JPH0296774A - Image forming device - Google Patents

Abstract

PURPOSE:To correct offset, thread, etc. arising on an endless belt member by detecting marks in the lateral direction with respect to the moving direction of the endless belt member and changing the relative position of a belt holding mechanism based on an output signal from the detecting means. CONSTITUTION:The marks a2 and b3 are provided in the position on the outer periphery of the belt 1; the position practically bisects the peripheral length of the belt 1 in its moving direction offsetting the belt 1. The belt 1 is provided with a mark reader 130. When the belt 1 is offsetting, photodetector, not one specific photodetector, outputs an electrical signal showing that marks a2 and b3 are detected whenever the belt 1 makes one turn. Thus, trouble such as offset and thread arising on the belt member 11 can be corrected without applying load to the endless belt member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an image forming apparatus, and in particular, for example, an MA forming apparatus in which an image bearing means, an intermediate transfer means, and a transfer material conveying means are constituted by a belt holding mechanism, an endless belt member, etc. Regarding.

As is well known, various types of image forming apparatuses have been developed in which electrophotographic methods, electrostatic recording methods, and the like are employed in the image forming process.

The various types of image forming apparatuses mentioned above include a photosensitive drum as an image carrier, peripheral equipment for the photosensitive drum,
Some types include an intermediate transfer drum, a transfer material conveyance mechanism, and the like. In recent years, in order to further improve the functions of photoreceptor drums, intermediate transfer drums, transfer material transport mechanisms, etc., endless belt members carrying photoreceptors have been adopted in place of photoreceptor drums, and intermediate transfer Image forming apparatuses have been developed in which endless belt members are used in drums and transfer material conveyance mechanisms, respectively. In image forming apparatuses that employ endless belt members for photoreceptors, intermediate transfer means, transfer material conveyance mechanisms, etc., it has become possible to improve many functions. It is indispensable to provide a means for suppressing the occurrence of belt deviation, meandering, etc. during driving, which are defects specific to the mechanism.

In other words, defects such as deviation or meandering when driving the belt are caused by the belt drive mechanism, the mechanical accuracy of the belt itself, changes in belt characteristics, and the transfer material entering the transfer material conveyance belt from the transfer material supply mechanism. Since vibrations that occur on the conveyor belt are caused by various forces applied from the outside, it is impossible to suppress the belt from shifting or meandering without providing some kind of means. It is.

Conventionally, the following methods have been adopted as means for correcting defects such as deviation or meandering of the belt.

(a) The diameter of the roller member that holds the endless belt member is set larger in the center part than in both end parts,
A method of forming the roller member force 5 as a whole to have a crown shape.

(b) A method of providing regulating members such as flanges at both ends of a roller member that holds an endless belt member.

(c) providing a sprocket at the end of the roller member;
A method of providing perforations at the same pitch as the pitch between the pawls of the sprocket at a portion of the endless belt member corresponding to the pawls of the tin rocket.

(d) A method in which a guide groove is provided in each roller member, and a yA guide rib is provided at a portion on the inner peripheral side of the endless belt member corresponding to the guide groove.

The four methods described above are all already known techniques, and are also disclosed in Japanese Patent Publication No. 17955/1983 and Japanese Patent Publication No. 17955/1983.
As published in Publication No. 2-12124, etc.,
There is also a method using a combination of the above-mentioned known techniques.

By the way, all of the above-mentioned methods have the following drawbacks. That is, the method explained in (a) is the most widely used correction method, but it is possible to correct the problem by making the roller member into a crown shape to distort the endless belt member and create an internal stress difference. In order to suppress the belt from shifting, it is necessary to use a belt made of a material with sufficient elasticity. Moreover, since the so-called permanent deformation of the belt member due to creep strain is prevented while utilizing the strain generated in the belt member,
For example, when using a rubber belt, as mentioned above, it is necessary to use a material with low rubber hardness and high elasticity, and its wall thickness must also be set to satisfy mechanical strength. . Therefore, the method described in (a) above is not suitable for use with photoreceptor belts, intermediate transfer belts, etc., as the image will be deformed due to distortion on the belt surface. In order to use this method, the thickness of the conveyor belt must be increased, so the transfer current must be set large, which is also not appropriate. Since the end portion on the side in the direction of movement is constantly subjected to thrust force, the end portion on the side in the moving direction of the belt member is likely to be deformed or destroyed, making it difficult to ensure stable operation over a long period of time. Such a problem can be solved by Japanese Patent Publication No. 57-60347 2, which is similar to the method related to (b) above.
The same problem may occur in proposals related to Publication No. 156544 and the like. The method described in (c), like the method described in (b) above, requires strength, especially tearing strength, in the belt member, and furthermore, the pitch accuracy of the sprocket and perforations depends on the movement of the belt member. Since this will greatly affect the accuracy of speed control, it should not be used for photoreceptor belts, intermediate transfer belts, and transfer material conveyance belts that require highly accurate movement speed control for transfers, including the formation of m* and visible images. The method explained in (d) suppresses the belt member from shifting by receiving the thrust force generated in the belt member at the end surface of the guide rib. The accuracy of the provided guide ribs will determine the accuracy of the movement speed control of the belt member. However, it is technically very difficult to attach the guide ribs to the inner circumferential side of the belt member with high mounting accuracy, so this is not suitable for mass production.

Therefore, in order to eliminate the various problems mentioned above in the above four types of methods, (e) at least tm of the plurality of roller members holding the endless belt member is
With respect to the roller member, a method in which the central axis of rotation of the roller member can be set at any angle with respect to the moving direction of the endless belt member.

was proposed. The method described in (E) above is particularly effective for belt members made of materials with a low dominant quality, and has the advantage of not being affected by the wall thickness of the belt member. A means for detecting this and a means for moving the rotation center axis of the roll member in response to an output signal from the means are required. Methods for detecting deviation of a belt member include (a) a method of detecting the end face of the belt member in the moving direction, and (b) a method of detecting an object to be detected along the entire circumference of the belt member. (C) A method of providing a pattern as a detection target over the entire circumference of the belt member; (d) A method of providing one or more 59 marks on the outer circumference of the belt member, etc. However, none of the methods described in (a) to (d) above.

There were some drawbacks as detailed below. That is.

The method explained in (a) is based on the premise that the straightness of the side end face in the moving direction of the belt member is guaranteed. The method explained in (b), which is technically difficult to create and process and is therefore impractical, requires highly accurate α-linearity for the line to be detected; It is technically difficult to provide the detection target line on the outer peripheral surface of the belt member while ensuring accurate straightness. Regarding the method explained in (C), it is still not easy to arrange the patterns on the outer circumferential side of the belt member while maintaining high precision straightness, so the method explained in (C) was not actually adopted. JP-A-54-24029, JP-A-54-117620
The above problem has not been resolved even in the proposals related to the Publication No.

Among the methods explained in (d), in the method in which one reference mark is provided on the outer circumferential side of the belt member, one
Since the reference mark can only be detected once during each rotation, the detection is intermittent, making it impossible to detect or correct deviation of the belt member with high precision.
In cases where multiple reference marks are provided on the outer circumferential side of the belt member, it is possible to determine whether or not deviation of the belt member occurs in a shorter period compared to one in which only one 2nd and semi-standard mark is provided. Although it is possible to detect whether
As in method C), it is difficult and impractical to arrange a plurality of reference marks on the outer circumferential side of the belt member while maintaining straightness and positional spacing between each reference mark with high precision. Therefore, although the method according to (e) above is capable of correcting malfunctions such as lopsided meandering of the belt member without causing a load on the belt member, This method has not been adopted in image forming apparatuses because there is no suitable means for continuously and highly accurately detecting whether or not such a problem has occurred.

Therefore, the present invention was devised in view of the above, and its purpose is to provide an image bearing means such as a photoreceptor, etc.
1J1 Suitable for continuously and highly accurately detecting whether or not the belt member has shifted or meandered in an image forming apparatus that uses endless belt members for the transfer means and the transfer material conveyance means. To provide an image forming station having a structure capable of correcting incompatibilities such as deviation and meandering occurring in an endless belt member without imposing a load on the endless belt member by providing a means for the same. It is.

] - The image forming apparatus according to the present invention provides 1! will be accomplished. In summary, the present invention extends from latent image formation to visible image formation! ! An image holding means for carrying out an image forming process; an intermediate transfer means for transferring the visible image formed on the image holding means; and a transfer material for transferring the visible image from the intermediate transfer means. In the image forming apparatus, each of the means is movable by a plurality of rotatable belt holding mechanisms arranged at a predetermined distance apart, and the belt holding mechanism. and an endless belt member held at P! a plurality of mark detection means for detecting the mark along a transverse direction with respect to the moving direction of the endless belt member, and the relative position l of the belt holding mechanism is determined based on an output signal from the mark detection means. This is an image type L&S device characterized by being provided with a variable adjustment means for variably adjusting.

Below, one embodiment of the present invention will be explained with reference to the drawings.
As is clear from the above description, in the image forming apparatus according to the present invention, all of the image 11 holding means, the intermediate transfer means, and the transfer material conveying means included in the apparatus are shown in FIG. It has a structure including a belt holding mechanism as shown and an endless belt member. The image carrying means is one in which an image forming process from layer image formation to visible image formation is executed;
The intermediate transfer means is for receiving the transfer of the visible image formed on the image bearing means, and the transfer material conveying means is for conveying the transfer material for receiving the transfer of the visible image on the intermediate transfer means. It is. Since the functions of each of the above means are already well known, detailed explanation thereof will be omitted. In FIG. 1, the main body of the image forming apparatus (
A belt holding mechanism, that is, a drive roller 4, a driven roller 7, a tension roller 5, and a supplementary roller 4, which individually constitute an image bearing means, an intermediate transfer means, and a transfer material conveyance means, are placed in an appropriate space area within the space (not shown). 7EO-roller 6, and an endless belt member, ie, belt l, which is wound around each of the rollers and moves in the direction of the thick arrow in FIG. 1. Each of the rollers described above is rotatably supported, and the driving roller 4 and the driven roller 7 are placed in a coordinating relationship and are both fixed at a predetermined position. The rotation shaft of the drive roller 4 has
A drive motor 8 is connected to drive the drive roller 4 to rotate in the direction of arrow B in FIG. The correction roller 6 is provided below the driven roller 7 in FIG. The correction roller 6 corrects defects such as deviation and meandering that occur in the belt 1. One end of the rotation shaft of the correction roller 6 is supported by a Biboft bearing 12, and the other end is supported by a bearing 9. There is. Bearing 9 is 1111
It is connected to a rod 11 coaxial with the rotation axis of an actuator 100 serving as a variable adjustment means, and the actuator 10.
FIG. 1A- with the correction roller 6 by the rod 11
It is configured to be rotatable in the A' direction. That is, the correction roller 6 is connected to the rod 11. The actuator 10 is operated via the bearing 9 so that the other end (i.e., the bearing 9 side) of the bipot 7 is moved in the direction of the arrow A in FIG.
-A' direction, so that the center axis of rotation of the correction roller 6 can form an arbitrary angle with the original position of the correction roller 6 along the moving direction of the bell (1). In this embodiment, a linear stepping motor is used as the IfiI actuator 10, and the rotation amount of the rotation center axis of the correction roller 6 is set as follows.
This can be easily done by varying the number of pulses of the drive command signal (pulse signal) that is output to the linear steering motor. For example, if the correction roller 6 is rotated from arrow C to arrow C' as shown in FIG. Unlike when the correction roller 6 is in the state shown by the broken line in the figure 8) Principle MC (the state shown by the solid line in Fig. When the winding position shifts from the state shown by the solid line in FIG. 4 to the state shown by the broken line in FIG. Therefore, in one embodiment according to the present invention,
Using the above principle, by rotating the center axis of rotation of the correction roller 6, a force that causes deviation in the same magnitude and in the opposite direction as the force that causes deviation generated in the bell (l) is generated. In this embodiment, on the outer circumferential side of the belt 1, there is a groove in the direction of movement of the belt 1. - side bell) 1 circumference approximately 2
Labels, ie, marks a2 and marks b3, are provided at equally divided positions, respectively. The mark a2 and mark b3 are selected to have different aspects (shapes, colors, etc.) so that they can be distinguished from each other. In Fig. 1 of belt l, on the F side,
A mark reading device 130 is provided. The mark reading device 130 includes a plurality of mark detection means, that is, a CCD element 13 in which a plurality of light receiving elements are arranged in parallel;
Mark a formed on the outer peripheral surface of the heald 1 on the element 13
2. The lens 14 is fixed to the CCD element 13 in order to form an image of the mark b3. Read the mark! a n L 31) is CC
A plurality of light receiving elements of the D element 13 are attached and fixed to the main body of the image forming apparatus (not shown) so as to be arranged in parallel along the lateral direction with respect to the moving direction of the belt 1.

FIG. 2 shows the configuration of a CCD element 13 of a mark reading device included in an image forming apparatus according to an embodiment of the present invention. As is clear from Figure 2, 1 installed in parallel
It consists of one light receiving element a to k. Eleven light receiving elements a, b, c, d, which constitute the CCD element 13,
ef, g, h, i, j, marks a2 . When the mark b3 passes through the detection area of each of these light-receiving elements, and the light beam incident on the light-receiving element whose detection area the mark has passed through changes temporarily, this causes the electrical signal output from the light-receiving element to also change. It is temporarily variable.

In the above-mentioned configuration, if the belt 1 does not shift and interlock, each time the belt 1 makes one revolution, the mark a , b3 is detected. An electric signal indicating that the belt 1 is shifted is output.
Each time the belt 1 makes one revolution, the marks a2. An electrical signal indicating that b3 has been detected will be output. Incidentally, the biasing speed of the belt l is determined by the pitch cap on the light receiving element a-, which constitutes the CCD element 13, and the mark a2. A belt that can be determined by the magnification of the lens 14 that focuses the image of b3 on each light receiving element of the CCD element 13! It can be determined by the amount of deviation of the belt l and the time required for the belt l to make one revolution.

) 1-h mark a2. Since two marks, mark b3, are provided, two memories are provided in the control system as shown in diagram t53 in order to individually store detection information for each of these marks.

FIG. 3 shows the configuration of a control system included in an image forming apparatus according to an embodiment of the present invention.0 A control system included in an image forming apparatus according to an embodiment of the present invention is The CCD element 13 clearly described with reference to FIG.
, a comparison calculation circuit 20 as an identification means, a yI'li processing means and a variable IR processing means, and a storage means, that is, a memory A.
21, memory B22, driver 23, and actuator 10 are shown on the right. The driver 23 is for driving the actuator 10, and is adapted to drive the actuator 10 based on a drive command signal output from the comparison calculation circuit 20. Memory A21 has mark a2 formed on bell) IJ:
It has been established in response to the The memory A21 stores a predetermined value when one of the light receiving elements constituting the CCDJ element 13 detects the mark a2 due to the movement of the belt 1. When mark a2 detection information is given from the comparison calculation circuit 20 due to the output of the tts signal, the mark a2 detection information is stored until new mark a2 detection information is given from the comparison calculation circuit 20. , # detection information is held.

Memory B22 is formed on bell)lh and mark b
3.

The memory B22 stores any of the light receiving elements constituting the COD element 13 by the movement of the belt 1.
3 is detected and a predetermined electric signal is output, when the mark b3 detection information is given from the comparison calculation circuit 20, the mark b3 detection information is stored, and the mark b3 detection information is 'fR'. The detection information is held until it is provided from the comparison M calculation circuit 20. The comparison calculation circuit 20 reads the electrical signal output from the CCD element 13, identifies whether the electrical signal is related to the detection of the mark a2 or the mark b3, and determines whether the electrical signal is related to the detection of the mark a2 or the mark b3. It is determined from which light-receiving element the output is from. The comparison calculation circuit 20 stores the mark detection information in the memory A21 based on the result of the identification.
Alternatively, it is output to memory B22. Comparison wave 1@path 20 has already been stored in memory A21 or memory B22.
The deviation amount and deviation speed of belt l are calculated based on the mark a2 (or mark b3) detection information stored in It is configured to output a drive command signal to the driver 23 in order to eliminate the line deviation based on the deviation amount 1 deviation speed.

Next, the operation of the control system having the above-mentioned configuration will be explained with reference to FIGS. 2 and 3. The following description of the belt deviation correction operation will be made on the assumption that the belt 1 is driven normally without deviation until the (m-1)th rotation, and that deviation occurs in the second (m)th rotation. That's it. When mark &2 passes under the CCDJ element 13 due to the movement of heald 1 (second
(See Figure A) 4 This changes the value of the electrical signal output from the light receiving element. The change in the electric signal value output from the light receiving element is read by the comparison calculation circuit 20, and the comparison @ calculation circuit 20 stores the mark a2 detection information indicating that the output signal from the light receiving element has changed by η1 into the memory A2.
Store it in 1. Belt 1 moves half a turn and reaches mark b3
When passes through one side of CCD element TF13 (Fig. 2-
(see B), thereby varying the value of the electrical signal output from the light receiving element g. 'ra output from light receiving element g
The change in the signal value is read by the comparison yII'lt circuit 20, and the comparison calculation circuit 20 stores in the memory E22 mark b3 detection information indicating that the output signal from the light receiving element g has changed. When the mark a2 passes under the CCD element 13 again (after the bell) 1 moves for another half turn (that is, the bell l moves for one turn) (see Fig. 2-C).
, whereby the values of the electrical signals output from the light receiving elements j, j are varied. The changes in the electric signal values output from the light-receiving elements I and j are read by the comparison calculation circuit 20, and the comparison calculation circuit 20 detects Markcro 2 detection information indicating that the output signals from the light-reception elements j and j have changed. is stored in the memory A21. At the same time, the mark mark 2 detection information read out from the memory A21 before the belt 1 moves one revolution (see FIG. 2-A) is compared with the mi mark a2 detection information to be newly stored in the memory A21, and the belt 1 is 1
In this case, it is recognized that the light-receiving element is offset by the amount of four IS.

The comparison calculation circuit 20 calculates the deviation amount of ly2 light receiving elements generated on the belt 1 from the electric signal output from the light receiving elements 1 and j from the time when the electric signal value output from the light receiving element changes. The deviation speed of the belt l is obtained by dividing by the elapsed time until the value changes, and a drive command signal is output to the driver 23 based on the obtained deviation speed of the belt l, and the actuator IO is activated. drive

Then, by driving the actuator 10, the correction roller 6 is moved by rmA, and the deviation of the belt 1 is canceled. When the belt 1 further moves outward by half a circumference (that is, the belt 1 moves one circumference) and the mark b3 passes below the CCD element 13 (see D# in FIG. 2), this causes the light receiving element to As a result, the values of the electrical signals output from I vary. The variable electrical signal values output from the light receiving elements ri, i are read by the comparison calculation circuit 20, and the comparison calculation circuit 20
Mark b3 detection information indicating that the output signal from I has changed is stored in the memory E22. At the same time, memory B22
Mark b before belt l moves one revolution read from
3 detection information (see Figure 2-B) and new memory B22.
Compare the mark b3 detection information to be stored in
(bell) It is recognized that an offset of two ly has occurred in l with two light receiving elements. Thereafter, through a routine similar to that described above, the actuator 10 is driven to move the correction roller 6, thereby canceling the deviation of the belt 1. When the belt 1 further moves out half a circle (that is, the belt l moves two revolutions) and the mark a2 passes under the CCD element 13 again, it is stored in the memory A21 as the mark mark 2 detection information as described above. At the same time, it is compared with the mark a2 detected t,'# signal stored in the memory a21 before the belt l moves one revolution (see Fig. 2, 9-C), and the above-mentioned correction operation is performed. Supplement 1: The operation is based on the mark a2 detection information stored in the memory A21 until just before, the mark b3 detection information stored in the memory B22, and the new CCD element. -13
Compare the mark a2 detection information and the mark b3 detection information obtained from 1j- respectively until the light-receiving elements that detect the same mark match between the new and old information.
be controlled.

In the embodiment described above, two marks are provided on the belt 1, and two memories are provided to store mark detection information in correspondence with these two marks. The number of marks and memories that go back in one go is F
The number M is preferably set according to the circumferential length of the belt used for the image bearing means, the intermediate transfer means, and the transfer material conveyance means, respectively.6 In one embodiment according to the present invention, It is not necessary to arrange the plurality of marks on the belt while maintaining the straightness with high precision along the moving direction of the belt, but it is necessary to arrange the marks so as to fit within the detection area of each light receiving element constituting the CCD element. In addition, the mark may be provided on either the outer circumferential surface or the inner circumferential surface of the belt, but when it is provided on the outer circumferential surface of the belt as in the present embodiment, the image formation It is necessary to set the memory at the end of the horizontal direction with respect to the moving direction of the bell so as not to interfere with It is also possible to provide one memory having enough marks to store mark detection information corresponding to the number of marks installed.

As explained above, according to the present invention, in image formation '1A21 in which endless belt members are used for the image bearing means, the intermediate transfer means, and the transfer material conveying means, the belt member is By providing means suitable for continuously and highly accurately detecting whether or not deviation or meandering has occurred, deviation or meandering that occurs in the endless belt member can be detected without imposing a load on the endless belt member. Image formation with a configuration that can correct defects such as meandering? t'11 can be provided.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a belt holding mechanism and an endless belt member that are provided as an image bearing means, an intermediate transfer means, and a transfer material conveying means, respectively, in an image forming apparatus according to an embodiment of the present invention. be. Figure 2 is. Mark reading included in the image forming apparatus according to an embodiment of the present invention? FIG. FIG. 3 is a block diagram showing the configuration of a control system included in an image forming apparatus according to an embodiment of the present invention.8 FIG. FIG. 3 is an explanatory diagram of the principle when correcting the offset of the image. Mark b: Drive roller: Tension loaf: Correction roller: Driven roller: 7 cutter: Comparison calculation circuit: Memory A Memory B Mark reading bag and

Claims (1)

[Scope of Claims] 1) An image bearing means for performing an image forming process from latent image formation to visible image formation, and intermediate transfer means for transferring the visible image formed on the image bearing means; An image forming apparatus comprising a transfer material conveying means for conveying a transfer material that receives the transfer of the visible image on the intermediate transfer means,
Each of the means includes a plurality of rotatable belt holding mechanisms arranged at a predetermined distance apart, and an endless belt member movably held by the belt holding mechanism, and A mark is provided on the endless belt member, and a plurality of mark detection means are provided for detecting the mark along a transverse direction with respect to a moving direction of the endless belt member,
An image forming apparatus comprising: a variable adjustment means for variably adjusting the relative position of the belt holding mechanism based on an output signal from the label detection means. 2) an image bearing means for performing an image formation process from latent image formation to visible image formation; an intermediate transfer means for receiving the transfer of the visible image formed on the image bearing means; An image forming apparatus comprising a transfer material conveying means for conveying a transfer material to which a visible image is transferred,
Each of the means includes a plurality of rotatable belt holding mechanisms arranged at a predetermined distance apart, and an endless belt member movably held by the belt holding mechanism, and A plurality of markers are provided on the endless belt member at equal intervals along the moving direction of the endless belt member, and a plurality of marker detecting means are provided for detecting the markers along a transverse direction with respect to the moving direction of the endless belt member. further comprising an identification means for identifying a mark detected by the mark detection means from among the plurality of marks provided on the endless belt member based on output signals from each of the mark detection means, and output from the identification means. A storage means is provided for storing individual sign detection data for each sign, and a signal newly output from the sign detection means is compared with sign identification data stored in the storage means corresponding to the signal. and a calculation processing means for determining the degree of deviation of the endless belt member, and a variable adjustment means for variably adjusting the relative position of the belt holding mechanism based on an output signal from the calculation processing means. image forming apparatus.