reduced. And contamination of the apparatus due to excess toner is prevented.

According to a second aspect of the present invention, after an electrostatic latent image of a document image formed by selectively exposing the surface of a photosensitive drum is developed by supplying toner from a developing device,
In an image forming apparatus configured to transfer the toner image on the peripheral surface of the photosensitive drum onto the transfer sheet fed from the transfer sheet stock unit by driving of the transfer unit, input means for inputting the size of the transfer sheet; A transfer paper length detecting means for detecting a length dimension of the transfer paper being fed toward the photosensitive drum by the driving of the transporting means; a transfer paper length detected by the transfer paper length detecting means; Paper length comparison and determination means for determining the length of the input transfer paper by comparing the length with the input transfer paper length input by the means;
Notifying means for notifying the transfer failure is provided, and the sheet length comparing / determining means outputs an alarm control signal for notifying an alarm to the notifying means when the detected transfer sheet length is different from the input transfer sheet length. It is characterized by being constituted so that.

According to the present invention, when the paper length comparing / determining means determines that the detected transfer paper length is shorter than the input transfer paper length, the notifying means notifies this based on the control signal from the paper length comparing / determining means. Since an alarm is issued to notify the user, the user of the apparatus can immediately recognize the abnormality and take action based on the alarm. Therefore, in the case where the alarm is not issued, the inconvenience of continuing the operation of the apparatus without noticing the abnormality can be reliably avoided, whereby it is possible to suppress the wasteful consumption of the toner in the future, and to reduce the unnecessary toner consumption. This prevents contamination in the apparatus.

According to a third aspect of the present invention, in the second aspect of the present invention, the paper length comparing / determining means is directed to the developing device when detecting that the detected transfer paper length is shorter than the input transfer paper length. It is characterized in that it is configured to output a control signal for interrupting the formation of a toner image on the photosensitive drum corresponding to a position after the rear end position of the transfer sheet.

According to the present invention, when the length of the detected transfer paper is shorter than the length of the input transfer paper, an alarm is issued and a toner image is formed on the photosensitive drum corresponding to the rear end position of the transfer paper and thereafter. Since the abnormality is not performed, the same effects as those of the first aspect can be obtained after the user is made aware of the abnormality.

The invention described in claim 4 is the invention according to claim 2 or 3.
In the invention described above, when the paper length comparison / determination means detects that the detected transfer paper length is different from the input transfer paper length, the paper length comparison / determination means may perform any one of an input change operation on the input means and a transfer paper size change operation. And a prohibition control signal for prohibiting image formation is output until the operation is performed.

According to the present invention, once an abnormality has occurred, the detected transfer paper length and the input transfer paper length are matched by a user's size input change operation or transfer paper size change operation (that is, the user can change the size). Since the image formation is prohibited (until the abnormality is eliminated by the above operation), the inconvenience that the transfer process is continuously performed while the abnormality is present is eliminated.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a plurality of the transfer paper stock sections are provided so as to stock transfer papers of different sizes, and the paper length comparison / determination means includes the detection section. When the transfer paper length is detected to be shorter than the input transfer paper length, the above-described prohibition control signal is output to the transfer paper stock portion related to this detection.

According to the present invention, even if any of the transfer paper stock sections is abnormal, the transfer processing can be performed on the transfer paper stocked in the normal transfer paper stock section. The inconvenience that the entire apparatus is affected by such a trouble is avoided.

[0018]

FIG. 1 is an explanatory side view showing an embodiment of the overall configuration of an image forming apparatus according to the present invention. In this embodiment, a digital copying machine is used as an image forming apparatus. As shown in FIG.
The digital copying machine is provided with a paper feed mechanism 10 provided at the bottom of the main body of the copying machine, a paper transport mechanism 20 provided above the paper feed mechanism 10, and a paper feed mechanism 20 provided above the paper transport mechanism 20. Image forming mechanism 30, a fixing device 40 disposed on a discharge side of the image forming mechanism 30, and an image reading device (scanner) 50 disposed above the image forming mechanism 30 and the fixing device 40. And an exposure device 33, and a control device 60 for controlling the operation of the entire copying machine.

The paper feed mechanism 10 includes a transfer paper sheet P1
Paper cassette (transfer paper stock unit) 1 for storing bundles of paper
1, a paper feed roller 12 provided above the outlet of the paper feed cassette 11 and having an arc-shaped outer peripheral portion, and a coil spring 1 for pushing up a bundle of transfer sheets P1 to the paper feed roller 12 side.
3, and a separating claw 15 provided at each of the upper ends of both ends in the width direction of the sheet feeding cassette 11. Paper cassette 1
As for No. 1, a plurality of types are prepared according to the size of the transfer paper P1. In the present embodiment, for A4 size paper, A3 size paper, B5 size paper, and B
Four types of paper feed cassettes 11 for four sizes of paper are employed.

The paper feed mechanism 10 has a manual feed tray (transfer paper stock section) 11 'projecting outside from a casing of the apparatus, separately from a paper feed cassette 11 provided in the apparatus. The manual feed tray 11 'is configured to be flexible so that original paper P2 of each size can be loaded. The manual feed tray 11 ′ is
1 and a feed roller similar to that provided in the printer 1, and the leading end faces a transport roller pair 22 described later.

When the paper feed roller 12 is rotated in a predetermined direction, the arc-shaped outer peripheral portion comes into contact with the uppermost transfer sheet P1, and the transfer sheet P1 is sent out to the right side in FIG. At this time, the sheet bundle of the transfer sheet P1 is separated by the separating claw 15, and only the transfer sheet P1 located at the uppermost position is 1 sheet.
Sheets are reliably supplied to the sheet transport mechanism 20 one by one.

The paper transport mechanism 20 converts the transport direction of the transfer paper P1 supplied from the paper feed mechanism 10 into an inversion guide 21 and the transfer paper P1 whose transport direction is inverted by the inversion guide 21 in FIG. A pair of conveying rollers 22 for conveying to the left and a leading end of the conveyed transfer sheet P1 are aligned in the width direction, and a timing for starting the transfer of the toner image in accordance with the rotation of a photosensitive drum 31 described later. Registration roller pair 23 and registration roller pair 2
Transfer guide 27 for accurately transporting the transfer sheet P1 from the position 3 to the transfer position where the photosensitive drum 31 and the transfer device 35 face each other;
A conveyance guide 24 for conveying the toner image 1 to the fixing device 40;
A discharge roller pair 25 for discharging the transfer paper on which the toner image is fixed by the fixing device 40 and the image has been formed onto a discharge tray 26, and a registration switch 28 provided concentrically with the roller above the registration roller pair 23. It is comprised including.

The registration roller pair 23 includes a transport roller pair 2
2. The rotation of the transfer sheet P1 is stopped until the transfer sheet P1 sent by the transfer roller 2 arrives. When the leading end of the transfer sheet P1 comes into contact with the registration roller pair 23, the distortion during conveyance is corrected, and the leading end in the width direction is adjusted. Aligned. Photoconductor drum 3
The distance between the exposure position and the transfer position of the toner image on the outer peripheral surface 1 and the distance from the registration roller pair 23 to the transfer position are set to be substantially equal. When the leading ends in the width direction of the transfer sheet P1 are aligned, the driving of the registration roller pair 23 and the exposure of the surface of the photosensitive drum 31 by the exposure device 33 are started almost simultaneously. Photoconductor drum 3
1 and registration roller pair 2
The toner image is transferred onto the transfer sheet P1 with almost no gap since the leading end of the transfer sheet P1 conveyed by 3 reaches the transfer position almost simultaneously.

The image forming mechanism 30 forms a predetermined toner image on the transfer paper P1 by an electrophotographic process, and is rotatably supported on a photosensitive member having a drum surface coated with a photoconductive substance. Drum 31 and photosensitive drum 3
Photoreceptor drum driving device 38 for rotating photoreceptor 1 in a predetermined direction at a predetermined speed, charging device 32 for applying a predetermined potential to the surface of photoreceptor drum 31 (to uniformly charge a predetermined charge), and document paper P2 An exposure device 33 for selectively forming an electrostatic latent image on the surface of the photosensitive drum by selectively exposing the surface of the photosensitive drum in accordance with the image of And a transfer device 35 for transferring the developed toner image on the photosensitive drum 31 to the surface of the transfer paper. ,
A cleaner 36 for removing (cleaning) toner remaining on the surface of the photosensitive drum, a charge eliminator 37 for removing charge on the surface of the photosensitive drum, and a charge charged on the transfer paper after the transfer of the toner image Brush 39 for removing dust
It is comprised including.

The charging device 32 is provided on the upstream side in the rotation direction of the photosensitive drum 31 with respect to an exposure position described later.
A wire is provided so as to face the surface of the photosensitive drum 31 at a predetermined distance, and a wire for generating a corona discharge when a high voltage is applied thereto, and a grid for applying a predetermined voltage (for example, +850 V) And a predetermined potential is applied to the surface of the photosensitive drum 31 by the wire and the grid.

The exposure device 33 includes a laser oscillator 331
And a polygon mirror 332 which is a rotating polyhedron for reflecting the laser beam output from the laser oscillator 331.
A fθ lens 334 for correcting the distortion of the laser beam reflected by the polygon mirror 332, and the light reflected by the polygon mirror 332 to the photosensitive drum 31
And a mirror 333 for re-reflection to the exposure position. The laser oscillator 331 is connected to an image reading device 5 described later.
0 outputs a laser beam based on the image data of the document read. The polygon mirror 332 rotates at a constant speed in a predetermined direction, and changes the angle of the mirror surface that reflects the laser beam output from the laser oscillator 331 every moment, so that the laser beam is shifted in the width direction of the photosensitive drum 31. It is designed to be scanned.

The photosensitive drum 31 is made of, for example, an organic photosensitive member (OPC: Organic) on the outer peripheral surface of a drum such as aluminum.
c Photo-conductive) A film of a photoconductive material such as a material is applied.
A constant surface potential (for example, +800)
V), a positive charge is charged. In this state, when the surface of the photosensitive drum 31 is selectively exposed by the exposure device 33, the potential of the exposed portion decreases due to the photoelectric effect of the photoconductive material applied to the surface. That is, an electrostatic latent image is formed on the surface of the photosensitive drum 31.

The developing device 34 is provided downstream of the exposure position in the rotation direction of the photosensitive drum 31 so as to face the surface of the photosensitive drum 31 at a predetermined distance, and has a predetermined distance. While holding the toner of
The toner is charged to, for example, a positive charge. When the portion of the electrostatic latent image formed on the surface of the photosensitive drum 31 approaches the developing device 34, the toner adheres to the surface of the photosensitive drum 31 from the developing device 34, thereby causing the toner to adhere on the surface of the photosensitive drum 31. An image will be formed.

The transfer device 35 is separated from the surface of the photosensitive drum 31 by a predetermined distance so that a gap is still formed even when the transfer sheet P1 is conveyed between the photosensitive drum 31 and the transfer device 35. Are provided so as to face each other,
By passing a transfer current having a polarity opposite to the surface potential of the photoconductor drum 31, toner adheres to the transfer sheet P <b> 1 interposed between the photoconductor drum 31 and the transfer device 35. This adhesion causes the toner image on the surface of the photosensitive drum 31 to be transferred to the transfer sheet P1.

The cleaner 36 is provided so as to be in contact with the surface of the photosensitive drum 31 and remains on the surface of the photosensitive drum 31 even after the transfer device 35 transfers the toner image to the transfer paper P1. This removes the remaining toner.

The static eliminator 37 is provided downstream of the cleaner 36 in the direction of rotation of the photosensitive drum 31 and upstream of the charger 32.
This is to remove the electric charge remaining on the surface of No. 1.

The fixing device 40 heats and presses the transfer sheet P1 onto which the toner image has been transferred by the image forming mechanism 30 by using a heating roller 41 and a pressing roller 42, and the toner image is transferred onto the transfer sheet P1. Is established.

The image reading device 50 includes a contact glass 51 also serving as a document table, an exposure lamp 52 for illuminating the document surface of the document paper P2 placed on the contact glass 51 from the inside, and a document paper P2 as a subject. CCD image
An imaging lens 57 for forming an image on a photoelectric conversion element 56 such as a line sensor; and mirrors 53, 54 and 55 for refracting and reflecting the optical axis of the imaging lens 57 connecting the original paper P2 and the photoelectric conversion element 56. In order to scan the original sheet P2 on the contact glass 51 from the left end to the right end in FIG. 1, the exposure lamp 52 and the mirror 53 and the mirrors 54 and 55 are moved in a moving space 58 so that the moving speed becomes 2: 1. And a scanning mechanism (not shown) for moving the inside.

An image of an area of a fixed width illuminated by the exposure lamp 52 of the original paper P2 placed on the contact glass 51 is formed on the photoelectric conversion element 56 by the imaging lens 57. Have an optically conjugate relationship. Exposure lamp 52 and mirror 53 by scanning mechanism
When scanning is started from the left end to the right end in FIG. 1 at the first speed, the mirrors 54 and 55 are simultaneously integrated to keep the optical path length from the original sheet P2 to the photoelectric conversion element 56 constant. Scanning is performed from the left end to the right end in FIG. 1 at a second speed which is の of the first speed. As a result, the entire surface of the original sheet P2 placed on the contact glass 51 can be scanned, and an image on the entire surface of the original sheet P2 can be read.

The image data of the original surface of the original sheet P2 input to the photoelectric conversion element 56 is digitized, and then digitized by the laser oscillator 331 from the polygon mirror 332, f.
Irradiation is performed on the surface of the photosensitive drum 31 via the lens 334 and the mirror 333. In the course of the digitizing process, a magnification process as set in advance is performed. Therefore, for example, even if the original sheet P2 is A5 size, if the magnification setting is 141%, the original image formed on the surface of the photosensitive drum 31 is A4 size. In general, the user determines the size of the transfer sheet P1 so as to match the size of the document image in consideration of the magnification process.

Although the size of the original sheet P2 is A5, there is a case where an A4 size transfer sheet P1 is consciously selected as a transfer sheet P1 even though it is the same size without performing any magnification processing. In the case, the original image is A4
Size. Therefore, the user selects the A4 size transfer sheet P1 even if the original sheet P2 is A5 size. However, the transfer image obtained on the transfer sheet P1 is in a state in which the surrounding margin occupies a very large area.

FIGS. 2A and 2B are perspective explanatory views showing an arrangement state of the registration switch 28 provided at the same position as the registration roller pair 23. FIG. 2A shows a state before the transfer paper P1 is supplied between the registration roller pair 23. (B) shows a state in which the transfer paper P1 is supplied between the registration roller pair 23.

As shown in FIG. 2, the registration roller pair 23 has a plurality of lower rollers 23a rotatably supported around a lower support shaft 23c, and a plurality of lower rollers 23a which come into contact with each lower roller 23a at an upper position. And a plurality of upper rollers 23b rotatably supported around the upper support shaft 23d so as to face each other. Each roller 23a, 23b
As shown in FIG. 2A, the transfer paper P is normally weakly urged by springs (not shown) in directions facing each other and is in contact with each other.
When the transfer sheet P1 is fed between the rollers 23a and 23b, the transfer sheet P1 is moved as shown in FIG.
The front edge of each roller 2 is opposed to the biasing force of the spring.
3a, 23b, each roller 23a, 23b
Are rotated while rotating in opposite directions.

The registration switch 28 is rotatably supported around an upper support shaft 23d supporting the upper roller 23b of the registration roller pair 23. The registration switch 28 includes a straight striker 2 whose upper end is externally fitted in sliding contact with the upper support shaft 23d.
8a, and a terminal strip 28b protruding upward from the upper end of the striker 28a. The length of the striker 28a is set to be slightly longer than the distance between the support shafts 23c and 23d, so that the distal end thereof is normally in contact with the lower support shaft 23c on the downstream side.

A striker-side contact 28c is provided at the tip of the terminal strip 28b, while a frame-side contact 28d facing the striker-side contact 28c is provided at an appropriate position on an unillustrated apparatus frame. 2
8a around the upper support shaft 23d in a clockwise direction (the tip of the striker 28a is
The striker side contact 28c is brought into contact with the frame side contact 28d by the rotation of an angle until the contact level becomes the same level as the contact position b).

Accordingly, the transfer paper P1 is
Is driven to the pair of registration rollers 23, the hanging down registration switch 28 (FIG. 2A) is pushed by the front edge of the transfer sheet P1 and rotates clockwise around the upper support shaft 23d. The striker-side contact 28c is turned to the frame-side contact 2 as shown in FIG.
8d, the conduction of the predetermined detection circuit thereby detects that the transfer sheet P1 has reached the registration switch 28, and the detection circuit is cut off by the striker side contact 28c being separated from the frame side contact 28d. It is detected that the transfer sheet P1 has passed through the pair of registration rollers 23.

The present invention detects the length of the transfer sheet P1 being conveyed by the registration switch 28, and detects the length of the transfer sheet P1 according to the input by the user. It is determined whether or not the length is shorter. If the length is shorter, control is performed so that a toner image is not formed on a portion of the photosensitive drum 31 corresponding to the rear end portion of the transfer sheet P1 and thereafter. Hereinafter, the image forming control will be described with reference to FIG.

FIG. 3 is a block diagram showing an embodiment of the image forming control according to the present invention. As shown in the block diagram, the image forming control is controlled by a control device 60 provided at an appropriate position in the apparatus. The control device 60 includes a CPU (Central Process).
ing Unit) 61 and a RAM (Random Access Memory) connected to the CPU 61.
y) 62 and the ROM (Read Only Memory)
ry) 63.

Further, a network control unit 65 is connected to the control device 60 via a communication line so that image forming processing can be performed by remote control from the network control unit 65.

The RAM 62 is an external storage device capable of freely reading and writing data, and detects values from sensors provided in various parts of the device and various values of intermediate processing and calculation results as required. Is written or read. The ROM 63 is a read-only external storage device in which an image processing program is stored in advance. Then, when power is supplied to the apparatus by turning on a power switch (not shown), the program in the ROM 63 is read into the CPU 61, and the CPU 61 drives each apparatus in the apparatus in accordance with the above-described program each time image forming processing is performed. A signal is output, whereby the image forming process is properly executed.

An operation unit 64 is connected to the control device 60, and various input operations are performed from the operation unit 64 to the control device 60, and various display outputs are performed based on control signals from the control device 60. Is performed. According to the present invention, the size of the transfer sheet P1 is input from the operation unit 64 to the control device 60.

The operation section 64 is provided with a transfer paper selection button (input means) 64a for this input operation.
In the present embodiment, an A4 button 64b, an A3 button 64c, a B5 button 64d, and a B4 button 64e are employed as the transfer paper selection buttons 64a. When the user turns on one of the transfer paper selection buttons 64a according to the size of the document, this information is input to the CPU 61.

On the other hand, the paper feed cassette 11 stores A4 size transfer paper P1 corresponding to the A4 button 64b, A3 button 64c, B5 button 64d and B4 button 64e.
Loaded in A4 cassette, A3 size transfer paper P1
A3 cassette loaded with, transfer paper P1 of B5 size
And a B4 cassette loaded with transfer paper P1 of B4 size are prepared. Separately, the apparatus is provided with a manual feed tray 11 '. Transfer paper P1 of various sizes is loaded into the manual feed tray 11' depending on the situation.

Therefore, the user determines whether or not the paper cassette 11 mounted on the apparatus matches the size selected by the transfer paper selection button 64a, or if the user selects the manual feed tray 11 '. Then, it is checked which size of the transfer paper P1 is loaded in the manual feed tray 11 ', and if they match, the start button (not shown) is turned on to copy the original paper P2, while it matches. If not, the paper feed cassette 11 is replaced or the transfer paper P1 in the manual feed tray 11 'is replaced.

By the way, even if the user pays close attention and recognizes that the type of the paper feed cassette 11 and the type of the transfer paper selection button 64a match, there is an operation error or misunderstanding, The type 11 and the type of the transfer paper selection button 64a do not always match. Therefore, for example, when copying a document image of A4 size, the user recognizes that the paper feed cassette 11 is also of A4 size, but in fact, the paper feed cassette 11 is of B4 size. Cases can happen frequently.

In such a case, if the transfer sheet P1 is B5 in spite of the fact that the original image is in A4 size (ie, although the input transfer sheet length L2 corresponds to the A4 size, If the detected transfer sheet length L1 is of B5 size), the apparatus performs the transfer process in accordance with the input transfer sheet length L2, and therefore, the rear side of the rear end position of the transfer sheet P1 on the photosensitive drum 31. Not only will the toner be supplied to the portion to perform useless transfer processing, but also the unnecessary supply of toner may cause contamination of the apparatus.

The present invention has been made in order to prevent such inconveniences caused by operation errors and misunderstandings. For this reason, the size selection information of the transfer paper P1 from the transfer paper selection button 64a and the registration information The length information of the transfer sheet P1 from the switch 28 is output to the CPU 61, and
1, a transfer paper length L1 detected based on these input values.
Paper length comparison / determination unit (paper length comparison / determination means) 61a that outputs a control signal so that a predetermined process described later is performed when the length of the paper does not match the length of the input paper L2.
And a timer 61b for calculating the length dimension of the resist switch 28 from the time between ON and OFF of the resist switch 28. Incidentally, in the present invention, a sensor is provided for detecting which size of the transfer paper P1 the paper feed cassette 11 is for, and which size of the transfer paper P1 is loaded in the manual feed tray 11 '. Therefore, the cost of the apparatus is reduced. Paper cassette 1
The user selects the operation unit 64 or the network control unit 65 by using one of the manual tray 1 and the manual feed tray 11 ′.
The setting is performed by a predetermined input operation to the control device 60 from the user.

The paper length comparison / determination section 61a provides the paper length of the transfer paper P1 (input transfer paper length L2) requested by the user based on the input signal from the transfer paper selection button 64a.
While calculating the actual length of the transfer sheet P1 (detected transfer sheet length L1) based on the detection signal (timing signal) from the registration switch 28, the detected transfer sheet length L1 and the input transfer sheet length are calculated. A comparison operation with L2 is performed.

Incidentally, the calculation of the sheet length of the transfer sheet P1 based on the timing signal from the registration switch 28 is performed as follows. That is, the registration switch 28
When the transfer sheet P1 is supplied between the pair of registration rollers 23, the leading edge of the transfer sheet P1 interferes with the striker 28a as shown in FIG. The clockwise rotation causes the striker side contact 28c to come into contact with the frame side contact 28d, thereby generating an electric signal. This electric signal is transmitted to the CPU 61
, The time is stored in the RAM 62 by the built-in timer.

Next, when the transfer sheet P1 moves out of the registration roller pair 23 by advancing, the transfer sheet P1 no longer exists between the registration roller pair 23, and the registration switch 28 is turned counterclockwise around the upper support shaft 23d. Rotate to contact frame side contact 2 of striker side contact 28c
The contact with 8d is released, and the electric signal is cut off.
When this interruption is input to the CPU 61, the time is recognized by the built-in timer. Continue RAM6
2 is called, the difference between the switch-off time and the switch-on time is calculated, and the difference between the switch-off time and the switch-on time is calculated.
The length of the transfer sheet P1 is calculated by multiplying the transfer speed input to M62.

Then, the paper length comparison / determination section 61a calculates the calculated length of the transfer paper P1 (detected transfer paper length L1).
If the length of the transfer sheet (input transfer sheet length L2) input from the transfer sheet selection button 64a matches (L1 = L2), no control signal is output in particular regarding the size difference. Therefore, in this case, a normal transfer process is performed. On the other hand, when the detected transfer paper length L1 is different from the input transfer paper length L2 (L1 ≠ L2), the control device 60 moves to the image forming section 3 including the image forming mechanism 30 and the fixing device 40. Various control signals are output, and a predetermined process (sheet mismatch processing) corresponding to the difference is executed.

That is, first, the sheet length comparison / determination section 61a
Means that when the length L1 of the detected transfer sheet is shorter than the length L2 of the input transfer sheet (L1 <L2), the supply of the toner to the portion of the photosensitive drum 31 corresponding to the rear end of the rear end of the transfer sheet P1 is inhibited. The control signal is transferred to the transfer device 35
Output to. Therefore, consumption of unnecessary toner is suppressed, and the inconvenience of the inside of the apparatus being contaminated with unnecessary toner is also eliminated.

The paper length comparison / determination section 61a determines that the detected transfer paper length L1 and the input transfer paper length L2 are different (L1 ≠
L2), this is notified, and the drive of the image forming unit 3 is stopped, and the image forming unit 3 is not controlled until the user performs an operation of matching the detected transfer paper length L1 with the input transfer paper length L2. The transfer process is completely prohibited for the paper feed cassette 11 or the manual feed tray 11 '.

Specifically, when the sheet length comparison / determination unit 61a determines that the detected transfer sheet length L1 and the input transfer sheet length L2 are different, the sheet length comparison / determination unit 61a
While outputting a control signal for alarm notification to the alarm device 64f of the operation unit 64 and the network control unit 65,
A control signal is output to the image forming section 3 to prohibit the subsequent transfer operation of the paper feed cassette 11 or the manual feed tray 11 'on the transfer paper P1. The user can recognize the paper mismatch by the alarm device 64f.

Further, once the paper length comparison / determination section 61a determines that the paper lengths do not match, the user performs an operation for resolving the paper mismatch (specifically, pressing the transfer paper selection button 64a again and pressing the paper feed cassette 11). Or the transfer of the transfer paper P1 in the manual feed tray 11 ') is prohibited.

Therefore, the user operates the transfer paper selection button 6
4a, the paper feed cassette 11 is replaced with one that matches the original image,
By performing an operation such as replacing the 1 'transfer paper P1 with a transfer paper that matches the transfer paper P1, and making the detected transfer paper length L1 and the input transfer paper length L2 coincide with each other, the prohibition process is canceled.

Then, the paper length comparison / determination section 61a controls the paper feed cassette 11 or the manual feed tray 1
Since the above-mentioned prohibition control signal is output only for 1 ′, the paper feed cassettes 11 and the manual feed tray 11 ′ other than the paper feed cassette 11 for which the above detection has been performed are performed.
Can be used.

Hereinafter, the paper size mismatch processing will be described with reference to a flowchart. FIG. 4 is a flowchart showing the flow of the paper mismatch processing.

As a precondition for performing the transfer process, the operation unit 6
4, the size of the transfer sheet P1 is set by operating the predetermined transfer sheet selection button 64a. Therefore, the user performs the transfer process so that the original image of the same size as the set transfer paper P1 is obtained. Then, the user first places the document sheet P2 at a predetermined position on the contact glass 51 with the document surface facing down. This completes the preparation for the transfer process.

Next, the transfer process is started by pressing a predetermined start button of the operation section 64 (S1), and the paper feed cassette 1 is driven by driving the paper feed mechanism 10.
The paper feeding in which the transfer paper P1 in the sheet No. 1 is fed toward the photosensitive drum 31 starts (S2). Next, when the transfer paper P1 passes between the registration roller pair 23,
An on / off signal (transport timing signal) from the registration switch 28 is input to the CPU 61, and the length of the transfer sheet P1 currently being fed is calculated from the elapsed time between on / off and the transport speed. (S3).

Next, the calculated length of the transfer sheet P1 (detected transfer sheet length L1) and the transfer sheet selection button 64
is compared with the input transfer paper length L2 set in step (a) (S4), and the detected transfer paper length L1 and the input transfer paper length L
If 2 is the same (L1 = L2) (actually, a predetermined allowable range is set and it is determined whether or not they are the same within the allowable range), step S5 is executed and the transfer operation is performed. Is continued (step S5), and the transfer process by which the transfer paper P1 is discharged to the discharge tray 26 ends.

If the detected transfer paper length L1 and the input transfer paper length L2 do not match in step S4 (NO in S4), the transfer operation by the image forming unit 3 is immediately stopped (S7), and An abnormality (paper size mismatch) is notified to the user via the alarm device 64f and the network control unit 65 (S8).

Next, the apparatus is set to a transfer inhibition mode in which the driving of the paper feed mechanism 10, the paper transport mechanism 20, the image forming mechanism 30, the fixing device 40, and the image reading device 50 is stopped. Cannot be performed (S9). The transfer sheet P <b> 1 that has been fed immediately before the photosensitive drum 31 is discharged toward the discharge tray 26.

When the length L1 of the detected transfer sheet is shorter than the length L2 of the input transfer sheet, the transfer sheet P1 is supplied in a state where the supply of excess toner to the photosensitive drum 31 is interrupted.
Is performed, and when the detected transfer paper length L1 is longer than the input transfer paper length L2, the normal transfer processing is performed on the transfer paper P1.

In order to release the transfer prohibition mode, the user presses the transfer paper selection button 64a again, replaces the paper feed cassette 11, and further replaces the prohibition mode such as replacing the transfer paper P1 in the manual feed tray 11 '. Perform the operation.
By doing so, the inhibition mode is released (S1
1) The process returns to step S1.

As described in detail above, according to the present invention, the transfer paper selection button 64a for inputting the length of the transfer paper P1 is used.
A registration switch 28 for detecting the length of the transfer sheet P1 being fed toward the photosensitive drum 31 by driving the registration roller pair 23, a detected transfer sheet length L1 detected by the registration switch 28, A paper length comparison / determination unit 61a for comparing the size of the transfer paper P1 input by the transfer paper selection button 64a with the input transfer paper length L2 to determine the length of the two; 61a is the detection transfer paper length L1
Is shorter than the input transfer paper length L2, the transfer device 35 is instructed to stop supplying toner to a portion of the photosensitive drum 31 corresponding to the rear end of the transfer paper P1 toward the developing device. When the length L1 of the detected transfer sheet is determined to be shorter than the length L2 of the input transfer sheet, the sheet length comparison / determination section 61a supplies the toner from the developing device 34 to the surface of the photosensitive drum 31. Is stopped, thereby suppressing wasteful consumption of toner and contributing to a reduction in running cost.
The inconvenience that the inside of the apparatus is contaminated with unnecessary toner is eliminated, and the inspection span for maintenance and the life of the apparatus can be extended.

Further, if the paper length comparison / determination section 61a is configured to output a control signal for issuing an alarm to the notifying means when the detected transfer paper length L1 and the input transfer paper length L2 do not match, it is possible to use the same. This alert allows the user to immediately recognize the abnormality and take action. Therefore, when an alarm is not issued, an abnormality is not noticed, and the inconvenience of continuing the operation of the apparatus can be reliably avoided, whereby it is possible to suppress the wasteful consumption of the toner thereafter, It is possible to effectively prevent contamination in the apparatus due to toner consumption.

In the above-described embodiment, as the image forming apparatus, the analog image information of the original image of the original sheet P2 scanned by the mirrors 53, 54, 55 is temporarily converted into digital information, and then converted from the laser oscillator 331. Although the so-called digital type, which irradiates the peripheral surface of the photosensitive drum 31 via the polygon mirror 332 and the like, is mentioned, the present invention is not limited to the image forming apparatus being a digital type. An analog type in which analog scanning information is directly applied to the peripheral surface of the photosensitive drum 31 may be used.

[0074]

According to the first aspect of the present invention, when the paper length comparing / determining means determines that the detected transfer paper length is shorter than the input transfer paper length, the paper length comparison / determination means moves the rearward position of the transfer paper toward the developing device. Outputs a suspend control signal for suspending the formation of a toner image on the photosensitive drum corresponding to, and thereby the supply of toner from the developing device to the surface of the photosensitive drum is stopped. When the length is shorter than the input transfer paper length, excess toner is not supplied to the peripheral surface of the photoreceptor drum, so that the consumption of the excess toner is suppressed, which contributes to a reduction in running cost, and also reduces contamination of the apparatus due to the excess toner. It can be effectively prevented.

According to the second aspect of the present invention, when the paper length comparing / determining means determines that the detected transfer paper length is shorter than the input transfer paper length, the notifying means based on the control signal from the paper length comparing / determining means. Generates an alarm to notify the user of this fact, so that the user of the apparatus can immediately recognize the abnormality and take action based on the alarm. Therefore, in the case where the alarm is not issued, the inconvenience of continuing the operation of the apparatus without noticing the abnormality can be reliably avoided, whereby it is possible to suppress the wasteful consumption of the toner in the future, and to reduce the unnecessary toner consumption. Can effectively prevent contamination in the apparatus.

According to the third aspect of the present invention, when the length of the detected transfer paper is shorter than the length of the detected transfer paper, an alarm is issued and, in addition, the photosensitive drum corresponding to the rear end position of the transfer paper and thereafter is placed on the photosensitive drum. Since the toner image is not transferred, the same effects as those of the first aspect can be obtained after making the user recognize the abnormality.

According to the fourth aspect of the present invention, once an abnormality has occurred, the image is not updated until the update input corresponding to the detected transfer sheet length is performed on the transfer sheet length input means (that is, until the abnormality is eliminated). Since the formation is prohibited, it is possible to eliminate the inconvenience of continuing to use the device while the abnormality is present.

According to the fifth aspect of the present invention, by providing a plurality of transfer sheet stock sections, when the length of the detected transfer sheet is shorter than the length of the input transfer sheet, only the transfer sheet stock section related to this detection will be used. Since the operation of the apparatus is prohibited, the transfer processing can be performed on the transfer paper stock part which has not been subjected to the prohibition process, thereby avoiding inconvenience that the entire apparatus is affected by a partial defect. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the entire configuration of an image forming apparatus according to the present invention.

FIG. 2 is a perspective explanatory view showing an arrangement state of a registration switch provided at the same position as a registration roller pair;
Indicates a state before the transfer sheet is supplied between the pair of registration rollers, and (b) indicates a state where the transfer sheet is supplied between the pair of registration rollers.

FIG. 3 is a block diagram illustrating an embodiment of image forming control according to the present invention.

FIG. 4 is a flowchart illustrating a flow of a paper mismatch process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Paper feed mechanism 11 Tray 11 Paper feed cassette (transfer paper stock part) 11 'Manual feed tray (transfer paper stock part) 12 Paper feed roller 13 Coil spring 15 Jaw claw 20 Paper transport mechanism 21 Reverse guide 22 Transport roller pair 23 Registration roller Pair 23a lower roller 23c lower support shaft 23b upper roller 23d upper support shaft 24 transport guide 25 discharge roller pair 26 discharge tray 27 transfer guide 28a striker 28c striker side contact 28d frame side contact 28 registration switch 28b terminal strip 3 image forming unit 30 image Forming mechanism 31 Photoreceptor drum 32 Charger 32 Charging device 33 Exposure device 331 Laser oscillator 332 Polygon mirror 333 Mirror 334 Lens 34 Developing device 35 Transfer device 36 Cleaner 37 Static eliminator Reference Signs List 38 photoconductor drum driving device 39 static elimination brush 40 fixing device 41 heating roller 42 pressure roller 50 image reading device 51 contact glass 52 exposure lamp 53, 54 mirror 56 photoelectric conversion element 57 imaging lens 58 moving space 60 control device 61 CPU 61a paper Length comparison / determination section 61b Timer 64 Operation section 64a Transfer paper selection button 64b A4 button 64c A3 button 64d B5 button 64e B4 button 64f Alarm device 65 Network control section L1 Transfer paper length L2 Original paper length P1 Transfer paper P2 Original paper

Continued on the front page (72) Inventor Tetsuro Tomoe 1-2-28 Tamazo, Chuo-ku, Osaka City Inside Kyocera Mita Corporation (72) Inventor Mitsutoshi Takemoto 1-2-28 Tamazo, Chuo-ku, Osaka City Kyocera Mita Corporation (72) Inventor Junya Yoda 1-2-28 Tamazo, Chuo-ku, Osaka City Inside Kyocera Mita Corporation (72) Inventor Shinji Yamamoto 1-2-28 Tamazo, Chuo-ku, Osaka City F-term in Kyocera Mita Corporation (72) Reference) 2H027 DC10 DE07 DE10 EE09 EF09 EK03 FA05 GA30 GB04 GB16 2H072 AA23 AB07

Claims (5)

[Claims] An electrostatic latent image of an original image formed by selectively exposing the surface of a photosensitive drum is developed by supplying toner from a developing device, and then a toner image on the peripheral surface of the photosensitive drum is formed. In an image forming apparatus configured to transfer onto a transfer sheet fed from a transfer sheet stock unit by driving of a transfer unit, an input unit for inputting a size of the transfer sheet, and a photosensitive drum is driven by driving of the transfer unit. Transfer paper length detection means for detecting the length dimension of the transfer paper being fed toward the printer, and the detected transfer paper length detected by the transfer paper length detection means and the input transfer paper length input by the input means. A sheet length comparing and judging means for comparing the length of the sheet with the developing device when the detected transfer sheet length is shorter than the input transfer sheet length; An image forming apparatus configured to output an interruption control signal for interrupting formation of a toner image on a photosensitive drum corresponding to a position after a rear end position of a transfer sheet. 2. After developing the electrostatic latent image of the original image formed by selectively exposing the surface of the photosensitive drum by supplying toner from a developing device, a toner image on the peripheral surface of the photosensitive drum is formed. In an image forming apparatus configured to transfer onto a transfer sheet fed from a transfer sheet stock unit by driving of a transfer unit, an input unit for inputting a size of the transfer sheet, and a photosensitive drum is driven by driving of the transfer unit. Transfer paper length detection means for detecting the length dimension of the transfer paper being fed toward the printer, the detected transfer paper length detected by the transfer paper length detection means, and the input transfer paper length input by the input means. Paper length comparison and determination means for comparing the lengths of the two to determine the length of the two, and notification means for notifying the transfer failure, wherein the paper length comparison and determination means An image forming apparatus configured to output an alarm control signal for notifying an alarm to the notifying unit when the sheet length is different from the input transfer sheet length. 3. The photosensitive drum corresponding to the rear end position of the transfer sheet after the rear end position of the transfer sheet toward the developing device when detecting that the detected transfer sheet length is shorter than the input transfer sheet length. The image forming apparatus according to claim 2, wherein the image forming apparatus is configured to output an interruption control signal for interrupting formation of a toner image on the image forming apparatus. 4. The sheet length comparing / determining means, when detecting that the detected transfer sheet length is different from the input transfer sheet length, performs one of an input change operation on the input means and a transfer sheet size change operation. 4. The image forming apparatus according to claim 2, wherein a prohibition control signal for prohibiting image formation is output until the operation is performed. 5. The transfer sheet stock section is provided in plural numbers so as to stock transfer sheets of different sizes, and the sheet length comparing / determining means detects that the detected transfer sheet length is shorter than the input transfer sheet length. 5. The image forming apparatus according to claim 4, wherein the prohibition control signal is output to the transfer paper stock unit related to the detection.