JP2004309799A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prolong the life of a detecting means of detecting a reference member which is arranged on an intermediate transfer body and on which image formation timing is based. <P>SOLUTION: The image forming apparatus is equipped with a photoreceptor 1, an intermediate transfer belt 2, a reference mark detecting means 36, and an apparatus control part 101. The apparatus control part 101 turns OFF the reference mark detecting means 36 during image formation in monochromatic image continuous formation. Further, when a monochromatic image is formed while held between a color image and a monochromatic image to form the color image and monochromatic image together, an image formation timing is generated in response to reference mark detection by the reference mark detecting means 36. In image formation in monochromatic image continuous formation, the reference mark detecting means 36 is turned OFF and after the image formation, the reference mark detecting means 36 is turned ON; and the intermediate transfer belt 2 is stopped at a specified position in response to the reference mark detection. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laser beam type image forming apparatus such as a printer or a copying machine that forms an electrostatic latent image on a photoconductor by irradiating the photoconductor with laser light, and in particular, is disposed in contact with the photoconductor. The present invention relates to an image forming apparatus that obtains a color image by transferring a plurality of toner images on an intermediate transfer member and transferring the toner images to a recording medium.
[0002]
[Prior art]
Conventionally, an electrostatic latent image is formed on a photoconductor by irradiating a laser beam to the photoconductor, and then the electrostatic latent image on the photoconductor is developed with toner, and the toner image on the photoconductor is transferred to an intermediate transfer member. 2. Description of the Related Art An image forming apparatus that obtains a color image by transferring a toner image on an intermediate transfer body to a recording medium is known. The configuration and operation of a conventional image forming apparatus will be described with reference to FIGS.
[0003]
FIG. 8 is a configuration diagram showing an internal structure of an image forming apparatus according to a conventional example. The image forming apparatus is configured as a full-color printer including an intermediate transfer body (intermediate transfer belt).
[0004]
In FIG. 8, a photosensitive drum (hereinafter simply referred to as "photosensitive member") 1 is provided inside the image forming apparatus so as to be rotatable in the direction of arrow A in the figure by a motor (not shown). As described later, an electrostatic latent image is formed on the surface of the photoconductor 1 by exposure, and a toner image is formed by attaching toner to the electrostatic latent image by development. Here, as the photoreceptor 1, a photoreceptor using amorphous silicon as a photosensitive material is taken as an example. Around the photoconductor 1, an intermediate transfer belt 2, a primary charger 7, an exposure device 8, a transfer charger (first transfer means) 10, a cleaner device 12, and a developing device 513 are arranged.
[0005]
The primary charger 7 uniformly negatively charges the surface of the photoconductor 1. The exposure device 8 includes a laser scanner, and performs exposure by irradiating the surface of the photoconductor 1 with a laser beam to form an electrostatic latent image on the surface of the photoconductor 1. The transfer charger 10 primarily transfers the toner image formed on the photoconductor 1 to the intermediate transfer belt 2. The cleaner device 12 cleans toner remaining on the surface of the photoconductor 1.
[0006]
The developing device 513 is configured as a rotary developing device including three color developing devices (developing rollers) 513Y, 513M, 513C and a black developing device (developing roller) 513K for performing full-color development. The color developing devices 513Y, 513M, 513C and the black developing device 513K convert the electrostatic latent images formed on the photoconductor 1 into Y (yellow), M (magenta), C (cyan), and K (black), respectively. Develop with the toner of When developing each color of Y, M, C, and K, the developing device 513 is rotated in the direction of arrow R in the figure by a motor (not shown), and the developing device for the color is positioned so as to contact the photoconductor 1. I do.
[0007]
The toner images of each color developed on the photoreceptor 1 are sequentially primary-transferred to an intermediate transfer belt 2 as an intermediate transfer body by a transfer charger 10, so that four color toner images are formed on the intermediate transfer belt 2. Superimposed. The intermediate transfer belt 2, which is an intermediate transfer member, is an endless belt that is wound around rollers 17, 18, 19, and 20 and is driven to circulate. The intermediate transfer belt 2 has a length enough to form (transfer) two images, for example, and is driven to rotate in the direction of the arrow in the figure.
[0008]
Of the rollers 17 to 20 around which the intermediate transfer belt 2 is stretched, the roller 17 has a shaft connected to a drive source (not shown) to function as a drive roller for driving the intermediate transfer belt 2. The roller 19 functions as a tension roller for adjusting the tension of the intermediate transfer belt 2, and the roller 19 functions as a backup roller for the transfer roller 21 as a secondary transfer unit. Between the backup roller 19 and the tension roller 20, a reference mark detecting means 36 for detecting a reference position of an image forming timing on the intermediate transfer belt 2 is arranged.
[0009]
The belt cleaner 22 is provided at a position facing the roller 17 with the intermediate transfer belt 2 interposed therebetween, and scrapes residual toner on the intermediate transfer belt 2 with a blade. The transfer roller 21 is provided at a position facing the roller 19 with the intermediate transfer belt 2 interposed therebetween, and secondary-transfers the toner image on the intermediate transfer belt 2 onto a recording medium. The fixing device 5 is provided on the downstream side of the transfer roller 21 and thermally fixes the toner image on the recording medium secondary-transferred by the transfer roller 21. The recording medium cassette 23 can store a plurality of recording media. A pickup roller 24 is provided at a recording medium feed-out opening of the recording medium cassette 23, and a pair of conveyance rollers 25 and 26 are provided on a recording medium conveyance path.
[0010]
The recording medium fed out of the recording medium cassette 23 to the transport path by the pickup roller 24 is fed by a pair of transport rollers 25 and 26 to a contact portion (nip portion) between the transfer roller 21 and the intermediate transfer belt 2. . The toner image formed on the intermediate transfer belt 2 is secondarily transferred onto the recording medium at the nip. Further, after the toner image on the recording medium is thermally fixed by the fixing device 5, the recording medium is discharged to a discharge tray (not shown) outside the image forming apparatus (in the direction of the arrow in the figure).
[0011]
In the color image forming apparatus having the above configuration, a color image is formed on a recording medium by the following steps. First, by applying a voltage to the primary charger 7, the surface of the photoconductor 1 is uniformly negatively charged to a predetermined (predetermined) potential of the charging section. Subsequently, the electrostatic latent image is formed on the surface of the photoconductor 1 by performing exposure using an exposure device 8 including a laser scanner so that the charged image portion on the photoconductor 1 has a predetermined exposure portion potential. Form. The exposure device 8 forms an electrostatic latent image corresponding to an image on the surface of the photoconductor 1 by being turned on and off based on an image signal output from a control unit (not shown).
[0012]
A developing bias set in advance for each color is applied to the developing rollers as the color developing devices 513Y, 513M, 513C and the black developing device 513K constituting the developing device 513, and the electrostatic latent on the photoconductor 1 is set. The image is developed with toner when passing through the position of the developing roller, and is visualized as a toner image. The visualized toner image is primary-transferred to the intermediate transfer belt 2 by the transfer charger 10, secondarily transferred to a recording medium by the transfer roller 21, and then sent to the fixing device 5. When a full-color image is formed, toners of four colors (Y, M, C, and K) are superposed on the intermediate transfer belt 2 and then transferred to a recording medium.
[0013]
The toner remaining on the photoconductor 1 is adjusted by a preliminary cleaning device (not shown) so that the residual toner is easily cleaned, and then removed and collected by the cleaner device 12. Finally, the photoreceptor 1 is uniformly discharged to around 0 volts by a discharger (not shown) to prepare for the next image forming cycle.
[0014]
The image forming timing in the color image forming apparatus is controlled based on a predetermined position (reference position) on the intermediate transfer belt 2. As described above, the intermediate transfer belt 2 is stretched around rollers including the drive roller 17, the tension rollers 18 and 20, and the backup roller 19, and a predetermined tension is given by the tension rollers 18 and 20.
[0015]
As described above, the reference between the backup roller 19 and the tension roller 20 is a light transmission type or light reflection type optical sensor for optically detecting the reference position of the image forming timing on the intermediate transfer belt 2. A mark detecting means 36 is provided. The reference mark detection means 36 outputs a reference mark detection signal by detecting a reference mark 41 (see FIG. 9) such as a reflective tape which is attached to the inner peripheral surface of the intermediate transfer belt 2 in advance.
[0016]
FIG. 9 shows the positional relationship between the intermediate transfer belt 2, the driving roller 17, the tension rollers 18 and 20, the rollers including the backup roller 19, the reference mark 41, and the reference mark detection means 36 in the image forming apparatus shown in FIG. It is the perspective view shown roughly.
[0017]
In FIG. 9, the reference mark 41 is previously attached to the inner peripheral surface of the intermediate transfer belt 2 and serves as a reference position for image forming timing. The reference mark detection means 36 is disposed inside the intermediate transfer belt 2 and between the backup roller 19 and the tension roller 20, and optically detects the reference mark 41 attached to the inner peripheral surface of the intermediate transfer belt 2. And outputs a reference mark detection signal.
[0018]
FIG. 10 is a timing chart showing the color image forming timing when one color image is obtained in the image forming apparatus shown in FIG.
[0019]
As described above, the intermediate transfer belt 2 is long enough to form (transfer) two images, and the reference mark detection unit 36 determines the timing of the image formation timing attached to the inner peripheral surface of the intermediate transfer belt 2. A reference mark 41 serving as a reference position is detected. The output timing of the reference mark detection signal accompanying the detection of the reference mark 41 by the reference mark detection means 36 is set as the exposure timing of the exposure device 8, and the formation of a color image is started.
[0020]
The example shown in FIG. 10 shows the image forming timing for forming one color image on the intermediate transfer belt 2 using the reference mark detection signal. In the drawing, the range indicated by the uppermost arrow is one cycle length, which is a length corresponding to one rotation of the intermediate transfer belt 2.
[0021]
In FIG. 10, first, the pre-rotation is performed until the intermediate transfer belt 2 performs a steady rotation at a predetermined stable speed, and when the intermediate transfer belt 2 is in the steady rotation, a reference mark is detected by the reference mark detection means 36. Then, a yellow video signal, which is the first color toner, is output, and the photoconductor 1 is exposed by the exposure device 8 to form a yellow toner image on the photoconductor 1. Before the yellow toner image formed on the photoconductor 1 reaches a position facing the transfer charger (first transfer unit) 10, the transfer charger 10 turns on the primary transfer bias, and Is transferred onto the intermediate transfer belt 2.
[0022]
The intermediate transfer belt 2 continues to rotate while holding the yellow toner image. In the same sequence as the above-described case of forming the yellow toner image, the magenta toner image is used, and then the cyan toner image is used. The toner image of each color on the photoreceptor 1 is transferred onto the intermediate transfer belt 2 by the transfer charger 10 and superposed thereon. Finally, a black toner image is formed on the photoconductor 1, and the black toner image on the photoconductor 1 is transferred to another three-color toner image on the intermediate transfer belt 2 by the transfer charger 10. As a result, a full-color toner image is formed on the intermediate transfer belt 2.
[0023]
The toner image on the intermediate transfer belt 2 is transferred from a recording medium cassette 23 by a pickup roller 24 and conveyed by a pair of conveying rollers 25 and 26, and at the same time as a position facing the transfer roller (second transfer means) 21. Is controlled to reach. Before the toner image on the intermediate transfer belt 2 and the recording medium reach a position facing the transfer roller 21, the secondary transfer bias of the transfer roller 21 is turned on. Thus, the toner image on the intermediate transfer belt 2 is transferred to the recording medium. By passing this recording medium through the fixing device 5, the toner image on the recording medium is fixed to the recording medium by heat, and a full-color image is obtained.
[0024]
However, when a monochrome monochrome image is formed, there is no need to superpose a single color toner on the intermediate transfer belt 2 as disclosed in the conventional proposal “electrophotographic apparatus”. It is possible to generate an image formation timing and to form an image irrespective of the timing (for example, see Patent Document 1). For this reason, in the formation of a monochrome monochrome image, while the reference mark is detected by the reference mark detecting means 36, the image is formed independently of the detection of the reference mark, that is, regardless of the position of the intermediate transfer belt 2. .
[0025]
FIG. 11 is a timing chart showing an image forming timing when a color image and a monochromatic image are mixed and image-formed and output in the image forming apparatus shown in FIG.
[0026]
In FIG. 11, the image forming timing when the first image is a color image, the second image and the third image are monochrome monochrome images, and the fourth image is a color image are shown. When forming the second and third monochrome monochromatic images, the image is formed ignoring the reference mark detection signal, as disclosed in the above-mentioned conventional proposal "electrophotographic apparatus". When forming the fourth color image, the reference mark detection signal output from the reference mark detection means 36 after the formation of the monochrome monochrome image is used as the image formation timing.
[0027]
[Patent Document 1]
Patent No. 3269093
[0028]
[Problems to be solved by the invention]
However, in the above-described conventional image forming apparatus, even when a monochrome monochrome image is formed (although image formation is performed irrespective of detection of the reference mark on the intermediate transfer belt), the reference mark detection operation by the reference mark detection unit is performed. Is a state that is always performed. In particular, even when a user who overwhelmingly prints a plurality of black-and-white single-color images in succession uses the image forming apparatus, for example, when wrinkles occur on the intermediate transfer belt as described later, image forming is performed. In order to obtain a reference mark detection signal serving as a reference, it is necessary to operate a reference mark detection means comprising a light transmission type or light reflection type optical sensor. However, there is a problem that the optical sensor as the reference mark detecting means has a lifetime, and the lifetime is shortened in accordance with the energizing time to the optical sensor.
[0029]
Further, if the operation of simply not detecting the reference mark by the reference mark detection means at the time of forming a monochrome monochrome image is performed, when a color image and a monochrome monochrome image are mixed and formed and output, the monochrome monochrome image is output. When the color image is formed independently of the reference mark detection, a part of the monochrome monochrome image is formed at the position where the color image is originally formed, and the color image is continuously formed at a predetermined timing from the reference mark detection time. A problem that it cannot be formed. In addition, since the image is formed while ignoring the reference mark, as shown in FIG. 11, it is necessary to form the color image after waiting for the next input reference mark detection signal, and the formation of the color image is delayed. There is a problem.
[0030]
Also, when forming a monochrome monochrome image, rotating the intermediate transfer body without detecting the reference mark and stopping the intermediate transfer body at an uncertain position, if the next image to be formed is a color image, Since the time for detecting the reference mark varies depending on the variation in the stop position of the intermediate transfer member, there is a problem that the time for forming the first color image becomes indefinite. Further, when the intermediate transfer member is in a belt shape (intermediate transfer belt), the intermediate transfer member is supported by a plurality of rollers. The portion of the intermediate transfer belt that is supported by the roller with a high applied tension causes the intermediate transfer belt to elongate, causing wrinkles. When a toner image is carried on the wrinkles, there is a problem that image density unevenness and color misregistration are caused. is there.
[0031]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of extending the life of a detection unit for detecting a reference member provided on an intermediate transfer member and serving as a reference for image forming timing.
[0032]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to claim 1, wherein a latent image is formed by exposing a photosensitive member, and the latent image is developed to form an image. In an image forming apparatus that forms an image by transferring an image on the intermediate transfer body to a recording medium after the image is transferred to a transfer body, a reference member serving as a reference for image formation timing disposed on the intermediate transfer body is used. It is characterized by comprising a detecting means for optically detecting, and a control means for stopping the operation of the detecting means during image formation when a single color image is continuously formed on a recording medium.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0034]
FIG. 2 is a configuration diagram illustrating an internal structure of the image forming apparatus according to the present embodiment. The image forming apparatus is configured as a full-color printer including an intermediate transfer body (intermediate transfer belt).
[0035]
2, the image forming apparatus includes a photoreceptor 1, an intermediate transfer belt 2, a fixing device 5, a primary charger 7, an exposure device 8, a transfer charger (first transfer unit) 10, a cleaner device 12, and a color developing device. 13, black developing device 14, drive roller 17, tension rollers 18, 20, backup roller 19, transfer roller (second transfer means) 21, recording medium cassette 23, pickup roller 24, transport roller pair 25, 26, reference mark detection Means 36 are provided. Around the photoconductor 1, an intermediate transfer belt 2, a primary charger 7, an exposure device 8, a color developing device 13, a black developing device 14, a transfer charger 10, and a cleaner device 12 are arranged. In addition, a cleaning charger is arranged at the preceding stage of the cleaner device 12, but is not shown.
[0036]
The image forming apparatus according to the present embodiment is different from the conventional image forming apparatus shown in FIG. 8 in the configuration of the developing device, and the configuration other than the developing device is the same. The description of the same parts other than the developing device is omitted. The developing device includes a color developing device 13 as a rotary developing device including three color developing devices 13Y, 13M, and 13C for full-color development, and a black developing device 14 fixed to always contact with the photoreceptor 1. It is composed of In the present embodiment, the black developing device 14 is configured as a fixed developing device, but may be configured as a rotary developing device as shown in FIG. 8 of the conventional example.
[0037]
The color developing device 13 (color developing devices 13Y, 13M, 13C) and the black developing device 14 develop the electrostatic latent images formed on the photoreceptor 1 with toners of respective colors of Y, M, C, and K, respectively. When developing each color of Y, M, and C, the color developing device 13 is rotated by a motor (not shown) in the direction of arrow R in the figure, and the developing device for the color is aligned so as to contact the photoconductor 1. . The black developing device 14 has a configuration in which the developing roller is always in contact with the photoconductor 1. When developing each color toner other than the black toner, the high voltage bias of the black developing device 14 is switched so that the black toner is not developed, and when developing the black toner, the high voltage bias of the black developing device 14 is switched so that the black toner is developed. Control is performed.
[0038]
FIG. 3 is a timing chart showing a color image forming timing when two color images are obtained in the present image forming apparatus.
[0039]
As the photoconductor 1 in the present embodiment, one using amorphous silicon as a photosensitive material will be described as an example. The intermediate transfer belt 2 is, for example, a circularly driven endless belt having a length that allows two images to be formed (transferred), and is attached to the inner peripheral surface of the intermediate transfer belt 2 by the reference mark detection unit 36. A reference mark 41 (referring to FIG. 6, a reference member) which is a reference position of the image forming timing (indicating the position of the intermediate transfer belt 2) is detected. The output time of the reference mark detection signal accompanying the detection of the reference mark 41 by the reference mark detection means 36 is set as the exposure timing of the exposure device 8, and the formation of a color image is started.
[0040]
The example shown in FIG. 3 shows the timing of forming two color images on the intermediate transfer belt 2 using the reference mark detection signal. In the drawing, the range indicated by the uppermost arrow is one cycle length, which is a length corresponding to one rotation of the intermediate transfer belt 2.
[0041]
In FIG. 3, first, the pre-rotation is performed until the intermediate transfer belt 2 rotates in a steady state at a predetermined stable speed, and when the intermediate transfer belt 2 is in the steady rotation, a reference mark is detected by the reference mark detection means 36. Then, a yellow video signal, which is the first color toner, is output, and the photoconductor 1 is exposed by the exposure device 8 to form a yellow toner image on the photoconductor 1. Before the yellow toner image formed on the photoconductor 1 reaches a position facing the transfer charger (first transfer unit) 10, the transfer charger 10 turns on the primary transfer bias, and Is transferred onto the intermediate transfer belt 2.
[0042]
The intermediate transfer belt 2 continues to rotate while holding the yellow toner image. In the same sequence as the above-described case of forming the yellow toner image, the magenta toner image is used, and then the cyan toner image is used. The toner image of each color on the photoreceptor 1 is transferred onto the intermediate transfer belt 2 by the transfer charger 10 and superposed thereon. Finally, a black toner image is formed on the photoconductor 1, and the black toner image on the photoconductor 1 is transferred to another three-color toner image on the intermediate transfer belt 2 by the transfer charger 10. As a result, a full-color toner image is formed on the intermediate transfer belt 2.
[0043]
The toner image on the intermediate transfer belt 2 is transferred from a recording medium cassette 23 by a pickup roller 24 and conveyed by a pair of conveying rollers 25 and 26, and at the same time as a position facing the transfer roller (second transfer means) 21. Is controlled to reach. Before the toner image on the intermediate transfer belt 2 and the recording medium reach a position facing the transfer roller 21, the secondary transfer bias of the transfer roller 21 is turned on. Thus, the toner image on the intermediate transfer belt 2 is transferred to the recording medium. By passing the recording medium through the fixing device 5, the toner image on the recording medium is fixed to the recording medium by heat, and a full-color image is obtained.
[0044]
FIG. 1 is a block diagram showing the configuration of a main part of the image forming apparatus, and best illustrates the features of the present embodiment.
[0045]
In FIG. 1, the image forming apparatus includes a photosensitive member 1, an intermediate transfer belt 2 (intermediate transfer member), an exposing device 8, a reference mark detecting unit 36 (detecting unit), an apparatus control unit 101 (control unit), and an image forming unit 102. It has. In the figure, reference numeral 103 denotes an image output device. FIG. 1 shows components directly related to the present invention, and the illustration of the color developing device 13, the black developing device 14, etc. shown in FIG. 2 is omitted.
[0046]
The image output device 103 (external device) is configured as, for example, a computer that can communicate with the image forming apparatus. The image output device 103 holds image data for forming an image in the image forming apparatus, and performs processing such as outputting an image signal 109 to the image forming apparatus in response to the image request signal 108 transmitted from the image forming apparatus.
[0047]
In the image forming apparatus, an apparatus control unit 101 controls each unit of the image forming apparatus, and includes a selecting unit 105, an image forming timing start signal A generating unit 106, and an image forming timing start signal B generating unit 107. . The image forming unit 102 performs processing such as outputting an image request signal 108 to the image output device 103 according to the image forming timing signal 116 generated by the device control unit 101, and performs FIFO (First In First Out). ) A memory 104 is provided.
[0048]
The image signal 109 output from the image output device 103 is temporarily stored in the FIFO memory 104 provided inside the image forming unit 102 of the image forming apparatus. The FIFO memory 104 is a memory for outputting exposure image data 110 corresponding to the image forming speed of the image forming apparatus. The exposure image data 110 output from the FIFO memory 104 is input to the exposure device 8. The exposure image data 110 is converted into a laser beam 111 whose ON / OFF is controlled by the exposure device 8 in accordance with the exposure image data 110, and the laser beam 111 is applied to the photoconductor 1.
[0049]
The device control unit 101 generates an image forming timing signal 116. First, the apparatus control unit 101 determines whether the image output form executed by the image output apparatus 103 to the image forming apparatus is a color image output, a continuous output of a single-color image, or a combination of a color image and a single-color image. In each case of whether or not to output an image (overlapping), the color / color notifying the presence / absence of a monochromatic image formed between the color image and the monochromatic image output from the image output device 103 is output. A single color / color single color mixed information signal 115 is input.
[0050]
The apparatus control unit 101 determines the reference mark detecting unit based on the conditions of the color / monochrome / color / monochrome mixed information signal 115 (color image output, continuous output of single color image, or image output of mixed color image and single color image). The ON / OFF switching 113 for the G.36 is switched. When outputting a color image or an image in which a color image and a single color image are mixed, the device control unit 101 switches the reference mark detection unit 36 ON (operation) by switching the ON / OFF switch 113 ON. In the case of continuous output of only a single-color image, the ON / OFF switch 113 is turned OFF, so that the reference mark detecting means 36 is turned OFF (stopped) during image formation.
[0051]
The ON / OFF setting of the reference mark detecting means 36 is set based on the condition of the color / monochrome / color / monochrome mixed information signal 115 input from the image output device 103 to the image forming apparatus as described above (image forming apparatus Setting from the outside), a mode setting (manual setting) of turning the reference mark detecting means 36 into an ON mode or an OFF mode by an operation unit (not shown) of the image forming apparatus, or copying by the image forming apparatus. In the case of a machine, any of settings (automatic setting) according to the image data (color image data, single-color image data, or single-color mixed-color image data) of the document read by the document reading unit may be used.
[0052]
A reference mark detection signal 114 output in accordance with the detection of the reference mark 41 attached to the intermediate transfer belt 2 by the reference mark detection unit 36 is input to the image forming timing start signal A generation unit 106 of the apparatus control unit 101. . The image forming timing start signal A generating unit 106 is a block that generates an image forming timing signal using the reference mark detection signal 114 as a trigger. The image formation timing start signal B generation unit 107 is a block that generates an image formation timing signal regardless of the reference mark detection signal 114 when a monochrome image is continuously formed on a recording medium and output.
[0053]
Either the image formation timing signal output from the image formation timing start signal A generator 106 or the image formation timing start signal B generator 107 is selected by the selector 105. The basis for this selection is the condition of the color / monochrome / color / monochrome mixed information signal 115 described above. That is, the selection unit 105 selects the image formation timing signal from the image formation timing start signal A generation unit 106 when a color image is output or when a color image and a single color image are mixedly output. The image forming timing signal from the forming timing start signal B generating unit 107 is selected and output to the image forming unit 102 as the image forming timing signal 116.
[0054]
Here, the reason for turning off the reference mark detecting means 36 during image formation at the time of continuous output of only the single-color image described above is as follows. As the reference mark detecting means 36, a light reflection type sensor or a light transmission type sensor is used, but the light source of these light sensors mostly uses an LED. Since the LED has a feature that its life is shortened in accordance with the energization time, when the reference mark detection means 36 is operated when the reference mark detection is not necessary during the formation of a single color image, the life of the LED is shortened accordingly. turn into. Therefore, in the present embodiment, as a method of extending the life of the LED as much as possible, the reference mark detection unit 36 is turned off during image formation when only a single color image is continuously formed.
[0055]
However, when the monochrome image is formed on the recording medium and the image forming operation is completed, the reference mark detecting means 36 is turned on (operated), and the intermediate transfer belt 2 is driven to rotate until the reference mark detection signal 114 is obtained. When the reference mark detection signal 114 is obtained, the apparatus control section 101 uses the reference mark detection signal 114 as a trigger to rotate and stop the intermediate transfer belt 2 by a predetermined movement amount from that time. The predetermined moving amount (predetermined moving distance) at the time of completion of the image formation of the single color image is determined by the reference mark detection signal 114 as a trigger at the time of the completion of the image formation of the color image or the image formation in which the color image and the single color image are mixed. Is a movement amount that can be stopped at the same position as the position where the intermediate transfer belt 2 is rotationally driven and stopped by a predetermined movement amount.
[0056]
Further, in the present embodiment, as shown in FIG. 2, the intermediate transfer belt 2 is employed as an intermediate transfer body, and the intermediate transfer belt 2 includes a driving roller 17, tension rollers 18 and 20, and a backup roller 19. A predetermined tension is given to the rollers by tension rollers 18 and 20. Therefore, when the environmental temperature at which the image forming apparatus is installed is high and the stop state of the intermediate transfer belt 2 continues for a long time, the intermediate transfer belt 2 expands at a portion supported by a roller having a strong tension applied to the intermediate transfer belt 2. This causes wrinkles. In FIG. 2, the tension roller 18 corresponds to the roller having the strong tension.
[0057]
Therefore, in the present embodiment, when the reference mark detection signal 114 is obtained from the reference mark detection means 36, the apparatus control section 101 rotates and stops the intermediate transfer belt 2 using the reference mark detection signal 114 as a trigger. In this case, the tension roller 18 coincides with the position of the intermediate transfer belt 2 corresponding to between two toner images (between Y1 and Y2 or between Y2 and M1) formed on the intermediate transfer belt shown in FIG. In this manner, the intermediate transfer belt 2 is driven to rotate by a predetermined movement amount and stopped from the time when the reference mark is detected. That is, the apparatus control unit 101 controls the intermediate transfer belt 2 to stop so that the position of the wrinkle generated on the intermediate transfer belt 2 does not affect the image.
[0058]
Next, an image forming timing when a color image and a monochromatic image are mixed and output as an image, and there is a monochromatic image formed between the color image and the monochromatic image will be described.
[0059]
From the image output device 103, along with the information that the color image and the single-color image are mixed and image-formed and output, a single-color image formed between the color image and the single-color image is placed on a recording medium during image formation. When the information indicating whether or not the image is to be generated is input to the device control unit 101 of the image forming apparatus, the device control unit 101 determines whether the monochrome image formed between the color image and the monochrome image is formed even during the monochrome image formation. The reference mark on the intermediate transfer belt 2 is detected without turning off the reference mark detection unit 36. Further, the selection unit 105 in the device control unit 101 outputs the image formation timing signal input from the image formation timing start signal A generation unit 106 to the image formation unit 102 as an image formation timing signal 116.
[0060]
FIG. 4 is a timing chart showing the image forming timing when there is a single color image sandwiched between a single color image and a single color image when a color image and a single color image are mixed and output in the present image forming apparatus. FIG.
[0061]
In FIG. 4, in the illustrated example, after one color image is formed (first sheet), two monochrome monochrome images are formed (second and third sheets), and the fourth sheet forms a color image again. The image forming timing.
[0062]
At the image forming timing shown in FIG. 11 of the conventional example, since a single-color image is formed while ignoring the reference mark detection signal, the color is not changed until the next reference mark detection signal is obtained after the formation of the single-color image. The process cannot be shifted to the image forming process.
[0063]
On the other hand, at the image forming timing shown in FIG. 4 of the present embodiment, even with respect to a single-color image formed between a color image and a single-color image, the image is formed based on the reference mark detection signal at the same timing as the color image. To perform the formation, the monochrome image on the intermediate transfer belt 2 is formed at the same position as the formation position of the color image. At the image forming timing of the color image formed next to the monochrome image, it is not necessary to wait for the next reference mark detection signal, and the formation of the color image can be started.
[0064]
Next, the features of the control of the present embodiment described above will be described with reference to FIGS.
[0065]
FIG. 5 is a flowchart showing a process for continuously forming a single-color image in the image forming apparatus. FIG. 6 is a flowchart showing a process in which a color image and a single-color image are mixed and output. FIG. 7 is a flowchart showing a process for forming a single-color image when there is a single-color image, and FIG. 7 is a flowchart showing a process for stopping the intermediate transfer belt when forming a single-color image continuously. The processing shown in each flowchart is executed by the apparatus control unit 101 of the image forming apparatus based on a program.
[0066]
In FIG. 5, during the formation of a monochrome monochrome image on a recording medium continuously (step S1), the reference mark detecting means 36 is turned off (step S2).
[0067]
In FIG. 6, when a color image and a single-color image are mixedly formed on a recording medium to form an image, and when there is a single-color image sandwiched between the color image and the single-color image, a single-color image is formed (step S11). Then, the image forming timing is generated based on the detection of the reference mark by the reference mark detection means 36 (step S12).
[0068]
In FIG. 7, during the image formation when forming a single-color image continuously on the recording medium (step S21), the reference mark detecting means 36 is turned off (step S22). The mark detection means 36 is turned on (step S24), and the intermediate transfer belt 2 is stopped at a predetermined position based on the detection of the reference mark by the reference mark detection means 36 (step S25).
[0069]
2, the tension rollers 18 and 20 for applying tension to the intermediate transfer belt 2 are positioned at predetermined positions on the intermediate transfer belt 2. The intermediate transfer belt 2 is stopped in such a manner that the position of the wrinkle generated on the intermediate transfer belt 2 is a place where the image formation is not affected (in other words, the position of the wrinkle generated on the intermediate transfer belt 2).
[0070]
As described above, according to the present embodiment, in a color image forming apparatus provided with the intermediate transfer belt 2, particularly when only a monochrome monochrome image is continuously formed on a plurality of recording media, the intermediate Since the reference mark detecting means 36 (light transmission type or light reflection type optical sensor) for detecting the reference position of the image forming timing on the transfer belt 2 is turned off and not operated, the LED used as the light source of the reference mark detecting means 36 It is possible to reduce the energizing time, and as a result, it is possible to extend the life of the reference mark detecting means 36.
[0071]
Further, conventionally, when a monochrome monochrome image is simply formed on a recording medium, the operation is such that the reference mark is not detected by the reference mark detection means 36, so that the color image and the monochrome monochrome image are mixed and imaged. In the case of forming, when forming a monochrome monochrome image without relation to the detection of the reference mark, a part of the monochrome monochrome image is formed at the position where the color image is originally formed, and from the time of the reference mark detection However, in the present embodiment, when a color image and a monochrome monochrome image are mixedly formed to form an image, the color image and the monochrome image cannot be formed continuously. In the case of forming a single-color image in the case where there is a single-color image formed between the two, the image formation is performed based on a reference mark detection signal output from the reference mark detection means 36. By generating timing, it becomes possible to improve the productivity of the color image.
[0072]
Also, when forming a monochrome monochrome image, the intermediate transfer belt 2 is rotated to form an image without detecting the reference mark by the reference mark detecting means 36, and when the image formation is completed and the intermediate transfer belt 2 is stopped. The reference mark is detected by turning on the reference mark detection means 36, and the intermediate transfer belt 2 is always stopped at a position where the intermediate transfer belt 2 is rotated by a predetermined amount based on the detection of the reference mark, thereby forming the next mark. When the image is a color image, the time for detecting the reference mark on the intermediate transfer belt 2 can be made constant, and the time for forming the first color image can be kept short and constant. .
[0073]
Further, conventionally, when the intermediate transfer member mounted on the image forming apparatus is the intermediate transfer belt 2 supported by a plurality of rollers, the environmental temperature of the image forming apparatus is high and the stop state of the intermediate transfer belt 2 is long. Subsequently, in a portion supported by a roller (tension roller) having a strong tension applied to the intermediate transfer belt 2, the intermediate transfer belt elongates to generate wrinkles, and if a toner image is carried on the wrinkles, an image is formed. In the present embodiment, the position of the wrinkle generated on the intermediate transfer belt 2 affects the image formation (transfer) on the intermediate transfer belt 2, although there has been a problem of causing the density unevenness and the color shift. By controlling the intermediate transfer belt 2 to be stopped so that the intermediate transfer belt 2 does not exist, it is possible to prevent image deterioration caused by wrinkles of the intermediate transfer belt 2 as in the related art. It made.
[0074]
In the above embodiment, the number of reference marks to be attached to the intermediate transfer belt 2 of the image forming apparatus has not been described, but the number of reference marks to be attached to the intermediate transfer belt 2 can be arbitrary. is there. In this case, if the number of reference marks is increased, the time until the reference marks are detected by the reference mark detection means 36 can be reduced.
[0075]
Further, in the above embodiment, the case where the image forming apparatus is a printer has been described as an example, but the present invention can be applied to a copying machine or a multifunction peripheral.
[0076]
According to the present invention, a software program (the flowcharts of FIGS. 5 to 7) for realizing the functions of the above-described embodiments is supplied to a computer or a CPU, and the computer or the CPU reads and executes the supplied program. Can be achieved by:
[0077]
In this case, the program is supplied directly from a storage medium on which the program is recorded, or is downloaded from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like. Supplied.
[0078]
The form of the program may be in the form of object code, program code executed by an interpreter, script data supplied to an OS (Operating System), or the like.
[0079]
According to the present invention, a storage medium storing a software program for realizing the functions of the above-described embodiments is supplied to a computer or a CPU, and the computer or the CPU reads and executes the program stored in the storage medium. Can also be achieved.
[0080]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
[0081]
Examples of storage media for storing program codes include ROM, RAM, NV-RAM, floppy (registered trademark) disk, hard disk, optical disk (registered trademark), magneto-optical disk, CD-ROM, MO, CD-R, and CD. -RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, and the like.
[0082]
The functions of the above-described embodiments are not only executed by executing the program code read from the computer, but also executed by the OS or the like running on the computer in part or all of the actual processing based on the instruction of the program code. This can also be realized by:
[0083]
Examples of embodiments of the present invention are listed below.
[0084]
[Embodiment 1] A latent image is formed by exposing a photoreceptor and an image is formed by developing the latent image, and an image on the photoreceptor is transferred to an intermediate transfer body. In an image forming apparatus that forms an image by transferring an image to a recording medium,
Detecting means for optically detecting a reference member serving as a reference for image forming timing disposed on the intermediate transfer member; and, during image formation when a monochrome image is continuously formed on a recording medium, the detecting means includes: An image forming apparatus comprising: a control unit that stops an operation.
[0085]
Second Embodiment The image forming apparatus according to the first embodiment, wherein the detection unit is a light transmission type or light reflection type optical sensor that detects the reference member of the intermediate transfer body.
[0086]
According to this embodiment, it is possible to reduce the energizing time to a light source such as an LED used as a light transmission type or a light reflection type as the detection means, and it is possible to extend the life of the detection means.
[0087]
[Embodiment 3] The control unit is configured to perform the image formation by mixing the color image and the monochrome image on the recording medium, and to perform the monochrome image when the monochrome image is formed between the monochrome image and the monochrome image. 2. The image forming apparatus according to claim 1, wherein at the time of forming, the image forming timing is generated based on the detection of the reference member by the detecting unit.
[0088]
According to this embodiment, it is possible to improve the productivity of a color image.
[0089]
[Embodiment 4] The control unit stops the operation of the detection unit during image formation when a single-color image is continuously formed on a recording medium, and after the image formation, terminates the detection unit. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer body is stopped at a predetermined position based on detection of the reference member by the detection unit.
[0090]
According to this embodiment, when the image to be formed next is a color image, the time for detecting the reference member of the intermediate transfer body is constant, and the time for forming the first color image can be kept short and constant. .
[0091]
[Embodiment 5] The intermediate transfer body is an endless belt that is wrapped around a plurality of rollers and driven to circulate, and the control unit determines that a position of a roller that applies tension to the intermediate transfer body among the plurality of rollers is The image forming apparatus according to claim 4, wherein the intermediate transfer body is stopped so as to be at a predetermined position on the intermediate transfer body.
[0092]
According to this embodiment, when wrinkles occur in the intermediate transfer body, the intermediate transfer body can be stopped so that the position of the wrinkles on the intermediate transfer body does not affect the image. It can be prevented.
[0093]
[Sixth Embodiment] The setting for setting the detection unit to the stop state or the operation state is set from an external device that can communicate with the image forming apparatus, or set from an operation unit provided in the image forming apparatus, or 5. The image forming apparatus according to claim 1, further comprising a setting corresponding to a document read image by a document reading unit included in the image forming apparatus.
[0094]
According to this embodiment, it is possible to arbitrarily select a setting for setting the detection unit to the stop state or the operation state, and to improve the usability of the image forming apparatus.
[0095]
Embodiment 7 The image forming apparatus according to any one of Embodiments 1 to 6, wherein the image forming apparatus is an apparatus selected from the group consisting of a printer, a copier, and a multifunction peripheral.
[0096]
According to this embodiment, it is possible to extend the life of a detection unit mounted on a printer, a copying machine, and a multifunction peripheral, which optically detects a reference of image forming timing.
[0097]
[Embodiment 8] A latent image is formed by exposing a photoreceptor and an image is formed by developing the latent image, and an image on the photoreceptor is transferred to an intermediate transfer body. In a control method executed by an image forming apparatus that forms an image by transferring an image to a recording medium,
A detection step of optically detecting a reference member serving as a reference for image formation timing provided on the intermediate transfer body by a detection unit, and during image formation when a single-color image is continuously formed on a recording medium, A control step of stopping the operation of the detection means.
[0098]
[Embodiment 9] In the detection step, the reference member is detected by a light transmission or light reflection type optical sensor that detects the reference member of the intermediate transfer body as the detection unit. The control method described.
[0099]
[Embodiment 10] In the control step, when a color image and a monochromatic image are mixedly formed on a recording medium to form an image, the monochromatic image formed when the monochromatic image is sandwiched between the color image and the monochromatic image is formed. The control method according to claim 8, wherein at the time of forming, the image forming timing is generated based on the detection of the reference member by the detecting step.
[0100]
[Embodiment 11] In the control step, the operation of the detection unit is stopped during image formation when a single color image is continuously formed on a recording medium, and after the image formation is completed, the detection unit is turned off. 9. The control method according to claim 8, wherein the intermediate transfer body is stopped at a predetermined position based on the detection of the reference member by the detection unit.
[0101]
[Embodiment 12] The intermediate transfer body is an endless belt that is wrapped around a plurality of rollers and driven to circulate, and in the control step, a position of a roller that applies tension to the intermediate transfer body among the plurality of rollers is The control method according to claim 11, wherein the intermediate transfer body is stopped so as to be at a predetermined position of the intermediate transfer body.
[0102]
[Thirteenth Embodiment] The setting for setting the detection unit to the stop state or the operation state is set from an external device capable of communicating with the image forming apparatus, or set from an operation unit included in the image forming apparatus, or The control method according to the eighth or eleventh embodiment, further comprising setting according to a document read image by a document reading unit provided in the image forming apparatus.
[0103]
[Embodiment 14] The control method according to any one of Embodiments 8 to 13, wherein the control method is applied to an image forming apparatus selected from the group consisting of a printer, a copier, and a multifunction peripheral. .
[0104]
[Embodiment 15] A latent image is formed by exposing a photoreceptor and an image is formed by developing the latent image, and an image on the photoreceptor is transferred to an intermediate transfer body. In a program for causing a computer to execute a control method of an image forming apparatus that forms an image by transferring an image to a recording medium,
A detection module for optically detecting a reference member serving as a reference for image formation timing provided on the intermediate transfer body by a detection unit, and during image formation when a single-color image is continuously formed on a recording medium, A program comprising: a control module that stops an operation of a detection unit.
[0105]
[Embodiment 16] A computer-readable storage medium storing the program according to Embodiment 15.
[0106]
【The invention's effect】
As described above in detail, according to the image forming apparatus of the first aspect, during image formation when a single-color image is continuously formed on a recording medium, the image forming timing of the image forming apparatus disposed on the intermediate transfer body is controlled. Since the operation of the detecting means for optically detecting the reference member serving as the reference is stopped, it is possible to reduce the energizing time to a light source such as an LED used in the optical detecting means, and as a result, The service life can be extended.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a main part of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating an internal structure of the image forming apparatus.
FIG. 3 is a timing chart showing color image formation timing when two color images are obtained in the image forming apparatus.
FIG. 4 is a timing chart showing image formation timing when a color image and a single-color image are mixed and a single-color image is formed sandwiched between the single-color images when forming and outputting the mixed image; It is.
FIG. 5 is a flowchart illustrating a process when a single color image is continuously formed in the image forming apparatus.
FIG. 6 is a flowchart illustrating processing for forming a single-color image when a color image and a single-color image are mixed and output in the image forming apparatus, and when there is a single-color image sandwiched between the single-color images; is there.
FIG. 7 is a flowchart illustrating an intermediate transfer belt stop control process when a single-color image is continuously formed in the image forming apparatus.
FIG. 8 is a configuration diagram illustrating an internal structure of an image forming apparatus according to a conventional example.
FIG. 9 is a perspective view showing an arrangement relationship of an intermediate transfer belt, rollers, reference marks, and reference mark detection means of the image forming apparatus.
FIG. 10 is a timing chart showing a color image forming timing when one color image is obtained in the image forming apparatus.
FIG. 11 is a timing chart showing an image forming timing when a color image and a single-color image are mixed and image-formed and output in the image forming apparatus.
[Explanation of symbols]
1 Photoconductor
2 Intermediate transfer belt
8 Exposure equipment
13 color developing device
14 Black developing device
36 fiducial mark detecting means
41 fiducial mark
101 Device control unit
102 Image forming unit
103 Image output device
105 Selector
106 Image formation timing start signal A generator
107 Image formation timing start signal B generator

Claims (1)

A latent image is formed by exposing the photoconductor, and the latent image is developed to form an image.The image on the photoconductor is transferred to an intermediate transfer body. In an image forming apparatus that forms an image by transferring,
Detecting means for optically detecting a reference member serving as a reference for image forming timing disposed on the intermediate transfer member; and, during image formation when a monochrome image is continuously formed on a recording medium, the detecting means includes: An image forming apparatus comprising: a control unit that stops an operation.

Images