JP2006171488A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a display image left remaining in a stopped condition, during transfer in an image display device which has a frame buffer and a function to transfer an image being displayed to a nonvolatile memory. <P>SOLUTION: In a normal condition or immediately before an image transfer to the nonvolatile memory, two frame buffer regions 101 and 102 are used in a double-buffer system for image display. When an image is transferred to the nonvolatile memory, the double-buffer system is changed into a single-buffer system, one of the frame buffer region 101 is used and the image transfer to a nonvolatile memory NVRAM is conducted from the other frame buffer 102 which is no longer used for image display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to frame buffer control for capturing an input image in a nonvolatile memory in an image display device such as a liquid crystal projector.

  2. Description of the Related Art Liquid crystal projectors that receive video or image (hereinafter referred to as image) signals from a video or PC and project the image on a screen have been developed. Examples of the use of the liquid crystal projector include a display device used for a business use presentation or a display device in a home use home theater. In such applications, there is a desire to display a company logo, a favorite image, or the like when the liquid crystal projector is activated.

  Many current liquid crystal projectors have a function of capturing a part or all of a frame in an input image and storing it in the liquid crystal projector or in an external non-volatile memory (NVRAM). With this function, logos and images stored in the non-volatile memory can be freely displayed when the liquid crystal projector is activated, and the user's merit is great.

  Usually, a liquid crystal projector is provided with a kind of video RAM called a frame buffer, and the entire frame is often stored in the frame period of an input image signal. In particular, as a configuration of the frame buffer, there is often a double buffering method in which an area is prepared so that two frames can be stored and reading and writing are performed asynchronously. FIG. 2 shows an outline of the double buffering method. Reference numeral 200 denotes an entire frame buffer, and 201 and 202 are areas for storing one frame.

  The capture is to transfer a part or all of an image of a specific frame in the frame buffer to a nonvolatile memory. It often takes time to transfer an image to a non-volatile memory. Therefore, in the prior art, the writing of the input image signal to the frame buffer is stopped in a state where the frame to be captured is stored in the frame buffer, and the image data is transferred from the frame buffer to the nonvolatile memory during that time. FIG. 3 shows a schematic diagram. Reference numeral 300 denotes the entire frame buffer, and writing is stopped. Similarly, 301 and 302 are areas each storing one frame.

  FIG. 6 shows a display screen example in the prior art. Reference numeral 600 denotes the entire display screen, and reference numeral 601 denotes a screen capture confirmation image. 602 is an option for performing screen capture, and 603 is an option for canceling screen capture. Here, it is assumed that the display image other than the menu is a moving image.

  FIG. 7 shows an example of a display screen when screen capture according to the prior art is executed. Reference numeral 700 denotes an entire display screen, and reference numeral 701 denotes a message indicating that capture is in progress. As described above, since writing to the frame buffer is stopped during this period and data is transferred to the nonvolatile memory, the display image is a still image even though the input image is a moving image.

FIG. 8 shows an example of a display screen at the end of screen capture in the prior art. A message 800 indicates the entire display screen, and a message 801 indicates that the capture is completed. Here, since the writing to the frame buffer is resumed, the display image becomes a moving image again.
JP 2001-332006 A

  In the conventional technology as described above, the user is kept waiting during the capture time, and even when a moving image is input to an image display device such as a liquid crystal projector, a still image is projected, which causes anxiety and inconvenience to the user. It was the cause of feeling.

  The present invention has been made to solve the above-described problems in the prior art. That is, according to the present invention, it is an object to realize an easy-to-use image display device that displays a moving image instead of a still image even during capture.

  In order to solve the above problems, an image display device according to the present invention is an image display device that processes an input image signal input for each frame and displays an image, and includes one frame included in the input image signal A frame buffer having first and second areas for storing the image data of the image, and reading / writing to the frame buffer so that the frame buffer is not switched to a temporally different frame during reading of the frame buffer. A first mode for selecting a read target area and a write area from the first and second areas for each frame period, and reading and writing to the frame buffer are performed in the first and second areas. A frame buffer control unit for controlling in one mode selected from the second mode performed only on one side; A non-volatile memory, an image capture unit that reads image data from the frame buffer and transfers the image data to the non-volatile memory, and image data read from the frame buffer or an image after image processing is performed on the image data And when the request to transfer the image of the frame buffer to the non-volatile memory occurs, the frame buffer control unit is one of the first and second regions. And reading and writing to the frame buffer in the second mode, and the image capture unit reads the image data written in the other area of the first and second areas, and It transfers to a non-volatile memory, It is characterized by the above-mentioned.

  According to the present invention, a moving image can be displayed by the single buffering method even while the display image is transferred to the nonvolatile memory, and the display image does not become a still image. Therefore, the user does not feel anxiety or inconvenience.

Hereinafter, preferable embodiments of the present invention will be listed.
[Embodiment 1]
An image display device that processes an input image signal input for each frame and displays an image,
A frame buffer comprising a first area and a second area for storing one frame of the input image;
Non-volatile memory;
A frame buffer control unit having a first control mode for controlling reading and writing to the frame buffer and a second control mode and capable of selecting them;
An image writing unit for writing an input image represented by the input image signal to the frame buffer according to a control mode of the frame buffer control unit;
According to the control mode of the frame buffer control unit, an image reading unit that reads an image from the frame buffer and outputs it as an output image;
An image capture unit that reads an image from the frame buffer and transfers the image to the nonvolatile memory;
An image capture receiving unit that receives a request to transfer the image of the frame buffer to the nonvolatile memory and notifies the frame buffer control unit;
A display unit for displaying the output image or an image after image processing is performed on the output image;
In the first control mode, the read target area and the write area are set for each frame period so as not to switch to a temporally different frame in the middle of the frame when reading to the frame buffer. And a mode for selecting from the second region,
The second control mode is a mode in which reading and writing are performed only on one of the first area and the second area in the frame buffer.
The frame buffer control unit
When the notification is received from the image capture acceptance unit when the first control mode is used, the second control mode is switched to the image capture unit and the image capture unit is no longer used. An image is transferred from either the first area or the second area to the nonvolatile memory,
Image display device.
[Embodiment 2]
The frame buffer control unit
When using the second control mode, if there is the notification from the image capture receiving unit, after switching to the first control mode while writing at least one frame, Switching to the second control mode, and causing the image capture unit to transfer an image from the first area that is no longer used or the second area to the nonvolatile memory. did,
The image display device according to the first embodiment.
[Embodiment 3]
When the image capture unit is transferring an image, the display unit displays an image indicating that the image is being transferred.
The image display device according to Embodiment 1 or 2.

Next, embodiments of the present invention will be described based on examples.
[First embodiment]
The first example corresponds to the first embodiment.
FIG. 4 is a block diagram showing a configuration of an image display apparatus according to an embodiment of the present invention. This display device constitutes a so-called liquid crystal projector. The configuration of the block diagram will be described below.

  In FIG. 4, reference numeral 400 denotes an A / D converter that receives an input analog RGB signal, performs analog-digital conversion, and outputs a digital RGB signal. When this conversion is performed, the input image signal has means for performing color processing such as brightness and contrast.

  A video decoder 401 receives an input composite NTSC signal and converts it into a digital YCbCr signal. When this conversion is performed, the input image signal has means for performing color processing such as brightness and contrast.

  In this embodiment, the input image signal is limited to the composite NTSC signal and the analog RGB signal, but the present invention is not limited to these signals. The input image signal may be a component signal, another video signal, or an IEEE 1394 AV signal.

A block 402 is generally called a scan converter. Either the input digital YCbCr signal or digital RGB signal is selected according to the input source setting. It has means for recognizing the frequency and resolution of the input image from the selected signal and writing it to the frame buffer 403 described later.
Also, there is means for reading the data on the frame buffer 403 at an appropriate frequency, converting it into an image signal of an appropriate resolution, and outputting it to the OSD circuit 404 described later.

  There are two types of writing and reading methods. The first is a double buffering method, in which an area for two frames is secured in the frame buffer 403 and reading and writing are performed asynchronously. In particular, control is performed to select each access target area at each frame period of reading and writing so that overtaking due to a difference in reading and writing frequency does not occur. In other words, the reading target area and the writing area are selected from the first area and the second area for each frame period so that the frame buffer 403 does not switch to a temporally different frame in the middle of the frame. To do.

  The second is a single buffering method in which an area for one frame is secured in the frame buffer 403 and reading and writing are always performed on that area. That is, one of the first area and the second area is selected and reading / writing is always performed on that area.

  Reference numeral 403 denotes a frame buffer which is means for temporarily storing an input image and an image to be displayed on the overlay. The recorded input image is read from the scan converter 402 asynchronously with writing. The recorded overlay image is read from the OSD control circuit 404 described later. As described above, the input image is written and read by the double buffering method and the single buffering method.

  Reference numeral 404 denotes an OSD (On Screen Display) circuit, which has means for reading an overlay image from the frame buffer 403 and overwriting (overlaying) the image output from the scan converter 402 in accordance with a set position. After the processing, the overwritten image signal is output to a D / A converter 405 described later. A typical overlay image is a menu image.

  Reference numeral 405 denotes a D / A converter, which converts digital RGB image information output from the OSD control circuit 404 into an analog signal for driving the light valve driving circuit 406 and outputs the analog signal.

  Reference numeral 406 denotes a light valve driving circuit. The light valve driving circuit drives an unillustrated light valve based on an image signal output from the D / A converter 405 to form an image. The light valve is, for example, a transmissive liquid crystal panel, a reflective liquid crystal panel, or a mirror device. Light from a light source (not shown) is transmitted or reflected by the light valve, and is projected as an image on a screen (not shown) through a lens device (not shown). The light valve driving circuit 406 can drive the light valve so that the image on the light valve is formed as it is, and the image is formed by reversing left and right, up and down, or left and right and up and down.

Reference numeral 407 denotes a RAM device necessary for the operation of a microcomputer 409 described later, and includes a stack and a work area.
Reference numeral 408 denotes a ROM device necessary for the operation of the microcomputer 409, which will be described later. Stored.

  Reference numeral 409 denotes a microcomputer that controls the entire liquid crystal projector shown in FIG. The main control of the projector device is a menu transition and an operation for setting a device related thereto. This detailed control will be described later.

Reference numeral 410 denotes a menu switch for receiving an instruction from the user to shift to a mode for setting by menu. When this menu switch is pressed, a transition to the menu display state in the menu non-display state is performed.
Reference numeral 411 denotes a selection switch for receiving a selection instruction from the user in the menu display state. When this selection switch is pressed, values are set in the menu display state, state transitions in the menu, and the like are performed.
Reference numeral 412 denotes a right switch for receiving a menu operation instruction to move the cursor right from the user in the menu display state.

Reference numeral 413 denotes a left switch for receiving a menu operation instruction to move the cursor left from the user in the menu display state.
Reference numeral 414 denotes a lower switch for receiving a menu operation instruction for moving the cursor down from the user in the menu display state.
Reference numeral 415 denotes an upper switch for receiving a menu operation instruction to move the cursor up from the user in the menu display state.
Reference numeral 416 denotes a nonvolatile memory (NVRAM) device that stores captured image data. The stored image data is retained even when no power is supplied to the projector.

  Here, the input analog RGB signal and composite NTSC signal correspond to the “input image signal” described in the first embodiment. The signal for driving the light valve output from the light valve driving circuit 406 corresponds to the “display image signal” described in the first embodiment. The frame buffer 403 corresponds to the “frame buffer” described in the first embodiment. The NVRAM 416 corresponds to the “nonvolatile memory” described in the first embodiment. The scan converter 402 and the microcomputer 409 correspond to the “frame buffer control unit” described in the first embodiment. The scan converter 402 corresponds to the “image writing unit” and the “image reading unit” described in the first embodiment, and the microcomputer 409 corresponds to the “image capture unit” described in the first embodiment. The switches 410 to 415 and the microcomputer 409 correspond to the “image capture receiving unit” described in the first embodiment.

Next, the operation process of this embodiment will be described. In this embodiment, the scan converter normally operates in a mode using a double buffering method.
FIG. 5 shows an example of the menu screen. In this embodiment, the microcomputer 409 switches the menu display state and the non-display state by pressing the menu switch 410. In the menu display state, a menu overlay image is transferred from the ROM 408 to the frame buffer 403 by the microcomputer 409 and displayed in a form superimposed on the input image by the OSD circuit 404.

  In FIG. 5, there is a menu 501 for the input image 500, which includes 502 for selecting an input source, 503 for changing contrast, 504 for changing brightness, and 406 for executing screen capture. There are four options. These options can be selected by the cursor, and the cursor can be shifted between the options by the upper switch 415 and the lower switch 414. In FIG. 5, the cursor is present in the option 504 for changing the brightness. Each parameter can be adjusted by pressing the selection switch 411, the right switch 412, and the left switch 413 while each option is selected. In particular, when the selection switch 411 is pressed while the screen capture option 505 is selected, a transition to the screen capture confirmation state occurs.

  FIG. 6 shows a screen example in the screen capture confirmation state. This screen is the same as the above-described prior art example. By pressing the right switch 412 and the left switch 413, either an option 602 for executing screen capture or an option 603 for canceling is selected. By depressing the selection switch 411 for each option, a transition to the screen capture execution state occurs in the former case, and a transition to the menu non-display state occurs in the latter case. When the former selection switch 411 is pressed, an event of “request to transfer frame buffer image to nonvolatile memory” occurs in the microcomputer 409.

  FIG. 9 shows a screen example in a screen capture execution state. At the time of transition to this state, the microcomputer 409 instructs the scan converter 402 to switch from the double buffering method to the single buffering method. Next, the microcomputer 409 inquires the scan converter 402 about the start address and end address of the frame buffer area (unused area) on the side not used for buffering. Thereafter, the microcomputer 409 reads the data in the unused area in the frame buffer 403 and sequentially writes to the NVRAM 416. FIG. 1 shows a schematic diagram of the frame buffer during the above process. Reference numeral 100 denotes the entire frame buffer, and writing to the second area 102 is stopped as the unused area. Image data is transferred from the second area 102 to the NVRAM 416 in FIG. 4, and simultaneously, reading and writing are performed in the first area 101 by the single buffering method. Therefore, a moving image can be output at this time.

  When this transfer ends, the microcomputer 409 instructs the scan converter 402 to switch from the single buffering method to the double buffering method. When all the operations are completed, a transition to the menu non-display state is performed. In this way, moving images are always displayed throughout the entire screen capture process. In this way, the present invention can be implemented.

[Second Embodiment]
This second example corresponds to the second embodiment.
As a second embodiment, an example in which the scan converter 402 is initially operating in a single buffering scheme can be considered. In this case, while the image for two frames is written in the frame buffer 403, the scan converter 402 is operated by the double buffering method. Thereafter, the same process as in the first embodiment is performed, and the present invention can be implemented by finally leaving the single buffer system.

[Third embodiment]
This third example corresponds to the third embodiment.
In addition to the first and second embodiments as a third embodiment, as shown in FIG. 10, an icon 1001 indicating that the screen is being captured is displayed in the screen 1000 in the screen capture execution state. You can also. This icon corresponds to “display indicating that an image is being transferred”. The present invention can also be implemented in this way.

As described above, according to the first embodiment, regarding the image display device operating in the double buffering method, the display image becomes a still image while the display image is transferred to the nonvolatile memory. Absent. If a movie is input, the movie is displayed and the usability is improved.
Even in the case of using the single buffering method, as shown in the second embodiment, by temporarily switching to the double buffering method until image data is written in at least two areas, The invention can be realized and the above-described advantages can be obtained.
Further, as shown in the third embodiment, during the transfer of the display image to the non-volatile memory, the display indicating that the image is being transferred is displayed to prevent the power from being accidentally turned off during the transfer. You can also.

It is a frame buffer schematic diagram at the time of capture execution in the image display apparatus according to an embodiment of the present invention. It is the Example of this invention, and the frame buffer schematic diagram at the normal time in a prior art. It is a frame buffer schematic diagram at the time of capture execution in the prior art. 1 is a block diagram of an image display device according to an embodiment of the present invention. FIG. 5 is a projected image diagram when the menu image is overlaid in the apparatus of FIG. 4. It is a figure which shows the example of a screen of the screen capture confirmation state in the apparatus of FIG. 4, and a prior art. It is a figure which shows the example of a screen of the screen capture execution state in a prior art. It is a figure which shows the example of a screen of the screen capture end in a prior art. It is a figure which shows the example of a screen of the screen capture execution state in the Example of this invention. It is a figure which shows the example of a screen of the screen capture execution state in the other Example of this invention.

Explanation of symbols

100, 200, 300, 403: frame buffer 101, 201, 301: first area 102, 202, 302: second area 400: A / D converter 401: video decoder 402: scan converter 404: OSD circuit 405: D / A converter 406: Light valve drive circuit 407: RAM device 408: ROM device 409: Microcomputer 410: Menu switch 411: Selection switch 412: Right switch 413: Left switch 414: Down switch 415: Up switch 416: Non-volatile Memory device

Claims (3)

An image display device that processes an input image signal input for each frame and displays an image,
A frame buffer having first and second regions for storing image data of one frame of the input image signal;
The first and second read target areas and the write areas are set for each frame period so that reading / writing to the frame buffer is not switched to a temporally different frame during reading of the frame buffer. Control is performed in one mode selected from a first mode selected from the first region and a second mode in which reading and writing to the frame buffer are performed only to one of the first and second regions. A frame buffer control unit to
Non-volatile memory;
An image capture unit that reads image data from the frame buffer and transfers the image data to the nonvolatile memory;
A display unit for displaying image data read from the frame buffer or an image after image processing is performed on the image data,
When a request to transfer the image of the frame buffer to the nonvolatile memory occurs,
The frame buffer control unit selects one of the first and second areas to control reading and writing to the frame buffer in the second mode;
The image capture unit reads image data written in the other of the first and second regions and transfers the read image data to the nonvolatile memory;
An image display device characterized by that.   The frame buffer control unit switches the operation mode to the first mode while writing at least one frame to the frame buffer when the transfer request occurs during operation in the second mode, One of the areas in which one frame is written in the first mode is switched to the second mode again as the other area, and the other area is notified to the image capture unit, and the image capture unit 2. The image display apparatus according to claim 1, wherein after receiving the notification, the image data of the notified area is transferred to the nonvolatile memory.   3. The image display device according to claim 1, wherein when the image capture unit is transferring image data, the display unit performs display indicating that the image data is being transferred.

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