JP2016127547A - Image forming apparatus and data transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and a data transmission method that are able to transmit a variety of information with fewer signal lines in addition to image data composed of C, M, Y, and K.SOLUTION: An image forming apparatus comprises: a transmission part 32 that transmits predetermined information other than image data by using this image data composed of C, M, Y, and K components and using values not obtainable by this image data, to a transmission path 25 for transmitting image data composed of the C, M, Y, and K color components; and a receiving part 22 that receives data transmitted through the transmission path 25, the receiving part 22, when the received data is a value obtainable by image data composed of the C, M, Y, and K color components, outputting this data as image data composed of the C, M, Y, and K color components, the receiving part 22, when the received data is a value not obtainable by image data composed of the C, M, Y, and K color components, converting the data into predetermined information and outputting the information.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus and a data transmission method for transmitting data such as image data to an image forming unit through a transmission path.

  In general, a color image forming apparatus forms a color image using a plurality of basic color toners and inks such as C (cyan), M (magenta), Y (yellow), and K (black). When the print job is input, the image forming apparatus analyzes the print data by the controller to generate image data (RIP processing), and transfers the generated image data to the image forming unit through the transmission path for printing. In the RIP process, density data (for example, 8-bit data) for each color component of C, M, Y, and K, and TAG (A) data indicating attributes such as characters / photos are generated.

  Furthermore, in recent years, an increasing number of customers desire to form images by accurately reproducing specific colors (special colors) that cannot be expressed by combinations of C, M, Y, and K color materials. For example, as shown in FIG. 10, it is desired that the spot color used for the company logo 100 be accurately reproduced on the printed matter. In order to meet such a demand, the image forming apparatus is required to support printing of spot color data.

  On the other hand, the amount of data to be transmitted from the controller to the image forming unit is increasing due to high image quality (multi-bit). If a cable having a large bus width (having a large number of lanes) is used to send a large amount of data at high speed, problems such as cable layout performance, quality deterioration, and cost increase will occur.

  For example, as shown in FIG. 11, in an image forming apparatus that does not support spot colors, C, M, Y, K, and A data and a horizontal synchronization signal ( HV), vertical synchronizing signal (VV), index signal (IDX) and the like are transmitted. In order to cope with the spot color, a signal line for transmitting the density data (X) of the spot color is further required as shown in FIG. Therefore, if the bus width of the cable is increased or a new cable is laid, the above-described problem becomes more remarkable.

  Patent Document 1 below shows whether or not a pixel for which an image is to be formed with a special color by expanding the number of bits of the TAG plane. In the case of a special color, the density data of the special color is replaced with the M color data instead of the C color data. Instead, an image forming apparatus that transmits the type of spot color is disclosed.

JP 2010-278494 A

  In the technique disclosed in Patent Document 1, it is necessary to extend the bits of the TAG plane, or when the extension cannot be performed, it is necessary to reduce the TAG information.

  Further, it is desirable that the number of signal lines between the controller and the image forming unit is as small as possible. For example, it is desired that signal lines for transmitting a synchronization signal such as a horizontal synchronization signal (HV) and a vertical synchronization signal (VV), a command between pages, and the like are also reduced.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a data transmission method capable of transmitting various information in addition to normal image data to an image forming unit with a small number of signal lines. The purpose is that.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] An image forming apparatus for transmitting data to an image forming unit using a transmission path for transmitting image data composed of a plurality of color components,
A transmission unit that transmits predetermined information other than the image data to the transmission path using the image data and a value that the image data cannot take;
When data transmitted through the transmission path is received, and when the received data is a value that the image data can take, the data is output as the image data, and the data is a value that the image data cannot take A receiving unit that converts the data into the predetermined information and outputs the information;
An image forming apparatus comprising:

  In the above invention and the invention described in [11] below, normal image data and information other than the image data can be transmitted through a transmission path for transmitting normal image data. Therefore, there is no need to add signal lines for transmitting information other than image data.

[2] In the image data, the maximum value of the sum of the plurality of color components is limited to a predetermined limit value that is smaller than the sum of the maximum values that each of the color components can take.
The image forming apparatus according to [1], wherein the transmission unit transmits the predetermined information using a value exceeding the limit value.

  In the above invention and the invention described in [12] below, predetermined information is transmitted using a region where the total value of the color components exceeds the limit value.

[3] The image forming apparatus according to [2], wherein the transmission unit transmits a plurality of types of information with different values exceeding the limit value.

  In the above invention and the invention described in [13] below, when there are a plurality of values in a region that is less than the sum of the maximum values that each color component can take and exceeds the limit value, the values that exceed the limit value are made different. Transmit multiple types of information.

[4] The transmission unit, when transmitting the predetermined information, generates a value exceeding the limit value only with a predetermined part of the plurality of color components. The image forming apparatus according to [2] or [3].

[5] The image forming apparatus according to [4], wherein the transmission unit transmits the predetermined information using color components other than the predetermined part of the color components.

  In the above invention and the inventions described in [4] and [14] and [15] below, various information can be transmitted by freely using other color components.

[6] Any one of [1] to [5], wherein the predetermined information includes spot color information for forming an image using a color material having a spot color different from the plurality of color components. The image forming apparatus according to one.

  In the above invention and the invention described in [16] below, the image data of the special color can be transmitted without increasing the number of signal lines.

[7] The image forming apparatus according to [6], wherein the transmission unit selects whether to transmit the image data or the spot color information in units of pixels.

[8] The image forming apparatus according to any one of [1] to [7], wherein the predetermined information includes an image synchronization signal.

  In the above invention and the invention described in [18] below, since the image synchronization signal can be transmitted using the transmission path for transmitting the image data, the number of signal lines conventionally provided for transmitting the synchronization signal is reduced. Can do.

[9] The image forming apparatus according to [8], wherein the predetermined information includes a predetermined command transmitted when the synchronization signal indicates that it is outside an effective area of the image.

  In the above invention and the invention described in [19] below, various commands can be transmitted using a transmission path for transmitting image data, so that the signal lines conventionally provided for transmitting these commands are reduced. be able to.

[10] The image forming apparatus according to any one of [1] to [9], wherein the transmission path includes a signal line for each color component.

[11] A data transmission method for transmitting data to an image forming unit using a transmission path for transmitting image data composed of a plurality of color components,
Using the transmission path, the image data and a predetermined information other than the image data are transmitted to the image forming unit using a value that the image data cannot take.
A data transmission method characterized by the above.

[12] In the image data, the maximum value of the sum of the plurality of color components is limited to a predetermined limit value that is smaller than the sum of the maximum values that each of the color components can take.
The data transmission method according to [11], wherein the predetermined information is transmitted using a value exceeding the limit value.

[13] The data transmission method according to [12], wherein a plurality of types of information are transmitted with different values exceeding the limit value.

[14] When the predetermined information is transmitted, a value exceeding the limit value is generated only by a predetermined part of the plurality of color components. [12] or [13] ] The data transmission method according to claim 1.

[15] The data transmission method according to [14], wherein the predetermined information is transmitted using color components other than the predetermined part of the color components.

[16] Any one of [11] to [15], wherein the predetermined information includes spot color information for forming an image using a color material having a spot color different from the plurality of color components. The data transmission method according to one.

[17] The data transmission method according to [16], wherein whether to transmit the image data or the spot color information is selected for each pixel.

[18] The data transmission method according to any one of [11] to [17], wherein the predetermined information includes an image synchronization signal.

[19] The data transmission method according to [18], wherein the predetermined information includes a predetermined command that is transmitted when the synchronization signal indicates that it is outside an effective area of an image.

[20] The data transmission method according to any one of [11] to [19], wherein the transmission path includes a signal line for each of the color components.

  According to the image forming apparatus and the data transmission method of the present invention, it is possible to further transmit other information using a transmission path for transmitting normal image data. It is possible to transmit data, and an increase in the number of signal lines can be prevented, and further the number of signal lines can be reduced.

1 is a diagram illustrating a schematic configuration of an image forming system according to an embodiment of the present invention. 2 is a block diagram illustrating a configuration of a portion that transmits data from a controller to the image forming apparatus main body. FIG. FIG. 5 is a diagram illustrating a relationship between a maximum toner amount and a toner amount limit value. FIG. 6 is a diagram illustrating an example of a method for reducing a toner amount to be equal to or less than a toner amount limit value. It is a figure which shows the data etc. which a transmission part produces | generates when a special color is used with the one part line of 1 line of main scanning direction. It is a figure which shows the data etc. which a transmission part produces | generates when the special color Z is used by the one part line pixel of a main scanning direction, and the special color S is used by another part. It is a figure which shows the example which embedded the synchronizing signal of the image in the component of C, M, Y, K. It is a figure which shows the example which embedded RXD and CTS in the component of C, M, and Y. It is a figure which shows an example of the conversion table showing the relationship between the data before embedding (and after decompression | restoration) and the data transmitted to a transmission line (data after embedding). It is a figure which shows an example of the image in which a spot color is used. FIG. 3 is a diagram illustrating an image data transmission system in an image forming apparatus that forms an image using C, M, Y, K, and A image data. FIG. 6 is a diagram illustrating an image data transmission system in a conventional image forming apparatus when a spot color is added.

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

  FIG. 1 is a diagram showing a schematic configuration of an image forming system 2 according to an embodiment of the present invention. The image forming system 2 has a copy function for forming and outputting a document image optically read by the scanner unit 8 on recording paper, and forming an image based on print data input from the outside on the recording paper. It performs the printing function to output. The image forming system 2 includes an image forming apparatus main body 5, a paper feeding device 6 connected to the front stage of the image forming apparatus main body 5, a post-processing apparatus 7 connected to the rear stage of the image forming apparatus main body 5, and print data. A controller 3 for analyzing and generating image data (RIP processing) is provided. The image forming apparatus includes an image forming apparatus main body 5 and a controller 3.

  The paper feeding device 6 can accommodate a large amount of recording paper and sends the recording paper one by one to the image forming apparatus main body 5 at the time of printing. The post-processing device 7 functions to perform processing such as folding, binding, and punching on the recording paper output from the image forming apparatus main body 5 and to store a large amount of printed recording paper. The controller 3 and the image forming apparatus main body 5 are connected by a transmission path 25.

  The image forming apparatus body 5 forms a two-dimensional image in which pixels are arranged in a main scanning direction and a sub-scanning direction orthogonal to the main scanning direction. The image forming apparatus main body 5 includes an engine (image forming unit) 10, an overall control unit 20 that performs control of operation of the entire apparatus, image processing such as tilt correction (skew correction), minute magnification change, and the like. A receiving unit 22 for receiving the data. The engine 10 includes an intermediate transfer belt 11 having a predetermined width that is looped endlessly, and yellow (Y), magenta (M), and cyan (color) that form a single color toner image on the intermediate transfer belt 11. C) Four image forming units 12Y, 12M, 12C, 12K, and 12Z for each color of black (K) and special color (Z), and a toner image formed on the recording paper are heated and fixed on the recording paper. A fixing device 13 to be used. The image forming units 12Y, 12M, 12C, 12K, and 12Z for each color are collectively referred to as the image forming unit 12.

  A normal image is formed as a color image using the image forming units 12Y, 12M, 12C, and 12K having C, M, Y, and K color components. The special color Z is a special color requested by a customer or the like. The special color Z is a color that cannot be accurately reproduced by a combination of C, M, Y, and K. For pixels that form an image using the special color Z, only the special color Z toner is used, and the C, M, Y, and K toners are not used. That is, whether to form an image using C, M, Y, or K toners or to form an image using the special color Z is selected on a pixel basis.

  The image forming units 12Y, 12M, 12C, 12K, and 12Z have the same structure although the colors of the toners used are different. The image forming units 12Y, 12M, 12C, 12K, and 12Z each have a cylindrical photosensitive drum 14 as an electrostatic latent image carrier on which an electrostatic latent image is formed. A device, a transfer device, a cleaning device, and the like are arranged and provided. Further, a laser unit 16 including a laser diode (LD) which is a laser element, a polygon mirror, various lenses, a mirror, and the like is provided. Further, the image forming units 12Y, 12M, 12C, 12K, and 12Z include an LD control unit that drives a laser diode of the corresponding laser unit 16.

  In each of the image forming units 12Y, 12M, 12C, 12K, and 12Z, the photosensitive drum 14 is driven by a driving unit (not shown) to rotate in a certain direction, and the charging device uniformly charges the photosensitive drum 14 to perform laser processing. The unit 16 forms an electrostatic latent image on the surface of the photosensitive drum 14 by scanning the photosensitive drum 14 (scanning in the main scanning direction) with a laser beam that is on / off controlled according to the image data of the corresponding color. To do.

  The developing device visualizes the electrostatic latent image on the photosensitive drum 14 with toner. The toner image formed on the surface of the photosensitive drum 14 is transferred to the intermediate transfer belt 11 at a location where it contacts the intermediate transfer belt 11. The cleaning device removes and collects toner remaining on the surface of the photosensitive drum 14 after the transfer by rubbing with a blade or the like.

  The intermediate transfer belt 11 is wound around a plurality of rollers and circulates in the direction of arrow A in the figure. In the process of turning, each color image (toner image) in the order of Y, M, C, K, and Z is superimposed on the intermediate transfer belt 11 by the image forming units 12Y, 12M, 12C, 12K, and 12Z, and is a full-color color image. Is synthesized. For the pixels using the spot color, only the spot color toner image is formed on the intermediate transfer belt 11. This color image is transferred from the intermediate transfer belt 11 to the recording paper at the secondary transfer position D. Further, the toner remaining on the intermediate transfer belt 11 is removed by a cleaning device 17 provided downstream of the secondary transfer position D. The fixing device 13 is provided at a position downstream of the secondary transfer position D in the middle of the recording paper conveyance path 18.

  The conveyance path 18 functions to convey the recording paper fed from the paper feeding device 6, pass the secondary transfer position D and the fixing device 13, and discharge the recording paper to the post-processing device 7 at the subsequent stage. The conveyance path 18 includes a conveyance roller and a guide that form a conveyance path, and a motor that drives the conveyance roller.

  In addition, the image forming apparatus main body 5 includes a scanner unit 8 that reads a document set on a document table by a user, an operation panel 9 that receives operations from the user and displays various screens.

  FIG. 2 is a diagram illustrating a portion related to transmission of image data. The controller 3 performs RIP processing on the print data to generate image data, outputs a synchronization signal and various commands to the image forming apparatus main body 5, and an image input from the image processing unit 31. A transmission unit 32 is provided that performs data embedding processing for reducing the number of signal lines necessary for transmission, a synchronization signal, and a command, and transmits the data, the synchronization signal, and the command to the image forming apparatus main body 5. The controller 3 may be configured as a server.

  The image processing unit 31 includes, as image data, density data (8 bits each) for each color component of C, M, Y, K, and Z, and TAG data indicating attributes such as whether each pixel is a character or a photograph (A) is generated. For pixels that do not use a spot color, image data having C, M, Y, K, and A as components is generated, and for pixels that use a spot color, image data having only Z and A as components are generated.

  Further, the image processing unit 31 is turned on from the head of the line in the main scanning direction to the end of the line, and the horizontal synchronization signal (HV) is turned off during the blanking period between the lines. Vertical synchronization signal (VV) which is turned on until the end and turned off in the blanking period between lines, an index signal (IDX) indicating the start position of the effective pixel for each line, an RXD signal used for serial communication, A CTS signal or the like is output. HV indicates an image area in the main scanning direction, VV indicates an image area in the sub-scanning direction, and IDX indicates a scanning timing of the laser beam.

  The transmission unit 32 has only the transmission path 25 for transmitting the C, M, Y, K, and A components in parallel, and the image data of each of the C, M, Y, K, A, and Z components, and the horizontal synchronization signal. (HV), vertical synchronization signal (VV), index signal (IDX), RXD signal, CTS signal information is embedded so as to be transmitted. Details of the embedding process will be described later.

  The receiving unit 22 included in the image forming apparatus main body 5 receives the data transmitted from the transmitting unit 32 of the controller 3 and performs a restoration process for restoring the data to the state before the embedding process. Here, the receiving unit 22 transmits data transmitted through a transmission path 25 for transmitting C, M, Y, K, and A components in parallel to each of C, M, Y, K, A, and Z. The information of the component image data, the horizontal synchronization signal (HV), the vertical synchronization signal (VV), the index signal (IDX), the RXD signal, and the CTS signal is restored and output to the overall control unit 20. Note that the overall control unit 20 also performs image processing such as cue correction and minute scaling on the image data output from the receiving unit 22. The overall control unit 20 outputs the C, M, Y, K, and A component signals, the horizontal synchronization signal (HV), the vertical synchronization signal (VV), and the index signal (IDX) to the image forming unit 12.

  The transmission unit 32 of the controller 3 performs the embedding process using the toner amount limitation. In image data of pixels that do not use a spot color, the density (toner amount) of each component is C: 8 bits (00 to FF), M: 8 bits (00 to FF), Y: 8 bits (00 to FF), K: 8 bits ( (00 to FF). If the value of each component is FF, an amount of toner corresponding to 100% for each color is put on the photosensitive drum 14. Therefore, as shown in FIG. 3, if all the values of the C, M, Y, and K components are all FF, the toner of each color is superimposed on the recording paper after transfer, and 400% of the toner is placed thereon. Become.

  However, if a certain amount or more of toner is applied to one pixel, a fixing failure occurs. Therefore, the image processing unit 31 of the controller 3 generates image data by restricting the amount of toner that does not exceed a certain amount. . Therefore, the image data output from the image processing unit 31 is corrected so as to be within the toner amount limit. In general, the total amount of C, M, Y, and K is limited so as not to exceed 275%.

  For example, as shown in FIG. 4, when C: 80%, M: 90%, Y: 95%, K: 40%, the total toner amount is 305%, which exceeds the limit value of 275% for the toner amount. Resulting in. As an example of a correction method in such a case, the same amount of toner is subtracted from each of C, M, and Y, and as an alternative, the toner of K is increased by one-third of the subtracted total toner amount. This is because when the same amount of C, M, and Y are mixed, a color substantially equal to K is reproduced.

  In the example of FIG. 4, 30% is subtracted from each of C, M, and Y, and K is increased by 30% to replace the toner amount by 60% and the total toner amount is corrected to 245%. ing. The correction method for limiting the toner amount to be equal to or less than the toner amount limit value is not limited to this, and may be arbitrary.

  Due to the toner amount limitation, data such as C: FF, M: FF, Y: FF, and K: FF is not sent in image data that does not use a spot color. Using this feature, any other data is embedded in the data composed of C, M, Y, and K components. That is, information other than the image data is transmitted using a value that cannot be obtained by image data composed of C, M, Y, and K color sentences.

  Specifically, the transmission unit 32 has data (for example, C: FF, M: FF, Y: FF (toner amount 300%) exceeding the toner amount limit value (275%) with only C, M, and Y components. ) To notify the receiving unit 22 on the image forming apparatus body 5 side that predetermined information different from normal image data represented by C, M, Y, and K is transmitted. Examples of predetermined information different from normal C, M, Y, and K image data include spot color image data, image synchronization signals (HV, VV, IDX), communication commands (RXD, CTS), and the like. is there.

  In this way, the transmission path 25 for transmitting image data composed of C, M, Y, and K components uses values that cannot be obtained by the image data, and C, M, Y, and K components. Since the predetermined information other than the image data constituted by is transmitted, it is not necessary to provide a separate transmission path in order to transmit the predetermined information.

<Embed spot color>
The special color Z is a color that cannot be accurately reproduced by a combination of C, M, Y, and K, and is characterized in that it is not used together with the C, M, Y, and K components for the same pixel. Therefore, whether or not the pixel uses the spot color Z is expressed by C, M, and Y components.

  For example, the pixels using the special color Z are C: FF, M: FF, Y: FF (total amount of toner of C, M, and Y is 300%), and the toner amount limit value (275%) with only these components. ) Is formed, and the receiving unit 22 of the image forming apparatus body 5 is notified that this pixel is a pixel using the spot color Z. At the same time, the density data of the special color Z is transmitted using the K component, and the special color data is notified using the A component (TAG). For pixels that do not use a spot color, the C, M, Y, K, and A components generated by the image processing unit 31 are directly transmitted to the receiving unit 22 of the image forming apparatus body 5 through the transmission path 25. Since the toner amount limitation works, if the C, M, Y, K, and A components generated by the image processing unit 31 are transmitted as they are, the total toner amount becomes equal to or less than the toner amount limit value (275%). .

  The receiving unit 22 receives data transmitted through the transmission path 25, and when the received data does not exceed the toner amount limit value, the data is normally set to C, M, Y, and K as color components. When the received data exceeds the toner amount limit value, the data is restored to predetermined information and output.

  FIG. 5 shows post-embedding data and the like generated by the transmission unit 32 when a spot color is used in some pixels of one line in the main scanning direction. In a normal line using C, M, Y, and K color components in the main scanning direction attention line 42 in the image 41 to be imaged, C, M, Each color component of Y and K transmits density data (Cdata, Mdata, Ydata, Kdata) of each color component, and A component transmits TAG (Adata).

  For pixels that use a spot color, the values of the C, M, and Y color components in the transmitted post-embedding data are all FF, the spot color density data (Zdata) is transmitted as the K component, and the A component Transmits TAG (Adata).

  In the case of handling a plurality of spot colors, the values of the C, M, and Y components are made different for each spot color in a range where the total exceeds 275%. For example, when dealing with a special color (Z) and a special color (S), the special color S is [C: FF, M: FF, Y: FF], and the special color S is [C: FE, M: FE, Y: FF]. Is provided with a pattern within a range exceeding the toner amount limit (275%), and information for identifying which spot color is embedded.

  FIG. 6 shows post-embedding data and the like generated by the transmission unit 22 when the spot color Z is used in some pixels of one line in the main scanning direction and the spot color S is used in the other part. . In the target line 44 in the main scanning direction in the image 43 to be formed, for pixels using normal C, M, Y, K color components, C, M, Each color component of Y and K transmits density data (Cdata, Mdata, Ydata, Kdata) of each component, and a component of A transmits TAG (Adata).

  For the pixel using the spot color Z, the values of the C, M, and Y color components in the transmitted post-embedding data are all FF, and the density data (Zdata) of the spot color is transmitted with the K component. The component transmits TAG (Adata). For pixels using the spot color S, the values of the C, M, and Y color components in the transmitted post-embedding data are all FE, FE, and FF, and the density data (Sdata) of the spot color S is used for the K component. The A component transmits TAG (Adata).

  In this way, using the transmission path 25 for transmitting image data composed of C, M, Y, and K components, image data composed of C, M, Y, and K components, Since the image data (spot color information) of the pixel using the spot color is transmitted using a value that cannot be obtained by the image data, it is not necessary to add a new transmission path in order to transmit the spot color image data.

  In addition, since only the C, M, and Y components, which are a part of the C, M, Y, and K components, exceed the toner amount limit value, other components (8 bits) are used. The density data of the spot color can be transmitted without reducing the number of gradations.

  In addition, since a plurality of values exceeding the toner amount limit value can be taken, different values can be obtained in the above example by differentiating values exceeding the toner amount limit value represented only by the C, M, and Y components. Can transmit the type of spot color.

<Embedding synchronization signal of image>
As described above, there are a horizontal synchronization signal (HV), a vertical synchronization signal (VV), and an index signal (IDX) as image synchronization signals. The vertical synchronization signal (VV) and the index signal (IDX) have a feature that they only transit outside the horizontal synchronization signal (HV) region (off period).

  Here, it is considered that the signal transition of the horizontal synchronizing signal (HV) is embedded in the C, M, and Y components. The image data is transmitted only during a period in which the horizontal synchronization signal (HV) is on. Therefore, a predetermined value that exceeds the toner amount limit value and is different from the value assigned to indicate the spot color may be assigned to the value indicating the off period of the horizontal synchronization signal (HV).

  For example, if C: FD (253), M: FD (253), and Y: FD (253) indicate that the horizontal synchronization signal (HV) is in the off period, an effective image area in the main scanning direction. Whether it is outside (HV = L) or not can be transmitted to the image forming apparatus main body 5 side. Then, the transition of the vertical synchronizing signal and the transition of the index signal are transmitted using the K component during the period outside the effective image area (HV = L) in the main scanning direction.

  For example, if a vertical synchronization signal (VV) is transmitted in the 1st bit of the K component and an index signal (IDX) is transmitted in the 2nd bit, an image synchronization signal is embedded in the data corresponding to the C, M, Y, and K components. In addition, it is possible to reduce the transmission paths of the horizontal synchronization signal (HV), vertical synchronization signal (VV), and index signal (IDX), which have been conventionally prepared exclusively. Note that image data is transmitted in the image area (HV = H). FIG. 7 shows an example in which an image synchronization signal is embedded in C, M, Y, K, and A components.

<Embedding commands between pages>
Further, various command signals to be transmitted from the controller 3 to the image forming apparatus main body 5 are embedded in a pattern exceeding the toner amount limit value. For example, when serial communication (UART signal exchange) is performed, the third bit of the K component is assigned to RXD and the fourth bit is assigned to CTS to exchange commands between pages. In the period between pages, the vertical synchronization signal (VV) is turned off.

  It is also possible to transmit an inter-page command using only the values of the C, M, and Y components without using the K component.

For example,
If C: FD (253), M: FD (253), Y: FD (253), RXD = L, CTS = L
If C: FC (252), M: FC (252), Y: FC (252), RXD = H, CTS = H
If C: FD (253), M: FB (251), Y: FB (251), RXD = H, CTS = L
If C: FD (253), M: FA (250), Y: FA (250), RXD = L, CTS = H
To exchange commands between pages.

  In all cases, the sum of the C, M, and Y components exceeds the toner amount limit value. FIG. 8 shows an example in which RXD and CTS are embedded in C, M, and Y components.

  FIG. 9 shows an example of a conversion table 50 showing the relationship between data before embedding (and after restoration) and data after embedding processing transmitted to the transmission path. The transmission unit 32 refers to such a conversion table 50 to perform embedding processing, and the reception unit 22 refers to the same conversion table 50 to perform restoration processing.

  As described above, in the image forming system 2 according to the present embodiment, only the transmission path 25 for transmitting the components of the basic colors (C, M, Y, K, A) is used. Since an image synchronization signal, a command between pages, and the like can be transmitted, an increase in the number of transmission paths can be prevented, and further, the number of transmission paths can be reduced.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  In the image forming system 2 according to each embodiment, the components C, M, Y, K, and A are components of normal image data. However, the components are not limited to this, and the image forming unit It is changed as appropriate depending on the number of color components normally used. Further, the limit value of the toner amount is not limited to the value exemplified in the embodiment.

  Information to be embedded by the embedding process is not limited to that exemplified in the embodiment, and may be arbitrary information. For example, if the limit value of the toner amount is 275%, there are 60 or more combinations of values exceeding 275% with only the C, M, and Y components, so that various information can be transmitted using them. it can. Furthermore, in the embodiment, only some components (C, M, and Y components) exceed the toner amount limit value, so that other components (K and A components) can be used freely. For example, when an image is formed by superimposing two types of spot colors on the same pixel, it is possible to transmit the density data of the first spot color as the K component and the density data of the second spot color as the A component. become.

  In the embodiment, the electrophotographic engine 10 is exemplified, but other methods such as an ink jet may be used.

  In the embodiment, the controller 3 is provided outside the image forming apparatus main body 5. However, the controller 3 may be provided inside the image forming apparatus main body 5. In this case, the transmission path 25 transmits a signal inside the apparatus.

DESCRIPTION OF SYMBOLS 2 ... Image forming system 3 ... Controller 5 ... Image forming apparatus main body 6 ... Paper feeder 7 ... Post-processing apparatus 8 ... Scanner part 9 ... Operation panel 10 ... Engine 11 ... Intermediate transfer belt 12 (12Y, 12M, 12C, 12K, 12Z) ... image forming section 13 ... fixing device 14 ... photosensitive drum 16 ... laser unit 17 ... cleaning device 18 ... transport path 20 ... overall control section 22 ... receiving section 25 ... transmission path 31 ... image processing section 32 ... transmitting section 41 ... Images to be formed (one special color)
42 ... attention line 43 ... image to be formed (two special colors)
44 ... attention line 50 ... conversion table A ... rotation direction D ... secondary transfer position

Claims (20)

An image forming apparatus for transmitting data to an image forming unit using a transmission path for transmitting image data composed of a plurality of color components,
A transmission unit that transmits predetermined information other than the image data to the transmission path using the image data and a value that the image data cannot take;
When data transmitted through the transmission path is received, and when the received data is a value that the image data can take, the data is output as the image data, and the data is a value that the image data cannot take A receiving unit that converts the data into the predetermined information and outputs the information;
An image forming apparatus comprising: In the image data, the maximum value of the sum of the plurality of color components is limited to a predetermined limit value that is smaller than the sum of the maximum values that each of the color components can take.
The image forming apparatus according to claim 1, wherein the transmission unit transmits the predetermined information using a value exceeding the limit value. The image forming apparatus according to claim 2, wherein the transmission unit transmits a plurality of types of information with different values exceeding the limit value. The transmission unit, when transmitting the predetermined information, generates a value exceeding the limit value only with a predetermined part of the plurality of color components. The image forming apparatus according to 3. The image forming apparatus according to claim 4, wherein the transmission unit transmits the predetermined information using a color component other than the predetermined part of the color components. 6. The predetermined information includes spot color information for forming an image using a color material having a spot color different from the plurality of color components. Image forming apparatus. The image forming apparatus according to claim 6, wherein the transmission unit selects whether to transmit the image data or the spot color information in units of pixels. The image forming apparatus according to claim 1, wherein the predetermined information includes an image synchronization signal. The image forming apparatus according to claim 8, wherein the predetermined information includes a predetermined command transmitted when the synchronization signal indicates that it is outside an effective area of the image. The image forming apparatus according to claim 1, wherein the transmission path includes a signal line for each of the color components. A data transmission method for transmitting data to an image forming unit using a transmission path for transmitting image data composed of a plurality of color components,
Using the transmission path, the image data and a predetermined information other than the image data are transmitted to the image forming unit using a value that the image data cannot take.
A data transmission method characterized by the above. In the image data, the maximum value of the sum of the plurality of color components is limited to a predetermined limit value that is smaller than the sum of the maximum values that each of the color components can take.
The data transmission method according to claim 11, wherein the predetermined information is transmitted using a value exceeding the limit value. The data transmission method according to claim 12, wherein a plurality of types of information are transmitted with different values exceeding the limit value. The data according to claim 12 or 13, wherein when the predetermined information is transmitted, a value exceeding the limit value is generated only with a predetermined part of the plurality of color components. Transmission method. The data transmission method according to claim 14, wherein the predetermined information is transmitted using a color component other than the predetermined part of the color components. 16. The predetermined information includes spot color information for forming an image by using a color material having a spot color different from the plurality of color components. Data transmission method. The data transmission method according to claim 16, wherein whether to transmit the image data or the spot color information is selected on a pixel basis. The data transmission method according to any one of claims 11 to 17, wherein the predetermined information includes an image synchronization signal. The data transmission method according to claim 18, wherein the predetermined information includes a predetermined command that is transmitted when the synchronization signal indicates that it is outside an effective area of an image. The data transmission method according to claim 11, wherein the transmission path includes a signal line for each of the color components.