JPH0522681A - Projection display - Google Patents

Abstract

PURPOSE:To improve the brightness and resolution of a projection image by using effectively the whole surface (all picture elements) of an image projector (liquid crystal projecting part) even at the time of a letter box signal. CONSTITUTION:The device is equipped with a liquid crystal projecting part 10 to project the usual image in which an aspect ratio is 3:4, a signal converting part 6 to extend, in a vertical scanning direction, a letter box signal S1b to blacken a part of the upper edge and lower edge of the vertical scanning direction of an image, an anamorphic lens 14 to convert the projection light, in which an aspect ratio is 3:4, to the aspect ratio 9:16 of the letter box signal S1b, and a letter box signal detecting part 4 to output a control signal SCONT of an active high while it is detected that an input component signal S1 is the letter box signal S1b, and when the control signal SCONT is an 'H' level, the signal converting part 6 and the anamorphic lens 14 are operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device which converts a television signal into projection light and projects it on a screen.

[0002]

2. Description of the Related Art In a typical display device, the aspect ratio (the aspect ratio of the screen) is 3: 4. The same applies to the projection display device. In high-definition broadcasting, the aspect ratio is 9:16. The aspect ratio of Vista Vision is 3: 5.55, and the aspect ratio of Cinemascope is 3: 7.

In television broadcasting of a movie program, the movie may be broadcast at the aspect ratio of the movie itself. In this case, by making the upper and lower parts of the image black, the feeling of the original movie is reproduced as it is. A signal in which a part of the image is black is called a letterbox signal.

Image projectors (light sources) in projection display devices include CRTs and liquid crystal panels. FIG. 8A shows a state in which an image based on a television signal having a normal aspect ratio k: i = 3: 4 is projected. FIG. 8B shows a state in which an image based on a letterbox signal having an aspect ratio j: i = 9: 16 is projected.

In the case of the image by the letterbox signal, the upper and lower parts are black as shown by the hatching.

[0006]

Conventionally, in a projection type display device having an aspect ratio of normal 3: 4, when an image is realized by the above letterbox signal, the image is projected as it is. It was Therefore, as described above, blackness appears in a part of the image, and in the image projector such as a CRT or a liquid crystal panel, a part corresponding to the blackness is not effectively used.

Since the image projector is also a light source, there is a disadvantage that the brightness of the image projected on the screen is deteriorated unless the part corresponding to the blackness is used at all.

Further, the resolution is deteriorated because the state is contracted in the vertical direction as compared with the case where the aspect ratio is 3: 4.

The present invention was devised in view of such circumstances, and it is an object of the present invention to improve the brightness and resolution of a projected image by effectively utilizing the entire surface of the image projector even in the case of a letterbox signal. To aim.

[0010]

A projection display apparatus according to the present invention comprises means for projecting a normal image having an aspect ratio of 3: 4, and a letterbox signal in which a part of the image in the vertical direction is black in the vertical scanning direction. Signal converting means for expanding the input light to the projection light having an aspect ratio of 3: 4, and optical conversion means for converting the projection light having an aspect ratio of 3: 4 into projection light having an aspect ratio of the letterbox signal, and detecting whether the input signal is a letterbox signal And a means for operating the signal conversion means and the optical conversion means when the detection result is a letterbox signal.

[0011]

When the signal is a letterbox signal, the image is expanded in the vertical scanning direction to have a size corresponding to the entire surface of the image projection means. Then, the optical conversion means restores the original aspect ratio of the letterbox signal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projection display apparatus according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical construction of the projection display apparatus according to the embodiment.

In the figure, 2 is an input terminal for R, G, and B component signals S1, 4 is a letterbox signal detecting section, 6 is a signal converting section, 8 is a signal switching section, and 10 is a liquid crystal projection as an image projector. 12 is an anamorphic lens setting unit, 14 is an anamorphic lens, and 16 is a screen.

The input terminal 2 is connected to the letterbox signal detecting section 4, the signal converting section 6, and the first input terminal a of the signal switching section 8.

The letterbox signal detector 4 determines whether or not the upper and lower ends of the component signal S1 input from the input terminal 2 in the vertical scanning direction are black portions based on the brightness level, and when they are black portions, letterbox. When it is determined that the signal is the signal S1b and the letterbox signal S1b is detected, a drive command is given to the signal conversion unit 6, the signal switching unit 8 is switched to the second input terminal b side, and the anamorphic Lens setting unit 12
High-level control signal S that gives a drive command to
_It outputs _CONT . When the component signal S1 is the normal signal S1a, the control signal S _CONT is “L”.
It becomes a level.

In the signal converter 6, the control signal S _CONT is "H".
At the time of level, the letterbox signal S1b is input, the number of scanning lines is increased to 4/3 times by the scanning line interpolation,
The interpolation component signal S2 is output to the second input terminal b of the signal switching unit 8. For example, in the case of the letterbox signal S1b having 360 scanning lines,
480 interpolation component signals S by scanning line interpolation
Converted to 2.

The liquid crystal projection unit 10 includes a strong light source such as a halogen lamp, a dichroic mirror for separating the light into R, G, B colors, and three liquid crystal panels for R, G, B colors.
Dichroic prism (none of the above is shown)
And a projection lens 10a and the like. The aspect ratio of all three liquid crystal panels is set to 3: 4.

The liquid crystal projection unit 10 outputs a component signal to each of the three liquid crystal panels, separates the strong light from the light source into R, G and B colors and irradiates the light of each color from the rear of each liquid crystal panel. Then, the three color optical images transmitted through each liquid crystal panel are combined by a dichroic prism and reproduced as a color image on the screen 16 through the projection lens 10a.

The anamorphic lens setting unit 12 retracts the anamorphic lens 14 from the projection lens 10a when the control signal S _CONT is at "L" level, while the control signal S _CONT is at "H" level. At this time, the anamorphic lens 14 is projected and moved to a position coaxially facing the front surface of the anamorphic lens 14 with respect to the projection lens 10a.

As shown in FIG. 2, the anamorphic lens 14 is a lens formed of a cylindrical curved surface and has a convex type and a concave type. In both cases, the cylinders forming the both surfaces thereof have their axial directions parallel to each other. Although the thickness gradually changes along a certain direction, the thickness change direction is arranged to be the vertical scanning direction. The convex type has a function of narrowing projection light in a single direction, and the concave type has a function of spreading projection light in a single direction. The conversion ratio of the aspect ratio can be arbitrarily set by appropriately adjusting the position and the distance between the convex type and the concave type in the optical axis direction.

Next, the operation of the projection type display device having the above configuration will be described.

First, a case where a normal signal S1a having an aspect ratio of 3: 4 as shown in FIG. 3 is input to the input terminal 2 will be described.

The letterbox signal detector 4 outputs the "L" level as the control signal S _CONT when receiving the normal signal S1a. Therefore, the signal conversion unit 6 becomes inactive, and the signal switching unit 8 becomes the first
The input terminal a side is switched to. Further, the anamorphic lens setting unit 12 keeps the anamorphic lens 14 in the retracted state.

As a result, the input normal signal S1a is
A direct signal is input to the liquid crystal projection unit 10 from the first input terminal a of the signal switching unit 8. The aspect ratio of the liquid crystal panel in the liquid crystal projection unit 10 is 3: 4, the aspect ratio of the input normal signal S1a is 3: 4, and the anamorphic lens 14 exists in front of the projection lens 10a. Therefore, the image P1a projected on the screen 16 from the projection lens 10a becomes an image having an aspect ratio of 3: 4, which is similar to the normal signal S1a in FIG. 3, as shown in FIG.

Next, a case where a letterbox signal S1b having an aspect ratio of 9:16 as shown in FIG. 5 is input to the input terminal 2 will be described.

When the letterbox signal S1b is input, the letterbox signal detector 4 receives the control signal S _CONT.
Outputs "H" level. Therefore, the signal conversion unit 6 is in the active state, and the signal switching unit 8 is in the state switched to the second input terminal b side. Also,
The anamorphic lens setting unit 12 drives the anamorphic lens 14 to project and move it to a position coaxially facing the projection lens 10a.

The activated signal converter 6 increases the number of scanning lines of the input letterbox signal S1b by 4/3 times by the scanning line interpolation. That is, it is enlarged in the vertical scanning direction as shown in FIG. For example, when the number of scanning lines in FIG. 5 is 360, the number of scanning lines of the interpolation component signal S2 is increased to 480, which is assigned to the entire vertical range of the aspect ratio 3: 4. The scanning line of the mask portion is deleted.

The interpolated component signal S2 whose aspect ratio is converted from 9:16 in FIG. 5 to 3: 4 in FIG. 6 as described above is the second input terminal b of the signal switching unit 8.
It is input to the liquid crystal projection unit 10 via. Liquid crystal projection unit 10
Since the aspect ratio of the liquid crystal panel is 3: 4, and the input interpolation component signal S2 also has the aspect ratio of 3: 4, the entire area of the liquid crystal panel can be effectively used.

Since the anamorphic lens 14 is coaxially faced in front of the projection lens 10a, an image having an aspect ratio of 3: 4 that has passed through the projection lens 10a is
The anamorphic lens 14 inversely converts the aspect ratio to a preset aspect ratio.

When the original letterbox signal S1b has an aspect ratio of 9:16, the anamorphic lens 14 is used.
The aspect ratio of the reverse conversion of is also preset to 9:16.

Therefore, the anamorphic lens 14
Image P2a that is projected through the screen 16 onto the screen 16
Is the letterbox signal S1 of FIG.
The image has an aspect ratio of 9:16, which is similar to b. Therefore, the image P2a on the screen 16 which has been expanded in the vertical scanning direction in the middle of the process but has been restored to the original aspect ratio is displayed.
Is not unnatural.

As described above, the letterbox signal S1b
Also in this case, since the entire area of the liquid crystal panel is effectively used, the brightness of the image projected on the screen 16 is improved as compared with the conventional example. Also, the resolution, which is limited by the number of pixels of the liquid crystal panel, is improved.

The CRT may be used as an image projector instead of the liquid crystal projection unit 10, and the same effect as described above can be obtained.

[0035]

As described above, according to the present invention, in the case of a letterbox signal, the image is expanded in the vertical scanning direction to the size of the entire surface of the image projecting means, so that the entire surface of the image projecting means is effectively used. Therefore, the brightness of the image projected on the screen can be improved. Further, since the image expanded by the image projection means is returned to the original aspect ratio by the optical conversion means, there is no unnaturalness as an image,
At the same time, the resolution can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a projection display apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an anamorphic lens in an example.

FIG. 3 is an image state diagram of a normal signal having an aspect ratio of 3: 4 in the example.

FIG. 4 is a state diagram of a projected image with an aspect ratio of 3: 4 in the example.

FIG. 5 is an image state diagram of a letterbox signal having an aspect ratio of 9:16 in the example.

FIG. 6 is an image state diagram of an interpolated component signal converted into an aspect ratio of 3: 4 in the example.

FIG. 7 is a state diagram of a projected image with an aspect ratio of 9:16 in the example.

FIG. 8 is a state diagram of projected images having different aspect ratios in the conventional example.

[Explanation of symbols]

 4 Letter Box Signal Detection Section 6 Signal Conversion Section 8 Signal Switching Section 10 Liquid Crystal Projection Section (Image Projection Means) 12 Anamorphic Lens Setting Section 14 Anamorphic Lens (Optical Conversion Means) 16 Screen

Claims (1)

Claim: What is claimed is: 1. A means for projecting a normal image having an aspect ratio of 3: 4, and a signal converting means for extending a letterbox signal in which a part of the image in the vertical direction is black in the vertical scanning direction. Optical conversion means for converting the projection light having an aspect ratio of 3: 4 into projection light having the aspect ratio of the letterbox signal, means for detecting whether or not the input signal is the letterbox signal, and the detection result thereof are letters. A projection type display device, wherein the signal conversion means and the optical conversion means are operated when the signal is a box signal.