JP2003241725A - Signal converting circuit and image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal converting circuit which makes a chip to be provided with a main circuit small-sized and decreases the number of pins while enabling two display signals differing in signal format to be outputted to reduce the cost of the chip and suppress its power consumption. <P>SOLUTION: This image display device is equipped with a main circuit 1 which generates a digital RGB signal according to a YUV 422 signal and outputs it to a 1st display device 3 and a signal converting circuit 2 which inputs and converts the digital RGB signal outputted by the main circuit 1 into an analog RGB signal and outputs it to a 2nd display device 4. The main circuit 1 and signal converting circuits 2 are formed in individual chips. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal conversion circuit which converts a display signal into a display signal of another signal format and outputs the signal, and an image display device using the signal conversion circuit.

[0002]

2. Description of the Related Art There is a technical demand for a signal output circuit that outputs a display signal to output two display signals having different signal formats. As a conventional technique related to this point, there is the following conventional technique. For example, in a digital camera, a digital LCD display unit provided to display a subject image before shooting or a recorded image after shooting, and an analog LC display unit provided as an electronic viewfinder.
And a D display may be provided and it is necessary to generate display signals for these two displays.

FIG. 3 is a block diagram of a signal output circuit according to the first prior art. As shown in FIG. 3, this conventional signal output circuit 101 is of a one-chip type,
Digital YUV422 signal input by DMA channel etc. (hereinafter simply referred to as "YUV signal")
Based on the above, a digital RGB signal and an analog RGB signal are generated and output. Digital RG
The B signal is output to a digital display device (for example, a digital LCD device) 106, and the analog RGB signal is output to an analog display device (for example, an analog LCD device) 107.

The signal output circuit 101 includes a signal converter 10
2, a timing generator 103, a multiplexer 104, and three digital signals corresponding to R, G, and B /
Analog (hereinafter referred to as "D / A") converter 105a-
And 105c.

The signal conversion unit 102 converts the YUV signal into a digital RGB signal and outputs signals of R, G and B color components in parallel. The timing generator 103 generates a synchronization signal for driving the display devices 106 and 107, and also generates a selection signal for driving the multiplexer 104. The multiplexer 104 multiplexes the R, G, and B signals output from the signal conversion unit 102 and outputs the multiplexed signals to the display device 106. Each D / A converter 105
a to 105c are R output from the signal conversion unit 102,
Display device 1 by taking in each signal of G and B and performing D / A conversion
It outputs to 07.

FIG. 4 is a block diagram of a signal output circuit according to the second conventional technique. As shown in FIG. 4, this conventional signal output circuit 111 is based on an input YUV signal, and is based on a color RGB sequential signal and a color field sequential format (hereinafter, referred to as “CF”).
S) data and generate and output. This signal output circuit 111 is also of a one-chip type. The digital RGB signal is output to the display device 106, and C
The FS data is output to the CFS format display device 116. In the configuration of FIG. 4, the signal converter 102,
The multiplexer 104 and the display device 106 are the same as those in FIG. 3, and detailed description thereof will be omitted.

The signal output circuit of FIG. 4 includes a first signal generator 111a for generating a digital RGB signal based on the YUV signal and a second signal generator 111a for generating CFS data based on the YUV signal. The signal generator 111b is provided. Each of the signal generators 111a and 111b has a YUV
The signals are input through individual signal lines (here, individual DMA channels).

The first signal generator 111a includes a signal converter 1 for converting a YUV signal into a digital RGB signal.
02, a multiplexer 104 for multiplexing the RGB signals given from the signal converter 102, and a multiplexer 1.
And a timing generator 112 for generating a selection signal for driving the display device 04 and a synchronization signal for driving the display device 106.

The second signal generating section 111b includes a signal converting circuit 113 for converting the YUV signal into a digital RGB signal and a generating circuit 115 for generating CFS data based on the RGB signal supplied from the signal converting circuit 113.
And a timing generator 114 for generating a selection signal for driving the generation circuit 115 and a synchronization signal for driving the display device 116.

[0010]

However, in the prior art of FIG. 3 described above, since the signal output circuit 101 is provided with the digital RGB signal output section and the analog RGB signal output section, Larger circuit 101,
An increase in the number of pins or the like occurs, which increases the cost of the circuit 101. Particularly, in the signal output circuit 101 shown in FIG. 3, the D / A converter 105a which is an analog processing circuit.
To 105c are digital processing circuits
2 and the multiplexer 104, the size is larger and the power consumption is larger. Therefore, the presence of the D / A converters 105a to 105c prevents the signal output circuit 101 from being downsized and the power consumption from being suppressed.

Further, regarding the prior art of FIG. 4 mentioned above,
Since the signal output circuit 111 is provided with the first signal generation unit 111a that generates and outputs digital RGB signals and the second signal generation unit 111b that generates and outputs CFS data, the circuit 111 is upsized. The number of pins will increase. In addition, in this signal output circuit 111, two DM signals are input to the YUV signals to the signal generation units 111a and 111b.
Since the A channel is used, there is also a problem that bus transactions increase and power consumption increases.

Therefore, in view of the above problems, the first aspect of the present invention
The purpose is to separate a main circuit for generating and outputting a first display signal and a signal conversion circuit for converting the first display signal into a second display signal of another signal format and outputting the same. With this configuration, it is possible to output two display signals having different signal formats, and at the same time, the size of the chip on which the main circuit is provided can be reduced, the number of pins can be reduced, and the cost of the chip can be reduced. An object of the present invention is to provide an image display device using.

A second object of the present invention is to provide a signal conversion circuit capable of suppressing the power consumption of a chip provided with a main circuit for generating and outputting a first display signal, and an image display device using the signal conversion circuit. .

[0014]

[Means for Solving the Problems] The technical means for achieving the above object is formed in a chip separate from a chip provided with a main circuit for generating and outputting a first display signal. It is characterized in that the first display signal outputted from the circuit is taken in, converted into a second display signal having a signal format different from that of the first display signal, and outputted.

Preferably, the first display signal is a digital display signal sampled into one color signal per pixel clock, and the second display signal is an analog display signal. The main circuit preferably generates the first display signal based on a digital input signal.

Also, preferably, the first display signal is a digital display signal sampled into a color signal of one color per pixel clock, and the second display signal is a digital display of a color plane sequential format. Is a display signal.

Further, preferably, when the first display signal is converted into the second display signal, an image in a part of a selected area in an image represented by the first display signal is displayed. It is preferable to generate and output the second display signal.

Preferably, when the first display signal is converted into the second display signal, the number of pixels of the image represented by the first display signal is changed and the changed pixel is changed. It is preferable to generate and output the second display signal representing an image corresponding to a number.

Further, the technical means for achieving the above object is, in the image display device using the signal conversion circuit according to any one of claims 1 to 5, the main circuit and that according to any one of claims 1 to 5. The signal conversion circuit according to any one of the above, and a first display device that displays an image based on the first display signal output by the main circuit,
A second display device that displays an image based on the second display signal output by the signal conversion circuit.

<Description of Terms> In the sense that the signal format of the display signal in the present invention is different, the difference between whether the display signal is a digital type or an analog type, and the difference in the substantial content type of the display signal (for example, RGB signals, CFS data, etc.).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> FIG. 1 is a block diagram of an image display device using a signal conversion circuit according to a first embodiment of the present invention. As shown in FIG. 1, this image display device includes a main circuit 1, a signal conversion circuit 2, a first display device 3, and a second display device 4. The main circuit 1 and the signal conversion circuit 2 are one-chip type circuits provided on separate chips.

Here, the first display device 3 and the second display device 4 display images based on display signals of different signal formats. In the present embodiment, the first display device 3 is a digital LCD device that displays an image using a digital RGB signal sampled into a color signal of one color per pixel clock, which is the first display signal, More specifically, for example, it is a main display unit provided on the back surface of the digital camera or the like and for displaying a subject image before photographing or a recorded image after photographing. Also, the second
The display device 4 of FIG.
It is an analog LCD device that displays an image by a GB signal, and more specifically, it is an electronic viewfinder of a digital camera, for example.

As shown in FIG. 1, the main circuit 1 includes a signal converter 11, a timing generator 12, and a multiplexer 13, and a digital YUV signal input by a DMA channel or the like is used as a first display signal. Is converted into a digital RGB signal and output to the first display device 3.

The signal converter 11 converts the YUV signal into a digital RGB signal and outputs the signals of the R, G and B color components in parallel. Timing generator 1
3 generates a synchronization signal for driving the first display device 3 and also generates a selection signal for driving the multiplexer 13. The multiplexer 13 multiplexes the R, G, and B signals output from the signal conversion unit 11 and outputs the multiplexed signals to the first display device 3.

As shown in FIG. 1, the signal conversion circuit 2 includes a signal conversion section 21 and three D / A converters 22a to 22c corresponding to R, G and B, and the main circuit 1 The output digital RGB signal is captured, converted into an analog RGB signal which is a second display signal, and output to the second display device 4.

The signal converter 21 takes in the multiplexed digital RGB signals and sync signals output from the main circuit 1, divides them into R, G, and B parallel signals, and requires timing adjustment and the like. Various types of processing and output. Further, the signal conversion unit 21 generates a synchronization signal for driving the second display device 4 based on the synchronization signal fetched from the main circuit 1, or newly generates and outputs the synchronization signal.

Each of the D / A converters 22a to 22c takes in the digital R, G, and B signals output from the signal converter 21, D / A converts them, and outputs them to the second display device 4. To do.

In some cases, it is necessary to extract an image of a part of the selected area from the display image (entire image) of the first display device 3 and display it on the second display device 4. In such a case, in addition to the above processing, the signal conversion unit 21 determines, based on the RGB signal input from the main circuit 1, a predetermined selection area in the entire image represented by the input RGB signal. An RGB signal representing the image inside is generated and output to the D / A converters 22a to 22b (first resizing processing). The signal converter 2
The first resizing process may be combined with the second resizing process described below.

Further, the number of display pixels (at least one of the number of horizontal pixels and the number of vertical pixels) of the first display device 3 and the second display device 4 may be different. In such a case, in addition to the above processing, the signal conversion unit 21 sets the number of display pixels (the number of horizontal pixels or the number of vertical pixels) of the image represented by the RGB signal input from the main circuit 1 to the second value. The D / A converters 22a to 22a are modified so as to correspond to the display pixel number of the display device 4, and the RGB signal corresponding to the changed display pixel number is reconfigured based on the input RBG signal.
2c is output (second resizing process).

As described above, according to this embodiment, the signal conversion circuit 2 for converting the digital RGB signal generated and output by the main circuit 1 into the analog RGB signal is used as a chip provided with the main circuit 1. Since it is formed on a separate chip, it is possible to output two display signals having different signal formats, the chip in which the main circuit 1 is provided can be downsized, the number of pins can be reduced, and the cost of the chip can be reduced. Can be achieved. In particular, by making the signal conversion circuit 2 which is an analog signal processing circuit a chip configuration different from the main circuit 1 which is a digital processing circuit, it is effective to reduce the size of the chip in which the main circuit 1 is provided and to suppress the power consumption. Can be done.

When it is necessary to extract an image of a part of the selected area from the display image (entire image) of the first display device 3 and display it on the second display device 4, the main circuit 1 While the generated digital RGB signal is input to the first display device 3 to display the entire image, the signal conversion circuit 2 outputs the digital RGB signal to the second display device 4.
By inputting an analog RGB signal generated by converting and processing so as to correspond to the display range of the second display device 4, the image of a part of the selected area in the entire image is displayed on the second display device 4. Can be displayed on. For example, in a digital camera or the like equipped with an electronic viewfinder in addition to the main display section, if the effective display area of the electronic viewfinder is narrower than the main display section, the entire image is displayed by a digital RGB signal. It is possible to display the image of the selected area in the entire image on the electronic viewfinder by the analog RGB signal while displaying the image on the display section of.

Further, when the number of display pixels (at least one of the number of horizontal pixels and the number of vertical pixels) of the first display device 3 and the second display device 4 is different, the signal conversion section 2
1 is a digital RG input from the main circuit 1.
Since the B signal is converted and processed so that the number of pixels thereof corresponds to that of the second display device 4, a digital RGB signal is generated. This can be easily handled without providing the circuit of. This makes it possible to easily cope with a digital camera provided with an electronic viewfinder in addition to the main display unit, even when the number of display pixels of the electronic viewfinder is smaller than that of the main display unit.

<Second Embodiment> FIG. 2 is a block diagram of an image display device using a signal conversion circuit according to a second embodiment of the present invention. The image display device according to the present embodiment is substantially different from the image display device according to the first embodiment described above.
The signal conversion circuit 31 is provided in place of the signal conversion circuit 2 described above, and the display device 32 is provided as the second display device 32 in place of the display device 4 described above. Therefore, the configurations of the main circuit 1 and the first display device 3 are not changed, and corresponding parts are designated by the same reference numerals and description thereof is omitted.

Like the signal conversion circuit 2, the signal conversion circuit 31 is also a one-chip type circuit provided on a chip separate from the main circuit 1. The second display device 32 is the second
Is a digital display device (LCD device or the like) that displays an image based on digital CFS data that is a display signal of, for example, and is provided as an electronic viewfinder of a digital camera.

The signal conversion circuit 31, as shown in FIG.
The signal conversion unit 33 and the first and second buffers 34 and 35
The digital RGB signal output from the main circuit 1 is captured, converted into CFS data which is a second display signal, and output to the second display device 32.

The signal converter 33 takes in the multiplexed digital RGB signals and sync signals output from the main circuit 1, uses the buffers 34 and 35 as temporary storage locations for image data, and takes them in. To C
It is converted into FS data and output to the second display device 32.
The signal conversion unit 33 also generates a synchronization signal for driving the second display device 32 based on the synchronization signal taken in from the main circuit 1 or newly generates and outputs the synchronization signal.

Further, when it is necessary to extract an image of a part of the selected area in the display image (entire image) of the first display device 3 and display it on the second display device 32, or
When the number of display pixels (at least one of the number of horizontal pixels and the number of vertical pixels) of the first display device 3 and the second display device 32 is different, as in the case of the above-described first embodiment, The signal conversion unit 33 uses the first resizing process and the second resizing process.
One of the resizing processes of 1 is executed alone, or both of them are executed in combination.

As described above, according to the present embodiment, the signal conversion circuit 31 for converting the digital RGB signal sampled into the color signal of one color per pixel clock generated and output by the main circuit 1 into the CFS data. Is formed on a chip different from the chip on which the main circuit 1 is provided, so that it is possible to output two display signals having different signal formats, while the size of the chip on which the main circuit 1 is provided is small and the number of pins It is possible to reduce the chip cost.

The signal conversion circuit 31 is the main circuit 1
Takes in the RGB signal which is the first display signal and converts it into CFS data which is the second display signal and outputs it, which is a source for generating each of the first and second display signals. The signal (YUV signal) only needs to be input to the main circuit 1, and it is not necessary to use two DMA channels for inputting the signal that is the source of the signal as in the second conventional technique described above, and power consumption is suppressed. can do.

Further, when it is necessary to extract an image of a part of the selected area from the display image (entire image) of the first display device 3 and display it on the second display device 32, or
Even when the first display device 3 and the second display device 32 have different display pixel numbers (at least one of the horizontal pixel number and the vertical pixel number), it is possible to easily cope with them without providing an additional circuit. You can

[0041]

According to the present invention, the signal conversion circuit for converting the first display signal into the second display signal and the main circuit for generating and outputting the first display signal are provided. It is possible to output two display signals with different signal formats, while reducing the size of the chip provided with the main circuit and reducing the number of pins. Reduction can be achieved.

The signal conversion circuit takes in the first display signal output from the main circuit, converts the first display signal into the second display signal, and outputs the second display signal. Therefore, the signal conversion circuit generates each of the first and second display signals. It is only necessary to input the original signal to the main circuit, and it is not necessary to use two DMA channels for inputting the original signal as in the second conventional technique, and power consumption can be suppressed. it can.

According to the second aspect of the present invention, the signal conversion circuit, which is an analog signal processing circuit, has a chip configuration different from that of the main circuit, which is a digital processing circuit. And power consumption can be suppressed.

According to the invention described in claim 4, while inputting the first display signal to the display device to display the whole image,
The second display signal can be input to another display device to display an image of a part of the selected area in the entire image. For example, in a digital camera equipped with an electronic viewfinder in addition to the main display unit, if the effective display area of the electronic viewfinder is narrower than the main display unit, the entire image is displayed by the first display signal. It is possible to display the image of the selected area in the entire image on the electronic viewfinder by the second display signal while displaying the image on the display section of.

According to the invention described in claim 5, a display device (first display device) for displaying by the first display signal.
And the display device (second display device) that performs display by the second display signal, the number of display pixels (at least one of the number of horizontal pixels and the number of vertical pixels) is different, the first display device The second display device corresponding to the number of display pixels of the second display device while outputting the first display signal corresponding to
The display signal can be generated and output by the signal conversion circuit. As a result, in digital cameras etc. equipped with an electronic viewfinder in addition to the main display,
It is possible to easily cope with the case where the number of display pixels of the electronic viewfinder is smaller than that of the main display section.

According to the sixth aspect of the present invention, the first and second display devices can be provided while reducing the size of the chip provided with the main circuit, reducing the number of pins, lowering the cost and suppressing the power consumption. It is possible to generate corresponding first and second display signals and display an image by both display devices.

[Brief description of drawings]

FIG. 1 is a block diagram of an image display device using a signal conversion circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an image display device using a signal conversion circuit according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a signal output circuit according to a first conventional technique.

FIG. 4 is a block diagram of a signal output circuit according to a second conventional technique.

[Explanation of symbols]

1 main circuit 2 signal conversion circuit 3 First display device 4 Second display device 11 Signal converter 12 Timing generator 13 multiplexer 21 signal converter 31 Signal conversion circuit 32 Second display device 33 Signal converter 34,35 buffers

Claims (6)

[Claims] 1. A chip formed separately from a chip provided with a main circuit for generating and outputting a first display signal, capturing the first display signal output from the main circuit, A signal conversion circuit, which converts and outputs a second display signal having a signal format different from that of the first display signal. 2. The signal conversion circuit according to claim 1, wherein the first display signal is a digital display signal sampled into a color signal of one color per pixel clock, and the second display signal. Is an analog display signal, and the main circuit generates the first display signal based on a digital input signal. 3. The signal conversion circuit according to claim 1, wherein the first display signal is a digital display signal sampled into a color signal of one color per pixel clock, and the second display signal. Is a signal conversion circuit characterized by being a digital display signal of a color plane sequential format. 4. The signal conversion circuit according to claim 1, wherein an image represented by the first display signal when converting the first display signal into the second display signal. A signal conversion circuit for generating and outputting the second display signal representing an image within a part of a selected area in the inside. 5. The signal conversion circuit according to claim 1, wherein an image represented by the first display signal when converting the first display signal into the second display signal. The signal conversion circuit is characterized in that the second display signal representing an image corresponding to the changed number of pixels is generated and output. 6. An image display device using the signal conversion circuit according to any one of claims 1 to 5, wherein the main circuit, the signal conversion circuit according to any one of claims 1 to 5, A first display device that displays an image based on the first display signal output by the main circuit, and a second display device that displays an image based on the second display signal output by the signal conversion circuit. An image display device comprising: a display device.