JPH08334763A - Display device - Google Patents

Abstract

PURPOSE: To improve the light transmittance of a liquid crystal shutter and the luminance of the display device itself without deteriorating chromaticity (color reproducbility). CONSTITUTION: A liquid crystal shutter 2 is constituted to have a yellow polarizing plate 11A which exhibits absorbance of 0.1 to 0.25 with respect to the absorption axis bearing in a visible region of a wavelength of >=600nm, a purple polarizing plate 11B which exhibits the absorbance of 0.4 to 1.2 with respect to the absorption axis bearing in the wavelength region of 400 to 500nm and exhibits the absorbance of 0.1 to 1.2 with respect to the absorption axis bearing in the visible region of the wavelength of >=640nm, a red polarizing plate 13A which exhibits the absorbance of <=0.2 with respect to the absorption axis bearing in the visible region of the wavelength of >=540nm, a cyan polarizing plate 13B which exhibits the absorbance of 0.25 to 0.75 with respect to the absorption axis bearing in the wavelength region of 400 to 550nm, one sheet of neutral polarizing plate 15 and two sheets of liquid crystal cells 12 and 14 which are subjected to switching control respectively by color signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a display device, which is provided with a liquid crystal shutter which is switching-controlled according to color signals sent in a field sequence and a cathode ray tube as a backlight of the liquid crystal shutter. And a display device configured as described above.

[0002]

2. Description of the Related Art Recently, a liquid crystal shutter composed of a plurality of polarizing plates and a plurality of liquid crystal cells, and a monochromatic display cathode ray tube (CR) used as a backlight of the liquid crystal shutter.
T) is proposed in combination with a display device,
It has been put to practical use (for details, see, for example, US Pat. No. 4,635,051).

This display device is characterized in that a full color image is reproduced by controlling ON / OFF of liquid crystal cells in a liquid crystal shutter in correspondence with R signal, G signal and B signal sent in a field sequence. To do.

Here, a conventional display device using a liquid crystal shutter will be described with reference to FIG. 26. As shown in the figure, the display device is a monochromatic display CRT 101.
And a liquid crystal shutter 10 arranged in front of the CRT 101.
2 and the liquid crystal shutter 102 is C
The first color polarizing plate 111, the first liquid crystal cell 112, the second color polarizing plate 113, the second
The liquid crystal cell 114 and the neutral polarizing plate 115 are arranged.

In the CRT 101, in one field period of a video signal, a luminance signal in one field period for red (hereinafter simply referred to as R signal Svr) and a luminance signal in one field period for green (hereinafter simply referred to as G signal). A signal Svg) and a luminance signal for one field period for blue (hereinafter, simply referred to as B signal Svb) are sequentially input.

Then, when the light beam based on the input of the R signal Svr is emitted from the CRT 101, for example, the first liquid crystal cell 112 is turned on and the second liquid crystal cell 114 is turned on.
By performing FF operation, the neutral polarizing plate 115
From the CRT 101 G signal Sv
When the light beam based on the input of g is emitted, the first liquid crystal cell 112 is turned off and the second liquid crystal cell 114 is turned off.
When the N operation is performed, a green light beam is emitted from the neutral polarization plate 115, and the B signal Svb is output from the CRT 101.
By turning on both the first and second liquid crystal cells 112 and 114 at the stage where the light beam based on the input of is emitted, a blue light beam is emitted from the neutral polarizing plate 115, and a series of these operations is repeated. The full-color image is displayed on the screen arranged in front of the liquid crystal shutter 102.

[0007]

The display device using the liquid crystal shutter 102 has the advantages of high contrast and high resolution, but has the drawback of low brightness. This is because the light transmittance of the liquid crystal shutter 102 is only about 5%.

As described above, the low light transmittance is due to the structure of the liquid crystal shutter 102, which is formed by stacking several color polarizing plates.

Therefore, it is necessary to increase the light transmittance of the liquid crystal shutter 102 by improving the color polarizing plate or by improving the light emission characteristics of the CRT 101 which is the backlight of the liquid crystal shutter 102. However, even if the color polarizing plate is simply improved, there is a problem of chromaticity, and it is not preferable to improve luminance by ignoring chromaticity. Therefore, it is necessary to maintain the chromaticity reference and improve the light transmittance of the liquid crystal shutter 102.

A method other than the method for increasing the light transmittance of the liquid crystal shutter 102 is C for increasing the brightness.
It is possible to increase the illuminance as a backlight by increasing the current (current supplied to the electron gun, anode current, etc.) flowing through the RT 101. However, in the case of this method, it is difficult to say that this method is always feasible due to problems in the circuit, especially in safety.

The present invention has been made in view of the above problems, and an object thereof is to improve the light transmittance of a liquid crystal shutter without causing deterioration of chromaticity (color reproducibility). Another object of the present invention is to provide a display device capable of improving the brightness of the display device itself.

Another object of the present invention is to provide a display device capable of lowering the level of current flowing in a cathode ray tube and reducing power consumption when brightness is not required to be improved. Especially.

[0013]

A display device according to the present invention comprises a liquid crystal shutter which is switching-controlled according to color signals sent in a field sequential manner, and a cathode ray tube as a backlight of the liquid crystal shutter. The liquid crystal shutter has a first absorption degree of 0.1 to 0.25 with respect to the absorption axis azimuth in the visible region of wavelength of 600 nm or more.
And a second polarizing plate having an absorption axis azimuth of 0.25 to 0.75 in the wavelength range of 400 nm to 550 nm, and an absorption axis azimuth of 0. In the visible region with a wavelength of 640 nm or more, showing an absorption of 4 to 1.2,
Third showing an absorption degree of 0.1 to 1.2 with respect to the absorption axis direction
Polarizing plate and in the visible range of 540 nm or more,
A fourth polarizing plate showing an absorption degree of 0.2 or less with respect to the absorption axis direction, one neutral polarizing plate, and two liquid crystal cells each of which is switching-controlled by the color signal. .

[0014]

In the display device according to the present invention, each of the polarizing plates constituting the liquid crystal shutter is designed to reduce the absorption (absorbance) with respect to the absorption axis direction in the characteristic wavelength range.

Specifically, regarding the first polarizing plate, 6
In the visible region with a wavelength of 00 nm or more, the absorption axis azimuth has an absorption degree of 0.1 to 0.25, and the second polarizing plate has an absorption axis azimuth of 0.25 to 0 in the wavelength range of 400 nm to 550 nm. The absorbance is 0.75.

For the third polarizing plate, 400 n
In the wavelength range of m to 500 nm, the absorbance is 0.4 to 1.2 with respect to the absorption axis azimuth, and in the visible region with a wavelength of 640 nm or more, the absorption axis direction is 0.1 to 1.
The absorbance is 2 and the fourth polarizing plate is 540 nm.
In the visible region of the above wavelength, the absorption axis direction is 0.
Absorption is 2 or less.

Generally, the spectral transmittance of a liquid crystal shutter is expressed by the following equation, and therefore the absorbance [A (λ) · m ·
It can be seen that the spectral transmittance is improved by decreasing d].

[0018]

[Equation 1]

Therefore, by setting the absorbances of the various polarizing plates as described above, the RGB spectral characteristics of the liquid crystal shutter are, for example, as shown in FIG. 7, compared with the conventional case (for example, shown in FIG. 4). , R, G, and B maximum transmittances are improved.

The brightness and color reproducibility of the display device using the liquid crystal shutter are determined by both the emission spectrum characteristic of the phosphor used in the cathode ray tube and the RGB spectral characteristic of the liquid crystal shutter. RGB of shutter
Since the spectral transmittance is improved, the brightness is improved and
Regarding color reproducibility, color reproducibility comparable to that of a color cathode ray tube can be obtained.

As described above, in the display device according to the present invention, the light transmittance of the liquid crystal shutter can be improved without degrading the chromaticity (color reproducibility), and the brightness of the display device itself can be improved. Can be raised. Further, when it is not necessary to improve the brightness, the level of the current flowing through the cathode ray tube can be lowered, and thus the power consumption can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the display device according to the present invention is applied to a display device using a liquid crystal shutter (hereinafter, simply referred to as a display device according to the embodiment) will be described with reference to FIGS.

As shown in FIG. 1, the display device according to this embodiment includes a CRT 1 for monochromatic display, a liquid crystal shutter 2 arranged in front of the CRT 1, and an RGB switching circuit for driving the liquid crystal shutter 2. 3 and a liquid crystal drive circuit 4, and the liquid crystal shutter 2 includes a first color polarizing plate 11, a first liquid crystal cell 12, and a second liquid crystal cell in order from the CRT 1 side.
The color polarizing plate 13, the second liquid crystal cell 14, and the neutral polarizing plate 15 are arranged.

The first color polarizing plate 11 has a horizontal absorption axis 11
a having a vertical transmission axis 11b and a second color polarization plate 13
Has a vertical absorption axis 13a and a horizontal transmission axis 13b, and the neutral polarizing plate 15 has a vertical absorption axis 15a and a horizontal transmission axis 15b.
b.

The optical axis 12a of the first liquid crystal cell 12
Is in the + 45 ° direction with respect to the horizontal axis, and the optical axis 14a of the second liquid crystal cell 14 is in the −45 ° direction with respect to the horizontal axis. The first liquid crystal cell 12 includes the liquid crystal drive circuit 4
ON operation is performed based on the ON signal from, the incident light ray is transmitted as it is, and OFF operation is performed based on the OFF signal from the liquid crystal drive circuit 4, and the incident light ray is a left rotation polarized light ray.
The second liquid crystal cell 14 is turned on based on the ON signal from the liquid crystal drive circuit 4, and transmits the incident light beam as it is,
An OFF operation is performed based on an OFF signal from the liquid crystal drive circuit 4, and the incident light ray is a right-handed polarized light ray.

The luminance signal Sv for three kinds of colors (red R, green G and blue B) is input to the CRT 1 from the signal processing system in the preceding stage for one field period of the video signal through the input terminal φin. That is, the CRT 1 has a luminance signal (hereinafter, simply referred to as an R signal Svr) in the one field period for red color in the one field period.
Then, a luminance signal for one field period for green (hereinafter, simply referred to as G signal Svg) and a luminance signal for one field period for blue (hereinafter, simply referred to as B signal Svb) are sequentially input. ing.

These R signal Svr, G signals Svg and B
In the signal Svb, the same sync signal as the field sync signal of the video signal is inserted at the beginning of each of the signals Svr, Svg and Svb.

The R signal Svr, the G signal Svg, and the B signal Svb are also input to the RGB color switching circuit 3 in the subsequent stage. This RGB color switching circuit 3 is
The R control signal Scr is output to the liquid crystal drive circuit 4 based on the input of the synchronization signal of the R signal Svr, and the G control signal S is output to the liquid crystal drive circuit 4 based on the input of the synchronization signal of the G signal Svg.
cg is output, and the B control signal Scb is output to the liquid crystal drive circuit 4 based on the input of the synchronization signal of the B signal Svb.

The liquid crystal drive circuit 4 receives the first and second R control signals Scr from the RGB color switching circuit 3.
ON signals Sn and O are supplied to the liquid crystal cells 12 and 14, respectively.
The FF signal Sf is output. As a result, the light ray based on the R signal Svr emitted from the CRT 1 passes through the vertical transmission axis 11b of the first color polarizing plate 11, passes through the first liquid crystal cell 12 as it is, and further the second color polarizing plate. Thirteen
After passing through the horizontal transmission axis 13b, the second liquid crystal cell 14 converts the light into right-handed polarized light. This right-handed polarized light ray is
After passing through the horizontal transmission axis 15b of the neutral polarizing plate 15 in the subsequent stage, it is emitted from the liquid crystal shutter 2 as a red ray.

Next, when the G color control signal Scg is output from the RGB color switching circuit 3, the liquid crystal drive circuit 4 supplies the OFF signal Sf to the first and second liquid crystal cells 12 and 14, respectively.
And an ON signal Sn are output. This allows CRT1
The light beam based on the G signal Svg emitted from the laser beam passes through the vertical transmission axis 11b of the first color polarizing plate 11 and is turned into a left-handed polarized light beam by the first liquid crystal cell 12. This left-handed polarized light beam is transmitted through the horizontal transmission axis 1 of the second color polarization plate 13.
3b and then the second liquid crystal cell 14 as it is,
Further, the horizontal transmission axis 15b of the neutral polarizing plate 15 in the subsequent stage
Will be emitted from the liquid crystal shutter 2 as a green ray.

Next, when the B color control signal Svb is output from the RGB color switching circuit 3, the liquid crystal drive circuit 4 supplies the ON signal Sn and the ON signal Sn to the first and second liquid crystal cells 12 and 14, respectively. Output. As a result, the light beam based on the B signal Svb emitted from the CRT 1 passes through the vertical transmission axis 11b of the first color polarizing plate 11, passes through the first liquid crystal cell 12 as it is, and further the second color polarizing plate. 1
3 passes through the horizontal transmission axis 13b, passes through the second liquid crystal cell 14 as it is, passes through the horizontal transmission axis 15b of the subsequent neutral polarizing plate 15, and is emitted from the liquid crystal shutter 2 as blue light. .

A series of operations of emitting the red light beam, emitting the green light beam and emitting the blue light beam is continuously performed in one field period of the video signal. For example, a screen is arranged in front of the liquid crystal shutter 2 and When a series of emitted light is projected, a full-color image is displayed on the screen.

As shown in FIG. 2, two polarizing plates are attached to each of the first color polarizing plate 11 and the second color polarizing plate 13 constituting the liquid crystal shutter 2 of the display device according to the present embodiment. The first color polarizing plate 11 is composed of a yellow polarizing plate 11A and a purple polarizing plate 1.
The second color polarizing plate 1 is configured by laminating 1B.
3 is configured by laminating a red polarizing plate 13A and a cyan polarizing plate 13B.

Polarizing plates (11A, 11B) and (13)
In the first polarizing plate 11, the yellow polarizing plate 11A is arranged so as to face the front surface of the CRT 1, and the purple polarizing plate 11B faces the incident side of the first liquid crystal cell 12. Arranged to do so. On the other hand, in the second polarizing plate 13, the red polarizing plate 13A is the first
The liquid crystal cell 12 is arranged so as to face the exit side of the liquid crystal cell 12, and the cyan polarizing plate 13B is arranged so as to face the entrance side of the second liquid crystal cell 14.

The display device according to the present embodiment is intended to increase the light transmittance of the liquid crystal shutter 2 as compared with a display device using a conventional liquid crystal shutter (hereinafter referred to as a display device according to the conventional example). I am trying.

In general, the light transmittance (shutter transmittance) of the liquid crystal shutter 2 is expressed by the above mathematical expression 1.

From the above formula 1, the shutter transmittance is calculated as CRT.
And the various polarizing plates (11A, 11B) and (13A, 1) constituting the liquid crystal shutter 2.
It can be seen that it largely depends on both of the light transmission characteristics of 3B). Therefore, the light transmittance of the liquid crystal shutter 2 is improved (improved).
In order to do so, it is necessary to improve the characteristics of the phosphor and the various polarizing plates (11A, 11B) and (13A, 13B) that form the phosphor screen of the CRT 1.

Various polarizing plates (11A, 11B) and (13
The light transmission characteristics of (A, 13B) vary depending on the type of dye, the concentration of the dye, the thickness, the stretching conditions, etc., and in particular, the dye concentration and the thickness have the following relationship.

[0039]

[Equation 2]

In the above equation, A (λ) · m · d is called the absorbance.

First, the display device according to the conventional example will be described, and then the display device according to the present embodiment (three embodiments).
Will be described.

In the display device according to the conventional example, the CR
The phosphor, which is a constituent element of the phosphor screen formed on the inner surface of the front panel of T1, has an emission spectrum, and as shown in the characteristic diagram of FIG.
The emission spectrum has sharp peaks in three kinds of wavelength regions near nm and around 620 nm. Examples of this phosphor include those of P45 type (commercially available).

Next, looking at the spectral characteristics of the various polarizing plates (11A, 11B) and (13A, 13B) in the display device according to the conventional example, first, the spectral transmittance of the transmission axis of the yellow polarizing plate 11A is shown in FIG. In the characteristic diagram of FIG. 9, as indicated by a curve a, a characteristic curve is shown in which the minimum wavelength is near 385 nm, the wavelength increases as the wavelength increases, and a saturation state (constant value) is reached at a wavelength of approximately 520 nm. The spectral transmittance at the wavelength has a value as shown in the column of the conventional example in the table of FIG.

On the other hand, as shown by the curve b in the characteristic diagram of FIG. 9, the spectral transmittance of the absorption axis rises sharply from around the wavelength of 440 nm and reaches a saturated state (constant value) at a wavelength of approximately 560 nm. That is, the spectral transmittance at each wavelength has a value as shown in the column of the conventional example in the table of FIG.

Next, as shown by the curve a in the characteristic diagram of FIG. 12, the spectral transmittance of the transmission axis of the purple polarizing plate 11B is steeply increased as the wavelength becomes longer with the minimum near the wavelength of 385 nm. , Becomes a maximum value at a wavelength of about 460 nm, and gradually decreases as the wavelength becomes longer, becomes a minimum value at a wavelength of about 580 nm, and gradually increases as the wavelength becomes longer, and becomes about 660.
A characteristic curve showing a saturated state (constant value) at a wavelength of nm is shown, and the spectral transmittance at each wavelength is a value as shown in the column of the conventional example in the table of FIG.

On the other hand, as shown by the curve b in the characteristic diagram of FIG. 12, the spectral transmittance of the absorption axis has a minimum at around the wavelength of 385 nm and sharply increases as the wavelength becomes longer.
It has a maximum value at a wavelength of about 440 nm, and gradually decreases as the wavelength becomes longer, and becomes 560 nm to 600 n.
It shows a characteristic curve in which the minimum value is obtained in the wavelength range over m, and the wavelength rises steeply as the wavelength becomes longer and becomes saturated (constant value) in the wavelength range of approximately 700 nm.
The spectral transmittance at each wavelength has a value as shown in the column of the conventional example in the table of FIG.

Next, as shown by the curve a in the characteristic diagram of FIG. 15, the spectral transmittance of the transmission axis of the red polarizing plate 13A increases sharply as the wavelength becomes longer with the minimum wavelength near 385 nm. , Becomes a maximum value at a wavelength of about 450 nm, gradually decreases as the wavelength becomes longer, and becomes a minimum value at a wavelength of about 530 nm, and gradually increases as the wavelength becomes longer, at about 610 nm.
A characteristic curve showing a saturated state (constant value) in the subsequent wavelength regions is shown, and the spectral transmittance at each wavelength is a value as shown in the column of the conventional example in the table of FIG.

On the other hand, as shown by the curve b in the characteristic diagram of FIG. 15, the spectral transmittance of the absorption axis is minimized near the wavelength of 385 nm and rises to the place where the wavelength becomes longer,
It has a maximum value at a wavelength of about 440 nm, and gradually decreases as the wavelength becomes longer, and 500 nm to 560 n
It maintains a substantially constant value in the wavelength range up to m, and rises sharply as the wavelength becomes longer, reaching approximately 640
17 shows a characteristic curve in which a saturated state (constant value) is obtained in the wavelength range after nm, and the spectral transmittance at each wavelength is shown in FIG.
The values are as shown in the conventional example column of the table.

Next, as shown by the curve a in the characteristic diagram of FIG. 18, the spectral transmittance of the cyan polarizing plate 13B is steeply increased as the wavelength becomes longer, with the minimum near the wavelength of 385 nm. , Approximately 430 nm to 470 n
It maintains a substantially constant value in the wavelength range over m, and gradually increases as the wavelength further increases to approximately 510n.
The characteristic curve shows a maximum value at the wavelength of m, and a gradual decrease as the wavelength becomes longer, and a substantially constant value in the wavelength range of approximately 640 nm and thereafter. The spectral transmittance at each wavelength is The values are as shown in the conventional example column of the table in FIG.

On the other hand, as shown by the curve b in the characteristic diagram of FIG. 18, the spectral transmittance of the absorption axis has a minimum value near the wavelength of 385 nm and sharply increases as the wavelength becomes longer.
It reaches the first maximum value at a wavelength of approximately 470 nm, and gradually decreases as the wavelength further increases, to approximately 640 nm.
Shows a characteristic curve in which the wavelength reaches a minimum value, and as the wavelength further increases, the wavelength reaches a second maximum value at a wavelength of approximately 660 nm, and then gradually decreases. The spectral transmittance at each wavelength is The values are as shown in the column of the conventional example in the table of FIG.

The RGB spectrum of the liquid crystal shutter 2 in the display device according to the conventional example is determined by the above-mentioned emission spectrum of the phosphor and the characteristics (spectral characteristics) of the spectral transmittances of the various polarizing plates (11A, 11B) and (13A, 13B). As shown in FIG. 4, the characteristic of transmittance (RGB spectral characteristic) is the maximum (transmittance of about 30%) in the vicinity of the wavelength of 460 nm for blue (B) as shown by the curve B, and the characteristic of green ( G) has a maximum (transmittance of about 37.25%) near the wavelength of 525 nm as shown by the curve G, and 700 nm as shown by the curve R for red (R).
In the subsequent wavelength range, it becomes a saturated state (transmittance of about 75%).

The luminance and color reproducibility of the display device according to the conventional example are determined by both the emission spectrum characteristic of the phosphor shown in FIG. 3 and the RGB spectral characteristic of the liquid crystal shutter 2 shown in FIG. FIG. 5 shows the color reproducibility of the display device according to the conventional example under such conditions.

The color reproducibility of the display device according to the conventional example is shown in FIG.
As shown in, the point corresponding to each chromaticity of R, G, and B (shown by ■) is located near the apex of the color reproducibility of the color CRT (the area indicated by the broken line) without external light. From this, it can be seen that the color reproducibility is similar to that of a color CRT and that the color CRT is good. However, since the shutter transmittance is as low as about 6%, improvement is required to improve the brightness.

Next, a display device according to this embodiment (three embodiments) will be described with reference to FIGS.

First, the display device according to the first embodiment will be described. CR in the display device according to the first embodiment
The phosphor, which is a constituent element of the phosphor screen formed on the inner surface of the front panel of T1, has a sharp peak in the vicinity of a wavelength of about 625 nm as shown by the curve B in the characteristic diagram of FIG. However, in other wavelength ranges,
It has a broad characteristic of 40% or less. An emission spectrum (same as the characteristic shown in FIG. 3) of the phosphor in the display device according to the conventional example is shown as a curve A.

Specifically, the phosphor screen has an emission spectrum with a peak near 450 nm and a wavelength of 400 nm.
-A phosphor having a characteristic of gently changing over a wavelength range of 500 nm, and a phosphor having an emission spectrum having a peak at around 540 nm and having a characteristic of gently changing over a wavelength range of 500 nm to 580 nm, and an emission spectrum of , And a phosphor having a peak in the wavelength range of 610 nm to 640 nm are mixed. Examples of the phosphor for forming the phosphor screen include those of P22 type (commercially available).

On the other hand, the yellow polarizing plate 11A, the purple polarizing plate 11B, and the red polarizing plate 1 which constitute the liquid crystal shutter 2.
3A and the cyan polarizing plate 13B are the same as the polarizing plates used in the display device according to the conventional example described above.

FIG. 8 shows the color reproducibility and the light transmittance of the display device according to the first embodiment. From FIG. 8, regarding the color reproducibility, the points corresponding to the chromaticities of R, G, and B (○
Is shown in FIG. 3), which is located near the apex of the color reproducibility of the color CRT (the area indicated by the broken line) without external light. Therefore, the color reproducibility similar to that of the conventional color CRT is obtained. It can be seen that it has and is good. Moreover, the light transmittance is 7.23, which is the light transmittance (6.1%) of the conventional example.
It is improved by about 17% compared to 7).

As described above, in the display device according to the first embodiment, while exhibiting color reproducibility similar to that of the color CRT,
Since the light transmittance is improved by about 17% as compared with the conventional case, the brightness of the display device itself can be increased without causing deterioration of chromaticity (color reproducibility).

Next, the display device according to the second embodiment will be described. CR in the display device according to the second embodiment
The phosphor used as the constituent element of the phosphor screen formed on the inner surface of the front panel of T1 is the phosphor used in the display device according to the first embodiment.

On the other hand, the yellow polarizing plate 11A, the purple polarizing plate 11B, and the red polarizing plate 1 which constitute the liquid crystal shutter 2.
3A and cyan polarizing plate 13B are obtained by reducing the amount of each dye of the various polarizing plates used in the display device according to the conventional example by 20%. Specifically, as shown in the above mathematical expression 1, various polarizing plates (11A, 11B) and (13A, 13B) are used.
The dye concentration m or thickness d in B) is reduced to reduce the absorbance [A
(Λ) · m · d] is reduced. As a result, as shown in Equation 1, the spectral transmittance T of the liquid crystal shutter 2 is
It is possible to improve (λ).

Here, the spectral characteristics of the various polarizing plates (11A, 11B) and (13A, 13B) are shown in FIGS. Note that, in FIGS. 9, 12, 15 and 18, the spectral characteristic curves of various polarizing plates (11A, 11B) and (13A, 13B) used in the display device according to the second example are curve A, respectively. And B, and the spectral characteristic curves of various polarizing plates used in the display device according to the conventional example are shown by curves a and b, respectively.

Specifically, the various polarizing plates (11A, 11B) and (13A, 11A, 11B) used in the display device according to the second embodiment.
13B), the spectral transmittance of the transmission axis of the yellow polarizing plate 11A is about 8% at maximum as compared with the conventional case (shown by the curve a) as shown by the curve A in FIG. The spectral transmittance at each wavelength has a value as shown in the column of the second embodiment of the table in FIG.

On the other hand, the spectral transmittance of the absorption axis is about 6% higher than the conventional case (shown by the curve b) as shown by the curve B in FIG. 9, and the spectral transmittance at each wavelength is increased. The rate is a value as shown in the column of the second embodiment of the table of FIG.

Next, as shown by the curve A in FIG. 12, the spectral transmittance of the transmission axis of the purple polarizing plate 11B is about 1.25% higher than that in the conventional case (shown by the curve a). Therefore, the spectral transmittance at each wavelength has a value as shown in the column of the second embodiment of the table of FIG.

On the other hand, as shown by the curve B in FIG. 12, the spectral transmittance of the absorption axis is about 3.75% higher than that in the conventional case (shown by the curve b) at each wavelength. The spectral transmittance has a value as shown in the column of the second embodiment of the table of FIG.

Next, as shown by the curve A in FIG. 15, the spectral transmittance of the red polarizing plate 13A becomes higher than the conventional case (shown by the curve a) by about 4.4% at the maximum. Therefore, the spectral transmittance at each wavelength has a value as shown in the column of the second embodiment of the table in FIG.

On the other hand, the spectral transmittance of the absorption axis is about 12% higher than the conventional case (shown by the curve b) as shown by the curve B in FIG. 15, and the spectral transmittance at each wavelength is increased. The rate is a value as shown in the column of the second embodiment of the table of FIG.

Next, as shown by the curve A in FIG. 18, the spectral transmittance of the cyan polarizing plate 13B is about 4% higher than the conventional case (shown by the curve a). The spectral transmittance at each wavelength has a value as shown in the column of the second embodiment of the table of FIG.

On the other hand, the spectral transmittance of the absorption axis is about 14% higher than the conventional case (shown by the curve b) as shown by the curve B in FIG. 18, and the spectral transmittance at each wavelength is increased. The rate is a value as shown in the column of the second embodiment of the table of FIG.

When the characteristics of the various polarizing plates (11A, 11B) and (13A, 13B) in the display device according to the second embodiment are viewed in terms of the absorption in the absorption axis direction (absorbance), the yellow polarizing plate 11A has a wavelength of 600 nm. In the visible region of the above wavelength, it exhibits an absorption degree of 0.1 to 0.25 with respect to the absorption axis azimuth, and the purple polarizing plate 11B is 400 nm to 500 n.
In the wavelength range of m, 0.4 to 1.
In the visible region having a wavelength of 640 nm or more, the absorbance is 0.1 to 1.2 with respect to the absorption axis direction.

The red polarizing plate 13A has a thickness of 540 nm.
In the visible region of the above wavelength, the absorption axis direction is 0.
It exhibits an absorption of 2 or less, and the cyan polarizing plate 13B is 400
In the wavelength range of nm to 550 nm, it exhibits an absorption degree of 0.25 to 0.75 with respect to the absorption axis direction.

As described above, in the display device according to the second embodiment, the phosphor having the emission spectrum characteristic shown in FIG. 6 and the curves A and B shown in FIGS. 9, 12, 15 and 18 are shown. Polarizing plates with spectral characteristics (11A, 11B)
And (13A, 13B) are used, the characteristic of the RGB spectral transmittance (RGB spectral characteristic) of the liquid crystal shutter 2 in the display device according to the second embodiment is blue (B) as shown in FIG. , As shown in curve B, 4
Maximum (transmittance of about 50%) near the wavelength of 60 nm,
As for the green (G), as shown by the curve G, 52
It has a maximum (transmittance of about 52.6%) near a wavelength of 5 nm, and for red (R), as shown by a curve R,
Saturated state (transmittance of about 8
9.5%).

Then, as shown in FIG. 21, the light transmittance of the display device according to the second embodiment is 9.54, which is about 54% as compared with the light transmittance (6.17) of the conventional example. Has improved. On the other hand, as for the color reproducibility, the transmission spectrum of each polarizing plate of the liquid crystal shutter 2 becomes broader, as indicated by points (indicated by Δ) corresponding to each chromaticity of R, G and B in FIG. Therefore, in the case of the display device according to the conventional example (shown by ▪), it is slightly lower than that of the color CRT.

However, the external light of the color CRT is about 300 [L
x] as the lower limit of the color reproduction area (area indicated by the dotted line),
The display device according to the second embodiment has improved color reproducibility shown in the lower limit region. Here, the lower limit of the color reproducibility is set to about 300 [Lx] of the external light of the color CRT because the external light condition in a normal general household is close to this, and the color reproduction of the television used in the general household is close. This is because the area is also close to this.

Therefore, it can be concluded that the display device according to the second embodiment can improve the light transmittance by about 50% without significantly impairing the color reproducibility.

Note that when manufacturing the display device according to the second embodiment, a modification thereof was also examined.
The display device according to this modification uses, as a phosphor that is a constituent element of the phosphor screen formed on the inner surface of the front panel of the CRT 1,
Using the phosphor used in the display device according to the first embodiment, the yellow polarizing plate 11A constituting the liquid crystal shutter 2,
As the purple polarizing plate 11B, the red polarizing plate 13A, and the cyan polarizing plate 13B, various polarizing plates used in the display device according to the conventional example in which the amount of each dye is reduced by 40% are used.

The light transmittance of the display device according to this modification is
As shown in FIG. 21, it is 13.13, which is a significant improvement of about 110% as compared with the light transmittance (6.17) of the conventional example. However, regarding the color reproducibility, points corresponding to the chromaticities of R, G, and B in FIG.
As shown in (3), the color CRT is deteriorated more than the color reproduction area (area indicated by a dotted line) of external light of about 300 [Lx].

Therefore, as in the display device according to the second embodiment, it is preferable to use the one in which the dye amount of each polarizing plate is reduced by 20% as compared with the conventional example.

Next, a display device according to the third embodiment will be described. In the display device according to the third embodiment,
As the phosphor that is a constituent element of the phosphor screen formed on the inner surface of the front panel of the CRT 1, the phosphor used in the display device according to the conventional example is used.

On the other hand, the yellow polarizing plate 11A, the purple polarizing plate 11B, and the red polarizing plate 1 which constitute the liquid crystal shutter 2.
Of 3A and cyan polarizing plate 13B, cyan polarizing plate 13
Other three types of polarizing plates 11A, 11B and 13 except B
A is the same as the polarizing plate used in the display device according to the second embodiment, and the cyan polarizing plate 13B has a dye amount of 40% in the cyan polarizing plate 13B used in the display device according to the conventional example.
% Reduced.

Now, the spectral characteristics of the cyan polarizing plate 13B used in the display device according to the third embodiment will be described with reference to FIG. 22. The spectral transmittance of the transmission axis of the cyan polarizing plate 13B is As shown by the curve A in FIG. 22, the maximum is about 5% higher than in the conventional case (shown by the curve a), and the spectral transmittance at each wavelength is the third embodiment of the table in FIG. The values are as shown in the column.

On the other hand, the spectral transmittance of the absorption axis is about 25% higher than the conventional case (shown by the curve b), as shown by the curve B in FIG. 22, and the spectral transmittance at each wavelength is increased. The rate is a value as shown in the column of the third embodiment of the table of FIG.

The light transmittance of the display device according to the third embodiment is 9.49 as shown in FIG. 25, which is improved by about 54% as compared with the light transmittance (6.17) of the conventional example. are doing. On the other hand, the color reproducibility is as shown by points (indicated by ◯) corresponding to the chromaticities of R, G and B in FIG.
Since the transmission spectrum of each polarization plate of the liquid crystal shutter 2 becomes broader, it is slightly lower than that of the color CRT in the case of the display device according to the conventional example (shown by ▪). However, similarly to the display device according to the second embodiment, when the color reproduction region (region indicated by a dotted line) of the external light of about 300 [Lx] of the color CRT is set as the lower limit, the display device according to the third embodiment is , The color reproducibility shown in the lower limit region is improved.

Therefore, also in the display device according to the third embodiment, similar to the display device according to the second embodiment, the light transmittance can be improved by about 50% without greatly impairing the color reproducibility. Can be concluded.

Note that, in manufacturing the display device according to the third embodiment, a modification thereof was also examined.
The display device according to this modification uses, as a phosphor that is a constituent element of the phosphor screen formed on the inner surface of the front panel of the CRT 1,
A yellow polarizing plate 11A, a purple polarizing plate 11B, a red polarizing plate 13A, and a cyan polarizing plate 1 which constitute the liquid crystal shutter 2 by using the phosphor used in the display device according to the conventional example.
As 3B, various polarizing plates used in the display device according to the conventional example in which the amount of each dye is reduced by 40% are used.

The light transmittance of the display device according to this modification is
As shown in FIG. 25, it is 11.79, which is a significant improvement of about 91% compared to the light transmittance (6.17) of the conventional example. However, regarding the color reproducibility, in FIG.
As indicated by the points (indicated by Δ) corresponding to the chromaticities of G and B, the color CRT is deteriorated more than the color reproduction area (area indicated by the dotted line) of the external light of about 300 [Lx].

Therefore, when the conventional CRT 1 is used as in the display device according to the third embodiment, three types of polarizing plates 11A and 11B except the cyan polarizing plate 13B are used.
It is preferable to use those in which the amount of the dyes of 13 and 13A is reduced by 20% as compared with the conventional example, and use the cyan polarizing plate 13B in which the amount of dye is reduced by 40% as compared with the conventional example.

As described above, in the display devices according to the first embodiment, the second embodiment, and the third embodiment, the light transmittance of the liquid crystal shutter 2 does not cause deterioration of chromaticity (color reproducibility). The brightness of the display device itself can be increased. Further, when the brightness is not required to be improved, the level of the current flowing through the CRT 1 can be lowered, so that the power consumption can be reduced.

[0090]

As described above, according to the display device of the present invention, the liquid crystal shutter which is switching-controlled according to the color signals sent in the field sequence, and the cathode ray tube as the backlight of the liquid crystal shutter. In the visible region of wavelength of 600 nm or more, the liquid crystal shutter has a first polarizing plate showing an absorption degree of 0.1 to 0.25 with respect to the absorption axis azimuth, and a wavelength region of 400 nm to 550 nm, A second polarizing plate having an absorption axis azimuth of 0.25 to 0.75 and an absorption axis azimuth of 0.4 to 1.2 in the wavelength range of 400 nm to 500 nm, and 640 nm. In the visible region of the above wavelength, the third polarizing plate showing the absorption degree of 0.1 to 1.2 with respect to the absorption axis direction and with respect to the absorption axis direction in the visible region of the wavelength of 540 nm or more. Te fourth indicating a 0.2 absorbance
Since it is configured to have the above polarizing plate, one neutral polarizing plate, and two liquid crystal cells each of which is switching-controlled by the color signal, deterioration of chromaticity (color reproducibility) is prevented. The light transmittance of the liquid crystal shutter can be improved without inviting it, and the brightness of the display device itself can be increased. In addition, when it is not necessary to improve the brightness,
Since the level of the current passed through the CRT can be lowered, the power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment (hereinafter, simply referred to as a display device according to an embodiment) in which a display device according to the present invention is applied to a display device having a liquid crystal shutter.

FIG. 2 is a configuration diagram showing a liquid crystal shutter used in the display device according to the present embodiment.

FIG. 3 is a characteristic diagram showing an emission spectrum of a phosphor used in a CRT of a display device according to a conventional example.

FIG. 4 is a characteristic diagram showing RGB spectral characteristics of a liquid crystal shutter used in a display device according to a conventional example.

FIG. 5 is a chromaticity diagram showing color reproducibility of a display device according to a conventional example.

FIG. 6 is a characteristic diagram showing an emission spectrum of a phosphor used in a CRT of the display device according to this example.

FIG. 7 is a characteristic diagram showing RGB spectral characteristics of a liquid crystal shutter used in the display device according to the present embodiment.

FIG. 8 is a chromaticity diagram showing color reproducibility of the display device according to the first example.

FIG. 9 is a characteristic diagram showing spectral characteristics of a yellow polarizing plate of a liquid crystal shutter used in a display device according to a second embodiment, and curves A and B are transmission axis directions of a yellow deflecting plate according to the second embodiment. And the spectral characteristics in the absorption axis direction, and the curves a and b show the spectral characteristics in the transmission axis direction and the absorption axis direction of the yellow deflector according to the conventional example.

FIG. 10 is a table showing spectral characteristics along a transmission axis of a yellow polarizing plate of a liquid crystal shutter used in a display device according to a second example together with a conventional example.

FIG. 11 is a table showing the spectral characteristics along the absorption axis of the yellow polarizing plate of the liquid crystal shutter used in the display device according to the second example together with the conventional example.

FIG. 12 is a characteristic diagram showing spectral characteristics of a purple polarizing plate of a liquid crystal shutter used in a display device according to a second embodiment, and curves A and B are transmission axis directions of a purple deflector according to the second embodiment. And the absorption axis direction spectral characteristics, and the curves a and b indicate the transmission axis direction and absorption axis direction spectral characteristics of the conventional purple deflector.

FIG. 13 is a table showing spectral characteristics along a transmission axis of a purple polarizing plate of a liquid crystal shutter used in a display device according to a second example together with a conventional example.

FIG. 14 is a table showing the spectral characteristics along the absorption axis of the purple polarizing plate of the liquid crystal shutter used in the display device according to the second example together with the conventional example.

FIG. 15 is a characteristic diagram showing spectral characteristics of a red polarizing plate of a liquid crystal shutter used in a display device according to a second example, and curves A and B are transmission axis directions of a red deflecting plate according to the second example. And the spectral characteristics in the absorption axis direction, and the curves a and b show the spectral characteristics in the transmission axis direction and the absorption axis direction of the red deflector according to the conventional example.

FIG. 16 is a table showing spectral characteristics along a transmission axis of a red polarizing plate of a liquid crystal shutter used in a display device according to a second example together with a conventional example.

FIG. 17 is a table showing the spectral characteristics along the absorption axis of the red polarizing plate of the liquid crystal shutter used in the display device according to the second example together with the conventional example.

FIG. 18 is a characteristic diagram showing spectral characteristics of a cyan polarizing plate of a liquid crystal shutter used in a display device according to a second example, and curves A and B are transmission axis directions of a cyan deflecting plate according to the second example. And the spectral characteristics in the absorption axis direction, and the curves a and b show the spectral characteristics in the transmission axis direction and the absorption axis direction of the cyan deflection plate according to the conventional example.

FIG. 19 is a table showing spectral characteristics along a transmission axis of a cyan polarizing plate of a liquid crystal shutter used in a display device according to a second example together with a conventional example.

FIG. 20 is a table showing the spectral characteristics along the absorption axis of the cyan polarizing plate of the liquid crystal shutter used in the display device of Example 2 together with the conventional example.

FIG. 21 is a chromaticity diagram showing color reproducibility of the display device according to the second example.

FIG. 22 is a characteristic diagram showing spectral characteristics of a cyan polarizing plate of a liquid crystal shutter used in a display device according to a third example, and curves A and B are transmission axis directions of a cyan deflecting plate according to the second example. And the spectral characteristics in the absorption axis direction, and the curves a and b show the spectral characteristics in the transmission axis direction and the absorption axis direction of the cyan deflection plate according to the conventional example.

FIG. 23 is a table showing the spectral characteristics along the transmission axis of the cyan polarizing plate of the liquid crystal shutter used in the display device of Example 3 together with the conventional example.

FIG. 24 is a table showing the spectral characteristics along the absorption axis of the cyan polarizing plate of the liquid crystal shutter used in the display device according to the third example together with the conventional example.

FIG. 25 is a chromaticity diagram showing color reproducibility of the display device according to the third example.

FIG. 26 is a configuration diagram showing a display device according to a conventional example using a liquid crystal shutter.

[Explanation of symbols]

 1 CRT 2 Liquid Crystal Shutter 3 RGB Switching Circuit 4 Liquid Crystal Driving Circuit 11 First Color Polarizing Plate 11A Yellow Polarizing Plate 11B Purple Polarizing Plate 12 First Liquid Crystal Cell 13 Second Color Polarizing Plate 13A Red Polarizing Plate 13B Cyan Polarizing Plate 14 Second liquid crystal cell 15 Neutral polarizing plate

Claims (4)

[Claims] 1. A liquid crystal shutter, which is switching-controlled according to color signals sent in a field sequence, and a cathode ray tube as a backlight of the liquid crystal shutter, wherein the liquid crystal shutter has a wavelength of 600 nm or more. A first polarizing plate showing an absorption axis azimuth of 0.1 to 0.25 in the visible region, and an absorption axis 0.25 to 0.75 in the wavelength range of 400 nm to 550 nm. The second polarizing plate shown, and in the wavelength range of 400 nm to 500 nm, exhibits an absorption degree of 0.4 to 1.2 with respect to the absorption axis azimuth, and 640 n
a third polarizing plate having an absorption axis azimuth of 0.1 to 1.2 in the visible range of m or more, and 0.2 or less with respect to the absorption axis azimuth in the visible of 540 nm or more. A display device comprising a fourth polarizing plate exhibiting an absorption degree, one neutral polarizing plate, and two liquid crystal cells each of which is switching-controlled by the color signal. . 2. The phosphor screen formed on the cathode ray tube comprises a first phosphor having an emission spectrum having a peak near 450 nm and having a characteristic that the emission spectrum changes gently over a wavelength range of 400 nm to 500 nm; The second fluorescent substance having a spectrum with a peak near 540 nm and having a characteristic that it changes gently over the wavelength range of 500 nm to 580 nm, and the third fluorescent substance whose emission spectrum has a peak in the wavelength range of 610 nm to 640 nm. The display device according to claim 1, wherein the display device is formed by mixing with a body. 3. The liquid crystal shutter comprises: a first to a fourth polarizing plate produced by reducing the respective absorptivities of the first to the fourth polarizing plate by up to 20%, and The display device according to claim 2, wherein the display device comprises a neutral polarizing plate and the two liquid crystal cells. 4. The liquid crystal shutter comprises a second polarizing plate manufactured by reducing the absorption of the second polarizing plate by up to 40%, and a first polarizing plate, a third polarizing plate and a fourth polarizing plate. It is configured to have first, third and fourth polarizing plates produced by reducing the respective absorbances by up to 20%, the above-mentioned one neutral polarizing plate and the above-mentioned two liquid crystal cells. 2. The phosphor screen formed on the cathode ray tube is formed of a phosphor whose emission spectrum has peaks in at least three wavelength regions near 420 nm, 545 nm and 620 nm. Display device.