JP2005141254A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized and low cost color image forming apparatus which outputs a color image of high precision and wide color reproduction range in a short period of time after receiving image information without requiring huge memory devices for image information. <P>SOLUTION: After completion of development of each color and before start of exposure of next color, the rotation of a photoreceptor is stopped. The color image is formed without providing the huge memory elements, and image forming operation is started before the entire color image information is sent. Further, during a period of stopping the photoreceptor after completion of development of each color and before start of exposure of next color, stable fixing is performed by controlling a fixing means to temperatures where thermal fixing is inplemented, and the color image is outputted in a short period of time after receiving image information. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus that forms an image on a sheet-like transfer material such as a printer, a copying machine, and a facsimile, and more particularly to an electrophotographic color image forming apparatus that forms a color image. It is.

  As a conventional electrophotographic color image forming apparatus, for example, a latent image is formed on a photoconductor disclosed in Patent Document 1 and the operation of developing with color toner is repeated to form a color toner image on the photoconductor. A multi-development batch transfer system that transfers a color toner image onto a transfer material, a latent image formed on a photoreceptor disclosed in Patent Document 2, developed with color toner, and developed and developed into a drum or belt shape A transfer drum system that forms a color image by repeating the operation of transferring to a transfer material carried on a transfer material carrier for each color and a latent image is formed on a photoconductor and developed with color toner. An intermediate transfer body for transferring a color toner image to a transfer material after forming a color toner image on the intermediate transfer medium by repeating the operation of transferring the toner image to a drum or belt-shaped intermediate transfer medium for each color Apparatus such as that known as expression is known.

JP-A-1-202771 Japanese Patent Application Laid-Open No. 60-33575

  In recent years, with the rapid progress of computers and the like, the opportunity to handle color images with digital signals has increased, and color image information has been handled by various devices, and the demand for outputting the color images with a color image forming apparatus has increased. ing.

  Since the conventional color image forming apparatus described above performs image formation for each color by a continuous operation, a color image forming apparatus can be formed at a time in order to form a color image based on color image information sent from various devices. A memory element for storing image information for an image is provided, and the image forming operation is started after the color image information is stored in the memory element.

  However, since the amount of information of the color image is enormous, the amount of memory elements for the necessary image information is enormous, making the image forming apparatus large and expensive, and forming a high-definition color image. Therefore, when the recording density is increased or when a large number of colors are used to obtain a wide color reproduction range, the amount of information of the color image becomes enormous and the size and cost of the apparatus are increased by providing a memory element for image information. The increase will be even greater.

  In addition, since the image forming operation is started after information for an image that can be formed at one time is stored in the memory element, the time required for output becomes long.

  However, if the color image forming apparatus does not include a memory element for image information that can be formed at a time, the color image information needs to be transmitted and received in accordance with the operation of the color image information forming apparatus. The device that can transmit the correct image information is limited to a special one.

  Accordingly, the present invention solves the above-described problems, and an object of the present invention is to cope with color image information transmitted from various devices at various speeds without having a huge memory device for image information. Another object of the present invention is to provide a small and low-cost color image forming apparatus capable of outputting a high-definition and wide color reproduction range color image in a short time after receiving image information.

  The image forming apparatus of the present invention uniformly charges the rotating photoreceptor, performs image exposure based on an image signal of a specific color, and develops the formed latent image with color toner for each color. A color image forming apparatus that repeatedly overlaps a plurality of toner images to form a color toner image, and transfers the color toner image to a transfer material, after the development of each color and before the start of exposure of the next color. A period in which the photosensitive member is stopped after the development of each color and before the start of the exposure of the next color. The inside is characterized in that the fixing means is controlled to a temperature at which heat fixing is possible.

  Here, the color toner image may be formed as follows and transferred to a transfer material. That is, a plurality of toner images may be superimposed on the photoconductor, and the color toner image formed on the photoconductor may be transferred to a transfer material. Alternatively, a transfer material carrier that rotates in synchronization with the photosensitive member may be provided, and a plurality of toner images may be superimposed on the transfer material carried on the transfer agent carrier to form a color toner image. Further, an intermediate transfer medium that rotates in synchronization with the photosensitive member may be provided, and a plurality of toner images may be superimposed on the intermediate transfer medium, and a color toner image formed on the intermediate transfer medium may be transferred to a transfer material.

  A color image is generally formed by superimposing three color images of cyan, magenta, and yellow, or four color images including black, and for forming an image of a color that cannot be formed by these colors alone. In addition, attempts have been made to further increase the number of colors used for image formation. The amount of information of this color image is very large because it is a multiple of the number of colors of monochrome information.

  Since the color image forming apparatus of the present invention includes a control unit that stops the circumferential movement of the photosensitive member after the completion of the development of each color and before the start of the exposure of the next color, each color image information is stored without storing all of the color image information. The formation of the toner image for each color can be stopped when the image information of that color is performed, and the image formation of the next color can be started when the image information is sent.

  Therefore, it is possible to form a color image corresponding to color image information transmitted at various speeds without providing a huge image information memory element, and image formation before all the color image information is sent. The operation can be started and a color image can be output in a short time after receiving the image information.

  Further, as a fixing method for fixing a toner image transferred onto a transfer material onto the transfer material, there is generally a heat fixing method in which the transfer material on which the toner image is transferred is heated to melt the toner image and fuse it to the transfer material. It is used. Various methods such as a heat roller fixing method are known as the heat fixing method, but each requires a time for raising the temperature of the heat fixing means to a fixing temperature and stabilizing the temperature.

  However, according to the color image forming apparatus of the present invention, the fixing unit is controlled to a temperature at which heat fixing can be performed during the period in which the photoconductor is stopped after the development of each color and before the start of exposure of the next color. Therefore, the time required for image formation including the stop period can be used as the temperature raising time of the fixing unit and the time for stabilizing the temperature, and stable fixing can be performed. Fixing can be performed, and a color image can be output in a short time after receiving image information.

  Hereinafter, the image forming apparatus of the present invention will be described in detail according to embodiments.

  Embodiment 1 FIG. 1 is a cross-sectional view of a color image forming apparatus showing an embodiment of the present invention. First, a color image forming process of this apparatus will be described. The color image forming apparatus shown in FIG. 1 is a device for transferring a plurality of toner images on a photoconductor 1 and transferring the color toner images formed on the photoconductor 1 to a transfer material 9 in general. This is called a transfer method. This method is a method by which a color image forming apparatus can be configured with a small number of components, and is suitable for providing a small-sized and low-cost color image forming apparatus.

  The photosensitive member 1 is rotationally driven in the direction of arrow A by a driving source (not shown). Around the photosensitive member 1, a charger 2, a laser scanning optical system 3, a yellow developing device 41, a magenta developing device 42, and a cyan developing device. 43, a black developing device 44, a transfer electrode 51, a separation electrode 52, and a cleaning device 6 that moves away from and in contact with the photoreceptor 1.

  First, the surface of the photosensitive member 1 is uniformly charged by the charger 2, the image is exposed according to the yellow image information by the laser scanning optical system 3 to form a latent image, and the latent image is developed by the yellow developer 41. Thus, a yellow toner image is formed. The laser scanning optical system 3 scans the photosensitive member 1 by deflecting a light beam emitted from a laser radiation device (not shown) by a deflector 31 provided with a polygon mirror.

  The photosensitive member 1 on which the yellow toner image is formed is stopped from rotating when the yellow toner image development is finished unless the magenta latent image forming the next toner image can be formed. The rotation is started again when the image can be formed.

  The photoreceptor 1 that has continued to rotate without stopping or has started to rotate again is charged by the charger 2 again, and is subjected to image exposure by the laser scanning optical system 3 in accordance with magenta image information to form a latent image. The latent image is developed by the magenta developing unit 42, and the magenta toner image is superimposed on the yellow toner image. Thereafter, the cyan toner image and the black toner image are developed in a similar manner, and a color toner image is formed on the photoreceptor 1.

  The transfer material 9 is sent to the transfer site by the paper feeding device 7, receives the transfer of the color toner image on the photoconductor 1 by the transfer electrode 51, is then separated from the photoconductor 1 by the separation electrode 52, and is transferred to the fixing device 8. Sent. The fixing device 8 is controlled by heating, and the color toner image is fixed on the transfer material 9 by the fixing device and is output.

  After the color toner image is transferred to the transfer material 9, the toner remaining on the photoconductor 1 is scraped off by the cleaning device 6 that is in a separated state from the photoconductor 1 when the color toner image is formed. The cleaned photoreceptor 1 can be transferred to the next color image forming process.

  As described above, the color image forming apparatus of FIG. 1 sequentially forms toner images on the photoconductor 1 while stopping the rotation of the photoconductor 1 as necessary after the completion of development of each color and before the start of exposure of the next color. Overlaid, a color toner image is formed, transferred onto the transfer paper 9, fixed, and output. Since the photosensitive member 1 is stopped before the start of the exposure of the next color, the timing of starting the image exposure corresponding to the image information of each color can be set according to the state in which the image information of each color is prepared. Even when the color image forming apparatus does not store the color image information in the memory element, it is possible to form a color image.

  Here, in the case where the time from when the photosensitive member 1 is stopped to when it is rotated again is very long, the toner image formed by changing the latent image to be developed due to the influence of dark decay that attenuates the surface potential of the photosensitive member 1 However, in this embodiment, even if the photosensitive member 1 is stopped for a long time, it is possible to form an image without any problem, and the contents thereof will be described below.

  In FIG. 1, L2 is a circumferential length from a portion of the photosensitive member 1 that is charged by the charger 2 to a portion of the photosensitive member 1 that receives development by the black developing unit 44 that is the most downstream developing device in the rotation direction of the photosensitive member 1. L1 is a developing device located second from the downstream side in the rotation direction of the photosensitive member 1 from a portion of the photosensitive member 1 that is charged by the charger 2. This is the peripheral length (the length of the path along the moving direction of the photosensitive member 1) to a portion that is developed by a certain cyan developing device 43.

  In the embodiment of FIG. 1, the development by the black developing unit 44 is performed last, and the yellow developing unit 41 may be controlled to stop the photosensitive member 1 before starting the exposure of the next color. , After completion of development by the magenta developing unit 42 and the cyan developing unit 43. The part of the photoreceptor 1 developed by these developing units is the part farthest from the part that is charged by the charger 2 of the photoreceptor 1 is the part developed by the cyan developing unit 43, and the length thereof is L1.

  The total circumferential length of the photosensitive member 1 in the embodiment of FIG. 1 is slightly larger than the sum of the length L1 and the length of the color image to be formed. Thus, in the case of the yellow developing unit 41 and the magenta developing unit 42, Of course, even when the rotation of the photoconductor 1 is stopped when the development by the cyan developing device 43 is completed, the leading end of the toner image on the photoconductor 1 is rotated in the direction of rotation of the photoconductor 1 from the portion charged by the charger 2. Located upstream. For this reason, when the rotation of the photosensitive member 1 is started again, the toner image already formed on the photosensitive member 1 can be favorably charged from the tip by the charger 2, and the latent image formation of black image information is performed. It is prevented that the influence of the change in the surface potential of the photoconductor 1 generated during the period in which the photoconductor 1 is stopped is exerted.

  Note that the order of development of each color is different from that of the present embodiment, and when development of another color is performed after development by the black developing unit 44 located on the most downstream side, the entire circumference of the photoreceptor 1 is increased. It is desirable to make it larger than the sum of the length L2 and the length of the color image to be formed.

  That is, when a plurality of developing devices perform development at different parts of the photosensitive member 1 as in the embodiment of FIG. 1, the most downstream in the moving direction of the photosensitive member 1 excluding the developing device that performs the last development. With respect to the developing unit located at the position 1, the entire peripheral length of the photosensitive member 1 is made larger than the sum of the peripheral length from the portion charged by the charger 2 of the photosensitive member 1 to the developing portion and the length of the color image to be formed. As a result, even when the photosensitive member 1 is stopped for a long time, it is possible to form an image without any problem. In addition, it is preferable to perform the development with the developing unit located on the most downstream side in the rotation direction of the photoconductor 1 as in the present embodiment because it is not necessary to enlarge the photoconductor 1.

  FIG. 2 is a block diagram showing a control unit of the color image forming apparatus of the embodiment of FIG. 1, and FIG. 3 is a time chart showing an operation example of the color image forming apparatus of the embodiment of FIG. FIG. 4 is a time chart showing an operation example of a conventional color image forming apparatus shown as a comparative example. The control and operation of the color image forming apparatus according to the embodiment of the present invention will be described below with reference to FIGS. 2 and 3, and compared with the operation of the conventional color image forming apparatus shown in FIG.

  First, the configuration of the control unit will be described with reference to FIG. This color image forming apparatus is a printer that creates a color hard copy based on image information transferred from an apparatus that outputs various image information, such as an image information forming apparatus, an image reading apparatus, an image processing apparatus, and an image display apparatus. And is controlled by the control means 100 to receive image information from an external image information output device, and form and output a color image.

  Image information sent from an external image information output device is received by the image information receiving unit 101 controlled by the control means 100 and stored in the memory element 102. Upon receiving the image information, the control means 100 outputs control signals to the deflector rotation control means 104 and the fixing temperature control means 105, monitors the rotation state of the deflector 31 and the temperature control state of the fixing device 9, and further receives the information. In accordance with the stored image information, a control signal is sent to the photoconductor driving means 106 to rotate and stop the photoconductor 1, and the image information stored in the memory element 102 is sequentially read out and sent to the laser control means 103 for image exposure. Control. In the memory element 102 from which the image information has been read, the image information newly received by the image information receiving unit 101 is stored.

  The color image forming apparatus controlled in the above configuration is controlled and operated as in the operation example shown in the time chart of FIG. FIG. 4 is a time chart when the conventional color image forming apparatus shown as a comparative example operates under the same conditions.

  3 and 4 show the state of the control means and the operation of the apparatus from when the color image forming apparatus starts receiving the image information by the image information receiving unit 101 until the output of the color image is completed. 3 and 4, the image information is received by the image information receiving unit 101, and the deflector rotation control is controlled by the deflector rotation control means 104 so that the deflector 31 is rotated. The fixing temperature control is controlled by the fixing temperature control means 105 so that the fixing device 9 can be heated and fixed. The photosensitive member drive is that the photosensitive member 1 is driven by the photosensitive member driving means 106. In the image exposure, the laser control unit 103 controls the laser radiation device of the laser scanning optical system 3 based on the image information to expose the image on the photosensitive member 1, and in the development, the latent image is developed by the developing device. OFF represents a state in which reception, control, driving, or the like is not performed, and ON represents a state in which reception, control, driving, or the like is performed. The symbols Y, M, C, and Bk entered in the chart of image information reception, image exposure, and development indicate that the image information that has been received and image exposure and the color that is being developed are yellow, magenta, Represents cyan and black.

  In FIG. 3, image information is sequentially transmitted from the outside in the order of yellow, magenta, cyan, and black, received by the image information receiving unit 101, and stored in a memory element 102 having a capacity for storing the amount of image information for one color. . When reception of image information from the outside is started, deflector rotation control and fixing temperature control are started, and preparation for image exposure and heat fixing is started.

  When all the yellow image information is received, when the deflector rotation control means 104 confirms that the rotation of the deflector 31 is stable in an exposureable state, the driving of the photosensitive member 1 is started. Yellow image exposure and development are performed in synchronization with the rotation of the photoreceptor 1. The magenta image information received by the image information receiving unit 101 is sequentially stored in the memory element 102 from which the image information has been read for yellow image exposure.

  If all the magenta image information has been received when the yellow development is completed, the driving of the photosensitive member 1 is continued. However, if all the magenta image information has not been received as shown in FIG. The driving of the photosensitive member 1 is stopped, and when all the magenta image information is received, the driving is started again, and image exposure and development are performed. Thereafter, the operations for cyan and black are performed in the same manner, and then transfer and fixing are performed to output an image. The deflector rotation control is stopped when the image exposure based on the black image information is completed, and the fixing temperature control is stopped when the image output is completed.

  As described above, since the memory element 102 repeatedly stores and reads out the image information of each color and uses the memory element 102 in common for each color, the color image forming apparatus of the present invention is A color image can be formed by the memory element 102 for image information for one color.

  In the time chart of FIG. 3, the case where the image information is received at a constant speed is described. However, the speed at which the image information is transmitted and received according to various situations of the external image information output apparatus and the type of image to be formed is as follows. Each changes. As can be inferred from the above-described explanation and the time chart of FIG. 3, the color image forming apparatus of the present invention is capable of printing a color image in a shorter time without stopping the driving of the photosensitive member 1 when image information is transmitted and received at high speed. Even when transmission / reception of image information is performed at a low speed or is interrupted in the middle, it is possible to operate at the same timing.

  In the fixing device 9, the fixing temperature control is started when the reception of the image information is started as described above, and preparation for heat fixing is started. For heating and fixing, it takes time to raise the temperature of the fixing device 9 to a fixing temperature and stabilize the temperature. However, the fixing is performed after the development of black, and the time chart of FIG. As shown in FIG. 3, since the fixing temperature control of the fixing device 9 is continued including the stop period of the photoconductor 1, the time for sufficiently raising the temperature of the fixing device 9 and stabilizing the temperature is sufficient before the fixing is performed. And stable fixing is possible.

  Further, in the color image forming apparatus of the present invention, the driving of the photosensitive member 1 can be stopped for each color, so that the yellow, magenta, and cyan latent images are formed and developed, and the temperature of the fixing device 9 is increased and the temperature is stabilized. If it is not sufficient, it is started, and it is confirmed that the temperature of the fixing device 9 is sufficiently raised and the temperature is stable before the black latent image is formed. At that point, the photosensitive member 1 is stopped and fixed. It is possible to wait for the temperature of the apparatus 9 to rise and to stabilize the temperature before starting the formation of a black latent image, and then to perform heat fixing, so that the latent image formation and development of yellow, magenta, and cyan can be performed. By starting without waiting for the temperature and temperature to stabilize, it is possible to output a color image in a short time after receiving image information.

  Further, as shown in the time chart of FIG. 3, the deflector 31 continues to rotate during the stop period of the photosensitive member 1. The deflector 31 rotates at a high speed in order to output a high-definition image at a high speed, and it takes time to increase the rotation speed of the deflector to stabilize the rotation speed and enable image exposure. During the period when the photosensitive member 1 is stopped, the rotation of the deflector 31 is continued, so that the rotation time of the deflector is stabilized before the rotation of the photosensitive member 1 and the exposure of the next color are started. Without the need, the next image formation can be started immediately after the reception of the image information of each color in a state where the rotation of the deflector 31 is stable, thereby outputting a color image in a short time. Is possible.

  (Comparative Example) The operation of a conventional color image forming apparatus will be described below with reference to FIG. However, the conventional color image forming apparatus is different in that the memory element 102 for storing image information shown in FIG. 2 has a capacity for storing the amount of image information of all color images.

  Image information is sequentially received by the image information receiving unit 101 in the order of yellow, magenta, cyan, and black, and stored in the memory element 102. When reception of image information from the outside is started, deflector rotation control and fixing temperature control are started.

  All the color image information is stored in the memory element, and when all the image information is received, the rotation of the deflector 31 is stable in an exposureable state, and the temperature at which the fixing device 9 can be heated and fixed. When it is confirmed that the temperature of the photosensitive member 1 has been increased, image driving and development are sequentially performed for yellow, magenta, cyan, and black in synchronization with the rotation of the photosensitive member 1, and transfer is performed. Then, fixing is performed and image output is performed. The deflector rotation control is stopped when the image exposure based on the black image information is completed, and the fixing temperature control is stopped when the image output is completed.

  In a conventional color image forming apparatus, all color image information is stored to cope with various situations of an external image information output apparatus and situations in which the speed at which image information is transmitted and received varies depending on the type of image to be formed. An enormous amount of memory element 102 is required, and the time from the reception of all the color image information to the end of image output in order to start the image forming operation is long, and the temperature at which the fixing device 9 can be heated and fixed Since the image forming operation is started after waiting for the temperature to rise and stabilize, the time until the end of image output is further increased.

  As described above, when the embodiment of the present invention is compared with the conventional example, according to the embodiment of the present invention, color image information transmitted at various speeds can be obtained without providing a huge memory device for image information. Correspondingly, a color image can be formed, the image forming operation can be started before all the color image information is received, and the image forming operation can be performed before the temperature rise of the fixing device 9 is completed. It is possible to start, and it is possible to output a color image in a short time after receiving image information.

  In the first embodiment, the case where the memory elements 102 for the image information for one color are provided and the image exposure is performed after the reception of the image information for each color is described, but the amount of the memory elements 102 is increased. It is also possible to perform color image output in a shorter time by more efficiently transmitting and receiving image information, or when the transmission speed of image information of an external image information output device is stable Estimate the amount of image information to be transmitted and received during the image forming operation, and start the operation prior to the end of receiving the image information for each color, or form a color image by the memory element 102 that has less image information for one color. It is also possible to perform.

  Second Embodiment FIG. 5 is a cross-sectional view of a color image forming apparatus showing another embodiment of the present invention. First, the color image forming process of this apparatus will be described. This color image forming apparatus superimposes a plurality of toner images on a transfer material 9 carried on a transfer material carrier 53 that rotates in synchronism with the photoreceptor 1, and is generally called a transfer drum system. Is. This method is a method for obtaining a high image quality because the toner image is directly transferred to the transfer material 9 for each color, and is suitable for providing a high-quality color image forming apparatus.

  The photosensitive member 1 is driven to rotate by a driving source (not shown). Around the photosensitive member 1, a charger 2, a laser scanning optical system 3, a yellow developing device 41, a magenta developing device 42, a cyan developing device 43, and a black developing device. The developing device 4 that carries the developing device 4 and rotates and conveys the selected developing device to a position facing the photoconductor 1, and the transfer material 9, and is synchronized with the photoconductor 1 by a common drive source. A rotating transfer material carrier 53 and a cleaning device 6 are provided.

  First, the surface of the photosensitive member 1 is uniformly charged by the charger 2, the image is exposed according to the yellow image information by the laser scanning optical system 3 to form a latent image, and the latent image is developed by the yellow developer 41. A yellow toner image is formed.

  The transfer material 9 is sent to the surface of the transfer material carrier 53 by the paper feeder 7, and the leading end of the transfer material 9 is held by a gripper (not shown) provided on the surface of the transfer material carrier 53. Is carried by the transfer material carrier 53 and rotated in synchronization with the photosensitive member 1. A transfer electrode 51 is provided at a position facing the photoconductor 1 inside the transfer material carrier 53, and the yellow toner image formed on the photoconductor 1 is transferred to the transfer material 9 carried on the transfer material carrier 53. Transcribed. After the toner image is transferred to the transfer material 9, the toner remaining on the photosensitive member 1 is scraped off by the cleaning device 6, and the cleaned photosensitive member 1 can move to the next image forming process.

  When the development of the yellow toner image is finished and the transfer of the yellow toner image to the transfer material 9 is finished, if the magenta latent image forming the next toner image cannot be formed, the transfer with the photosensitive member 1 is performed. The material carrier 53 stops rotating and starts rotating again when the magenta latent image can be formed.

  The photosensitive member 1 that has continued to rotate without stopping or has started rotating again is subjected to image exposure according to magenta image information to form a latent image, and the latent image is developed by the magenta developing device 42, and the transfer material. The magenta toner image is transferred onto the yellow toner image on the transfer material 9 carried on the carrier 53 so as to overlap therewith. Thereafter, similarly, a cyan toner image and a black toner image are superimposed and transferred to form a color toner image on the transfer material 9.

  The transfer material 9 on which the color toner image is formed is provided at a position facing the separation claw 54 and the separation claw 54 inside the transfer material carrier 53 by removing the gripper held at the front end of the transfer material 9 (not shown). The separation electrode 52 is separated from the transfer material carrier 53 and sent to the fixing device 8. The fixing device 8 is controlled by heating, and the color toner image is fixed on the transfer material 9 by the fixing device and is output.

  As described above, the color image forming apparatus of FIG. 5 stops the rotation of the photosensitive member 1 and the transfer material carrier 53 as necessary before the start of the exposure of the next color after the development and transfer of each color is completed. Then, the toner images are sequentially transferred onto the transfer material 9 carried on the transfer material carrier 53 to form a color toner image, which is fixed and outputted. Since the photosensitive member 1 is stopped before the start of the exposure of the next color, the timing of starting the image exposure corresponding to the image information of each color can be set according to the state in which the image information of each color is prepared. 2. Like the first embodiment described with reference to FIG. 3, it is possible to form a color image corresponding to color image information transmitted at various speeds without providing a huge memory device for image information. In addition, an image forming operation can be started before all color image information is received, and a color image can be output in a short time after receiving the image information. Further, the effect of continuing the fixing temperature control of the fixing device 9 and continuing the rotation of the deflector 31 during the stop period in which the driving of the photosensitive member 1 is stopped for each color is the same as in the first embodiment. I can get it.

  Here, in the case where the time from when the photosensitive member 1 is stopped to when it is rotated again is very long, the toner image formed by changing the latent image to be developed due to the influence of dark decay that attenuates the surface potential of the photosensitive member 1 However, even in this embodiment, even when the photosensitive member 1 is stopped for a long time as in the first embodiment, it is possible to form an image without any problem, and the contents thereof will be described below.

  In FIG. 5, L is a circumferential length from the portion of the photosensitive member 1 that is charged by the charger 2 to the portion of the photosensitive member 1 that is subjected to development by the selected developing device of the developing device 4 (along the moving direction of the photosensitive member 1). LT is the length of the path), and LT is from the portion charged by the charger 2 of the photoreceptor 1 to the portion where the toner image on the photoreceptor 1 is transferred to the transfer material 9 carried on the transfer material carrier 53. (The length of the path along the moving direction of the photosensitive member 1).

  The peripheral length of the transfer material carrier 53 in the embodiment of FIG. 5 is slightly larger than the sum of the length LT and the length of the color image to be formed. Thus, even when the rotation of the photosensitive member 1 and the transfer material carrier 53 is stopped when the transfer is completed, the rotation is started again and the transfer material 9 already formed on the transfer material carrier 53 is formed. The toner image transferred to be superimposed on the toner image can be formed on the photosensitive member 1 that has been charged by the charger 2 after the rotation is resumed, and the photosensitive member 1 has stopped for the latent image formation. The influence of the change in the surface potential of the photoconductor 1 generated during the period is prevented.

  That is, in order to transfer the toner image of each color on the transfer material 9 carried on the transfer material carrier 53, the length obtained by subtracting the length of the color image formed from the peripheral length of the transfer material carrier 53 is photosensitive. The body 1 rotates without forming a latent image. In this embodiment, the length of rotation of the photoconductor 1 without forming the latent image becomes larger than the length LT. When the transfer is stopped at the end of the transfer, the surface of the photoconductor 1 on which the next latent image is formed is After the rotation is resumed, the portion charged by the charger 2 is prevented from being affected by dark decay. Note that the photosensitive member 1 and the transfer material carrier 53 are driven so that their peripheral speeds substantially coincide.

  Here, assuming that the circumferential length of the transfer material carrier 53 is slightly larger than the sum of the length L and the length of the color image to be formed, the development of the respective colors is completed when the photosensitive member 1 and the transfer material carrier 53 are finished. Also in the case of stopping the rotation, it is possible to prevent the influence of the dark decay of the photosensitive member 1 that occurs during the period in which the photosensitive member 1 is stopped, as described above, and thereby transfer to the embodiment of FIG. The material carrier 53 can be downsized. However, when the rotation of the photoconductor 1 and the transfer material carrier 53 is stopped when the development of the toner images of the respective colors is completed, the toner image formed on the photoconductor 1 is transferred to the transfer material carrier 53 at the transfer site. Since the transfer is stopped on the transfer material 9 carried on the photosensitive member 1, the transfer material 9 carried on the photosensitive member 1 and the transfer material carrier 53 does not slide and always stops at the same speed. When the sliding occurs, there is a possibility that the toner image is rubbed and disturbed.

  For this reason, the circumferential length L of the transfer material carrier 53 is from the portion of the photosensitive member 1 charged by the charger 2 to the portion of the photosensitive member 1 subjected to development by the selected developing device of the developing device 4. By making the length larger than the sum of the lengths of the color images to be formed, it is possible to form a color image without being affected by the dark decay of the photosensitive member 1 even when stopped for a long time. The color to be formed is the peripheral length LT from the portion of the photoreceptor 1 charged by the charger 2 to the portion where the toner image on the photoreceptor 1 is transferred to the transfer material 9 carried on the transfer material carrier 53. When the transfer material 9 slid on the photosensitive member 1 and the transfer material carrier 53 is slid when stopping and resuming the rotation, there is no influence of the dark decay of the photosensitive member 1 by making it larger than the sum of the images. Color image formation that is not affected by A further preferred order.

  As described above, the color image forming apparatus of the embodiment of FIG. 5 has a black developing unit 44, a yellow developing unit 41, a magenta developing unit 42, a cyan developing unit 43, and a black developing unit 44. Is provided with a developing device 4 that conveys the toner to a position facing the photoconductor 1, and the selected developing device develops the photoconductor 1 at a common position. The use of such a developing device 4 in the color image forming apparatus of the present invention has a common peripheral length from a portion charged by the charger 2 of the photoreceptor 1 to a portion subjected to development. Regardless of the order of use, it is possible to carry out the present invention without the influence of the dark decay of the photosensitive member 1, and further, the charging of the photosensitive member 1 compared to the case where the developing device is separately arranged around the photosensitive member 1. The peripheral length L from the portion charged by the charger 2 to the portion to be developed by the developing device, and the portion from the portion charged by the charger 2 of the photosensitive member 1 to the portion to transfer the toner image on the photosensitive member 1 to the transfer material 9 Since it is easy to shorten the circumference LT, it is very preferable. Such a developing device 4 can be applied to both the above-described method of the first embodiment and the method of the third embodiment described later.

  Embodiment 3 FIG. 6 is a cross-sectional view of a color image forming apparatus showing another embodiment of the present invention. First, the color image forming process of this apparatus will be described. This color image forming apparatus superimposes a plurality of toner images on an intermediate transfer medium 55 that rotates in synchronization with the photosensitive member 1 and transfers the color toner image formed on the intermediate transfer medium 55 to a transfer material 9. Yes, it is generally called an intermediate transfer body method. In this method, since the toner image is transferred to the intermediate transfer medium 55 and then transferred to the transfer material 9, the selection range of the transfer material 9 can be widened, and a color image compatible with many types of transfer materials 9. Suitable for providing a forming apparatus.

  The photosensitive member 1 is rotationally driven by a driving source (not shown). Around the photosensitive member 1, a charger 2, a laser scanning optical system 3, a yellow developing device 41, a magenta developing device 42, a cyan developing device 43, and a black developing device. A belt-shaped intermediate transfer medium 55 and a cleaning device 6 which are wound around a roll 44, a roll-shaped primary transfer electrode 56 and driven by a drive source common to the photosensitive member 1 are disposed.

  First, the surface of the photosensitive member 1 is uniformly charged by the charger 2, the image is exposed according to the yellow image information by the laser scanning optical system 3 to form a latent image, and the latent image is developed by the yellow developer 41. A yellow toner image is formed.

  The intermediate transfer medium 55 is driven in synchronization with the photoreceptor 1, and the yellow toner image formed on the photoreceptor 1 is transferred to the intermediate transfer medium 55. After the toner image is transferred to the intermediate transfer medium 55, the toner remaining on the photosensitive member 1 is scraped off by the cleaning device 6, and the cleaned photosensitive member 1 can move to the next image forming process.

  When the development of the yellow toner image is finished and the transfer of the yellow toner image to the intermediate transfer medium 55 is finished, if the magenta latent image forming the next toner image cannot be formed, the yellow toner image When the development is completed, the driving of the photosensitive member 1 and the intermediate transfer medium 55 is stopped, and when the magenta latent image can be formed, the driving is started again.

  The photosensitive member 1 that has continued to rotate without stopping or has started rotating again is subjected to image exposure in accordance with magenta image information to form a latent image, and the magenta developing unit 42 develops the latent image, and intermediate transfer is performed. The magenta toner image is transferred onto the yellow toner image on the medium 55 so as to overlap it. Thereafter, similarly, a cyan toner image and a black toner image are superimposed and transferred to form a color toner image on the intermediate transfer medium 55.

  The transfer material 9 is sent to the secondary transfer portion by the paper feeding device 7, and after the color toner image on the intermediate transfer medium 55 is transferred by the secondary transfer electrode 57, it is sent to the fixing device 8. The fixing device 8 is controlled by heating, and the color toner image is fixed on the transfer material 9 by the fixing device and is output. The secondary transfer electrode 57 has a roll shape, and is separated from the intermediate transfer medium 55 in the process of forming a color toner image on the intermediate transfer medium 55, and faces the intermediate transfer medium 55 during transfer. The transfer material 9 is nipped and conveyed while being transferred.

  After the color toner image is transferred to the transfer material 9, the remaining toner on the intermediate transfer medium 55 is pressed against the photosensitive member 1 by the intermediate transfer medium cleaning device 61 when the color toner image is formed. The intermediate transfer medium 55 that has been scraped and cleaned can be transferred to the next color image forming process.

  As described above, the color image forming apparatus of FIG. 6 stops the rotation of the photosensitive member 1 as necessary after the completion of the development of each color and the transfer to the intermediate transfer medium 55 before the start of the exposure of the next color. The toner image is sequentially transferred onto the intermediate transfer medium 55 to form a color toner image, transferred to the transfer material 9, fixed, and output. Since the photosensitive member 1 is stopped before the start of the exposure of the next color, the timing of starting the image exposure corresponding to the image information of each color can be set according to the state in which the image information of each color is prepared. 2. Similar to the first embodiment described with reference to FIG. 3 and the second embodiment described with reference to FIG. 5, it does not include a huge memory element for image information, and corresponds to color image information transmitted at various speeds. A color image can be formed, an image forming operation can be started before all color image information is received, and a color image can be output in a short time after receiving the image information. Further, the effects of continuing the fixing temperature control of the fixing device 9 and continuing the rotation of the deflector 31 during the stop period in which the driving of the photosensitive member 1 is stopped for each color are the same as those in the first embodiment. It can be obtained as in Example 2.

  Here, in the case where the time from when the photosensitive member 1 is stopped to when it is rotated again is very long, the toner image formed by changing the latent image to be developed due to the influence of dark decay that attenuates the surface potential of the photosensitive member 1 However, even in this embodiment, even when the photosensitive member 1 is stopped for a long time as in the first and second embodiments, image formation can be performed without any problem, and the contents thereof will be described below. To do.

  In FIG. 6, L2 is a circumferential length from a portion of the photosensitive member 1 that is charged by the charger 2 to a portion of the photosensitive member 1 that receives development by the black developing unit 44 that is the most downstream developing unit in the rotation direction of the photosensitive member 1. L1 is a developing device located second from the downstream side in the rotation direction of the photosensitive member 1 from a portion of the photosensitive member 1 that is charged by the charger 2. The peripheral length (the length of the path along the moving direction of the photosensitive member 1) to the portion to be developed by a certain cyan developing device 43, and LT is the photosensitive member from the portion to be charged by the charger 2 of the photosensitive member 1. 1 is a circumference (a length of a path along the moving direction of the photosensitive member 1) to a portion where the toner image on 1 is transferred to the intermediate transfer medium 55.

  The circumferential length of the intermediate transfer medium 55 in the embodiment of FIG. 6 is slightly larger than the sum of the length LT and the length of the color image to be formed. Thus, even when the driving of the photosensitive member 1 and the intermediate transfer medium 55 is stopped when the transfer is completed, the driving is started again and the toner is transferred onto the toner image already formed on the intermediate transfer medium 55. The image can be formed on the photosensitive member 1 charged by the charger 2 after resumption of driving, and the surface of the photosensitive member 1 generated during the period when the photosensitive member 1 was stopped for the latent image formation. The influence of the change in potential is prevented.

  That is, since the toner images of the respective colors are transferred onto the intermediate transfer medium 55, the photoreceptor 1 does not form a latent image for the length obtained by subtracting the length of the color image formed from the peripheral length of the intermediate transfer medium 55. Rotate to. In this embodiment, the length of rotation of the photoconductor 1 without forming the latent image becomes larger than the length LT. When the transfer is stopped at the end of the transfer, the surface of the photoconductor 1 on which the next latent image is formed is After the rotation is resumed, the portion charged by the charger 2 is prevented from being affected by dark decay. Note that the photosensitive member 1 and the intermediate transfer medium 55 are driven so that their peripheral speeds substantially coincide.

  Here, assuming that the peripheral length of the intermediate transfer medium 55 is slightly larger than the sum of the length L1 and the length of the color image to be formed, the photosensitive member 1 and the intermediate transfer medium 55 are driven when the development of each color is completed. Also in the case of stopping, it is possible to prevent the influence of the dark decay of the photosensitive member 1 that occurs during the period in which the photosensitive member 1 is stopped, as described above, thereby preventing the intermediate transfer medium from the embodiment of FIG. 55 can be reduced in size. Further, by making the peripheral length of the intermediate transfer medium 55 larger than the sum of the length L2 and the length of the color image to be formed, it occurs in the period in which the photoreceptor 1 is stopped for the latent image formation regardless of the order of development. Similar to the first embodiment, the influence of the dark decay of the photosensitive member 1 is prevented.

  However, when the driving of the photoreceptor 1 and the intermediate transfer medium 55 is stopped when the development of the toner images of the respective colors is completed, the toner image formed on the photoreceptor 1 at the primary transfer site is transferred to the intermediate transfer medium 55. Since the transfer is stopped in the transferred state, it is necessary that the photosensitive member 1 and the intermediate transfer medium 55 are always stopped at the same speed and restarted without sliding, and sliding occurs. In such a case, the toner image may be rubbed and disturbed.

  For this reason, the circumferential length of the intermediate transfer medium 55 is defined as the circumferential length L1 from the portion of the photosensitive member 1 charged by the charger 2 to the portion of the photosensitive member 1 subjected to development by the selected developing device of the developing device 4 or By making it larger than the sum of the length of L2 and the color image to be formed, it is possible to form a color image without being affected by the dark decay of the photosensitive member 1 even when stopped for a long time. The length is made larger than the sum of the peripheral length LT from the portion of the photoreceptor 1 charged by the charger 2 to the portion where the toner image on the photoreceptor 1 is transferred to the intermediate transfer medium 55 and the color image to be formed. Thus, there is no influence of the dark decay of the photosensitive member 1, and even when the photosensitive member 1 and the intermediate transfer medium 55 slide when stopping and resuming driving, it is possible to form a color image that is not affected by this. preferable.

  As described above, the present invention is a transfer drum generally suitable for the miniaturization and cost reduction shown in the first embodiment, generally called a multiple development batch transfer system, and generally suitable for high image quality shown in the second embodiment. Implemented on a color image forming apparatus that repeats the operation of performing image exposure on a photoreceptor and developing with color toner, such as a system called a system and a system generally called an intermediate transfer body system with a wide selection range of transfer materials shown in the third embodiment. Is possible. Further, although the embodiments have been described with respect to a printer that receives an image signal from the outside and outputs a color image, the present invention is not limited to this, and an image information forming apparatus, an image reading apparatus, and an image processing are provided inside the apparatus. Various apparatuses including an apparatus, an image display apparatus and the like can also be implemented.

1 is a cross-sectional view of an apparatus showing an embodiment of a color image forming apparatus of the present invention. The block diagram which shows control of the Example of FIG. The time chart which shows the operation example of the Example of FIG. 6 is a time chart showing an example of operation of a conventional color image forming apparatus. FIG. 5 is a cross-sectional view of an apparatus showing another embodiment of the color image forming apparatus of the present invention. FIG. 6 is a cross-sectional view of a device showing still another embodiment of the color image forming apparatus of the present invention.

Explanation of symbols

      DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Laser scanning optical system 4 Developing device 6 Cleaning device 7 Feeding device 8 Fixing device 9 Transfer material 31 Deflector 41 Yellow developing device 42 Magenta developing device 43 Cyan developing device 44 Black developing device 51 Transfer electrode 52 Separation electrode 53 Transfer material carrier 54 Separation claw 55 Intermediate transfer medium 56 Primary transfer electrode 57 Secondary transfer electrode 61 Intermediate transfer medium cleaning device 100 Control means 101 Image information receiving unit 102 Memory element 103 Laser control means 104 Deflector rotation control means 105 Fixing temperature control means 106 Photoconductor driving means

Claims (4)

Uniform charging is applied to the rotating photoreceptor, image exposure is performed based on an image signal of a specific color, and the operation of developing the formed latent image with color toner is repeated for each color, and a plurality of toner images are superimposed. In a color image forming apparatus that forms a color toner image and transfers the color toner image to a transfer material,
Control means for stopping the circumferential movement of the photosensitive member after the development of each color and before the start of exposure of the next color;
Fixing means for heating and fixing the toner image transferred to the transfer material,
A color image forming apparatus, wherein the fixing unit is controlled to a temperature at which heat fixing is possible during a period in which the photosensitive member is stopped after the development of each color is completed and before the exposure of the next color is started.   The color image forming apparatus according to claim 1, wherein a plurality of toner images are superimposed on the photoconductor, and a color toner image formed on the photoconductor is transferred to the transfer material.   The color image forming apparatus according to claim 1, further comprising a transfer material carrier that rotates in synchronization with the photoconductor, and a plurality of toner images superimposed on the transfer material carried on the transfer agent carrier.   2. An intermediate transfer medium that rotates in synchronization with the photosensitive member, a plurality of toner images are superimposed on the intermediate transfer medium, and a color toner image formed on the intermediate transfer medium is transferred to the transfer material. The color image forming apparatus described.

Images