JP2019168568A - Image forming device - Google Patents

Abstract

To provide an image forming device with which it is possible to print with high productivity without omitting the detection of a carried toner amount in fixing temperature control.SOLUTION: The image forming device comprises: read means (105) for reading a document by moving an image sensor; image processing means (115) for processing the image data of the document read by the read means on the basis of previously set setting information; image analysis means (116) for detecting a carried amount of toner on the basis of the image data processed by the image processing means; image analysis execution determination means (123) for determining whether or not the image analysis means is executable, on the basis of the setting information used by the image processing means; and fixing means (133) for determining a fixing temperature on the basis of the carried amount of toner detected by the image analysis means. When it is determined by the image analysis execution determination means that the image analysis means is executable, the carried amount of toner is detected by the image analysis means while the image sensor is moving.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus that thermally fixes a toner image formed by an electrophotographic method onto a transfer sheet.

  In recent years, there has been an increasing market demand for energy saving and high speed for OA devices such as printers and copiers. In an image forming apparatus that thermally fixes a toner image formed by an electrophotographic method onto a transfer paper, it is important to improve the power consumption and fixing speed of the fixing device in order to achieve these required performances.

  Usually, the fixing temperature and fixing speed of the fixing device are determined in consideration of the maximum amount of color material that can be placed on the transfer paper in order to obtain stable fixing properties. In a full-color copying machine, an image is formed by superimposing a plurality of color materials such as CMYK (cyan, magenta, yellow, and black). Tend to increase). Further, since the toner application amount is closely related to an area where the image forming apparatus can express a color (hereinafter referred to as a color reproduction area), a sufficient toner application amount is required to maintain high image quality.

  However, when the toner application amount of the entire image exceeds a predetermined value, or when the toner is applied so as to fill a continuous area of a predetermined size determined by the characteristics of the fixing device (hereinafter referred to as a “detection area”), A high fixing temperature or a long fixing time is required. In the former case, power consumption increases, and in the latter case, the printing speed decreases. Therefore, the fixing temperature and fixing speed of the fixing device are changed according to the maximum amount of applied toner in the image.

  In addition, there is a problem that high-speed printing cannot be performed in the case of an image forming apparatus that takes time to perform image processing and toner application amount detection itself. When the detection of the toner application amount is not completed within a predetermined time, there is a technique that controls the fixing temperature adjustment based on a provisional toner application value (see Patent Document 1).

Japanese Patent Laying-Open No. 2015-206984

  However, in Patent Document 1 described above, since the fixing temperature adjustment is performed based on the provisional toner application amount, not the toner application amount calculated by image analysis, accurate fixing temperature adjustment control cannot be performed.

  The present invention has been made in view of the above problems, and the present invention has been made in view of such problems. An image capable of accurate fixing temperature control while suppressing a decrease in printing speed. An object is to provide a forming apparatus.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a reading unit that reads an original by moving an image sensor, and an image that performs image processing on image data of the original read by the reading unit based on preset setting information. A processing unit, an image analysis execution determination unit that determines whether or not to perform image analysis for fixing temperature adjustment based on setting information used by the image processing unit, and a toner load based on image data image-processed by the image processing unit An image analysis unit that detects the amount of toner and a fixing unit that determines a fixing temperature based on the amount of applied toner detected by the image analysis unit, and the image analysis execution determination unit determines that the image analysis unit can be implemented. In this case, the amount of applied toner is detected by the image analysis means while the image sensor of the reading means is moving.

  According to the present invention, it is possible to perform accurate fixing temperature control while suppressing a decrease in printing speed.

2 is a hardware block diagram of the image forming apparatus. FIG. 1 is a configuration diagram of a scanner of an image forming apparatus. 2 is a block diagram of an image processing unit of the image forming apparatus. FIG. 1 is a diagram illustrating a configuration of an image forming apparatus. FIG. 6 is a diagram illustrating a relationship between a toner loading value and a fixing temperature. It is a flowchart which shows the copy process of a process control part. 6 is a flowchart illustrating document reading processing of a scanner I / F. It is a flowchart which shows the image analysis implementation availability determination process of an image analysis implementation determination part. 6 is a flowchart illustrating toner applied amount detection processing. FIG. 6 is a diagram illustrating toner applied amount detection processing. It is a figure which shows the effect of image analysis implementation judgment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a hardware block diagram of the entire image forming apparatus according to the present embodiment. In the figure, a control unit 102 including a bus 110 and a CPU 111 controls the overall operation of the image forming apparatus 101. The bus 110 is a data path between structural elements included in the control unit 102. The CPU 111 reads out a control program stored in the ROM 112 and performs various controls such as reading / printing / communication. The RAM 113 is used as a temporary storage area such as a main memory or work area for the CPU 111. The storage 114 stores image data and various programs. The process control unit 122 controls the execution order of processes in the control unit 102. The control unit 102 further includes various interfaces (I / F) and a system bus 110.

  The image analysis unit 116 analyzes the image data and determines the necessity of fixing temperature control and the fixing temperature. The operation unit I / F 117 connects the operation unit 103 and the control unit 102. The operation unit 103 is provided with a display panel, and has a role of receiving an operation / input / instruction by the user and requesting the control unit 103 to instruct a process. A network I / F 118 connects the control unit 102 (image forming apparatus 101) to a wired LAN or a wireless LAN. The serial I / F 119 connects the control unit 102 (image forming apparatus 101) to an external device.

  The image forming apparatus 101 can transmit and receive image data and various types of information to and from an external apparatus via the network I / F 118 and the serial I / F 119. For example, the image forming apparatus 101 can receive print data from an external apparatus and print it with the printer 104, and can transmit the image data read by the scanner 105 to the external apparatus. A printer I / F 120 connects the printer 104 and the control unit 102. Image data to be printed by the printer 104 is transferred from the control unit 102 via the printer I / F 120 and printed on a recording material by the printer 104. The printer 104 has an image forming unit 133, a paper transport unit 134, a fixing device unit 135, and a temperature detection unit 136. The image forming unit 131 forms a toner image of data supplied from the printer I / F 120 on the transfer belt.

  The paper transport unit 132 transports the paper to the toner image position on the transfer belt. The fixing device unit 133 fixes the toner image on the paper by heating and pressurizing to a desired temperature using the temperature detecting unit 134 that is in contact with the fixing device unit 133. The scanner I / F 121 connects the scanner 105 and the control unit 102. The scanner 105 reads an image on a document to generate image data, and inputs the image data to the control unit 102 via the scanner I / F 121. The image processing unit 115 performs image processing such as color tone correction, binarization, color space conversion, and filter processing on the image data developed in the RAM 113, and performs image data conforming to a predetermined standard such as JBIG or JPEG. A processing unit that performs encoding and decoding. Based on the image processing setting information of the image processing unit 115, the image analysis execution determining unit 123 determines whether or not fixing temperature adjustment image analysis can be performed.

  FIG. 2 is a diagram illustrating a configuration example of the scanner 105. The scanner 105 includes a scanner lower part 201 and a scanner upper part 202. The upper scanner portion 201 includes a reflector that reflects the light emitted from the light sources 205 and 206 of the lower scanner portion 202. The scanner lower part 202 includes a document table 203 and an image sensor 204. The document table 203 is composed of a transparent plate such as a glass plate. The scanner upper part 201 can be opened and closed with respect to the scanner lower part 202 by an opening / closing mechanism (not shown). By opening and closing the scanner upper part 201, the scanner 105 can exchange a document placed on the document table 203.

  The image sensor 204 in the lower scanner section 202 functions as an original image reading unit on the original table 203. The image sensor 204 includes a pair of light sources 205 and 206, a lens 207, and a photoelectric conversion unit 208 as irradiation means. Light emitted from the LED light sources 205 and 206 is reflected by the surface of the document placed on the document table 203, and the reflected light is input to the photoelectric conversion unit 208 via the lens 207. The photoelectric conversion unit 208 generates image data by converting the input reflected light into an electrical signal. The LED light sources 205 and 206 have a plurality of LED elements and light guides arranged along the main scanning direction (depth direction in FIG. 2). The LED light sources 205 and 206 irradiate the surface of the document through the light guide with the light emitted from each LED element. The photoelectric conversion unit 208 includes a plurality of photoelectric elements arranged in the main scanning direction.

  FIG. 3 is a diagram illustrating a configuration example of the image processing unit 115. The image processing unit 115 includes an input DMA unit 311 and an output DMA unit 312 that perform transmission and reception of image data, a JBIG unit 301 that performs image processing on the image data, a JPEG unit 302, a scaling unit 303, a RIP unit 304, and 2 It consists of a value unit 305. The operation of each unit can be changed by image processing setting information received from the processing control unit 122.

  The input DMA unit 311 outputs the data input from the I / F connected to the bus 110 or the RAM 113 to the JBIG unit 301, JPEG unit 302, scaling unit 303, RIP unit 304, and binarization unit 305. To do. The JBIG unit 301 decompresses JBIG-compressed image data input from the input DMA unit 311 and outputs the image data to the output DMA unit 312. Alternatively, JBIG compression is performed on the bitmap format image data input from the input DMA unit 311 and output to the output DMA unit 312. The JPEG unit 302 decompresses JPEG-compressed image data input from the input DMA unit 311 and outputs the image data to the output DMA unit 312. Alternatively, JPEG compression is performed on the bitmap format image data input from the input DMA unit 311 and output to the output DMA unit 312.

  The scaling unit 303 enlarges or reduces the bitmap format image data input from the input DMA unit 311 based on a value set in advance in the scaling unit 303 and outputs the image data to the output DMA unit 312. Based on the values set in advance in the RIP unit 304 for the intermediate data generated from the PDL data input from the RIP unit 304 and the input DMA unit 311, image data in bitmap format is generated, and the output DMA unit 312. Output to. The binarization unit 305 performs binary bit map format image data based on a value set in advance in the binarization unit 305 with respect to the multilevel bit map format image data input from the input DMA unit 311. Is generated and output to the output DMA unit 312. The output DMA unit 312 inputs data from the JBIG unit 301, the JPEG unit 302, the scaling unit 303, the RIP unit 304, and the binarization unit 305, and connects to the bus 110 based on values set in advance in the DMA unit. The image data is output to the I / F or RAM 113.

  FIG. 4 is a cross-sectional view of the printer 104. The printer 104 transfers the toner image formed on the photosensitive drum 11 to the sheet P, fixes the image on the sheet P with the fixing device 40, and forms an image on the sheet P. The printer 0122 includes an image forming unit 10 that forms toner images of respective colors of Y (yellow), M (magenta), C (cyan), and Bk (black). The image forming unit 10 includes four photosensitive drums 11 (11Y, 11M, 11C, and 11Bk) corresponding to the colors Y, M, C, and Bk in order from the left side of FIG.

  Around each photosensitive drum 11, a charger 12, a laser scanner unit 13, a developing device 14, a primary transfer blade 17, and a cleaner 15 are arranged. The photosensitive drum 11 is rotationally driven in the arrow direction (counterclockwise direction in FIG. 4) by a driving source. Around the photosensitive drum 11, a charger 12, a laser scanner unit 13, a developing device 14, a primary transfer blade 17, and a cleaner 15 are arranged in order along the rotation direction. The surface of the photosensitive drum 11 is charged in advance by a charger 12. Thereafter, the photosensitive drum 11 is exposed by a laser scanner unit 13 that emits laser light in accordance with image information to form an electrostatic latent image. The electrostatic latent image is converted into a Bk color toner image by the developing device 14. At this time, the same process is performed for the other colors.

  The toner images on the respective photosensitive drums 11 are sequentially primary transferred onto the intermediate transfer belt 31 by the primary transfer blade 17. After the primary transfer, the toner remaining without being transferred to the photosensitive drum 11 is removed by the cleaner 15. In this way, the surface of the photosensitive drum 11 is cleaned, and the next image can be formed. The sheets P placed on the feeding cassette 20 or the multi-feed tray 25 are fed one by one by the feeding mechanism and fed to the registration roller pair 23. The registration roller pair 23 temporarily stops the sheet P, and corrects the direction of the sheet P when the sheet P is skewed with respect to the conveyance direction. The registration roller pair 23 sends the sheet P between the intermediate transfer belt 31 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 31. The roller 35 transfers the color toner image on the belt 31 to the sheet P. Thereafter, the sheet P is fed toward the fixing device 40.

  The fixing device 40 heats and pressurizes the toner image on the sheet P to fix it on the sheet P. The sheet P that has exited the fixing device 40 passes through a conveyance path and is sent out onto a paper discharge tray by a paper discharge roller. When duplex printing is specified, the sheet printed on the first side is sent out onto the paper discharge tray by the paper discharge roller, and immediately before the trailing edge passes through the paper discharge roller, Rotation is converted to reverse. As a result, the sheet P is switched back and introduced into the re-conveying path. Then, the front and back surfaces are reversed and conveyed to the registration roller pair 23 again. Thereafter, as in the case of the first side, it is transferred and fixed, and is discharged as a double-sided printed matter.

  FIG. 5 illustrates a method for calculating the fixing temperature necessary for fixing the target page according to the detected toner amount as a result of the toner amount detection. As described above, the toner application amount means the toner application amount per unit area on the image data. In order to fix the toner on the recording paper without causing a fixing failure, it is necessary to set the temperature of the fixing device 40 to a fixing temperature at which the maximum amount of applied toner in the target page can be reliably fixed. At this time, since the maximum amount of applied toner differs depending on the image data to be printed, the temperature required for fixing also differs for each image data. The larger the maximum amount of applied toner, the higher the temperature required for the fixing device 40 to fix the toner.

  FIG. 5B is a diagram showing the relationship between the toner amount in the image forming apparatus 101 according to the present embodiment and the fixing temperature required for the toner fixing by the fixing device 40. In FIG. 5A, the horizontal axis indicates the amount of applied toner, and the vertical axis indicates the temperature required for the fixing device 40 to fix the toner onto the recording paper.

  In FIG. 5A, for example, when the result of toner application amount detection is 200%, the minimum temperature required for toner fixing is T1. Similarly, when the applied toner amount detection results are 150%, 100%, and 50%, the minimum temperatures required for toner fixing are T2, T3, and T4, respectively. If the fixing temperature of the fixing device 40 is increased to a temperature at which the maximum toner load value appearing in the image data can be fixed, a problem of toner fixing failure may occur when the toner related to the image data is subjected to toner fixing processing. There is no. Therefore, the minimum temperature necessary for fixing the toner to be printed can be obtained from the result of the toner amount detection.

  FIG. 5B is a diagram showing a data table in which the relationship between the applied toner amount and the fixing temperature of the fixing device 40 is normalized. In FIG. 5B, for example, when the result of toner application amount detection is 200% or more, the lowest temperature required for the fixing device 40 to fix the toner onto the recording paper is the highest reference temperature (ref). On the other hand, when the result of detecting the amount of applied toner is 50% or less, the minimum temperature required for the fixing device 40 to fix the toner onto the recording paper 11 is 10 degrees lower than the reference temperature (ref) (ref-10 °). Can be seen.

  Copy processing of the processing control unit 122 in this embodiment will be described with reference to the flowchart of FIG. The processing control unit 122 receives a copy execution instruction from the operation unit 117 (S601). The processing control unit 122 transmits a document reading instruction to the scanner I / F 121 (S602). Subsequently, in order to sequentially perform image processing on the image data read by the scanner I / F 121, the processing control unit 122 transmits image processing setting information and an image processing execution instruction to the image processing unit 115 (S603). When the reading of the document is completed, the processing control unit 122 receives a document reading completion notification from the scanner I / F 121 (S604). When the image processing is completed, the processing control unit 122 receives an image processing completion notification from the image processing unit 115 (S605).

  Subsequently, the processing control unit 122 transmits the image processing setting information of the image processing unit 115 and the image analysis execution determination instruction to the image analysis execution determination unit 123 (S606). The process control unit 122 receives an image analysis execution determination notification from the image analysis execution determination unit 123 (S607). If image analysis can be performed, the process proceeds to step S609. If image analysis cannot be performed, the process proceeds to step S611.

  In step S609, an image analysis instruction is transmitted to the image analysis unit 116 to perform image analysis. When the image analysis is completed, the process control unit 122 receives an image analysis result notification from the image analysis unit 116 (S610). In step S611, a sensor movement completion notification is received from the scanner I / F 121. After receiving the sensor movement completion notification, if a print instruction is received from the operation unit 103 in step S612, the process proceeds to step S613. If a print instruction has not been received, the process proceeds to step S616.

  In step S616, when a reading instruction for the next original is received from the operation unit, the process proceeds to step S602, where the original is read again. For example, when it is necessary to read a plurality of originals as in 4 in 1 printing, an instruction to read the next original may be received from the operation unit 103. In step S613, if image analysis has been performed in step S610, the process proceeds to step S614. If image analysis has not been performed, the process proceeds to step S617. In step S614, based on the image analysis result received from the image analysis unit 116, the processing control unit 122 transmits a fixing temperature adjustment control instruction to the printer I / F 120. Subsequently, a print start instruction is transmitted to the printer I / F, and printing is started.

  A document reading process of the scanner I / F 121 in the present embodiment will be described with reference to a flowchart of FIG. The scanner I / F 121 receives a document reading instruction from the processing control unit 122 (S701). The scanner I / F 121 transmits a document reading instruction to the scanner 105 (S702). The image data read and generated by the scanner 105 is sequentially transmitted to the image processing unit 115.

  When the reading of the document is completed, the scanner I / F 121 receives a document reading completion notification from the scanner 105. In order to return the image sensor to the position before reading the document, the scanner I / F transmits an image sensor movement instruction to the scanner 105 (S704). When the movement of the image sensor is completed, the scanner I / F 121 receives an image sensor movement completion notification from the scanner 105 (S705). The scanner I / F transmits an image sensor movement completion notification to the processing control unit (S706).

  The document reading process of the scanner I / F 121 in the present embodiment will be described with reference to the flowchart of FIG.

  The image analysis execution determination unit 123 receives the image processing setting information and the image analysis execution determination instruction from the processing control unit 122 (S801). It is determined from the image processing setting information whether or not layout processing (enlargement / reduction / rotation processing) is required for the image data read by the scanner 105 (S802). If layout processing is not necessary, the applied toner amount can be calculated from the image read by the scanner 105.

  Therefore, the process proceeds to step S803 to notify the processing control unit that image analysis can be performed. If layout processing is necessary, the process proceeds to step S803. If layout processing is necessary, the applied toner amount cannot be calculated from the image read by the scanner 105. Therefore, the process proceeds to step S804, and the processing control unit is notified that image analysis cannot be performed.

  FIG. 9A is a flowchart showing the applied toner amount detection process in the present embodiment. Note that the CPU 103 performs the applied toner amount detection processing shown in the flowchart. First, in step S901, a one-line search window is set at the upper end of the image for the input bitmap format image data. In step S <b> 902, the amount of applied toner in units of lines is calculated for the line in which the search window is set. FIG. 10 is a diagram for explaining the applied toner amount detection process in the present embodiment. 1011 in FIG. 10 is the amount of applied toner in line units.

  In step S <b> 903, the smaller amount of the applied toner amount in units of lines obtained in step S <b> 902 and the continuous line result stored in the RAM 113 are overwritten in the RAM 1004 as new continuous line results. If no value is held in the continuous line result, the applied toner amount in units of lines obtained in S902 is stored in the RAM 113 as a new continuous line result. As indicated by reference numeral 1012 in FIG. 10, the minimum value of the toner applied amount of eight consecutive lines is set as a continuous line result 1013.

  If it is determined in S904 that the position of the search window is on a line that is a multiple of 8 from the top, the process proceeds to S906. If the position of the search window is on a line other than a multiple of 8 from the top, the process proceeds to S905.

  In S905, the search window is moved down one line, and the process returns to S902. In step S <b> 906, the larger of the continuous line result stored in the RAM 113 and the final result stored in the RAM 113 is overwritten in the RAM 113 as a new final result. If no value is held in the final result, the continuous line result is stored in the RAM 113 as a new final result. As indicated by reference numeral 1014 in FIG. 10, the maximum value among the continuous line results is set as the final result of the applied toner amount. If the position of the search window is at the lower end of the image in S907, the process proceeds to S908. If the position of the search window is not at the lower end of the image, the process proceeds to S905. In step S908, the final result stored in the RAM 113 is stored in the RAM 113 as the amount of applied toner of the image.

  FIG. 9B is a flowchart showing the applied toner amount detection processing for each line in the present embodiment. It should be noted that the CPU 111 performs the applied toner amount detection processing for each line shown in the flowchart. First, in S911, a search window of 16 × 1 pixels is set at the left end of the image for the input bitmap format image data. There is a search window as 1002 in FIG. In S912, the applied toner amount is calculated for the pixel group in which the search window is set. The sum of the density of each color is obtained for each pixel, and the sum of the highest density among the pixels in the search window is set as the toner application amount.

  In S <b> 913, the larger amount of the applied toner amount obtained in S <b> 912 and the line result stored in the RAM 113 is overwritten in the RAM 113 as a new line result. If no value is held in the line result, the applied toner amount obtained in S912 is stored in the RAM 113 as a new line result. As indicated by 1003 in FIG. 10, the maximum value among the line results is set as the toner applied amount of this line. In S914, if the position of the search window is at the right end of the image, the process proceeds to S916. If the position of the search window is not at the right end of the image, the process proceeds to S915.

  In S915, the search window is moved 4 pixels to the right, and the process returns to S912. In step S <b> 916, the line result stored in the RAM 113 is stored in the RAM 113 as the applied toner amount of this line.

  FIG. 11 is a diagram showing the effect of image analysis execution determination in the present embodiment. FIG. 11A is a diagram illustrating timing from document reading to printing in a conventional copy process. For page N, when the processing control unit 122 receives a copy execution instruction from the operation unit 103, it requests the scanner I / F 121 to read a document.

  Next, the processing control unit 122 waits for the image sensor movement completion notification of the scanner I / F 121 and instructs the scanner I / F to read the N + 1 page document. Then, after all the scanner I / Fs read all the originals, image analysis and printing of each page are performed. FIG. 11B is a diagram illustrating timing from document reading to printing in the copy processing according to the present embodiment. For page N, when the processing control unit 122 receives a copy execution instruction from the operation unit 103, it requests the scanner I / F 121 to read a document.

  After receiving the document reading completion notification from the scanner I / F 121, the processing control unit 122 transmits an image analysis execution determination instruction by the image analysis execution determination unit 123. When the image analysis execution determination unit 123 determines that image analysis can be performed, the image analysis instruction is immediately transmitted to the image analysis unit 116. For this reason, it is possible to perform image analysis during movement of the image sensor 204 as compared with the conventional case.

  As a result, it can be seen that the printing time per page is shorter in FIG. 11B than in FIG. According to this embodiment, by performing image analysis while the image sensor 204 is moving, it is possible to shorten the printing time per page without omitting image analysis processing.

105 Scanner 116 Image Analysis Unit 123 Image Analysis Execution Determination Unit 133 Fixing Device Unit 204 Image Sensor

Claims (1)

Reading means for reading a document by moving an image sensor;
Image processing means for performing image processing on image data of a document read by the reading means based on preset setting information;
Image analysis execution determination means for determining whether or not to perform image analysis for fixing temperature control based on setting information used by the image processing means;
Image analysis means for detecting the amount of applied toner based on the image data image-processed by the image processing means;
Fixing means for determining a fixing temperature based on the amount of applied toner detected by the image analysis means,
When the image analysis execution determination unit determines that the image analysis unit can be executed, the image analysis unit detects the amount of applied toner while the image sensor of the reading unit is moving. Image forming apparatus.