JPH0923355A - Horizontal outline correction circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the man-hour of projector production and the product cost by laterally inverting a picture with a simple structure. SOLUTION: An input video signal S1 has the high-band component eliminated by recursive filters 11 and 13 and a time base inverter 12 of a low pass filter 10 and is timewisely inverted and is inputted to a time base inverter 14 and a delay line 15. Then, the video signal S1 inverted back by the time base inverter 14 and a delay inverted video signal S15 timewisely delayed by the delay line 15 are outputted to a selector 16. When the selector 16 selects the delay inverted video signal S15, the delay inverted video signal S15 is subtracted from a delay video signal S20 of a delay compensation circuit 20 by a subtractor 22 to generate a high-band video signal 22 where the high band is emphasized. This high-band video signal S22 is inputted to an adder 24 through a multiplier 23 and is added to a delay video signal S21 of a delay compensation circuit 21. As the result, a video signal S2 which is laterally inverted and has the high band emphasized furthermore is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal contour correction circuit capable of horizontally reversing an image on a projector.

[0002]

2. Description of the Related Art There are two types of projectors that project image light onto a screen and draw the image on the screen.
The first projector is a front projection type projector, and as shown in FIG. 3, the front projection type projector 100 emits light forward and draws an image directly on the screen 101. The second projector is a rear projector, and as shown in FIG. 4, this projector has a structure in which light emitted from the projector main body 110 is reflected by mirrors 111 and 112 and then projected onto the screen 101. There is.

By the way, the front projection type projector 1
When 00 is applied as the projector main body 110 of the rear projector, the R, G, and B lights from the projector main body 110 are reflected by the mirrors 111 and 112. It will be drawn.

Therefore, in such a rear projector, for example, as in the technique described in Japanese Patent Laid-Open No. 63-52586, a dedicated device for left-right reversal is added in the projector body 110. FIG. 5 is a block diagram of this dedicated device. In FIG. 3, when the image is not horizontally inverted, after the switch 200 is opened, the shift direction of the bidirectional shift register 201 and the data input direction are set to the positive direction, and the video signal is set to the bidirectional shift register 201. Add to the liquid crystal color display panel 202 via. Then, when the light of the light source 203 is passed through the condenser lens group 204 and the liquid crystal color display panel 202 and projected onto the screen 101 from the projection lens 205, a normal image is drawn on the screen 101.

On the contrary, when the image is horizontally reversed, after the switch 200 is closed, the image is horizontally reversed.
The shift direction of the bidirectional shift register 201 and the data input direction are made negative, and the video signal is applied to the liquid crystal color display panel 202 via the bidirectional shift register 201.
Then, the light of the light source 203 is passed through the condenser lens group 204, and is projected from the projection lens 205 to the screen 101.
An image that is horizontally reversed, that is, a normal image is projected. Further, as another technique for performing the left-right reversal, there is a method of using a device dedicated to the left-right reversal or inverting the arrangement of the wiring lines on the substrate side.

[0006]

However, when the front projection type projector 100 is applied as the projector main body 110 of the rear projector, a device dedicated to left / right reversal or a device dedicated to left / right reversal, which has a complicated structure and is expensive, is used. However, since it is necessary to reverse the arrangement of the wirings on the substrate side, the number of manufacturing steps of the projector and the circuit scale are increased, and the product cost is increased.

The present invention has been conceived in view of the above problems, and provides a horizontal contour correction circuit that enables the left and right of an image to be reversed with a simple structure, thereby reducing the man-hours and product cost of manufacturing a projector. To aim.

[0008]

In order to achieve the above object, a horizontal contour correction circuit according to the invention of claim 1 is formed by removing the high frequency component of an input video signal and inverting the time axis in units of horizontal lines. To generate a first video signal and a second video signal formed by reversing the time axis in units of horizontal lines with respect to the first video signal, and generating the first or second video signal.
A low-pass filter capable of selecting and outputting any one of the video signals, and outputting a first delayed video signal formed by delaying the input video signal by a time delay generated by the low-pass filter. 1 delay compensation circuit,
First or second selected and output by the low-pass filter
And a subtracter for subtracting the video signal of 1. from the first delayed video signal.

With this configuration, the low-pass filter removes the high-frequency component of the input video signal and generates the first video signal in which the time axis is inverted in units of horizontal lines, and at the same time, generates a first video signal with respect to the first video signal. As a result, a second video signal in which the time axis is inverted again in units of horizontal lines is generated. Here, when the first video signal is selected, in the subtractor,
The selectively output first video signal is subtracted from the first delay video signal of the first delay compensating circuit to generate a video signal in which the arrangement is reversed for each horizontal line and having only a high frequency band. . When the second video signal is selected, the second video signal that is selectively output is subtracted from the first delayed video signal of the first delay compensation circuit by the subtractor, and the arrangement is normal and high. A video signal having only a region is generated.

According to a second aspect of the present invention, in the horizontal contour correction circuit according to the first aspect, the low-pass filter includes a first recursive filter for removing high frequency components of the input video signal, and the first recursive filter. A first time axis inverter for inverting the time axis in units of horizontal lines, and the same frequency characteristic as the first recursive filter, and the phase generated by the first recursive filter. A second recursive filter for removing distortion from the output video signal of the first time-axis inverter to generate the first video signal and a first video signal from the second recursive filter. Then, the time axis is inverted again in units of horizontal lines to generate the second video signal, and the first image from the second recursive filter is generated. A delay line for delaying the signal by a time delay generated in the second time axis inverter to generate a third video signal; and selecting either the second or the third video signal. , And a selector for outputting to the subtractor.

With this configuration, the high frequency component of the input video signal is removed by the first recursive filter of the low-pass filter, and the time axis of the video signal from the first recursive filter is removed by the first time axis inverter. Are inverted in horizontal line units. Then, in the second recursive filter, the phase distortion generated by the first recursive filter is removed, and the first video signal is generated. Then, the time axis of the first video signal is inverted again in units of horizontal lines by the second time axis inverter to generate the second video signal. And in parallel with this,
The delay line delays the first video signal by the time delay generated in the second time-axis inverter to generate the third video signal. When either the second or the third video signal is selected by the selector, the selected video signal is output to the subtractor.

According to a third aspect of the present invention, the horizontal contour correction circuit according to the first or second aspect is provided with a multiplier for multiplying the video signal from the subtractor by a coefficient and outputting the result.

With this configuration, the multiplier multiplies the video signal from the subtractor by the coefficient and outputs the result.

According to a fourth aspect of the present invention, in the horizontal contour correction circuit according to the third aspect, the second delay compensation circuit delays the input video signal by a time delay generated in the subtractor and the multiplier. And an adder for adding the video signal from the second delay compensation circuit and the video signal from the multiplier.

With this configuration, the video signal from the second delay compensation circuit and the video signal from the multiplier are added by the adder to generate a video signal in which the high frequency component is further emphasized.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a liquid crystal projector to which a horizontal contour correction circuit according to an embodiment of the present invention is applied, and FIG. 2 is a block diagram showing the horizontal contour correction circuit.

As shown in FIG. 1, the liquid crystal projector is
An A / D converter 1, a horizontal contour correction circuit 2, a vertical contour correction circuit 3, a gamma correction circuit 4, a D / A converter 5, a liquid crystal driver 6, and a liquid crystal device 7 are provided. The A / D converter 1 is a converter that converts an analog video signal into a digital video signal S1 and inputs the digital video signal S1 to the horizontal contour correction circuit 2. The horizontal contour correction circuit 2 is A
The left / right of the video signal S1 input from the / D converter 1 is inverted and the output video signal S2 is output to the vertical contour correction circuit 3
Is a circuit that can be input to, and specifically has the structure shown in FIG.

As shown in FIG. 2, the horizontal contour correction circuit 2 includes a low-pass filter (LPF) 10 and parallel delay compensation circuits 20 and 21 (first and second delay compensation circuits).
The subtracter 22, the multiplier 23, and the adder 24 are provided. The low-pass filter 10 includes a recursive filter 11 (first recursive filter), a time axis inverter 12 (first time axis inverter), a recursive filter 13 (second recursive filter), and a recursive filter connected in series. A time axis inverter 14 connected in parallel with the filter 13.
(Second time axis inverter), delay line 15, and selector 1
6.

The recursive filter 11 is the A / D of FIG.
It is a filter that filters the high frequency components of the frequencies of the R, G, B video signals S1 input from the converter 1 and outputs the video signal S11 to the time axis inverter 12. The time axis inverter 12 inverts the time axis of the video signal S11 from the recursive filter 11 in units of horizontal lines, and outputs the inverted video signal S12 to the recursive filter 13.
Is a device that outputs to

The recursive filter 13 is a filter having the same frequency characteristic as the recursive filter 11,
Inverted video signal S generated by recursive filter 11
It has the function of removing the phase distortion in 12. The time axis inverter 14 inverts the time axis of the inverted video signal S13 (first video signal) from the recursive filter 13 again in units of horizontal lines, restores it to the video signal S1 (second video signal), and returns it to the selector 16 Is a device that outputs to.

The delay line 15 delays the inverted video signal S13 by the time delay generated in the time axis inverter 14, and outputs the delayed inverted video signal S15 (third video signal) to the selector 1
It is a wire rod that outputs to 6. The selector 16 is for selecting either the video signal S1 from the time axis inverter 14 or the delayed inverted video signal S15 from the delay line 15, and a control signal C from a controller (not shown).
Depending on the video signal S1 or the delayed inverted video signal S15.
It has a function to output either of the above.

The delay compensation circuit 20 includes the A / D converter 1
Is a circuit that delays the video signal S1 from (1) to the time delay generated by the low-pass filter 10 and outputs the delayed video signal S20 (first delayed video signal) to the subtractor 22. The subtractor 22 subtracts the video signal S1 or the delayed inverted video signal S15 output from the low-pass filter 10 and having only the low frequency component from the delayed video signal S20 from the delay compensation circuit 20 to have only the high frequency component. It is a device that outputs the above-described high-frequency video signal S22 to the multiplier 23.

The multiplier 23 multiplies the high frequency band video signal S22 from the subtractor 22 by a coefficient and outputs the high frequency band video signal S23.
Is a device that outputs The delay compensation circuit 21 subtracts the video signal S1 from the A / D converter 1 from the subtractor 22,
The delayed video signal S21 (second delayed video signal) is delayed by the time delay generated by the multiplier 23 and the adder 2
It is a circuit for outputting to 4.

The adder 24 includes a delayed video signal S21 from the delay compensation circuit 21 and a high frequency video signal S2 from the multiplier 23.
The video signal S in which 3 and are added to further emphasize the high frequency component.
2 is generated and the video signal S2 is input to the vertical contour correction circuit 3 of FIG.

The vertical contour correction circuit 3 is a circuit capable of correcting vertical blurring of the video signal S2 from the horizontal contour correction circuit 2 and outputting the corrected video signal S3 to the gamma correction circuit 4, which is well known. It has a circuit structure. The gamma correction circuit 4 is a circuit that performs gamma correction on gradation on the video signal S3 from the vertical contour correction circuit 3 and outputs the corrected video signal S4 to the D / A converter 5, which is well known. It has a circuit structure. The D / A converter 5 is a converter that converts the digital video signal S4 into an analog video signal S5 and inputs it to the liquid crystal driver 6.

The liquid crystal driver 6 is a driver that outputs a video signal S6 for driving the liquid crystal device 7 to the liquid crystal device 7 based on the video signal S5 from the D / A converter 5, and has a well-known structure. There is. Liquid crystal device 7
Is a known device that emits light based on the video signal S6 from the liquid crystal driver 6.

Next, the operation of the horizontal contour correction circuit of this embodiment will be described. A / D converter 1 of FIG.
When the video signal S1 converted from analog to digital in is output to the horizontal contour correction circuit 2, the video signal S1 includes a low-pass filter 10 as shown in FIG.
It is input to the delay compensation circuits 20 and 21. The video signal S1 input to the low-pass filter 10 has high-frequency components filtered by the recursive filter 11, and the video signal S1
1 is output to the time axis inverter 12. Then, the video signal S11 is time-inverted in horizontal line units in the time axis inverter 12, and is output to the recursive filter 13 as an inverted video signal S12.

Then, in the inverted video signal S12, after the phase distortion is removed by the recursive filter 13,
The inverted video signal S13 is output to the time axis inverter 14 and the delay line 15. The inverted video signal S13 input to the time axis inverter 14 has its time axis inverted again in units of horizontal lines, is returned to the video signal S1, and is output to the selector 16. On the other hand, the inverted video signal S13 input to the delay line 15 is time-delayed by the time delay generated in the time axis inverter 14 and is output to the selector 16 as a delayed inverted video signal S15.

At this time, when the image is horizontally inverted, a control signal C for selecting the delayed inverted image signal S15 is selected by the selector 16 by a controller (not shown).
Output to As a result, the delayed inverted video signal S15 is output from the selector 16 to the subtractor 22.

On the other hand, the video signal S1 input from the A / D converter 1 to the delay compensation circuit 20 is the low-pass filter 1
It is delayed by the time delay caused by 0, and is output to the subtractor 22 as a delayed video signal S20 having the same phase as the delayed inverted video signal S15. Thereby, in the subtractor 22, from the delayed video signal S20 from the delay compensation circuit 20,
The delayed inverted video signal S15 output from the low-pass filter 10 and having only the low frequency component is subtracted. As a result, an inverted high frequency video signal S22 having only high frequency components is generated and output to the multiplier 23.

The high frequency image signal S22 is coefficient-multiplied by the multiplier 23 and output to the adder 24 as the high frequency image signal S23. As a result, the A / D converter 1
Subtracter 22 and multiplier 23 for the video signal S1 from
Delayed video signal S delayed by the time delay
Since 21 is output from the delay compensation circuit 21 to the adder 24, the adder 24 delays the delayed video signal S21 having the same phase as the high-frequency video signal S23 and the high-frequency video signal S from the multiplier 23.
23 and 23 are added. As a result, the video signal S2 in which the high frequency component is further emphasized is generated by the multiplier 23 and input to the vertical contour correction circuit 3 of FIG.

That is, the selector 16 selects the left-right inversion of the image, so that the image signal S2 in which the arrangement is reversed in the horizontal line unit and the high frequency region is emphasized is output from the horizontal outline correction circuit 2 to the vertical outline correction circuit. 3 will be output.

If the image is not horizontally reversed,
A controller (not shown) outputs a control signal C for selecting the video signal S1 to the selector 16. As a result, the non-inverted high-frequency video signal S22 having only high-frequency components is output to the multiplier 23 in the subtractor 22, and the non-inverted video signal S2 in which the high-frequency components are further emphasized in the adder 24. Is generated and input to the vertical contour correction circuit 3 in FIG. In other words, the selector 16 does not select the left-right inversion of the image, so that the horizontal contour correction circuit 2 outputs the video signal S2 in which the arrangement is normal and the high range is emphasized to the vertical contour correction circuit 3. Become.

As described above, in the horizontal contour correction circuit 2, when the inverted or non-inverted video signal S2 in which the high frequency band is emphasized is input to the vertical contour correction circuit 3, the vertical contour of the video signal S2 is corrected. Then, the video signal S3 is output to the gamma correction circuit 4. Then, this video signal S3 is
The gamma correction circuit 4 performs gamma correction, and the corrected video signal S4 is converted from digital to analog video signal S5 by the D / A converter 5 and then output to the liquid crystal driver 6. As a result, the liquid crystal driver 6 drives the liquid crystal device 7 based on the video signal S5. As a result, a normal image is displayed on the screen (not shown) by the light emission of the liquid crystal device 7.

[0035]

As described above, according to the horizontal contour correcting circuit of the present invention, it is possible to reverse the image horizontally with a simple structure. Therefore, when applying the front projection type projector to the rear projector, By providing the horizontal contour correction circuit in the projector, there is an effect that the man-hours for manufacturing the projector and the product cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a liquid crystal projector to which a horizontal contour correction circuit according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a horizontal contour correction circuit.

FIG. 3 is a schematic view showing a front projection type projector.

FIG. 4 is a schematic cross-sectional view showing the structure of a rear projector.

FIG. 5 is a block diagram showing a conventional device for horizontally reversing video images.

[Explanation of symbols]

 2 Horizontal contour correction circuit 10 Low-pass filter 11, 13 Recursive filter 12, 14 Time axis inverter 15 Delay line 16 Selector 20, 21 Delay compensation circuit 22 Subtractor 23 Multiplier 24 Adder S1 Input video signal S2 Output video signal

Claims (4)

[Claims] 1. A first video signal formed by removing a high frequency component of an input video signal and inverting the time axis in units of horizontal lines, and a time axis in units of horizontal lines with respect to the first video signal. A low-pass filter that can generate a second video signal that is inverted and formed again, and select and output either the first or second video signal; and a low-pass filter for the input video signal. A first delay compensating circuit for outputting a first delayed video signal formed by delaying the generated time delay, and the first or second selectively output by the low-pass filter.
A horizontal subtraction circuit for subtracting the video signal of 1 from the first delayed video signal, and a horizontal contour correction circuit. 2. The low-pass filter includes a first recursive filter that removes high frequency components of the input video signal, and a time axis is inverted in horizontal line units with respect to the video signal from the first recursive filter. And a first time axis inverter having the same frequency characteristic as the first recursive filter, and phase distortion caused by the first recursive filter is removed from the output video signal of the first time axis inverter. Then, the time axis of the second recursive filter for generating the first video signal and the first video signal from the second recursive filter are inverted again in units of horizontal lines, and A second time axis inverter for generating a second video signal, and a time delay generated in the second time axis inverter with respect to the first video signal from the second recursive filter. A delay line for generating a third video signal is delayed and, by selecting one of the second or third video signal,
The horizontal contour correction circuit according to claim 1, further comprising: a selector that outputs to the subtractor. 3. The horizontal contour correction circuit according to claim 1, further comprising a multiplier that multiplies the video signal from the subtractor by a coefficient and outputs the product. 4. A second delay unit for delaying the input video signal by a time delay generated by the subtractor and the multiplier.
4. The horizontal contour correction circuit according to claim 3, further comprising: a delay compensation circuit according to claim 2, and an adder configured to add the video signal from the second delay compensation circuit and the video signal from the multiplier.