JP2000099719A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device capable of providing an easily observable contour-emphasized picture by cutting off noises. SOLUTION: A peaking circuit 10 for operating/outputting a digital signal outputted from an A/D conversion circuit 5 for converting an inputted analog signal into a digital signal so that a display image is emphasized at its contour is connected to the output side of the circuit 5. A digital signal switching circuit 18 for switching the execution or non-execution of contour emphasizing operation by the circuit 10 is connected to the output side of the circuit 10. A filter 7 for removing a signal other than a prescribed analog image signal from an input signal is connected to the upstream side of the input side of the circuit 10. An analog signal switching circuit 6 for passing the input signal through the filter 7 when contour emphasis operation is executed by the circuit 10 or inputting the input signal to the circuit 5 without passing it through the filter 7 when the operation is not executed is connected to the input side of the circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for enhancing the outline of a display image.

[0002]

2. Description of the Related Art Conventionally, a viewfinder for a studio camera used in a studio such as a television station is mainly composed of C.
Although RT is used, recently, low power consumption and light weight of the viewfinder are desired, and application of the TFT type liquid crystal display device to a viewfinder for a studio camera is expected. Along with this, development of a contour emphasizing circuit with less noise by digital arithmetic processing required for focusing has been desired.

[0003] In an image signal conversion circuit used in a conventional studio camera, an input analog signal itself has an A / A signal.
It is input to a D conversion circuit, converted into a digital signal and output, sent to a peaking circuit electrically connected to the A / D conversion circuit, subjected to arithmetic processing, and easily focused on an image by a viewfinder. The image has been contour-enhanced to make it possible.

In the above-described conventional image signal conversion circuit, since the input analog signal itself is directly input to the A / D conversion circuit, a signal other than the desired analog image signal, that is, noise is also converted to a digital signal by A / D conversion. In addition, since the noise itself is also emphasized by the peaking circuit, an emphasis effect is obtained even though the image is out of focus, and there is a problem that the viewfinder screen becomes difficult to see. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide an image display device which can provide an outline emphasizing screen which is easy to see by cutting noise.

[0005]

In the image display device according to the present invention, in the drive circuit, the output side of the A / D conversion means for converting the input analog image signal into a digital signal is supplied from the A / D conversion means. A peaking means for calculating and outputting the output digital signal so that the displayed image is contour-enhanced is connected, and connected to an output side of the peaking means to switch execution or non-execution of the contour emphasis calculation by the peaking means. A signal switching means is provided, and a filter for removing a signal other than a predetermined analog image signal from an input signal is provided upstream of the input side of the A / D conversion means, and the digital signal switching means is operated in conjunction with the peaking means. The input signal is passed through the above filter when the contour enhancement calculation is performed, and the input signal is filtered when the contour calculation is not performed. Those which means switching analog signals for input to said A / D converting means connected to the input side of the A / D converter without being.

According to this image display device, when it is desired to emphasize the outline of the image on the display screen, the digital signal switching means is switched to the operation execution side, and the analog signal switching means is also switched to the input signal filtering side. This filter removes signals other than the predetermined analog image signal, that is, noise. Therefore, a predetermined analog image signal is digitally processed by A / D conversion means,
Next, since the digital image signal is subjected to the contour emphasis calculation by the peaking means and outputted, it is possible to provide a contour emphasis screen in which noise is cut on the display screen so as to be easily seen.

When the contour enhancement of the image is not required, the digital signal switching means is switched to the non-execution side and the analog signal switching means is switched to the input signal filter non-passing side.

In another image display apparatus according to the present invention, in a drive circuit, a digital signal output from the A / D conversion means is supplied to an output side of an A / D conversion means for converting an input analog image signal into a digital signal. Digital signal switching means for connecting a peaking means for calculating / outputting a signal so that a displayed image is contour-emphasized and connecting the signal to an output side of the peaking means to switch execution or non-execution of the contour emphasis calculation by the peaking means A / D
On the upstream side of the input side of the conversion means, at least two filters for removing signals having a frequency outside the predetermined analog signal and different frequencies from the input signal are provided,
The input signal is passed through a desired filter among the at least two filters when the contour emphasis calculation is performed by the peaking means in conjunction with the digital signal switching means, and when the contour emphasis calculation is not performed, the input signal is An analog signal switching means for inputting to the A / D conversion means through a desired filter among the remaining filters or without passing through these filters is provided.

According to this image display device, when it is desired to emphasize the outline of the image on the display screen, the digital signal switching means is switched to the operation execution side, and the analog signal switching means is adjusted to at least the frequency of the noise to be removed. Switching is performed so that a desired filter is selected from the two filters, and desired noise is removed by the selection filter. Therefore, the predetermined analog image signal is A / D
Since the digital image signal is digitally processed by the conversion means, and then the digital image signal is subjected to the contour emphasis calculation by the peaking means and outputted, it is possible to provide an easy-to-see contour emphasis screen in which noise is cut on the display screen.

When the enhancement of the contour of the image is unnecessary, the digital signal switching means is switched to the non-operation-executing side, and the analog signal switching means is switched to the desired filter side or the input signal side of the remaining at least two filters. Switch to the filter non-connection side.

[0011]

Next, an embodiment of an image display device according to the present invention will be described with reference to the drawings. As shown in FIG. 1, a video display device according to a first embodiment of the present invention includes a driving circuit 1 to which an analog video signal is input, a signal line driver 2 and a scanning line driver 3 connected to the driving circuit 1.
And a liquid crystal display panel 4 for displaying a screen based on signals from the signal line driver 2 and the scanning line driver 3. The liquid crystal display panel 4 may be, for example, an STN type liquid crystal display panel or a TFT type liquid crystal display panel.

The drive circuit 1 has an image signal conversion circuit as shown in FIG. This image signal conversion circuit
A peaking circuit 10 for calculating and outputting the outline of the displayed image is provided, and an A / D conversion circuit 5 for converting an analog image signal input into a digital signal on the input side upstream of the peaking circuit 10 is provided. The peaking circuit 10 is electrically connected. An analog signal switching circuit 6 is connected to the A / D conversion circuit 5 on the input side upstream of the A / D conversion circuit 5. Further, an analog signal switching circuit 6
And a low-pass filter 7 for removing a signal other than a predetermined analog image signal, that is, noise, from the input analog signal.
Output terminals are connected. An input terminal of the low-pass filter 7 and an input terminal of the analog signal switching circuit 6 are connected to an analog image signal input terminal. The noise varies depending on a predetermined analog image signal. For example, when the sampling frequency of the A / D conversion circuit of the signal is about 30 MHz, the noise is about 1 MHz.
A signal of 5 MHz or more becomes noise.

The peaking circuit 10 enhances the outline of the image signal so that the focus can be easily adjusted by a view finder in a studio camera incorporating the liquid crystal display panel 4, for example.
12, two subtraction circuits 13 and 14, two addition circuits 1
5, 17 and a digital circuit formed by combining the multiplication circuit 16.

The first delay circuit 11 and the second delay circuit 12 connected to the first delay circuit 11 are subjected to A / D conversion by the A / D conversion circuit 5.
The converted digital signal d is delayed by one clock as shown in FIG. 3 to generate signals e and f shown in FIG. 3 and the signal is output by the second subtraction circuit 14 connected in parallel to the second delay circuit 12. By subtracting the signal d from e, a change in the image signal when the signal is delayed by one clock is detected, and is output from the second subtraction circuit 14 as a signal g. The second subtraction circuit 14 is connected between the A / D conversion circuit 5 and the first delay circuit 11, and is connected between the first delay circuit 11 and the second delay circuit 12. . As shown in FIG. 3, as the signal g, when the image signal changes with time, a signal having a certain non-zero amplitude is output, and the greater the change, the greater the amplitude.

In the second subtraction circuit 14, the difference between the signal e and the signal one clock before is calculated, but the first subtraction circuit 13 calculates the signal one clock after the signal e. f
Then, a signal h shown in FIG. 3 which is opposite in polarity to the signal g and is delayed by one clock is output. First subtraction circuit 1
3 is connected between the first delay circuit 11 and the second delay circuit 12 and is also connected to the second delay circuit 12.

The addition circuit 15 adds the signal g and the signal h to output a signal i shown in FIG. 3 which emphasizes the video signal in both positive and negative directions. This addition circuit 15 is connected to the first subtraction circuit 13 and also to the second subtraction circuit 14. The multiplication circuit 16 connected to the addition circuit 15
A signal j obtained by adjusting the degree of emphasis and multiplying the signal i by n (n indicates the degree of emphasis) is output. This signal j and the original signal e are added by the adder circuit 17 to output a signal k shown in FIG. This addition circuit 17
Connected to the multiplication circuit 16 and the first delay circuit 11
And the second delay circuit 12. This contour emphasis effect occurs when the video signal changes rapidly over time.
Appears noticeably.

A first delay circuit 11 and a second delay circuit 12
The digital signal switching circuit 18 is connected to the intermediate point of the above and the multiplication circuit 16. Digital signal switching circuit 18
Switches between execution and non-execution of the contour emphasis calculation by the peaking circuit 10. The analog signal switching circuit 6
When a contour emphasis operation is executed by an arithmetic control signal input from the outside to the connection line 19, the output is switched to the output side of the adder circuit 18 and the analog signal switching circuit 6 is also connected to the low-pass line. Connect to the output side of filter 7. On the other hand, when the contour emphasis calculation is not performed, the digital signal switching circuit 1
8 disconnects the connection with the adder circuit 17 and the first delay circuit 11
The analog signal switching circuit 6 also disconnects from the low-pass filter 7 and passes the input analog signal to the A / D conversion circuit 5 as it is.

When an image signal is displayed on a TFT type liquid crystal display device, a time-varying image signal is sampled at a certain time interval, and the position is shifted in time according to the sampled data. Therefore, a temporal change in the image signal means a change in the displayed image depending on the position when viewed from the displayed image. What sharply changes the image depending on the normal position is the contour of the display object. From the above, the effect of enhancing the contour by the peaking circuit can be obtained.

In the viewfinder, the contour emphasis effect is used for focusing. When the image is out of focus, the image is blurred, and the temporal change in the image signal (change in the image signal depending on the position) is small, and almost no enhancement effect can be obtained. The change in the image signal depending on the position at the outline of the display object becomes large, and an outline emphasis effect can be obtained. It is conceivable to add a low-pass filter to the image signal, but if the low-pass filter is added, there is a problem that the resolution of the original image signal is reduced. Therefore, in the present embodiment, a low-pass filter is inserted to cut noise only when the peaking circuit is operated (during focusing), and the low-pass filter is removed when the original video is viewed.

The operation of the circuit shown in FIG. 2 will be described. To operate the peaking circuit 10, first, the analog signal switching circuit 6 selects the analog signal b that has passed through the low-pass filter 7 and outputs it as the signal c. After the analog signal c is converted into the digital signal d by the A / D conversion circuit 5, the signal e is converted into the signal d by the second subtraction circuit 14.
And outputs a signal g. Meanwhile, the first
The subtraction circuit 13 performs an operation of subtracting the signal f from the signal e to output a signal h. The first addition circuit 15 performs an operation of adding the signal g and the signal h, and outputs a signal i. Next, the signal i is emphasized n times by the multiplying circuit 16 to output a signal j, and the second adding circuit 17 performs an addition operation of the signal e and the signal j to output a signal k.
This signal k passes through the digital signal switching circuit 18,
It is output as a digital image signal.

When the peaking circuit 10 is not operated, first, the analog signal switching circuit 6 selects an original analog image signal a which does not pass through the low-pass filter 7 and outputs it as a signal c. Next, the signal c is A / D
The conversion circuit 5 outputs a digital signal d, and the signal e that has passed through the first delay circuit 11 is output directly as a digital image signal through the digital signal switching circuit 18. Thus, the ON and O of the peaking circuit 10
The FF and the passage and non-passage of the original analog image signal to the low-pass filter 7 are switched by sending an arithmetic control signal to each of the analog signal switching circuit 6 and the digital signal switching circuit 18.

Next, a second embodiment of the image display device according to the present invention will be described with reference to FIG. The second embodiment is an image display device in which the cutoff frequency of a low-pass filter that passes therethrough is changed at the time of focusing and when an original image is viewed, so that a low-pass filter having characteristics suitable for each can be selected. The same members as those in the first embodiment described above are denoted by the same reference numerals in FIG. 4, and the description of these members will be omitted. Note that the basic block structure of the second embodiment is the same as that of FIG. In FIG. 4, two low-pass filters 37 and 38 are provided on the input side of the analog signal switching circuit 36 connected to the input side of the A / D conversion circuit 5.
Are connected, and an analog image signal is input to each input terminal of these low-pass filters.

Of these low-pass filters, the first low-pass filter 37 has a cut-off frequency of 8 to 12.
MHz, which cuts noise without lowering the resolution of the video signal. The second low-pass filter 38 has a cutoff frequency of 4 to 6 MHz, and cuts noise when the contour emphasis circuit operates. The analog signal switching circuit 36 includes these low-pass filters 37,
38 is switched by the operation control signal.

Next, the operation of the image signal conversion circuit shown in FIG. 4 will be described. When the peaking circuit 10 is operated, first, the analog signal switching circuit 36 is connected to the first low-pass filter 37, passes the signal b1 passing through the filter 37, and outputs the signal c. After that, the signal processing described in the first embodiment is performed. That is, A / D
After the conversion circuit 5 converts the analog signal c into a digital signal d, the second subtraction circuit 14 performs an operation of subtracting the signal d from the signal e, and outputs a signal g. Further, the first subtraction circuit 13 performs an operation of subtracting the signal f from the signal e to output a signal h. Further, the first addition circuit 15 performs an operation of adding the signal g and the signal h, and
The signal i is output. Then, the signal i
Is emphasized n times and a signal j is output, and the second addition circuit 1
7 to perform an addition operation on the signal e and the signal j to obtain a signal k.
Is output. This signal k is supplied to the digital signal switching circuit 18.
And is output as a digital image signal.

When the peaking circuit 10 is not operated, the analog signal switching circuit 36 is connected to the second low-pass filter 38, and the analog signal b2 passing through the filter 38 passes through the analog signal switching circuit 36 and becomes the signal c. Is output. Next, the signal c is supplied to the A / D conversion circuit 5.
As a result, the signal e is output as a digital signal d, and the signal e that has passed through the first delay circuit 11 is directly output as a digital image signal through the digital signal switching circuit 18.
As described above, the ON / OFF of the peaking circuit and the switching of the low-pass filters 37 and 38 are switched by sending the operation control signals to the analog and digital switching circuits 36 and 18, respectively.

[0026]

As described above, according to the image display device of the present invention, a clear display with no noise and high resolution can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an image display device according to the present invention.

FIG. 2 is a block diagram of an image signal conversion circuit portion in a drive circuit of the image display device shown in FIG.

FIG. 3 is a timing chart for explaining the operation of the image signal conversion circuit shown in FIG. 2;

FIG. 4 is a block diagram showing a second embodiment of the image display device according to the present invention, and showing an image signal conversion circuit portion in a drive circuit thereof.

[Explanation of symbols]

 7, 37, 38 Low-pass filter 6, 36 Analog signal switching circuit 5 A / D conversion circuit 10 Peaking circuit 11, 12 Delay circuit 13, 14, Subtraction circuit 15, 17 Addition circuit 16 Multiplication circuit 18 Digital signal switching circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/232 H04N 5/262 // H04N 5/262 G06F 15/68 350

Claims (2)

[Claims] 1. A driving circuit of an image display device for displaying an image signal on a display screen, wherein an output from the A / D conversion means is output to an A / D conversion means for converting an input analog image signal into a digital signal. A peaking means for calculating and outputting the obtained digital signal so that the displayed image is contour-emphasized, and connecting the peaking means to the output side of the peaking means to switch execution or non-execution of the contour emphasis calculation by the peaking means. Signal switching means, a filter for removing a signal outside a predetermined analog image signal from an input signal is provided on the input side upstream of the A / D conversion means, and in conjunction with the digital signal switching means,
Analog signal switching means for passing the input signal through the filter when the contour emphasis calculation is performed by the peaking means and inputting the input signal to the A / D conversion means without passing the filter when the contour emphasis calculation is not performed Is connected to the input side of the A / D conversion means. 2. A driving circuit of an image display device for displaying an image signal on a display screen, wherein an output from the A / D conversion means is output to an A / D conversion means for converting an input analog image signal into a digital signal. A peaking means for calculating and outputting the obtained digital signal so that the displayed image is contour-emphasized, and connecting the peaking means to the output side of the peaking means to switch execution or non-execution of the contour emphasis calculation by the peaking means. Signal switching means is provided, and at least two filters for removing different frequency signals, which are signals outside the predetermined analog image signal, are provided on the input side upstream of the A / D conversion means. When the peaking means executes the contour emphasis calculation in conjunction with the digital signal switching means, the input signal is At least two of the filters are passed through a desired filter. When the contour enhancement operation is not performed, the input signal is passed through a desired filter among the remaining filters of the at least two filters or without passing through these filters. An image display device comprising an analog signal switching means for inputting to an D conversion means.