JP2011051312A - Image forming apparatus and displaying method in the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus including both an image forming part forming an image on a recording material and a display displaying an image and to provide a displaying method in the image forming apparatus displaying an image without influences on an image forming operation while attaining reduction in size and cost of the apparatus. <P>SOLUTION: The image forming apparatus includes an image forming part 50 forming an image on a recording material, a display 22 displaying an image, and a control means 70 controlling the image forming part 50 and outputting, to the display 22, periodically image data corresponding to images to be displayed at a predetermined frame rate. The control means 70 changes the frame rate corresponding to the contents of the image displayed on the display 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including both an image forming unit that forms an image on a recording material and a display unit that displays an image, and a display method in the device.

  Some image forming apparatuses that form an image on a recording material such as paper are provided with a display unit for notifying a user of information such as an operation method and an operation progress state. For example, in the image forming apparatus described in Patent Document 1, a help menu is displayed on a liquid crystal display provided in the apparatus so that a user can easily perform an operation with a small amount of work.

  In order to realize such a function, the conventional image forming apparatus is provided with a dedicated device such as a controller IC for controlling the liquid crystal display and a memory for storing display data.

Japanese Patent Laid-Open No. 2008-186112 (for example, FIGS. 2 and 3)

  This type of apparatus is required to be further reduced in size and cost. For this reason, it is desired that the control of the display unit, which has been conventionally performed by a dedicated device, be incorporated in an SOC (System On a Chip) that controls the entire apparatus. In this case, the SOC is required to perform a process of displaying a predetermined video on the display unit while performing an image forming operation for forming an image on the recording material. On the other hand, the video to be displayed has become complicated with the increase in the number of functions of the apparatus. For this reason, there is a concern that the display processing may affect the image forming operation, and it has become difficult to perform video display and image forming operation in parallel on a single SOC.

  Some embodiments according to the present invention provide an image forming apparatus that includes both an image forming unit that forms an image on a recording material and a display unit that displays an image, and a display method in the device. The present invention provides a technique capable of displaying an image without affecting the image forming operation and reducing the size and cost of the apparatus.

  In order to solve the above problems, an image forming apparatus according to the present invention controls an image forming unit that forms an image on a recording material, a display unit that displays an image, the image forming unit, and the display unit. And control means for periodically outputting video data corresponding to the video to be displayed at a predetermined frame rate, wherein the control means sets the frame rate according to the content of the video to be displayed on the display unit. It is characterized by changing.

  According to another aspect of the present invention, there is provided a display method in an image forming apparatus, wherein an image forming process for forming an image on a recording material and a predetermined frame rate on a display unit while performing the image forming process. And a display step of displaying predetermined video by providing video data, and changing a frame rate of video data corresponding to the video displayed on the display unit according to the content of the video displayed on the display unit It is characterized by.

  In the conventional display method, video data is always supplied to the display unit at a constant frame rate. Therefore, in order to give video data to the display unit, it is necessary to interrupt the operation for image formation at a constant timing regardless of the content of the video to be displayed. On the other hand, in the invention configured as described above, by changing the frame rate according to the content of the video, it is possible to prevent the processing for displaying the video from affecting the image forming operation. Can do. Further, by optimizing the allocation of the video display processing and the image formation processing with a variable frame rate, a dedicated device for display can be omitted. For this reason, it is possible to reduce the size and cost of the apparatus while enabling complex video display.

  In these inventions, it is desirable that the frame rate when the video displayed on the display unit is a still image is smaller than the frame rate when the video displayed on the display unit is a moving image. Since a still image does not require a high frame rate, it is possible to devote more processing time to an image forming operation by reducing the frame rate.

  Here, the frame rate when the video to be displayed on the display unit is a still image may be the lowest value among a plurality of settable values. By doing so, it is possible to secure the maximum processing time for image formation. It should be noted that the frame rate at this time can be set, for example, corresponding to the flicker value, that is, the lowest value in a range where the flicker is not visible. By doing so, it is possible to secure a processing time for image formation without degrading the quality of the video.

  Further, when the image forming operation is being performed, the frame rate is set according to the content of the video displayed on the display unit, while when the image forming operation is not being performed, the frame rate is set to a predetermined constant value. It may be. If the image forming operation is not executed, it is possible to devote time to the processing for displaying the image, and in this way, various complicated images can be displayed. On the other hand, by changing the frame rate when executing the image forming operation, it is possible to suppress the influence of the video display on the image forming operation.

  Further, when the image forming operation is being performed, the set value of the frame rate set according to the content of the video displayed on the display unit may be decreased according to the progress of the image forming operation. Even if the frame rate is variable, there is a possibility that the processing for image formation and the processing for video display may conflict. In such a case, the influence on the image forming operation can be prevented by changing the frame rate from the set value to a lower value.

  The present invention is particularly effective in an image forming apparatus configured such that control data necessary for an image forming operation and video data to be given to a display unit are stored in the same storage element. By storing these data in the same storage element, the size and cost of the apparatus can be reduced. However, there is a problem in that both processes compete for access to the storage element, that is, while the storage element is accessed for one process, access to the storage element is limited for the other process. Since access to the storage element for display processing is performed at a constant interval according to the frame rate, such access contention can be avoided by appropriately changing the frame rate.

1 is a perspective view illustrating a photo printer that is an embodiment of the present invention. FIG. FIG. 2 is a diagram illustrating an outline of an internal configuration of a photo printer. FIG. 2 is a block diagram showing an electrical configuration of the photo printer of FIG. 1. The block diagram which shows the structure of a LCD controller. The block diagram which shows the structure of a synchronous signal generation part. The flowchart which shows a frame rate determination process. The flowchart which shows a frame rate update process. The flowchart which shows an underrun error process. The figure which shows an example of transition of the frame rate in this embodiment.

  FIG. 1 is a perspective view showing a photo printer according to an embodiment of the present invention. FIG. 2 is a diagram showing an outline of the internal configuration of the photo printer. In the photo printer 10, a printing mechanism 50 is built in the printer main body 12, and printing on the paper P is executed in response to an operation command from the controller 70 that controls the printing mechanism 50. Then, the printed paper P is discharged to the front surface of the printer main body 12.

  A front door 14 is attached to the front surface of the printer main body 12 so as to be freely opened and closed. The front door 14 is a lid for opening and closing the front surface of the printer main body 12. In the open state, it functions as a paper discharge tray for receiving the paper P discharged from the print mechanism 50. In addition, various memory card slots 16 provided on the front surface of the printer main body 12 can be used by the user. That is, in this state, the user can insert the memory card M storing the image file to be printed into the memory card slot 16. Furthermore, in this embodiment, a disc such as a CD-R (Compact Disc Recordable) or a video DVD (Digital Versatile Disc) can be used as a storage medium in addition to a memory card. Yes. That is, an optical disc drive 13 is provided at the base portion of the printer main body 12.

  An operation panel 20 is provided on the upper surface of the printer main body 12, and a cover 30 is attached to an inner side of the upper surface of the printer main body 12 so as to be freely opened and closed. The cover 30 is a resin plate formed in a size that can cover the upper surface of the printer body 12, and exposes the surface of the operation panel 20 to the outside in the open state. On the other hand, when the cover 30 is closed, the entire operation panel 20 is covered.

  The operation panel 20 includes a display unit 22 configured by, for example, an LCD (Liquid Crystal Display) that displays characters, graphics, symbols, and the like, and a button group 24 arranged around the display unit 22. . As shown in FIG. 2, the button group 24 includes a power button 24a for turning on / off the power, a menu button 24b for calling the main menu screen, canceling the operation in the middle, and interrupting the printing on the paper P in the middle. A cancel button 24c for performing printing, a print button 24d for instructing execution of printing on the paper P, a save button 24e for saving an edited image in the memory card M inserted in the memory card slot 16, a display unit Each of the up / down / left / right arrow buttons 24f to 24i operated when selecting a desired option from the plurality of options displayed on the screen 22 or moving the cursor, and the up / down / left / right arrow buttons 24f to 24i. O for instructing that the option selected by the arrow buttons 24f to 24i arranged in the center is selected. A button 24j, a display switching button 24k for switching the screen display on the display unit 22, a left guide selection button 24l for selecting a left guide displayed on the display unit 22, and a right for selecting a right guide displayed on the display unit 22. It includes a guide selection button 24m, a paper discharge tray open button 24n for opening the front door 14 having a function as a paper discharge tray, and the like.

  Further, in order to confirm the display content of the display unit 22, the cover 30 is provided with a window 32 having the same size as the display unit 22. That is, when the cover 30 is in the closed state, the user can check the display content of the display unit 22 through the window 32. On the other hand, when the cover 30 is in the open state, the display unit 22 can be adjusted to a desired angle as shown in FIG.

  Thus, when the cover 30 is in the open state, the cover 30 is held while being inclined obliquely rearward with respect to the operation panel 20 and can be used as a tray for supplying the paper P to the print mechanism 50. . Further, at the back of the operation panel 20, a paper feed port 28 of the printing mechanism 50 is provided, and a pair of paper guides 29 that are slid in the left-right direction so that the guide width matches the paper width are provided. .

  Then, the paper P is sent to the print mechanism 50 through the paper supply port 28 and printing is executed. As shown in FIG. 2, the carriage 53 is driven by a timing belt 51 spanned in a loop shape in the left-right direction and reciprocates left and right along the guide 52. The carriage 53 is provided with a sensor 57 that detects the left and right edges and the upper and lower edges of the paper P. In other words, the sensor 57 detects the left and right edges of the paper when the carriage 53 scans in the left-right direction before printing with respect to the paper set in the paper supply port 28, and enables recognition of the paper width. The trailing edge of the paper is detected in the middle, and the paper length can be recognized.

  The carriage 53 is mounted with an ink cartridge 54 that individually accommodates ink of each color such as cyan, magenta, yellow, and black. Each of these ink cartridges 54 is connected to a print head 55. The print head 55 applies pressure to the ink from the ink cartridge 54 and ejects the ink from the nozzle (not shown) toward the paper P. In this embodiment, the print head 55 employs a method in which a voltage is applied to the piezoelectric element to deform the piezoelectric element and pressurize the ink. However, a voltage is applied to the heating resistor (for example, a heater) to apply the ink. You may employ | adopt the system which pressurizes ink with the bubble generated by heating. The printed paper P is sent out to the opened front door (paper discharge tray) 14 by the transport roller 56. For image formation, toner or developer may be used instead of ink.

  A cap 58 is provided at a position facing the print head 55 when the carriage 53 shown in FIG. 2 is moved to the rightmost cap position within the movable range. The cap 58 covers the nozzles of the print head 55 when the printing operation is not performed for a long time, thereby preventing clogging of the nozzles due to drying of the ink. Even when the apparatus is in the power-off state, the carriage 53 is positioned at the cap position and the nozzle is capped.

  FIG. 3 is a block diagram showing an electrical configuration of the photo printer of FIG. The controller 70 is configured as an SOC (System On a Chip) in which a plurality of functional blocks are integrated on one chip, and has a system bus 700 as shown in FIG. The system bus 700 includes a CPU 701, a flash ROM 702, a DDR (Double Data Rate) controller 703, an IDE (Integrated Drive Electronics) interface 704, an EEPROM 711, a card interface 706, a DMA (Direct Memory Access) controller 707, and a print data output unit 708. And an LCD controller 709 and the like are connected.

  The CPU 701 performs arithmetic processing for executing operation control of the print mechanism 50. The flash ROM 702 is a nonvolatile memory that can be electrically rewritten repeatedly, and stores a program (firmware) necessary for the control of the CPU 701 and various data and tables necessary for the control. The EEPROM 711 is also an electrically rewritable memory, and stores and saves data to be saved even when the apparatus is turned off.

  The DDR controller 703 is externally attached to the controller 70 and controls access to a DDR type high-speed RAM 79 that temporarily stores data necessary for the operation of the CPU 701 and data processing. The card interface 706 communicates with the memory card slot 16 and reads image data of an external storage medium such as the memory card M inserted into the memory card slot 16. The card interface 706 writes image data to the memory card M in order to save an edited image or the like. The IDE interface 704 controls transmission / reception of data to / from the optical disk drive 13.

  The CPU 701 performs necessary image processing on image data provided from an external storage medium such as a memory card M read by the card interface 706, generates print data corresponding to an image to be printed by the print mechanism 50, and The print data is output to the print data output unit 708. For example, composite image data obtained by combining image data read from the memory card M and image frame data read from the flash ROM 702 is generated and output to the print data output unit 708. The print data output unit 708 generates a print control signal based on the image data created by the CPU 701 and outputs the print control signal to the print mechanism 50. The printing mechanism 50 executes a printing operation based on the printing control signal, and forms an image corresponding to the image file on the paper.

  In addition, the CPU 701 performs polling to check whether or not each operation button constituting the button group 24 is pressed by the user at a constant cycle, for example, at an interval of 200 msec, and this indicates that the user has operated any of the operation buttons. When is detected, a reception process corresponding to the operated button is executed. For example, when the power button 24a is pressed by the user while the apparatus is powered on, the power supply to each part of the apparatus is stopped. Further, for example, when the print button 24d is pressed, image data is given to the print data output unit 708 to create a print control signal, and the print mechanism 50 performs a print operation.

  Further, the CPU 701 also performs processing for creating video data corresponding to video to be displayed on the display unit 22 (hereinafter referred to as “display processing”). In addition to the preview image corresponding to the image formed by the print mechanism 50, the video to be displayed on the display unit 22 includes a still image, an animation video, and a demonstration for notifying the user of the operation method and the progress of processing. Videos. The contents of the video other than the preview image are predetermined, and the video data corresponding to these videos are stored in the flash ROM 702.

  Along with the video data, the flash ROM 702 also stores information indicating whether the video is a still image, an animation, or a moving image, and information about an optimum frame rate for displaying the video. The still image referred to here is an image in which the display content does not change for a certain period of time if there is no change in the user's operation or progress of processing. An animation image is an image with a simple motion such as blinking a part of the image or moving a specific character on the screen. A moving image is an image that has a smooth movement on the entire screen.

  The CPU 701 stores the video data read from the flash ROM 702 and processed as necessary, for example, combined with a preview image, in the RAM 79. The video data thus created on the RAM 79 is periodically sent to the LCD controller 709 via the DMA controller 707, and the LCD controller 709 generates a video signal based on the received video data and outputs it to the display unit 22. As a result, an image corresponding to the video data is displayed on the display unit 22.

  FIG. 4 is a block diagram showing the configuration of the LCD controller. The LCD controller 709 includes an input unit 901, a line buffer 902, a compression unit 903, a VRAM control unit 904, a VRAM 905, an expansion unit 906, an output data generation unit 907, an SPI control unit 908, a backlight control unit 909, a setting register 910, and the like. It has.

  The input unit 901 functions as a conversion unit (S / P conversion unit) that converts data transmitted from the DMA controller 707 by 5-wire serial communication into 24-bit parallel data. This 24-bit data is an image (QVGA size; 320 dots × 240 dots) to be displayed on the display unit 22 expressed in 8 bits for each color of RGB.

  The line buffer 902 temporarily stores the 24-bit video data output from the input unit 901 and sends it to the compression unit 903 at a predetermined timing. The compression unit 903 compresses the video data to 50% or less, and stores the compressed data in the VRAM 905 via the VRAM control unit 904. The compression processing may be lossy compression as long as deterioration of the quality of the video displayed on the display unit 22 is not noticeable.

  The VRAM 905 is a frame memory for video data, and only has a capacity capable of storing data obtained by further compressing a QVGA size image to 50% or less, and has a relatively small capacity. For example, it may be about 28980 words in a 32-bit configuration. The decompression unit 906 decompresses the compressed data read from the VRAM 905 via the VRAM control unit 904, and outputs the decompressed data to the output data generation unit 907 as video data (48 bits) for two screens.

  The output data generation unit 907 performs signal processing such as stripe delta conversion and gamma correction on the given 48-bit data, and sends the data to the display unit 22 in a predetermined data transmission order. The output data generation unit 907 includes a synchronization signal generation unit 920 that generates various synchronization signals for operating the display unit 22. The configuration of the synchronization signal generation unit 920 will be described later.

  The SPI control unit 908 sends a control command to the display unit 22 by an SPI (Serial Peripheral Interface) method. The backlight control unit 909 controls the brightness of the screen by giving the display unit 22 a control signal BL instructing the lighting duty of a backlight (not shown) provided in the display unit 22. Since the configuration and function of each of these functional blocks are known, the description thereof is omitted here.

  The setting register 910 holds an internal register value for determining the operation mode of the LCD controller 709. Data from the input unit 901 is input to the setting register 910. As will be described below, some of the setting values of the setting register 910 are set based on data provided from the input unit 901.

  FIG. 5 is a block diagram showing the configuration of the synchronization signal generator. The synchronization signal generation unit 920 includes three counters 921, 922, and 923, each of which is a programmable counter. An original clock signal MCLK generated by an original clock generator (not shown) is input to the first counter 921, and the first counter 921 generates a clock signal obtained by dividing the clock signal by an appropriate division ratio. This is output as a pixel clock signal DCLK that determines the transmission cycle of the video data sent to the display unit 22. The frequency division ratio is determined by two setting values stored in the setting register 910, that is, each setting value of the frequency division ratio 1 and the frequency division ratio 2.

  The pixel clock signal DCLK is also input to the second counter 922. The second counter 922 further divides the pixel signal clock DCLK to generate and output a horizontal synchronization signal HSYNC. More specifically, a predetermined back porch determined by an H back porch setting value and an H front porch setting value set in the setting register 910 into a signal obtained by dividing the pixel signal clock DCLK to a predetermined frequency dividing ratio. The signal given the front porch is output as the horizontal synchronization signal HSYNC.

  Similarly, the third counter 923 divides the horizontal synchronization signal HSYNC output from the second counter 922 and further sets the V back porch setting value and the V front porch setting value set in the setting register 910. A signal given a predetermined back porch and front porch is output as a vertical synchronization signal VSYNC. These signals are transmitted to the display unit 22 which is an LCD display and used for display timing control on the display unit 22.

  Of the set values stored in the setting register 910, “frequency division ratio 1” and “frequency division ratio 2” are set by data supplied from the input unit 901. The input unit 901 sets data for setting “frequency division ratio 1” and “frequency division ratio 2” based on data (described later) attached to video data supplied from the RAM 79 via the DMA controller 707. To 910.

  As described above, the flash ROM 702 stores information on the type of video and the optimum frame rate in addition to the video data to be displayed on the display unit 22. When processing the video data read from the flash ROM 702 and writing it to the RAM 79, the CPU 701 calculates at what frame rate the video is to be displayed based on the information and the progress of the printing operation, and the result is calculated data. At the same time, it is written in the RAM 79. Then, this data is sent to the input unit 901 of the LCD controller 709 and further written into the setting register 910, whereby the frequency division ratio 1 and the frequency division ratio 2 in the setting register 910 are set.

  Therefore, in this embodiment, when the pixel clock signal DCLK is generated from the original clock signal MCLK according to the content of the video to be displayed on the display unit 22, more specifically according to the content of the video and the progress of the printing operation. The frequency division ratio is determined. Since the pixel clock signal DCLK is an original clock signal of the horizontal synchronization signal HSYNC and the vertical synchronization signal VSYNC, the period of the timing signal sent to the display unit 22 according to the set values of the division ratio 1 and the division ratio 2 Can be changed. That is, the frame rate of the display unit 22 can be changed and set.

  Thus, in this embodiment, the frame rate of the display unit 22 is changed and set according to the content of the video to be displayed and the progress of the printing operation. This is to prevent a conflict between the printing operation executed by the controller 70 and the display process. As described above, in this embodiment, the CPU 701 on the controller 70 performs all of generation of print data to be sent to the print mechanism 50, reception of operation input to the button group 24, and processing of video data to be displayed on the display unit 22. Is going by. For this reason, while the CPU 701 is performing one process, the other processes are in a waiting state. In addition, the print data, intermediate data for generating the print data, and video data to be displayed on the display unit 22 are all stored in the same RAM 79, and two or more of these data cannot be read / written simultaneously. That is, while data is being read or written for any of the processes, the RAM 79 is occupied by the process, and this also causes a wait for the process.

  Here, the display of the video on the display unit 22 has a strong meaning of providing an additional service to the user, and its priority is lower than that of the operation input reception or the printing operation. Therefore, it is not preferable to put another process on standby in order to perform the display process. Therefore, in this embodiment, the processing in the controller 70 is optimized by changing the frame rate of the display unit 22 according to the content of the video to be displayed and the progress of the printing operation, and the display processing is performed as a cause. It avoids stagnating input and printing operations.

  That is, there are the following problems when the frame rate of the display unit 22 is set to a fixed value. First, if you want to display complex content such as moving images, you need to set the frame rate high in advance, but if you do this, high-speed processing is always required for display. Processing with SOC becomes difficult. This does not change even when the amount of video data to be displayed is essentially a still image. This necessitates the provision of a display-only device, which increases the size of the device and increases the cost of the device. On the other hand, if the frame rate is set to be low in order to enable processing with one SOC, a function of displaying a fast moving video or the like cannot be realized.

  On the other hand, in this embodiment, first, by enabling the frame rate to be set according to the content of the video to be displayed, the processing in the controller 70 is optimized according to the content of the video. be able to. Secondly, processing can be further optimized by making it possible to change the frame rate even in accordance with the progress of the printing operation. For this reason, in this embodiment, it is possible to prevent the display processing from affecting the printing operation while controlling the operation of the entire apparatus with one SOC. As a result, in this embodiment, it is possible to display various images without affecting the printing operation while reducing the size and cost of the apparatus. Hereinafter, specific processing contents for determining the frame rate will be described.

  FIG. 6 is a flowchart showing the frame rate determination process. Strictly speaking, this process is a process for determining a required value of the frame rate corresponding to the current situation. In this frame rate determination process, it is necessary to change the contents of the video that the CPU 701 should display on the display unit 22 immediately after the apparatus is turned on, immediately after the end of the printing operation, and according to an operation input by the user. Sometimes, it is executed by the CPU 701.

  First, it is determined whether or not the trigger for executing the process is a change in display content (step S100). If the display content is not changed, that is, immediately after the power is turned on or after the printing operation is finished, the process proceeds to step S160 described later. If the display content has been changed, it is subsequently determined whether the display content after the change is a still image (step S110). If the display content is a still image, the frame rate request value R is set to 10 Hz (or fps; frame per second) (step S111).

  The frame rate of 10 Hz is a so-called flicker value that is not practical when the flicker is noticed below this value. In the case of a still image, it is not necessary to update (refresh) the image for each frame in principle, but it is difficult to keep the alignment of the liquid crystal for a long time without refreshing the display by the LCD. Therefore, by setting the frame rate to a low speed at which the flicker is not noticeable, image disturbance is prevented, and the access interval to the RAM 79 is widened to prevent competition with the printing operation. That is, a value of 10 Hz is a lower limit value of the frame rate from the viewpoint of video quality.

  If the display content is not a still image, it is further determined whether or not it is a moving image (step S120). If the display content is a moving image, the frame rate request value R is set to 60 Hz (step S121). The frame rate of 60 Hz is the same speed as that of television broadcasting and the like, and a moving image can be displayed smoothly. Therefore, no further frame rate is required. In other words, this type of device only needs to have hardware capable of realizing a frame rate of 60 Hz. That is, the rate of 60 Hz is the upper limit value on hardware.

  When the display content is not a moving image, the video to be displayed is an animation image. Here, a low-speed animation image created at a frame rate of 10 fps or less, a medium-speed animation image of 30 fps or less, a high-speed animation of 50 fps or less, or more is assumed as the animation image. The CPU 701 determines at which frame rate the animation image has been created (steps S130, S140, S150), and the frame rate request value R in the display unit 22 is set to 10 Hz, 30 Hz, 50 Hz and the like according to the determination result. One of 60 Hz is set (steps S131, S141, S151 and S160). Step S160 is also executed immediately after the power is turned on and when the printing operation is completed, and the required value R of the frame rate is set to the upper limit value 60 Hz. When the required value R of the frame rate is thus determined, a frame rate update process (step S170) for actually changing and setting the frame rate is subsequently executed.

  FIG. 7 is a flowchart showing the frame rate update process. In this process, a pixel clock period, a horizontal synchronization period, a vertical synchronization period, etc. corresponding to the determined frame rate request value R are calculated (step S201). Then, the current frame rate setting value C is updated to the required value R (step S202). More specifically, the parameter frequency division ratio 1 and the frequency division ratio 2 corresponding to the new frame rate setting value are written in the RAM 79. These parameters are given to the LCD controller 709 via the DMA controller 707 and written to the setting register 910 from the input unit 901 so that the calculated pixel clock period, horizontal synchronization period, vertical synchronization period, etc. It becomes a new set value (step S203). As a result, the frame rate is changed.

  Even in this case, there is a possibility that the display process and the printing operation conflict. For example, there is a case where the frame rate is set to a relatively high value as in the case where the video to be displayed is a moving image, and at the same time the printing operation must be performed. When the frame rate is high, data transfer from the RAM 79 to the LCD controller 709 via the DMA controller 707 is performed with high frequency (for example, every 1/60 second). There may be a conflict between the data transfer and the access to the RAM 79 for the printing operation.

  Such a situation can be dealt with as follows. That is, a higher priority is given to the CPU 701 than to the DMA controller 707 for accessing the RAM 79. As a result, when access from both competes, the printing operation by the CPU 701 is prioritized, and the waiting for the printing operation is avoided. On the other hand, when viewed from the DMA controller 707, an appropriate response cannot be obtained in response to an access request to the RAM 79, so that an underrun error state occurs. Therefore, the occurrence of an underrun error of the DMA controller 707 is notified to the CPU 701, and the CPU 701 that has detected the error executes the following underrun error processing, whereby the problem can be solved.

  FIG. 8 is a flowchart showing underrun error processing. When it is detected that an underrun error has occurred in the access from the DMA controller 707 to the RAM 79, the CPU 701 sets a constant value (in this example, 20 Hz as an example, but not limited to this) from the current frame rate setting value C. The subtracted value is set as a new frame rate request value R (step S301). Here, when the set required value R is smaller than the lower limit value Cmin in the specification of the apparatus (step S302), the required value R is set as the lower limit value Cmin (step S303). The lower limit value Cmin in this embodiment is a frequency of 10 Hz corresponding to the flicker value. Then, the frame rate update process (FIG. 7) is executed again (step S304).

  As a result, the frame rate is changed to a set value corresponding to the new required value R. This state is maintained until the printing operation is completed. This set value is a value lower than a predetermined rate corresponding to the content of the video. For this reason, since the frequency of access from the DMA controller 707 to the RAM 79 is reduced and the occupation time is also reduced, the printing operation by the CPU 701 is performed more smoothly. On the other hand, the video data transfer from the LCD controller 709 to the display unit 22 is executed at a rate lower than the original frame rate. For this reason, the smoothness in displaying moving images and animation images is somewhat lost, but the display control itself does not fail. In addition, it has no effect on still images that do not require a high frame rate or slowly moving animation images.

  FIG. 9 is a diagram showing an example of the transition of the frame rate in this embodiment. According to the above-described processing, immediately after the power is turned on (time t = 0), the frame rate is set to 60 Hz, which is the upper limit value in the apparatus configuration. Thereafter, a printing operation is started. As a result, when an underrun error is detected at time t1, the frame rate is changed to 40 Hz. At this time, the required value R of the frame rate required from the video content does not match the actual set value C. When the printing operation ends at time t2, the frame rate determination process is executed again, and the frame rate is returned to the original value of 60 Hz.

  If an underrun error occurs at time t3 due to a new printing operation, the frame rate is changed to 40 Hz. If an underrun error is detected again in this state (time t4), the frame rate is further reduced to 20 Hz. When the video is changed to a still image at time t5, the frame rate is a value corresponding to the still image and is set to 10 Hz (flicker value) which is a lower limit value in the apparatus configuration. Thus, when an underrun error is not detected, the frame rate request value R and the set value C match. The same can be considered when the required value R of the frame rate required according to the content of the video is a numerical value other than the above.

  As described above, in this embodiment, the display frame rate of the display unit 22 by the LCD is not set to a fixed value, but is set according to the content of the video to be displayed. This prevents the display process from competing with the printing operation in the controller 70 and affecting the printing operation. In addition, by making the frame rate variable, it is possible to perform display processing on the same SOC that processes the printing operation, and it is not necessary to use a dedicated device for display processing. Further, since the processing data for the printing operation and the video data to be displayed are stored in the single RAM 79, it is not necessary to provide a separate memory. For this reason, in this embodiment, it is possible to reduce the size and cost of the apparatus.

  More specifically, the frame rate is low when the video to be displayed is a still image, and the frame rate is higher when it is an animation image or a moving image. Thus, while reducing the frame rate for video that does not require a high frame rate, the frame rate is set high for video that requires a high frame rate. Process allocation can be optimized to avoid process contention.

  In addition, when contention occurs in this way, it is possible to prevent the display processing from affecting the printing operation by setting the video display frame rate to be lower than the original value.

  As described above, in this embodiment, the print mechanism 50 corresponds to the “image forming unit” of the present invention, and the display unit 22 corresponds to the “display unit” of the present invention. Further, the controller 70 functions as a “control unit” of the present invention. Further, the RAM 79 in this embodiment functions as a “memory element” of the present invention. Further, the printing operation in this embodiment corresponds to “image forming operation” and “image forming process” of the present invention, and the display processing of this embodiment corresponds to “display process” of the present invention. Further, the video data written in the RAM 79 by the CPU 701 corresponds to “video data” of the present invention, and information regarding the video type and frame rate corresponds to “control data”.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the frame rate is set according to the content of the video displayed on the display unit 22 regardless of whether or not the printing operation is being executed. Instead of this, the following may be used. That is, since data is frequently transferred between the CPU 701 and the RAM 79 when a printing operation is being executed, a process conflict may occur if an additional display process is added here. However, the controller 70 that inherently has sufficient ability to process the printing operation can perform the display processing with a sufficient margin when the printing operation is not being executed. Therefore, it is not necessary to change the frame rate when the printing operation is not being executed. For example, the frame rate may be fixed to an upper limit value of 60 Hz.

  In the above embodiment, the image file stored in the memory card M is read and the printing operation is performed. However, the data format of the image file and the storage medium thereof are not limited to those described above, and there are various known types. Things can be used. For example, a storage medium having a magnetic disk or a stick-shaped storage medium may be used. Furthermore, devices that have a function of storing captured image files, such as digital cameras and mobile phones, that can read image files by communication means such as cables or wireless / infrared communication are also described in this document. The invention can be applied.

  The print mechanism 50 in the above embodiment is an ink jet printer, but may be an electrophotographic printer, for example. Moreover, although the display part 22 in the said embodiment displays an image with an LCD display, you may display an image with other display systems, such as an EL (electroluminescent element) display.

  In the above-described embodiment, the present invention is applied to a photo printer having a display function for displaying an image corresponding to an image file and a printing function for printing the image. However, the present invention is not limited to the photo printer, and the present invention can be applied to all devices having a display function and a printing function. In particular, the present invention is particularly effective for devices that are required to be small and low cost.

  DESCRIPTION OF SYMBOLS 22 ... Display part (display part), 50 ... Print mechanism (image formation part), 70 ... Controller (control means), 79 ... RAM (memory | storage element) 707 ... DMA controller, 709 ... LCD controller

Claims (8)

An image forming unit that forms an image on a recording material;
A display unit for displaying images;
A control unit that controls the image forming unit and periodically outputs video data corresponding to a video to be displayed at a predetermined frame rate to the display unit;
The image forming apparatus according to claim 1, wherein the control unit changes the frame rate in accordance with a content of an image displayed on the display unit.   2. The image formation according to claim 1, wherein the control unit makes a frame rate when a video displayed on the display unit is a still image smaller than a frame rate when a video displayed on the display unit is a moving image. apparatus.   The image forming apparatus according to claim 2, wherein the control unit sets a frame rate when a video displayed on the display unit is a still image to a minimum value among a plurality of settable values.   The image forming apparatus according to claim 3, wherein the minimum value of the frame rate is set to a value corresponding to a flicker value.   The control means executes the image forming operation while setting the frame rate according to the content of the video to be displayed on the display unit when an image forming operation for forming an image on the image forming unit is being executed. 5. The image forming apparatus according to claim 1, wherein when the frame rate is not set, the frame rate is set to a predetermined constant value.   When the image forming operation for causing the image forming unit to form an image is being executed, the control unit uses the setting value of the frame rate set according to the content of the video displayed on the display unit for the image forming operation. The image forming apparatus according to claim 1, wherein the image forming apparatus is lowered according to a progress state.   7. The image forming apparatus according to claim 1, wherein control data for controlling the image forming unit and video data to be given to the display unit are stored in the same storage element. An image forming process for forming an image on a recording material;
A display step of displaying predetermined video by giving video data at a predetermined frame rate to the display unit while performing the image forming step;
A display method in an image forming apparatus, wherein a frame rate of video data corresponding to video to be displayed on the display unit is changed according to contents of video to be displayed on the display unit.

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