JPH103090A - Field sequential color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field sequential color display device preventing the color shading between video fields. SOLUTION: A sequential color signal generating means 5 generates a sequential color signal for driving a monochromatic CRT 4 from three-primary color signals. A liquid crystal shutter 30 is constituted of plural color polarizing plates 11, 13 and a neutral polarizing plate 12 to be arranged on an optical axis in series with respect to the monochromatic CRT 4 and plural liquid crystal cells 21, 22 to be arranged in among them on the optical axis in series. A polarization direction control means 6 controls polarization directions of color lights by driving axes of polarizations of the liquid crystal cells 21, 22 so that the color shading is not generated. By such a constitution, a full color video having high chrominance purity in which the color shading is not generated is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen-sequential color display device, and more particularly to a screen-sequential color display device for performing color display by switching three primary color signals.

[0002]

2. Description of the Related Art At present, a screen sequential color display device has been put to practical use as a color display device. This screen sequential color display device includes a Liquid Crystal S (LCS).
Hutter) system is used. The LCS method is
A liquid crystal shutter composed of a liquid crystal cell and a color polarizer is synchronized with the switching timing, and a CRT (Cathod) is generated by a frame-sequential video signal of red (R), blue (B) and green (G).
A full-color image is obtained by driving an e-Ray Tube.

On the other hand, a screen-sequential color display device using a liquid crystal shutter has a problem that color mixing (color shading) occurs between video fields due to a delay in response speed of a liquid crystal cell constituting the liquid crystal shutter. FIG. 7 is a diagram showing response characteristics of the liquid crystal cell. The vertical axis represents relative luminance [%] and the horizontal axis represents time t [ms], and the response characteristic curve Cs of the liquid crystal cell is shown. From this figure, the liquid crystal cell is O
It can be seen that when switching from N to OFF, it is not possible to switch immediately and it takes 1 [ms].

For this reason, even if the color is switched during the vertical blanking period, the color is not completely switched within this period, so that color shading occurs at the head of the video signal of the next color.

Next, color shading will be described in detail. Table 1 shows ON / OF of the driving signal of the liquid crystal cell.
The color selection accompanying F is shown.

[0006]

[Table 1] Drive signals for driving the liquid crystal cell (Sd21, Sd2
If 2) is (ON, OFF), R is selected. When the drive signals (Sd21, Sd22) are (ON, ON), B is selected. When the drive signals (Sd21, Sd22) are (OFF, ON), G is selected.

FIG. 8 is a diagram showing a state of switching timing at which color shading occurs. Field F
21 shows the response of the liquid crystal cell in which both (Sd21, Sd22) are ON, and the image of B is generated according to Table 3. Then, in the field F22, (Sd
21, Sd22) shows the response of the liquid crystal cell in the (OFF, ON) state, and should generate a G image. However, the liquid crystal cell driven by Sd21 is turned on.
Since the response from switching to OFF is slow, both liquid crystal cells may be in the ON state.
Therefore, B is mixed in the field section 76, and color shading occurs.

Similarly, in the field F23, (Sd21,
Sd22) indicates the response of the liquid crystal cell in the state of (ON, OFF), and an R image should be generated.
However, the liquid crystal cell driven by Sd22 changes from ON to O
Since the response until switching to the FF is slow, both liquid crystal cells may be in the ON state. Also in this field section 77, B is mixed and color shading occurs.

To solve such a problem, for example, US Pat. No. 4652087 proposes that an electrode of a liquid crystal cell is divided into n parts in a direction perpendicular to a plane corresponding to an image area. In this method, the shutter timing of each of the n-divided electrodes is sequentially shifted within a range of 1-1 / n fields, thereby switching ahead of the original timing.

[0010]

However, in the conventional example described above, in a low temperature region of 10 ° C. or less, the response speed of the liquid crystal cell is further delayed and exceeds the correction range. Shading occurs.

Further, in order to divide the electrodes of the liquid crystal cell, a large-scale manufacturing apparatus such as a laser beam processing apparatus and a photolithography / etching apparatus is required.
Further, since a drive element or the like corresponding to the number of electrode divisions is required, the product cost is significantly increased.

The present invention has been made in view of the above points, and has been made in view of enabling a full-color image of high color purity without causing color shading without dividing electrodes of a liquid crystal cell constituting a liquid crystal shutter. An object is to provide a sequential color display device.

[0013]

According to the present invention, in order to solve the above-mentioned problems, a monochrome CRT for displaying an image of a change in luminance and a monochrome CRT for displaying an image of a change in luminance are provided in a frame sequential color display device which performs color display by switching three primary color signals. A sequential color signal generating means for generating a sequential color signal for driving the monochrome CRT from a plurality of color polarizers arranged in series on the optical axis with respect to the monochrome CRT; A liquid crystal shutter composed of a plurality of liquid crystal cells arranged in series, and when the polarization axis of the liquid crystal cell is driven and two or more liquid crystal cells are simultaneously turned on, the light transmittance of the liquid crystal shutter is minimized. And a polarization direction control means for controlling the polarization direction of the colored light so as to obtain a plane sequential color display device.

Here, the sequential color signal generating means generates a sequential color signal for driving a monochrome CRT from the three primary color signals. The liquid crystal shutter includes a plurality of color polarizers arranged in series on the optical axis with respect to the monochrome CRT, and a plurality of liquid crystal cells arranged in series on the optical axis between the color polarizers. The polarization direction control means controls the polarization direction of the color light so as to minimize the light transmittance of the liquid crystal shutter when two or more liquid crystal cells are simultaneously turned on by driving the polarization axis of the liquid crystal cell.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a principle diagram of a screen sequential color display device. The screen sequential color display device is a monochrome CRT
4, sequential color signal generating means 5 for sequentially generating color signals,
The liquid crystal shutter 30 includes the color polarizers 11 and 13, the neutral polarizer 12, and the liquid crystal cells 21 and 22, and the polarization direction control unit 6 that drives the liquid crystal cells 21 and 22 to control the polarization direction of the color light. .

Next, the operation of each means will be described. The sequential color signal generation unit 5 performs γ correction on the R, G, and B after the matrix conversion, compresses the time axis, and generates a sequential color signal synchronized with the field synchronization signal. The monochrome CRT 4 is driven by the sequential color signals. That is, the monochrome CRT 4 sequentially displays images of luminance changes corresponding to the respective level changes of the color signals.

The liquid crystal shutter 30 is a monochrome CRT 4
, Color polarizers 11 and 13, neutral polarizer 12, and liquid crystal cells 21 and 22 arranged in series on the optical axis. The color polarizers 11 and 13 and the neutral polarizer 12 have a horizontal polarization axis and a vertical polarization axis, respectively, and selectively transmit the set color light. Liquid crystal cells 21 and 22
Polarizes colored light. Details will be described later.

The polarization direction control means 6 includes liquid crystal cells 21 and 2
When the two polarization axes are driven and turned on at the same time, the polarization direction of the color light is controlled so that the light transmittance of the liquid crystal shutter 30 is minimized. Here, the minimum transmitted light is BLACK (black) in color.

As a specific control of the polarization direction, the polarization axes of the liquid crystal cells 21 and 22 are driven at the voltage levels of the drive signals Sd1 and Sd2 synchronized with the field synchronization signal. When the drive signal is ON, the polarization axis of the liquid crystal cell is not driven, and the color light is transmitted without polarization. When the driving signal is OFF, the polarization axis of the liquid crystal cell is rotated by 90 °, and the color light is polarized and transmitted.

Next, an outline of the LCS type frame sequential color display device will be described. FIG. 2 is a diagram showing a configuration example of a monochrome CRT and a liquid crystal shutter. The monochrome CRT 4, which is an image generation source, is driven by three primary color video signals sent in a frame-sequential manner.

On the front of the monochrome CRT 4, two color polarizers 11 and 13 and two liquid crystal cells 21 and 2 are arranged.
2 and a liquid crystal shutter 30 including one neutral polarizing plate 12 are provided. The liquid crystal cells 21 and 22 are driven by the driving signals Sd1 and Sd2 from the polarization direction control means.
It is a liquid crystal cell with a high-speed response that is turned ON / OFF. With such a liquid crystal shutter 30, color selection synchronized with the video signals of the three primary colors is performed.

Next, the selection of colors when color light is transmitted through the color polarizers 11 and 13 and the neutral polarizer 12 will be described. The horizontal polarization axis Cy (G, B) of the color polarizer 11 closest to the screen of the monochrome CRT 4 is:
G and B and Cy (cyan) which is a combined color light of G and B are selectively transmitted. Further, the vertical polarization axis R selectively transmits the R color light.

On the other hand, the neutral polarizing plate 12 facing the color polarizing plate 11 via the liquid crystal cell 21 has a horizontal polarization axis O (BLACK) as a light absorption axis and transmitted light as BLA.
CK. The vertical polarization axis W (R, G, B) is R,
G, B and W (white), which is a composite color light thereof, are transmitted.

Further, the color deflecting plate 13 facing the neutral deflecting plate 12 via the liquid crystal cell 22 has a horizontal axis YL (R, G) of YL (yellow) which is a combined color light of R and G and R and G. Is selectively transmitted. In addition, the vertical polarization axis B
Selectively transmits the B color light.

Next, the optical operation of the liquid crystal shutter when the present invention is applied will be described. Table 2 shows the color selection accompanying the ON / OFF of the drive signal of the liquid crystal cell to which the present invention is applied.

[0026]

[Table 2] When the drive signals (Sd1, Sd2) are (ON, OFF), R is selected. (Sd1, Sd2) is (OFF, O
In the case of N), B is selected. When (Sd1, Sd2) is (OFF, OFF), G is selected. And
BLAC when (Sd1, Sd2) is (ON, ON)
It is controlled by the polarization direction control means so that K is selected.

FIG. 3 is a diagram showing switching timings at which color shading is prevented. Field F1
(Sd1, Sd2) shows the response of the liquid crystal cell in the (ON, OFF) state, and the R image is generated by the combination of the color selections shown in Table 2. Then, in the field F2, (Sd1, Sd2) is set to (OFF, O
The response of the liquid crystal cell in the N) state is shown. In the related art, since the response until the liquid crystal cell corresponding to the drive signal Sd1 switches from ON to OFF is slow, both liquid crystal cells are in the ON state, and color shading occurs in the field section. However, in the present embodiment, when both (Sd1, Sd2) are in the (ON, ON) state, the color selection is controlled to be BLACK, so that no color shading occurs in the field section 71.

In the field F3, (Sd1, Sd
d2) shows the response of the liquid crystal cell in the state of (OFF, OFF). Conventionally, the response until the liquid crystal cell corresponding to the drive signal Sd2 switches from ON to OFF is slow, so that two liquid crystal cells are in the (OFF, ON) state, and color shading occurs in the field section. . However, in the (OFF, ON) state due to the combination of color selections shown in Table 2, the field section 72
B is generated. Therefore, also in this case, G and B
Since color is near color, color shading does not occur visually.

FIG. 4 is a diagram showing a color switching operation of a liquid crystal shutter including two liquid crystal cells. The liquid crystal shutter includes two liquid crystal cells, two color polarizers 11 and 13, and one neutral polarizer 12. The liquid crystal cells driven by the drive signal Sd1 include a liquid crystal cell 21a that is turned on and a liquid crystal cell 2 that is turned off.
1b. Further, the liquid crystal cell driven by the drive signal Sd2 includes a liquid crystal cell 22a which is turned on,
And a liquid crystal cell 22b that is turned off.

Here, when the driving signal Sd1 or Sd2 turns on the liquid crystal cell, the polarization direction does not change. In the OFF state, the polarization direction is rotated by 90 °.

For example, a monochrome CR is generated by a BLACK signal.
When T is driven, both liquid crystal cells are turned on. Each axis of the color polarizer 11 has a horizontal polarization axis Cy.
Since (G, B) and the vertical polarization axis R, the incident light W transmits G, B in the horizontal direction and R in the vertical direction. And O
Since the polarization direction is not changed by the liquid crystal cell 21a in the N state, the color light transmitted through the color polarizer 11 is
a is transmitted as it is. And the neutral polarizer 1
The color light is cut off by the horizontal polarization axis O (BLACK) of No. 2 and only R common to the vertical polarization axis W (R, G, B) is transmitted through the neutral polarizer 12.

Since the polarization direction is not changed by the liquid crystal cell 22a in the ON state at the next stage, R is equal to the liquid crystal cell 22a.
Is transmitted as it is. Since the vertical polarization axis B of the color polarizing plate 13 transmits only B, R is blocked and the color light finally becomes BLACK.

When the monochrome CRT is driven by the R signal, the liquid crystal cell 21a is turned on and the liquid crystal cell 22b is turned on.
The state becomes FF. Since each axis of the color polarizing plate 11 is a horizontal polarization axis Cy (G, B) and a vertical polarization axis R, the incident light W transmits G, B in the horizontal direction and R in the vertical direction. Since the polarization direction is not changed by the liquid crystal cell 21a in the ON state, the color light transmitted through the color polarizing plate 11 is transmitted through the liquid crystal cell 21a as it is. Then, the color light is blocked by the horizontal polarization axis O (BLACK) of the neutral polarizer 12, and only R common to the vertical polarization axis W (R, G, B) passes through the neutral polarizer 12.

The liquid crystal cell 22b in the OFF state at the next stage is
Changes the polarization direction by 90 °, R rotates the liquid crystal cell 22b by 90 ° and transmits R. Since the horizontal optical axis YL (R, G) of the color polarizing plate 13 transmits R and G, G is cut off and the color light finally becomes R.

When the monochrome CRT is driven by the B signal, the liquid crystal cell 21b is turned off and the liquid crystal cell 22a is turned on. Since each axis of the color polarizing plate 11 is a horizontal polarization axis Cy (G, B) and a vertical polarization axis R, the incident light W transmits G, B in the horizontal direction and R in the vertical direction. Since the polarization direction is changed by 90 ° by the liquid crystal cell 21b in the OFF state, the color light transmitted through the color polarizing plate 11 is transmitted by rotating the liquid crystal cell 21b by 90 °. And
Horizontal polarization axis O (BLACK) of neutral polarizer 12
, The color light is cut off, and G and B, which are common to the vertical polarization axis W (R, G, B), pass through the neutral polarizer 12.

Since the polarization direction is not changed by the liquid crystal cell 22a in the ON state at the next stage, G and B are not changed by the liquid crystal cell 2a.
2a is transmitted as it is. Then, since the vertical polarization axis B of the color polarizing plate 13 transmits only B, the color light finally becomes B.

When the monochrome CRT is driven by the G signal, both the liquid crystal cells 21b and 22b are turned off. Each axis of the color polarizer 11 has a horizontal polarization axis Cy.
Since (G, B) and the vertical polarization axis R, the incident light W transmits G, B in the horizontal direction and R in the vertical direction. And O
Since the polarization direction is changed by 90 ° by the liquid crystal cell 21b in the FF state, the color light transmitted through the color polarizer 11 is transmitted by rotating the liquid crystal cell 21b by 90 °. Then, the color light is blocked by the horizontal polarization axis O (BLACK) of the neutral polarizer 12, and G, which is common to the vertical polarization axis W (R, G, B),
B transmits through the neutral polarizer 12.

The liquid crystal cell 22b in the OFF state at the next stage is
G and B pass through the liquid crystal cell 22b by rotating the liquid crystal cell 22b by 90 °. The horizontal polarization axis YL (R, G) of the color polarizer 13 transmits R and G, so that R is blocked and the color light finally becomes G.

Next, a second embodiment of the present invention will be described. In the second embodiment, a liquid crystal shutter including three liquid crystal cells and four color polarizing plates is used. Table 3 shows the color selection according to ON / OFF of the drive signal of the liquid crystal cell.

[0040]

[Table 3] The drive signals (Sd11, Sd12, Sd13) are (ON,
OFF, OFF), R is selected. (Sd1
(1, Sd12, Sd13) are (OFF, ON, OFF)
In the case of, B is selected. (Sd11, Sd12, Sd
If (13) is (OFF, OFF, ON), G is selected. (Sd11, Sd12, Sd13) are (ON, ON, OFF), (ON, OFF, ON),
In the case of the states (OFF, ON, ON) and (ON, ON, ON), the polarization direction control means controls such that BLACK is selected.

FIG. 5 is a diagram showing switching timing at which color shading is prevented. Field F1
In (1), (Sd11, Sd12, Sd13) becomes (ON, O
4 shows the response of the liquid crystal cell in the FF, OFF) state. Conventionally, the liquid crystal cell corresponding to the drive signal Sd13 is O
Since the response until switching from N to OFF is slow, Sd
The two liquid crystal cells corresponding to Sd11 and Sd13 are both O
In the N state, color shading occurred in the field section. However, in this embodiment, (ON,
In the case of OFF, ON) state, BLAC is selected as the color selection.
Since the control is made to be K, color shading does not occur in the field section 73.

In the field F12, (Sd1
(1, Sd12, Sd13) are (OFF, ON, OFF)
3 shows the response of the liquid crystal cell in the state of FIG. Conventionally, since the response until the liquid crystal cell corresponding to the drive signal Sd11 switches from ON to OFF is slow, Sd11 and Sd12
Both liquid crystal cells corresponding to are turned on,
Color shading occurred in the field section. However, in the present invention, in the (ON, ON, OFF) state, the color selection is controlled so as to be BLACK, so that color shading does not occur in the field section 74.

Further, in the field F13, (Sd1
1, Sd12, Sd13) are (OFF, OFF, ON)
3 shows the response of the liquid crystal cell in the state of FIG. Conventionally, since the response until the liquid crystal cell corresponding to the drive signal Sd12 switches from ON to OFF is slow, Sd12 and Sd13
Both liquid crystal cells corresponding to are turned on,
Color shading occurred in the field section. However, in the present invention, in the (OFF, ON, ON) state, the color selection is controlled so as to be BLACK, so that color shading does not occur in the field section 75.

As described above, in the second embodiment, in the field section where color shading occurs, the polarization direction of the liquid crystal cell is controlled so that BLACK having the minimum light transmittance is selectively output. did. Thus, it is possible to prevent color shading between video fields caused by a delay in the response speed of the liquid crystal cell.

In the first embodiment, there is a field section in which color shading does not visually occur by considering a combination of color selection. On the other hand, in the second embodiment, by increasing the number of liquid crystal cells and neutral polarizers, all states that occur immediately after switching can be set to BLACK. Therefore, it is not necessary to consider a combination of color selections, and no color shading occurs.

FIG. 6 is a diagram showing a color switching operation of a liquid crystal shutter including three liquid crystal cells. The liquid crystal shutter of the second embodiment has a larger number of liquid crystal cells and neutral polarizers than the liquid crystal shutter of the first embodiment shown in FIG.

The liquid crystal shutter according to the second embodiment
It comprises two liquid crystal cells, two color polarizers 15 and 16 and two neutral polarizers 14 and 17. The liquid crystal cell driven by the drive signal Sd11 includes a liquid crystal cell 23a that is turned on and a liquid crystal cell 23b that is turned off. Further, the liquid crystal cell driven by the drive signal Sd12 turns on the liquid crystal cell 24a
And a liquid crystal cell 24b that is turned off. The liquid crystal cell driven by the drive signal Sd13 is:
The liquid crystal cell 25a is turned on and the liquid crystal cell 25b is turned off.

Here, when the liquid crystal cell is turned on by the drive signals Sd11, S12, S13, the polarization direction does not change. In the OFF state, the polarization direction is rotated by 90 °.

For example, a monochrome CR is generated by a BLACK signal.
When T is driven, the liquid crystal cells 23a, 24a, 2
5a are both turned on. Each axis of the neutral polarizer 14 has a horizontal polarization axis O (BLACK) and a vertical polarization axis W
Since (R, G, B), the incident light W is transmitted in the vertical direction. Since the polarization direction is not changed by the liquid crystal cell 23a in the ON state, the color light transmitted through the neutral polarizer 14 passes through the liquid crystal cell 23a as it is. Then, the vertical polarization axis R of the color polarizing plate 15 and the R
Only the light passes through the color deflecting plate 15.

Since the polarization direction is not changed by the liquid crystal cell 24a in the next ON state, R is equal to the liquid crystal cell 24a.
Is transmitted as it is. Since there is no color light common to the color polarizer 16, the color light is BLACK.
Therefore, the color light remains BLACK even after passing through the liquid crystal cell 25a and the neutral polarizer 17.

When the monochrome CRT is driven by the R signal, the liquid crystal cell 23a is turned on and the liquid crystal cell 24b is turned on.
The FF and the liquid crystal cell 25b are turned off. Each axis of the neutral polarizer 14 has a horizontal polarization axis O (BRAC
K) and the vertical polarization axis W (R, G, B), the incident light W is transmitted in the vertical direction. Since the polarization direction is not changed by the liquid crystal cell 23a in the ON state, the color light transmitted through the neutral polarizer 14 is transmitted through the liquid crystal cell 23a as it is. The vertical polarization axis R of the color polarizer 15
Only R common to the above is transmitted through the color polarizing plate 15.

The liquid crystal cell 24b in the OFF state at the next stage is also provided.
Changes the polarization direction by 90 °, R rotates the liquid crystal cell 24b by 90 ° and transmits the liquid crystal cell 24b. Since the horizontal polarization axes YL (R, G) of the color polarizer 16 transmit R and G, G is cut off and the color light becomes R.

Further, since the polarization direction is changed by 90 ° by the liquid crystal cell 25b in the OFF state, R is
b is rotated 90 ° and transmitted. Since the vertical polarization axis W (R, G, B) of the neutral polarizer 17 transmits R, G, and B, G and B are blocked, and the color light finally becomes R.

When the monochrome CRT is driven by the B signal, the liquid crystal cell 23b is turned off, the liquid crystal cell 24a is turned on, and the liquid crystal cell 25b is turned off. Each axis of the neutral polarizer 14 has a horizontal polarization axis O (BRAC
K) and the vertical polarization axis W (R, G, B), the incident light W is transmitted in the vertical direction. Since the polarization direction is changed by 90 ° by the liquid crystal cell 23b in the OFF state, the color light transmitted through the neutral polarizer 14 is transmitted by rotating the liquid crystal cell 23b by 90 °. Then, only G and B, which are common to the horizontal polarization axis Cy (G, B) of the color polarizing plate 15, pass through the color polarizing plate 15.

Since the polarization direction is not changed by the liquid crystal cell 24a in the ON state at the next stage, G and B are set in the liquid crystal cell 2a.
4a is transmitted as it is. The horizontal polarization axis YL (R, G) of the color polarizer 16 transmits R and G,
B is cut off and the color light becomes G.

Further, the polarization direction is changed by 90 ° by the liquid crystal cell 25b in the OFF state.
b is rotated 90 ° and transmitted. Since the vertical polarization axis W (R, G, B) of the neutral polarizer 17 transmits R, G, and B, R and B are cut off, and the color light finally becomes G.

When the monochrome CRT is driven by the G signal, the liquid crystal cell 23b is turned off, the liquid crystal cell 24b is turned off, and the liquid crystal cell 25a is turned on. Each axis of the neutral polarizer 14 has a horizontal polarization axis O (BRAC
K) and the vertical polarization axis W (R, G, B), the incident light W is transmitted in the vertical direction. Since the polarization direction is changed by 90 ° by the liquid crystal cell 23b in the OFF state, the color light transmitted through the neutral polarizer 14 is rotated by 90 ° and passes through the liquid crystal cell 23b. Then, only G and B, which are common to the horizontal polarization axis Cy (G, B) of the color polarizing plate 15, pass through the color polarizing plate 15.

Further, the liquid crystal cell 24b in the OFF state at the next stage is
The polarization direction changes by 90 °, so that the color light transmitted through the color polarizer 15 is rotated by 90 ° in the liquid crystal cell 24b and transmitted. Since the vertical polarization axis B of the color polarizing plate 16 transmits B, the color light becomes B.

Further, since the polarization direction is not changed by the liquid crystal cell 25a in the ON state, B passes through the liquid crystal cell 25a as it is. The vertical polarization axis W (R, G, B) of the neutral polarizer 17 transmits R, G, and B, so that R and G are blocked, and the color light finally becomes B.

As described above, in the field section where color shading occurs, the polarization direction of the liquid crystal cell is controlled so that BLACK having the minimum light transmittance is selectively output. Thus, it is possible to prevent color shading between video fields caused by a delay in the response speed of the liquid crystal cell.

Further, since it is not necessary to divide the electrodes of the liquid crystal cell, the structure of the liquid crystal shutter can be manufactured simply and inexpensively. The monochrome CRT is not limited to a normal type but may be a flat type CRT. Further, a flat display such as a liquid crystal display or a plasma display may be employed.

Although the liquid crystal cell is turned on / off according to the voltage level of the drive signal, the liquid crystal cell may be turned on / off by changing the frequency of the drive signal.

[0063]

As described above, in the present invention, the polarization direction of the liquid crystal cell is controlled so that BLACK having the minimum light transmittance is selectively output in the field section where color shading occurs. As a result, color shading between image fields caused by a delay in the response speed of the liquid crystal shutter can be prevented, and a full-color image with high color purity can be realized.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a frame sequential color display device according to the present invention.

FIG. 2 is a diagram illustrating a configuration of a monochrome CRT and a liquid crystal shutter.

FIG. 3 is a diagram showing a switching timing at which color shading is prevented.

FIG. 4 is a diagram illustrating a color switching operation of a liquid crystal shutter including two liquid crystal cells.

FIG. 5 is a diagram showing a switching timing at which color shading is prevented.

FIG. 6 is a diagram illustrating a color switching operation of a liquid crystal shutter including three liquid crystal cells.

FIG. 7 is a diagram showing response characteristics of a liquid crystal cell.

FIG. 8 is a diagram illustrating switching timing at which color shading occurs.

[Explanation of symbols]

4 ... monochrome CRT, 5 ... color signal generation means, 6 ...
Polarization direction control means, 11, 13 ... Color polarizing plate, 12 ...
Neutral polarizing plate, 21, 22: liquid crystal cell, 30: liquid crystal shutter

Claims (3)

[Claims] 1. A screen sequential color display device for performing color display by switching three primary color signals, wherein a monochrome CRT for displaying an image with a change in luminance and a sequential color signal for driving the monochrome CRT are generated from the three primary color signals. A liquid crystal shutter comprising: a color signal generating means; a plurality of color polarizers arranged in series on the optical axis with respect to the monochrome CRT; and a plurality of liquid crystal cells arranged in series on the optical axis between the color polarizers. And a polarization direction control means for controlling the polarization direction of the color light so as to minimize the light transmittance of the liquid crystal shutter when two or more liquid crystal cells are simultaneously turned on by driving the polarization axis of the liquid crystal cell. A screen sequential color display device, comprising: 2. The liquid crystal cell according to claim 1, wherein the polarization direction control means drives a plurality of the liquid crystal cells simultaneously so as to control the polarization direction of the color light on the entire surface corresponding to the image area. Screen sequential color display device. 3. The polarization direction control means generates a drive signal for driving a polarization axis of the liquid crystal cell, and controls a polarization direction of the color light according to a voltage level of the drive signal. Item 1. A screen sequential color display device according to Item 1.