JP2008225305A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing an image formation start timing from being delayed due to a communication error. <P>SOLUTION: The image forming apparatus includes an LED array 42 with LED chips 44, and generates correction data to expose a recording medium by the LED array 42 is formed based on delivery time data set so as to make the light emission amounts of respective LEDs uniform and previously stored in an EEPROM 48. In transmitting the formed correction data to the LED array 42, whether the correction data is normally received or the abnormality occurs is identified, and when it is identified that the correction data is normal, differential data showing a difference between the correction data and the delivery time data is stored in the EEPROM 48, on the other hand, when it is identified that the correction data is not normal, the correction data is retransmitted, and when it is identified that the correction data is not normally received even though the data is retransmitted the prescribed number of times, the transmission of the correction data is stopped, and correction data reproduced based on the differential data and the delivery time data stored in the EEPROM 48 is used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In image forming apparatuses such as printers, copiers, and facsimiles, an information processing apparatus is incorporated together with driving parts such as a fan and a motor that are sources of noise when data is transmitted and received.

  In this type of image forming apparatus, it has been proposed to use an LED print head using LEDs as recording elements as the recording head.

  In general, an LED print head has an LED array in which LED chips in which a large number of LEDs are arranged in a line are arranged, and a plurality of rod lenses arranged in order to form an image of light output from the LEDs on the surface of the photoreceptor. And a SELFOC lens. In the image forming apparatus, each LED of the LED print head is driven based on the image data, light is output toward the photoconductor, and the light output by the Selfoc lens is imaged on the surface of the photoconductor. Perform exposure based on the image data of the photoconductor, and move the photoconductor and the LED print head relative to each other (this movement direction is referred to as the “sub-scanning direction”) to move the exposure position and form an image on the photoconductor To do.

  In such an image forming apparatus using an LED print head, the variation in the amount of output energy becomes unevenness in the exposure energy distribution, which appears on the image as a streak in the sub-scanning direction, causing a reduction in image quality.

  Therefore, in an image forming apparatus using an LED print head, it is necessary to correct the light emission amount and the light emission timing in accordance with the manufacturing variation for each LED element and the manufacturing variation of the chip.

  In order to perform this correction, correction data may be exchanged by communication between the image forming apparatus main body and the LED print head when the power is turned on or when printing is performed. If noise or a communication error occurs during transmission of this correction data, depending on the degree of noise, there is a risk of reducing the image quality, so it is necessary to repeat transmission until transmission of the correction data ends normally . For this reason, depending on the degree of noise or communication error, it takes a long time to start printing.

Conventionally, in an LED print head with a dot correction function, a plurality of sets of correction data are stored in a correction data storage ROM provided in the LED print head, and a user selects desired correction data from the plurality of sets of correction data. Thus, it has been proposed to configure so as to perform printing without printing unevenness according to the density (see, for example, Patent Document 1). However, this technique does not consider the case where it takes time to select / switch correction data due to a communication error or the like.
JP 2003-276245 A

  An object of the present invention is to provide an image forming apparatus capable of preventing a delay in image formation start timing due to a communication error.

  In order to solve the above problems, the invention described in claim 1 is an image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged, and the amount of light emitted from each light emitting element. Generating means for generating exposure correction data for exposing the recording medium by the recording head, based on the light amount correction data set to make the image uniform, and transmitting the exposure correction data to the recording head A transmission unit; a reception unit provided in the recording head for receiving the exposure correction data; and whether the exposure correction data is normally received by the reception unit and is received by the reception unit or whether an abnormality has occurred. An identification means for identifying the image, a holding means for holding the correction data for exposure, which is provided in the recording head and is identified as normal by the identification means, and the identification means When the received exposure correction data is identified as not normal, the exposure correction data is retransmitted by the transmitting means, and the retransmitting is performed by a predetermined number of times by the identifying means. A recording head for controlling the recording head to stop the transmission of the exposure correction data by the transmission unit and apply the exposure correction data held in the holding unit when it is not identified as being normally received Control means.

  According to the first aspect of the present invention, when the exposure correction data cannot be normally transmitted to the recording head, the exposure correction data is stopped and the exposure correction data held in the recording head is stored. Therefore, it is possible to prevent the image formation start timing from being delayed due to a communication error.

  The recording head holding means holds the exposure correction data identified as having been normally received by the identification means, so that exposure can be performed better than using the light amount correction data.

  According to a second aspect of the present invention, there is provided an image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged, in order to make the light emission amount of each light emitting element uniform. Based on the set light amount correction data, a generation unit that generates exposure correction data for exposing the recording medium by the recording head, a transmission unit that transmits the exposure correction data to the recording head, and the recording A receiving unit provided on the head for receiving the exposure correction data; and an identification unit provided on the recording head for identifying whether the exposure correction data has been normally received by the receiving unit or whether an abnormality has occurred. The difference between the light amount correction data and the light amount correction data provided in the recording head and the exposure correction data identified as normal by the identification unit and the light amount correction data. When the exposure correction data received by the identification means and the holding means for holding the difference data is identified as not normal, the exposure correction data is retransmitted by the transmission means, and a preset number of times When the re-transmission only does not identify that the data has been normally received by the identification unit, the transmission unit stops transmitting the exposure correction data, and the difference data held in the holding unit indicates The recording head is controlled to apply the correction data when the difference is smaller than a preset difference, and the exposure correction data derived based on the light amount correction data and the difference data in other cases. Recording head control means.

  According to the second aspect of the present invention, when the exposure correction data cannot be normally transmitted to the recording head, the transmission of the exposure correction data is stopped, the light amount correction data held in the recording head, and Since any of the exposure correction data derived based on the light amount correction data and the difference data is used, it is possible to prevent the image formation start timing from being delayed due to a communication error.

  In addition, since the light amount correction data and the difference data with a small capacity are held, the storage capacity for holding the light amount correction data and the exposure correction data can be saved as compared with the case where the light amount correction data and the exposure correction data are held separately. it can.

Furthermore, the invention described in claim 3 is an image forming apparatus provided with a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged, in order to make the light emission quantity of each light emitting element uniform. Based on the set light amount correction data, a generation unit that generates exposure correction data for exposing the recording medium by the recording head, a transmission unit that transmits the exposure correction data to the recording head, and the recording A receiving unit provided on the head for receiving the exposure correction data; and an identification unit provided on the recording head for identifying whether the exposure correction data has been normally received by the receiving unit or whether an abnormality has occurred. Detecting means for detecting an operating environmental temperature of the recording head; and the exposure correction data and the correction data provided in the recording head and generated by the generating means. The difference data indicating the difference between the data, along with the advance plural kinds held in each of the operating environment temperature, a holding means for holding the light quantity correction data,
When it is determined that the exposure correction data received by the identification means is not normal, the transmission correction data is retransmitted by the transmission means, and the retransmission is performed a predetermined number of times. The operating environment temperature detected by the detection means among the difference data held by the holding means when the transmission means stops sending the exposure correction data when the identification means does not identify that the data has been normally received. Recording head control means for controlling the recording head so as to derive and apply the exposure correction data based on the difference data corresponding to the correction data and the correction data.

  According to the third aspect of the present invention, when the exposure correction data cannot be normally transmitted to the recording head, the transmission of the exposure correction data is stopped, and a plurality of difference data held in the recording head are stored. Since the exposure correction data derived using either one is used, it is possible to prevent the image formation start timing from being delayed due to a communication error.

  In particular, paying attention to the characteristic that the amount of light emitted from the light-emitting element varies depending on the temperature, a plurality of types of difference data are held according to the operating environment temperature, and according to the operating environment temperature detected by the detecting means. Since the exposure correction data is derived using the difference data, fine control can be realized.

  In addition, the difference data corresponding to the operating environment temperature is stored together with the light amount correction data, and the exposure correction data is derived based on the difference data and the light amount correction data. As compared with the case where a plurality of correction data is held, the storage capacity for holding can be saved.

  Further, in the invention according to any one of claims 1 to 3, as in the invention according to claim 4, the recording head control means is configured so that the power supply to the recording head is started each time the power supply is started. The generating correction unit may generate the exposure correction data, and the transmission unit may transmit the exposure correction data.

  As described above, the present invention has an excellent effect of preventing the image formation start timing from being delayed due to a communication error. Further, as a secondary effect, not only the light amount correction data is used but also the stored exposure correction data is used, so that there is an effect that the deterioration in image quality is minimized. Further, when only the difference data is held, it can be held with a smaller capacity than storing all the correction data for exposure, which is useful for cost reduction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows a configuration of an image forming apparatus 10 according to the present embodiment. As shown in the figure, the image forming apparatus 10 has an endless belt-like intermediate transfer belt 14 that is stretched around a plurality of winding rollers 12 and conveyed in the direction of arrow E by driving a motor (not shown). A plurality of image forming units 15 (details will be described later) are arranged along the longitudinal direction.

  Note that the image forming apparatus 10 in the present embodiment also supports color image formation, and toners corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). Image forming units 15Y, 15M, 15C, and 15K that form images are provided. Hereinafter, the members provided for each color are shown by adding alphabets (Y / M / C / K) indicating the respective colors at the end of the reference numerals. The description will be made by omitting the alphabet at the end of the code.

  The different color toner images formed by the image forming units 15 are transferred onto the intermediate transfer belt 14 so as to overlap each other on the belt surface of the intermediate transfer belt 14. As a result, a color toner image is formed on the intermediate transfer belt 14. In this embodiment, the toner image in which the four color toner images are transferred in a superimposed manner is referred to as a final toner image.

  On the downstream side of the four image forming units 15 in the conveying direction of the intermediate transfer belt 14, a transfer device 26 including two rollers 26A and 26B facing each other is disposed. The final toner image formed on the intermediate transfer body belt 14 is sent between the rollers 26A and 26B, taken out from the paper tray 29 provided at the bottom of the image forming apparatus 10, and is similarly supplied to the rollers 26A and 26B. It is transferred to the paper 28 that has been conveyed in between.

  In addition, a fixing device 30 including a pressure roller 30A and a heating roller 30B is disposed on the conveyance path of the paper 28 onto which the final toner image has been transferred. The paper 28 conveyed to the fixing device 30 is nipped and conveyed by the pressure roller 30A and the heating roller 30B, whereby the toner on the paper 28 is melted and pressed against the paper 28 to be fixed. As a result, a desired image (color image) is formed on the paper 28. The paper 28 on which the image is formed is discharged out of the apparatus.

  On the other hand, a cleaner 32 that collects the toner remaining on the intermediate transfer belt without being transferred to the paper 28 by the transfer device 26 is disposed downstream of the transfer device 26 in the transport direction of the intermediate transfer belt 14. Yes. The cleaner 32 is provided with a blade 34 so as to be in contact with the intermediate transfer belt 14, and collects residual toner by rubbing it.

  FIG. 2 shows the configuration of the image forming unit 15. Since the configuration of the image forming unit 15 for each color is the same, the description will be made with the last symbol indicating each color omitted.

  As shown in the figure, the image forming unit 15 includes a photosensitive drum 16 that is disposed in contact with the intermediate transfer belt 14 and rotates at a predetermined speed in the arrow F direction.

  A charging roller 18 for uniformly charging the surface of the photosensitive drum 16 to a predetermined potential is disposed on the peripheral surface of each photosensitive drum 16. The charging roller 18 is a conductive roller, and its peripheral surface is in contact with the peripheral surface of the photosensitive drum 16, and is arranged so that the axial direction of the charging roller 18 coincides with the axial direction of the photosensitive drum 16. Has been.

  Further, an LED having a light source as an LED (light emitting diode) for forming an electrostatic latent image on the photosensitive drum 16 is provided on the peripheral surface downstream of the charging roller 18 in the rotation direction F of each photosensitive drum 16. A print head (LPH) 20 (details will be described later) is provided. The LPH 20 forms an electrostatic latent image on the photosensitive drum 16 by irradiating the photosensitive drum 16 with a light beam according to the image data.

  Further, an electrostatic latent image formed on the photosensitive drum 16 is surrounded by toner of a predetermined color (yellow / magenta / cyan / black) around the downstream side of the LPH 20 in the rotation direction F of each photosensitive drum 16. A developing device 22 for developing and forming a toner image is provided.

  As shown in the figure, the developing unit 22 includes a developing roller 38 and a blade 40 that are disposed close to the photosensitive drum 16. A developing bias is applied to the developing roller 38, and the toner loaded in the developing device 22 is attached to the peripheral surface. As the developing roller 38 rotates in the rotation direction G, the toner attached to the developing roller 38 is conveyed to the surface of the photosensitive drum 16, and the toner is rubbed against the photosensitive drum 16 to form on the photosensitive drum 16. The developed electrostatic latent image is developed.

  Further, a transfer roller 25 for transferring the toner image on each photoconductive drum 16 to the intermediate transfer belt 14 is provided around the downstream side of the developing device 22 in the rotation direction F of each photoconductive drum 16. . The transfer roller 25 is charged to a predetermined potential and rotates in a direction indicated by an arrow H to convey the intermediate transfer belt 14 at a predetermined speed and sequentially face the photosensitive drum 16. As a result, the transfer roller 25 transfers the toner on the photosensitive drum 16 onto the intermediate transfer belt 14.

  A cleaning blade 24 that collects residual toner such as transfer residual toner and retransfer toner on the photosensitive drum 16 is disposed downstream of the transfer roller 25 on the peripheral surface of the photosensitive drum 16. The cleaning blade 24 is arranged so that one side is in contact with the photosensitive drum 16, and toner remaining on the photosensitive drum 16 without being transferred to the intermediate transfer belt 14, or on the photosensitive drum 16 at the time of transfer. The toner of other colors that have adhered to the toner is scraped off and collected.

  FIG. 3 is a schematic diagram illustrating an example of the configuration of the LPH 20. As shown in the figure, the LPH 20 includes an LED array 42 and a selfoc lens array 46.

  As shown in the figure, in the LED array 42, a large number (for example, 256) of LEDs are arranged in a line on a printed circuit board 42A on which a circuit for supplying various signals for controlling the driving of the LED array 42 is formed. A plurality of LED chips 44 arranged in an array are arranged. The number of LEDs in the entire LED array 42 corresponds to the number of pixels (dots) corresponding to the resolution, for example, up to A3 size (420 mm × 297 mm) paper, and about 7020 when printing at 600 dpi in the main scanning direction. One is provided.

  Further, as shown in the figure, the LED chips 44 are arranged such that the arrangement directions of the respective LEDs coincide with the main scanning direction, and the positions of the plurality of LED chips 44 are alternately shifted by a predetermined pitch. They are arranged in the main scanning direction (staggered arrangement) and attached to the printed circuit board 42A. As described above, the staggered arrangement allows the positions of the LED chips 44 adjacent in the main scanning direction to be overlapped with each other so that the intervals between the LEDs do not vary.

  The LED chips 44 may be arranged in a line regardless of the staggered arrangement as long as the LEDs are arranged at regular intervals in the main scanning direction, or one LED chip 44 may be arranged instead of a plurality. May be arranged only.

  The SELFOC lens array 46 is provided between the LED array 42 and the photosensitive drum 16 as an imaging lens. The SELFOC lens array 46 is composed of, for example, refractive index distribution type rod lenses arranged at a pitch corresponding to each pixel (dot) corresponding to the resolution, and sensitizes the light beam emitted from each LED. An image is formed on the body drum 12.

  FIG. 4 is a block diagram illustrating a configuration of a control system in the image forming apparatus 10 according to the embodiment. As shown in the figure, the image forming apparatus 10 includes a main body control unit 66 that controls the operation of the entire apparatus.

  The main body control unit 66 includes a CPU (central processing unit) 50 that controls the operation of the entire apparatus, a ROM 52, a RAM 54, an image control circuit 56, an input / output port (I / O) 58, and a communication interface (I / F) 64. It is configured. These CPU 50, ROM 52, RAM 54, image control circuit 56, I / O port 58, and communication I / F 64 are each connected to the bus 51.

  The ROM 52 stores in advance various programs, various data, and the like including a control program that mainly controls the entire apparatus executed by the CPU 50. The RAM 54 temporarily stores various data associated with the processing of the CPU 50.

  The communication I / F 64 is connected to an external terminal by wire or wirelessly via a network or communication line (not shown), and receives image data to be recorded on the paper 28 from the external terminal.

  The I / O port 58 is connected to a motor 60 for driving each drive unit, a fan 62 for releasing heat in the apparatus, and the like. The I / O port 58 outputs a control signal from the CPU 50 to each part, and appropriately inputs a signal indicating an operation state of each part to the CPU 50.

  The image control circuit 56 is connected to the LED arrays 42Y, 42M, 42C, and 42K for the LPHs 20Y, 20M, 20C, and 20K for the respective colors. The image control circuit 56 performs predetermined processing on the image data input via the I / F 64 and converts the image data into a data structure that can be decoded by each of the CMYK color LED arrays 42Y, 42M, 42C, and 42K. It converts and outputs to each LED array 42Y, 42M, 42C, 42K.

  Further, in the image control circuit 56, each time the power of the LED array 42 is turned on, correction data for eliminating the manufacturing variation of the LED chips 44 constituting the LED arrays 42Y, 42M, 42C, and 42K is stored in each LED array. It is generated every 42Y, 42M, 42C, 42K. The generated correction data is output to each LED array 42Y, 42M, 42C, 42K. The correction data includes correction information such as the light emission amount and the light emission timing.

  Each of the LED arrays 42Y, 42M, 42C, and 42K includes a head control circuit 40, a plurality of LED chips 44, and an EEPROM 48. The EEPROM 48 and each LED chip 44 are connected to the head control circuit 40, respectively. .

  In the EEPROM 48, correction data (hereinafter referred to as “shipment data”) for eliminating the manufacturing variation of each LED chip 44 at the time of shipment of the LPH 20 from the factory is stored in advance.

  That is, the amount of light emitted when the same drive control is performed on each LED included in the LED chip 44 is not the same. Therefore, correction data for setting the light emission amount of each LED to a preset reference light amount is derived in advance at the time of factory shipment of each LED chip 44 and stored as shipment data.

  The head control circuit 40 temporarily stores the image data input from the image control unit 56 and the correction data generated and output by the image control circuit 56 in a temporary storage area (RAM) in the head control circuit 40. It memorize | stores and drives each LED of the LED chip 44 based on these information.

  FIG. 5 shows a control function block diagram relating to generation and communication of correction data. As shown in the figure, the image control unit 56 includes an LED print head (LPH) control unit 72 and a correction data generation unit 74. The LPH control unit 72 is connected to the correction data generation unit 74 and the LED array 42.

  When a signal indicating that the LED array 42 is to be turned on is input to the image control unit 56, the power supply control unit (not shown) is instructed to supply power to the LED array 42, and the LPH control unit The power supply start processing for the head drive circuit 40 is executed by 72.

  In the LPH control unit 72, as a power supply start process, an output of a transmission request for shipping data to the LED array 42, a correction data generation instruction based on the received shipping data to the correction data generation unit 74, and a correction data generation unit 74 Processing such as transmission of the generated correction data to the head drive circuit 40 and detection of occurrence of an abnormality in the communication state is executed.

  The correction data generation unit 74 further updates the shipping data based on information according to manufacturing variations and changes over time in the characteristics of each part related to image formation of the image forming apparatus 10. In other words, since the shipping data is data for each LED chip 44 for making the amount of light uniform, an assembly error when incorporating the image forming apparatus 10 into the image forming apparatus 10, a slight inclination of the surface of the photosensitive drum 16, and the like. The light emission timing and light emission are further considered by taking into consideration the optical path difference caused by distortion, the assembly error when incorporating into the LED array 42, and the correction of the light emission timing in consideration of the displacement in the sub-scanning direction due to the staggered arrangement. Correction data is generated so as to adjust the amount of light and the like.

  In this embodiment, after the correction data is transmitted, the LPH control unit 72 transmits a correction data return request to the LED array 42, and the correction data returned from the LED array 42 in response to the request. However, if it matches the correction data transmitted by the LPH control unit 72, it is determined that the transmission state is normal, and a correction data reflection instruction is transmitted to the LED array 42. On the other hand, if the returned correction data does not match the transmitted correction data, it is determined as a communication error and the same correction data is transmitted (retransmission).

  Whether or not the correction data matches can be determined by using, for example, a method of adding a checksum to the end of data to be transmitted. In this case, the data to be transmitted as correction data is regarded as a numerical value, the sum of the numerical values is derived as a checksum at the end of the data, and based on the sum of the numerical values derived based on the transmitted correction data and the returned correction data Compared with the sum of the numerical values derived in this way, if they match, it is judged normal. On the other hand, if they do not match, it is determined that a communication error has occurred.

  In addition, the LPH control unit 72 detects that the communication state is abnormal when the correction data cannot be normally transmitted even if the re-transmission is repeatedly performed a predetermined number of times (M). When detecting an abnormality in the communication state, the LPH control unit 72 stops the transmission of correction data in the current power supply start process and transmits a reset signal indicating self-recovery to the LED array 42.

  On the other hand, the head drive circuit 40 of the LED array 42 includes an operation control unit 80, a data creation unit 82, and a chip drive unit 84. The operation control unit 80 is connected to a correction data storage unit (EEPROM) 48, a data creation unit 82, and a chip drive unit 84.

  The operation control unit 80 is connected to the LPH control unit 72 of the image control unit 56, and controls the operation of the LPH 20 (LED array 42) based on a control signal and image data input from the LPH control unit 72.

  When the operation control unit 80 receives the shipment data transmission request, the operation control unit 80 reads the shipment data from the correction data storage unit 48 and transmits it to the LPH control unit 72.

  When the operation control unit 80 receives the correction data transmitted from the LPH control unit 72, the operation control unit 80 temporarily stores the correction data in the built-in RAM.

  In this embodiment, when a correction data return request is received from the LPH control unit 72, the operation control unit 80 returns the received correction data and issues an instruction to reflect the correction data from the LPH control unit 72. When the data is received, the received correction data is output to the chip control unit 84, and the data creation unit 82 creates differential data. When creating the difference data, the shipping data read from the correction data storage unit 48, the received correction data, and a difference data creation instruction are output to the data creation unit 82.

  When the operation control unit 80 receives the reset signal from the LPH control unit 72, the operation control unit 80 reads out the shipping data and the difference data from the correction data storage unit 48 and outputs the data to the data creation unit 82. Outputs the instruction to reproduce the previous correction data.

  In the data creation unit 82, when a difference data creation instruction is input from the operation control unit 80, creation of difference data indicating a difference between the shipping data and the correction data and output of the created difference data to the operation control unit 80. I do.

  When the difference data created by the data creation unit 82 is input, the operation control unit 80 updates the difference data in the correction data storage unit 48 to the created difference data.

  In addition, when an instruction to reproduce the previous correction data is input, the data creation unit 82 creates reproduction correction data and outputs the reproduction data to the chip control unit 84.

  The chip drive unit 84 is connected to each LED chip 44 provided in the LED array 42, and image data input via the operation control unit 80 and correction data input via the operation control unit 80 or A drive signal for each LED generated based on the reproduction correction data input from the data creation unit 82 is supplied to each LED chip 44 to control the lighting state of each LED.

  Next, the operation of the present embodiment will be described.

  FIG. 6 is a flowchart showing an example of the flow of power supply start processing according to the present embodiment. Note that this power supply start processing is performed when power is supplied to the image forming apparatus 10 main body or power supply to some parts including the LED array 42 although the power of the image forming apparatus 10 itself in the power saving mode or the like is not cut off. This is part of the processing that is mainly executed by the CPU 50 when returning from a state where the power is shut off to a normal operation state.

  First, in step 100, 0 is set (reset) in the error count E, and in the next step 102, a shipping data transmission request is transmitted to the LED array 42, and then the process proceeds to step 104.

  In step 104, reception of shipment data from the LED array 42 is waited. In the next step 106, correction data is generated according to the received shipment data and the state of the image forming apparatus 10.

  Note that the state of the image forming apparatus 10 includes an assembling error when assembled in the image forming apparatus 10, an optical path difference caused by a slight inclination or distortion of the surface of the photosensitive drum 16, and assembling when assembled in the LED array 42. For example, correction of light emission timing in consideration of an error and an arrangement position shift in the sub-scanning direction due to the staggered arrangement. The correction data includes data corresponding to the light emission timing and the light emission amount for each LED.

  In step 108, transmission of correction data to the LED array 42 is executed. In the next step 109, a reply request for the transmitted correction data is transmitted, and then the process proceeds to step 110.

  In step 110, the correction data is waited for in response, and then the process proceeds to step 112 to determine whether or not the returned correction data is normal. If the determination is negative, the process proceeds to step 114.

  In step 114, 1 is added to the number of errors E, and then the process proceeds to step 116. Whether or not the number of errors E is smaller than a preset threshold value M (M is the number of times the correction data is retransmitted). Determine whether. If the determination is affirmative, the process proceeds to step 118 to retransmit the correction data, and then returns to step 109 again.

  On the other hand, if a negative determination is made in step 116, it is determined that the communication state is abnormal, the process proceeds to step 120, a transmission stop signal is transmitted to the LED array 42, and then the process proceeds to step 122.

  Here, the larger the threshold M, the longer the time required for the power supply start processing and the time until the start of image formation, but the probability that the generated correction data can be transmitted increases. On the other hand, the smaller the threshold M, the shorter the time required for the power supply start process and the time until the start of image formation, but the probability that the generated correction data can be transmitted becomes lower. Therefore, the threshold value M can be set as appropriate depending on the frequency of occurrence of communication errors, the degree to which the delay in image formation and image quality deterioration are allowed, and the like.

  Note that the threshold value M may be set to 0 when a delay in time until the start of image formation cannot be tolerated. In this case, when an error signal is received, retransmission is not performed.

  The threshold value M may be configured to be changeable during maintenance or the like, or may be configured to be changeable by the user.

  On the other hand, if an affirmative determination is made in step 112, the process proceeds to step 113, a correction data reflection instruction is transmitted to the LED array 42, and then the process proceeds to step 122.

  In step 122, it is determined whether or not to end the power supply start process. The determination is affirmative when the correction data for all the LED chips 44 of all the LED arrays 42 is a processing target, and the power supply start processing ends. If there is correction data that has not yet been processed in this power supply start process, the determination in step 122 is negative, and the correction data that has not yet been processed is returned to step 100 again. .

  FIG. 7 shows a flowchart of an example of the flow of the reception data reflection process executed when the LED array 42 receives the reception data reflection instruction transmitted from the LPH control unit 72 in the power supply start process. Yes.

  First, in step 136, the received correction data is output to the chip controller 84 and reflected. The chip control unit 84 reflects the correction data by changing the control parameters of the LEDs of the LED chip 44 corresponding to the correction data based on the correction data.

  In the next step 138, difference data is created based on the received correction data and the shipping data stored in the correction data storage unit 48. Thereafter, the process proceeds to step 140, the difference data is updated, and the received data reflection process is terminated. Thereby, the difference data stored in the correction data storage unit 48 is set as data based on the correction data received normally.

  That is, when the communication state between the image control unit 56 and the LED array 42 is good, the correction data is normally received, and the received correction data is reflected in the subsequent control of the LED chip 44. At this time, difference data is created and stored in the correction data storage unit 48 so that the latest correction data can be derived.

  FIG. 8 shows, as an example, a flowchart showing the flow of reset signal reception processing executed when the LED array 42 receives a reset signal transmitted from the image control unit 56 in the power supply start processing. Yes.

  First, in step 150, the shipping data and difference data stored in the correction data storage unit 48 are read, and the process proceeds to the next step 152 to create reproduction correction data based on the shipping data and difference data.

  In the next step 154, the created reproduction correction data is output and reflected on the chip controller 84, and then the reset signal reception process is terminated.

  The chip control unit 84 reflects the reproduction correction data by changing the control parameters of each LED of the LED chip 44 corresponding to the reproduction correction data based on the reproduction correction data.

  As described above, according to the present embodiment, the LED array 42 provided with the LED chip 44 in which a plurality of LEDs are arranged as a light emitting element is provided, and set to make the light emission amount of each LED uniform. When the correction data for exposing the recording medium is generated by the LED array 42 based on the shipping data stored in the EEPROM 48 in advance, and the generated correction data is transmitted to the LED array 42, the correction data is normal. If it is identified whether it is received or abnormal, and if it is identified as normal, difference data indicating the difference between the correction data and the shipping data is stored in the EEPROM 48, and the received exposure correction data is normal. If it is determined that it is not, the correction data is retransmitted, and even if it is retransmitted a preset number of times, it is received normally. If it is not identified, the transmission of the correction data is stopped, and the correction data reproduced from the most recently received correction data derived based on the difference data held in the EEPROM 48 and the shipping data is applied. Therefore, it is possible to prevent the image formation start timing from being delayed.

  By preventing the delay of the image formation start timing, not only the waiting time of the user can be reduced, but also the driving time of peripheral components such as the photosensitive drum 16 and the intermediate transfer belt 14 is reduced. It can prevent wear and life reduction.

  In this embodiment, the number of communication errors is accumulated every time correction data is transmitted, and a reset signal is transmitted when a predetermined number of times is reached. It is not limited.

  For example, the number of errors in a preset period unit may be accumulated, and a reset signal may be transmitted when a predetermined number is reached.

  Further, the threshold value M may be selected according to a mode such as color printing or monochrome printing. For example, in the case of black-and-white printing, power supply processing is performed only on the black LED array 42K, so adjustment with the image forming units 15 of other colors is unnecessary. For this reason, in the case of monochrome printing, there is no problem even if the threshold value M is set extremely small. Furthermore, in the case of black and white printing, generation and communication itself are not performed, but reproduction correction data derived using the difference data held in the EEPROM 48 is used, and in the case of color printing, the threshold value M is set to 100, for example. The communication may be configured to succeed as much as possible.

  Further, in the present embodiment, a mode in which only one difference data is held has been described, but a mode in which a plurality of difference data is held in accordance with a processing pattern and a process to be executed is selected based on the processing pattern. It can also be.

  For example, a plurality of types of difference data are held according to the operating environment temperature of the LPH 20, and a temperature detection sensor for detecting the operating environment temperature of the LPH 20 is installed inside the image forming apparatus 10, and according to the detected temperature. Difference data can be used.

  Note that the configuration of the image forming apparatus 10 (see FIGS. 1 to 4) and the flow of processing (see FIGS. 5 to 8) in the above embodiment are merely examples, and can be changed as appropriate.

  For example, in the above-described embodiment, the mode in which the image control circuit 56 determines whether or not there is a communication error has been described. However, the determination and the determination of whether there is a communication abnormality may be performed by the CPU 50.

(Other forms)
Further, in the above embodiment, the mode of determining the communication state on the main body control unit side has been described. However, the present invention is not limited to this, and the head drive circuit 40 on the LPH 20 (LED array 42) side includes A communication state determination function may be provided.

  Other forms of processing on the main body control unit side and processing on the LED array 42 side will be described with reference to FIGS. 9 to 11.

  The configuration of the image forming apparatus according to another embodiment is the same as the configuration of the image forming apparatus 10 according to the above embodiment, and only the function of each circuit is different. Therefore, illustration and description are omitted.

  FIG. 9 is a flowchart showing an example of the flow of power supply start processing according to another embodiment. The other power supply start processing is performed when power to the image forming apparatus 10 main body is turned on or power to some parts including the LED array 42 although the power of the image forming apparatus 10 itself such as the power saving mode is not turned off. This is part of the processing that is executed mainly by the CPU 50 when returning from the state where the supply of power is interrupted to the normal operation state.

  First, in step 200, 0 is set (reset) in the error count E, and in the next step 202, a shipping data transmission request is transmitted to the LED array 42, and then the process proceeds to step 204.

  In step 204, reception of shipment data from the LED array 42 is waited. In the next step 206, correction data is generated according to the received shipment data and the state of the image forming apparatus 10.

  Note that the state of the image forming apparatus 10 includes an assembling error when assembled in the image forming apparatus 10, an optical path difference caused by a slight inclination or distortion of the surface of the photosensitive drum 16, and assembling when assembled in the LED array 42. For example, correction of light emission timing in consideration of an error and an arrangement position shift in the sub-scanning direction due to the staggered arrangement. The correction data includes data corresponding to the light emission timing and the light emission amount for each LED.

  In step 208, correction data is transmitted to the LED array 42, and in the next step 210, reception of a reception signal is awaited.

  When the received signal is received, the process proceeds to the next step 212 to determine whether or not the received signal is good. If the determination is negative, the process proceeds to step 214.

  In step 214, 1 is added to the error number E, and then the process proceeds to step 216. Whether the error number E is smaller than a preset threshold value M (M is the number of times the correction data is retransmitted). Determine whether. If the determination is affirmative, the process proceeds to step 218, the correction data is retransmitted, and then the process returns to step 210 again.

  On the other hand, if a negative determination is made in step 216, it is determined that the communication state is abnormal, the process proceeds to step 220, a transmission stop signal is transmitted to the LED array 42, and then the process proceeds to step 222.

  Here, the larger the threshold M, the longer the time required for the power supply start processing and the time until the start of image formation, but the probability that the generated correction data can be transmitted increases. On the other hand, the smaller the threshold M, the shorter the time required for the power supply start process and the time until the start of image formation, but the probability that the generated correction data can be transmitted becomes lower. Therefore, the threshold value M can be set as appropriate depending on the frequency of occurrence of communication errors, the degree to which the delay in image formation and image quality deterioration are allowed, and the like.

  Note that the threshold value M may be set to 0 when a delay in time until the start of image formation cannot be tolerated. In this case, when an error signal is received, retransmission is not performed.

  The threshold value M may be configured to be changeable during maintenance or the like, or may be configured to be changeable by the user.

  On the other hand, if the determination in step 212 is affirmative, the process proceeds to step 222.

  In step 222, it is determined whether or not to end the power supply start process. The determination is affirmative when the correction data for all the LED chips 44 of all the LED arrays 42 is a processing target, and the power supply start processing ends. If there is correction data that has not yet been processed in the power supply start process, the determination in step 222 is negative, and the correction data that has not been processed yet returns to step 200 again. .

  FIG. 10 is a flowchart showing an example of the flow of correction data reception processing executed when the LED array 42 receives correction data generated in the power supply start processing.

  First, in step 230, it is checked whether the received data is normal. In the next step 232, it is determined whether the received data is normal as a result of the check.

  If the determination in step 232 is affirmative, the process proceeds to step 234, a reception signal indicating a good signal is transmitted to the image control unit 56 side, and then the process proceeds to step 236, where the received correction data is subjected to chip control. This is output to the unit 84 and reflected.

  Note that the chip control unit 84 reflects the correction data by changing the control parameters of each LED of the LED chip 44 corresponding to the correction data based on the correction data.

  In the next step 238, difference data is created based on the received correction data and the shipping data stored in the correction data storage unit 48. Thereafter, the process proceeds to step 240, the difference data is updated, and the correction data reception process is terminated. Thereby, the difference data stored in the correction data storage unit 48 is made data based on the received correction data.

  On the other hand, if it is determined that the received data is not normal, a negative determination is made in step 232, the process proceeds to step 242 and a reception signal indicating an error signal is transmitted to the image control unit 56 side, and steps 234 to 240 are performed. The correction data reception process is terminated without executing the process.

  That is, when the communication state between the image control unit 56 and the LED array 42 is good, the correction data is normally received, and the received correction data is reflected in the subsequent control of the LED chip 44. At this time, difference data is created and stored in the correction data storage unit 48 so that the latest correction data can be derived.

  FIG. 11 shows, as an example, a flowchart showing the flow of the reproduction correction data creation process executed when the LED array 42 receives the transmission stop signal transmitted from the image control unit 56 in the power supply start process. Has been.

  First, in step 250, the shipping data and difference data stored in the correction data storage unit 48 are read, and the process proceeds to the next step 252 to create reproduction correction data based on the shipping data and difference data.

  In the next step 254, the created reproduction correction data is output to the chip control unit 84 and reflected, and then the reproduction correction data creation process is terminated.

  The chip control unit 84 reflects the reproduction correction data by changing the control parameters of each LED of the LED chip 44 corresponding to the reproduction correction data based on the reproduction correction data.

1 shows an overall configuration of an image forming apparatus according to an embodiment. 1 is a schematic diagram illustrating a configuration of an image forming unit according to an embodiment. It is the schematic which shows the structure of the LED print head which concerns on embodiment. 1 is a block diagram illustrating an outline of a configuration of an electric system of an image forming apparatus according to an embodiment. 3 is a functional block diagram related to communication control between an image control unit and an LPH of the image forming apparatus according to the embodiment. FIG. It is a flowchart which shows the flow of the power supply start process which concerns on embodiment. It is a flowchart which shows the flow of the reception data reflection process which concerns on embodiment. It is a flowchart which shows the flow of the reset signal reception process which concerns on embodiment. It is a flowchart which shows the flow of the power supply start process which concerns on another form. It is a flowchart which shows the flow of the correction data reception process which concerns on another form. It is a flowchart which shows the flow of the reproduction correction data creation process which concerns on another form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Intermediate transfer belt 16 Photosensitive drum 18 Charging roller 20 LED print head 22 Developer 24 Cleaning blade 40 Head control circuit (receiving means)
42 LED array (recording head)
44 LED chip (light emitting element array)
46 Selfoc lens array 48 EEPROM (holding means)
50 CPU
51 bus 52 ROM
54 RAM
56 Image control circuit (generation means, transmission means, recording head control means, identification means)
58 I / O port 60 Motor 62 Fan 66 Main unit controller

Claims (5)

An image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged,
Generating means for generating exposure correction data for exposing the recording medium by the recording head based on the light amount correction data set to make the light emission amount of each light emitting element uniform;
Transmitting means for transmitting the exposure correction data to the recording head;
A receiving means provided in the recording head for receiving the exposure correction data;
Identifying means for identifying whether the correction data for exposure received by the receiving means is normal or abnormal;
A holding unit that is provided in the recording head and holds exposure correction data identified as normal by the identification unit;
When it is determined that the exposure correction data received by the identification means is not normal, the exposure correction data is retransmitted by the transmission means, and the retransmission is performed for a preset number of times or time. If the identification means does not identify that the data has been normally received, the recording head is adapted to stop the transmission of the exposure correction data by the transmission means and apply the exposure correction data held in the holding means. Recording head control means for controlling
An image forming apparatus. An image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged,
Generating means for generating exposure correction data for exposing the recording medium by the recording head based on the light amount correction data set to make the light emission amount of each light emitting element uniform;
Transmitting means for transmitting the exposure correction data to the recording head;
A receiving means provided in the recording head for receiving the exposure correction data;
Identifying means for identifying whether the correction data for exposure received by the receiving means is normal or abnormal;
A holding unit that is provided in the recording head and holds difference data indicating a difference between the light amount correction data and the exposure correction data identified as normal by the identification unit and the light amount correction data;
When it is determined that the exposure correction data received by the identification means is not normal, the exposure correction data is retransmitted by the transmission means, and the retransmission is performed for a preset number of times or time. If the identification means does not identify that the data has been received normally, the transmission means stops transmitting the exposure correction data and applies the exposure correction data derived based on the light amount correction data and the difference data. A recording head control means for controlling the recording head,
An image forming apparatus. An image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged,
Generating means for generating exposure correction data for exposing the recording medium by the recording head based on the light amount correction data set to make the light emission amount of each light emitting element uniform;
Transmitting means for transmitting the exposure correction data to the recording head;
A receiving means provided in the recording head for receiving the exposure correction data;
Identifying means for identifying whether the correction data for exposure received by the receiving means is normal or abnormal;
A holding unit that is provided in the recording head and holds difference data indicating a difference between the light amount correction data and the exposure correction data identified as normal by the identification unit and the light amount correction data;
When it is determined that the exposure correction data received by the identification means is not normal, the exposure correction data is retransmitted by the transmission means, and the retransmission is performed for a preset number of times or time. If the identification means does not identify that the data has been received normally, the transmission means stops transmitting the exposure correction data, and the difference indicated by the difference data held in the holding means is greater than a preset difference. Recording head control means for controlling the recording head so as to apply the correction data in the other case, and in other cases, exposure correction data derived based on the light amount correction data and the difference data;
An image forming apparatus. An image forming apparatus including a recording head provided with a light emitting element array in which a plurality of light emitting elements are arranged,
Generating means for generating exposure correction data for exposing the recording medium by the recording head based on the light amount correction data set to make the light emission amount of each light emitting element uniform;
Transmitting means for transmitting the exposure correction data to the recording head;
A receiving means provided in the recording head for receiving the exposure correction data;
Identifying means for identifying whether the correction data for exposure received by the receiving means is normal or abnormal;
Detecting means for detecting an operating environment temperature of the recording head;
A plurality of types of difference data indicating the difference between the correction data for exposure and the correction data provided by the generation unit provided in the recording head are held in advance for each operating environment temperature, and the light amount correction data is stored. Holding means for holding;
When it is determined that the exposure correction data received by the identification means is not normal, the exposure correction data is retransmitted by the transmission means, and the retransmission is performed for a preset number of times or time. If the identification means does not identify that the data has been received normally, the transmission means stops transmitting the exposure correction data, and the detection means detects the difference data held in the holding means. A recording head control means for controlling the recording head so as to derive and apply the exposure correction data based on difference data according to an environmental temperature and the light amount correction data;
An image forming apparatus.   The recording head control unit generates the exposure correction data by the generation unit and transmits the exposure correction data by the transmission unit every time power supply to the recording head is started. The image forming apparatus according to any one of claims 1 to 4.

Images