JP2002014315A - Projection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch a projected image between a state with priority to brightness and a state with priority to color purity. SOLUTION: A white light source 13 and a spectral means composed of dichroic mirrors 15R, 15G and reflection mirrors 18, 19, 20 are housed in a casing 12 of a projection type liquid crystal display device 11. The light spectrally divided by the spectral means is made to irradiate liquid crystal panels 22R, 22G, 22B for red, green and blue colors, respectively, and then again synthesized by a dichroic prism 23 and projected by a projection lens 24. A narrow band green filter 31G is mounted detachably on the optical path of the green light and operation of the circuit in the device is switched by attaching or detaching the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal display device for displaying an image by projecting image light on a screen.

[0002]

2. Description of the Related Art Conventionally, a projection type liquid crystal display device generates white light from a white light source and converts the white light into three colors of red (R), green (G), and blue (B) using a dichroic mirror. The liquid crystal panel divides the light into three colors, irradiates the liquid crystal panel with the three colors, controls the light transmittance with the liquid crystal panel, synthesizes the three colors with a dichroic prism, and magnifies the synthesized light with a projection lens to screen or the like. Had been projected. Here, in a conventional general liquid crystal display device, the setting of the color reproducibility is fixed, and the image quality is set with priority on brightness, so that the color reproducibility is poor. In response to this, Japanese Patent Application Laid-Open No. 3-103
No. 842 discloses a projection-type liquid crystal display device in which a narrow-band green filter is provided in an optical path of green light to improve color purity. When a large image is projected as described above, the brightness is insufficient and the projected image is dark, which is inconvenient.

In the conventional liquid crystal display device, when the image quality is set with priority on brightness, the noise of a cooling fan that cools the device is at a level of concern when the brightness is pursued.

[0004]

In the above-mentioned conventional projection type liquid crystal display device, when image quality is set with priority on brightness,
The color reproducibility was poor, and the noise of the cooling fan for cooling the display device was increasing. On the other hand, when a narrow band green filter is provided in the optical path of green light to improve color purity, when a large image is projected, the brightness is insufficient and a dark projected image is disadvantageous.

Accordingly, an object of the present invention is to provide a projection type liquid crystal display device capable of switching a projected image between a state of giving priority to brightness and a state of giving priority to color purity.

[0006]

The present invention provides a white light source,
Spectral means for dispersing the light of the white light source into red, green, and blue light, and liquid crystal panels for red, green, and blue respectively arranged on the optical path of the red, green, and blue light separated by the dispersive means Synthesizing means for synthesizing the red, green, and blue lights respectively passing through the red, green, and blue liquid crystal panels, and projection optical means for projecting the light synthesized by the synthesizing means,
A narrow-band green filter that is detachably inserted on the optical path of the green light and cuts low-frequency and high-frequency components of the wavelength band of the green light, and switches an operation mode according to attachment and detachment of the green filter. And a mode switching means.

According to the above configuration, the projected image can be switched between the state of giving priority to brightness and the state of giving priority to color purity by detachably inserting the green filter into the optical path of green light.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a projection type liquid crystal display device according to the present invention.

In FIG. 1, reference numeral 11 denotes a projection type liquid crystal display device. A white light source unit 13 and ultraviolet light of the light from the white light source unit 13 are provided in a housing 12 of the projection type liquid crystal display device 11. -IR filter 1 that absorbs infrared rays
4, a dichroic mirror 15R that reflects red and transmits green and blue, a dichroic mirror 15G that reflects green and transmits blue, and relay lenses 16, 17 and reflecting mirrors 18, 19, and 20 are arranged. . The light split by the light splitting means is applied to red, green, and blue liquid crystal panels 22R, 22G, and 22B through red, green, and blue condensing lenses 21R, 21G, and 21B. , 22G, and 22B are combined by a dichroic prism 23 and projected through a projection lens 24 of projection optical means.

Further, the projection type liquid crystal display device 11 has a narrow band green filter 31G for cutting a low band and a high band in a wavelength band of the green light, which can be detachably mounted on an optical path of the green light. A mode changeover switch 32 for detecting the attachment / detachment is provided.

The white light source unit 13 is composed of a high-luminance and high-efficiency lamp (hereinafter, referred to as an HID lamp) 41 of a white light source and a parabolic reflector 42, and a parabolic reflector 42 is arranged behind the HID lamp 41. A UV-IR filter 14 is arranged in front.

The parabolic reflector 42 is an HID lamp 4
The illumination light from No. 1 is reflected toward the UV-IR filter 14. The illumination light reflected from the parabolic reflector 42 is removed as ultraviolet light and infrared light by the UV-IR filter 14, and is emitted as parallel light.

On the central axis 43 of the light emitted from the UV-IR filter 14, a dichroic mirror 15R is arranged at an angle of 45 degrees with respect to the central axis 43.

The dichroic mirror 15R reflects only red light and transmits other color lights. On the central axis 44 of the red light reflected by the dichroic mirror 15R, a reflecting mirror 18 is disposed at an angle of 45 degrees with respect to this central axis.
Reflects red light from R. A red condensing lens 21R and a red liquid crystal panel 22R are arranged on a central axis 45 of the light reflected by the reflection mirror 18, and the red liquid crystal panel 22R transmits through the incident side and the outgoing side. Polarizers whose axes or absorption axes differ from each other by 90 degrees are placed.

The red light reflected by the reflection mirror 18 is condensed by a condensing lens 21R for red, polarized by an incident-side polarizing plate, and is incident on a liquid crystal panel 22R for red.

On the other hand, on the central axis 46 of the illumination light transmitted through the dichroic mirror 15R, 45
A dichroic mirror 15G is disposed at an angle. The dichroic mirror 15G reflects only green light and transmits other color light (blue light). On the central axis 47 of the green light reflected by the dichroic mirror 15G, a condensing lens 21G for green, a green filter 31G, and a liquid crystal panel 22G for green are arranged. The liquid crystal panel 22G for green has polarizing plates whose transmission axes or absorption axes differ from each other by 90 degrees on the incident side and the emission side.

The green light reflected by the dichroic mirror 15G is condensed by a condensing lens 21G for green, and low and high frequency components in a green wavelength band are cut by a green filter 31G. The light is polarized and enters the green liquid crystal panel 22G.

On the center axis 48 of the blue light transmitted through the dichroic mirror 15G, the relay lens 16 and the reflection mirror 19 are arranged at an angle of 45 degrees with respect to the center axis 48. The blue light transmitted through the dichroic mirror 15G is reflected by the reflection mirror 19. Reflection mirror 19
On the central axis 49 of the blue light reflected by the
7 and the reflection mirror 20 inclined 45 degrees with respect to the central axis 49.
Is arranged. The reflection mirror 20 is a reflection mirror 19.
And reflects the blue light transmitted through the relay lens 17. A blue condensing lens 21B and a blue liquid crystal panel 22B are arranged on the central axis 50 of the blue light reflected by the reflection mirror 20. Liquid crystal panel 22B for blue
Means that the transmission axis or absorption axis is 9
Polarizers that differ by 0 degrees are placed.

The blue light reflected by the reflection mirror 20 is condensed by a condensing lens 21B for blue light, is polarized by an incident side polarizing plate, and is incident on a liquid crystal panel 22B for blue light.

Liquid crystal panels 22R, 22 for red, green, and blue
G and 22B are controlled in transmittance by a drive voltage generated based on a video signal, and emit red, green, and blue video lights, respectively.

The dichroic prism 23 has red, green,
The light emitted from the blue liquid crystal panels 22R, 22G, and 22B is combined to emit color image light. Projection lens 2
Reference numeral 4 enlarges the image light from the dichroic prism 23 and projects it on a screen.

In this embodiment, since the blue light has a long optical path length, optical correction is performed by the light condensing function and the image forming function of the relay lenses 16 and 17.

In the present embodiment, the green filter 3
1G is a glass filter containing a pigment or a dye, and can collect light with high color purity.
Further, in the present embodiment, the switch 32 is turned on by inserting the green filter 31, and the light amount of the white light source, the number of rotations of the cooling fan, and the drive condition of the liquid crystal panel are changed.

FIG. 2 is a block diagram showing a circuit in the liquid crystal display device.

In FIG. 2, a mode change switch 3
2 is turned on and off by attaching and detaching the green filter 31G.
Feed to 1. The microcomputer 71 switches between the home theater mode and the presentation mode based on the on / off state of the mode changeover switch 32. In accordance with the switched mode, the drive circuits 72R, 72G, 72B, Light source power supply circuit 73
And the fan speed control circuit 74 is controlled.

Drive circuits 72R, 72 for red, green, and blue
2G and 72B are controlled by the microcomputer 71 to control the liquid crystal panels 22R, 22G and 22 for red, green and blue, respectively.
Drive B is performed.

The light source power supply circuit 73 includes a microcomputer 71
Is supplied to the HID lamp 41 based on the control of (1).

The fan speed control circuit 74 includes a microcomputer 7
1 (in particular, the white light source unit 1)
3) The rotation of the cooling fan 75 for cooling is controlled.

The operation of such an embodiment will be described with reference to FIGS.

FIG. 3 shows the wavelength characteristics of the incident light on the liquid crystal panel 22G for green color, and FIG. 4 shows the gamma characteristics of the drive circuits 72R, 72B, 72G of the liquid crystal panel.

The mode switch 32 is turned on when the green filter 31G is inserted, and the green filter 3G is turned on.
Turns off when 1G is removed.

When the green filter 31G is removed from the device 11, the wavelength characteristic of the incident light on the liquid crystal panel 22G for green has a wide band transmittance as shown by A1 in FIG. 3, and the mode switch 32 is turned off. The microcomputer 71 selects the presentation mode. As a result, the drive circuits 72 for red, green, and blue
R, 72G, and 72B are liquid crystal panels 2 for red, green, and blue.
The presentation mode drive is performed for the 2R, 22G, and 22B. Thereby, the drive circuit 72
The gamma characteristics of R, 72B, and 72G correspond to the characteristic A shown in FIG.
It becomes 2. The light source power supply circuit 73 supplies a power supply voltage to the HID lamp 41 to emit light at the maximum level. Further, the fan speed control circuit 74 drives the cooling fan 75 to rotate at high speed.

As a result, it is possible to obtain image quality giving priority to brightness as a projected image of the projection type liquid crystal display device 11, which is suitable for a case where a relatively large image is to be projected, such as for a presentation or a classroom.

When attached to the green filter 31G device 11, the wavelength characteristic of the incident light on the green liquid crystal panel 22G is the same as that of the narrow band where the low and high bands are cut as shown by B1 in FIG. Become. On the other hand, the mode changeover switch 32 is turned off, and the microcomputer 71 selects the home theater mode and transfers the preset color purity priority data to the drive circuits 72 for red, green, and blue.
R, 72G, and 72B, and drives the liquid crystal panels 22R, 22G, and 22B for red, green, and blue with priority on color purity. The gamma characteristics of the drive circuits 72R, 72B, and 72G are in the state of B2 shown in FIG. 3, and the transmittance is increased at a portion where the panel transfer voltage is low, and the transmittance is reduced at a portion where the panel transfer voltage is high. This allows
White peaks can be suppressed, and the black side can have rich characteristics and rich gradation expression. Further, the microcomputer 22 controls the light source power supply circuit 73 to reduce the amount of light of the white light source (HID lamp) 41, and controls the fan rotation speed control circuit 31 to reduce the rotation speed of the cooling fan 73 and reduce the cooling fan speed. 32
Reduce noise.

This makes it possible to obtain an image projected on the projection type liquid crystal display device 11 with high color purity and good color balance, and furthermore, it is possible to reduce the noise of the cooling fan 32. This is suitable for displaying images in a quiet viewing environment.

As described above, according to the present embodiment,
A narrow-band green filter 31G is detachably attached to the light path of the green light, and in conjunction therewith, the light amount of the HID lamp 41, the number of rotations of the cooling fan 75, the liquid crystal panel 22 for red, green, and blue.
By changing the drive conditions of R, 22G, and 22B, green light with high color purity can be obtained and an image with good color reproducibility can be displayed. Also, for home theater applications, the brightness of the viewing environment does not need to be as bright as for presentation applications, so that a white light source (HID lamp) 41
, The fan noise can be reduced, and a quiet viewing environment can be obtained. In addition, in the present embodiment, since the green filter 31G is detachable, when no filter is inserted, it can be used for a presentation use in which brightness is prioritized similarly to the related art. In this way, the projected image can be switched between the state of giving priority to brightness and the state of giving priority to color purity,
Video display suitable for various uses can be performed.

In the embodiment shown in FIG. 1, the cooling fan 7
5 is configured to cool the entire inside of the housing 12,
The cooling fan 72 may be configured to cool the HID lamp 41 or the liquid crystal panels 22R, 22G, and 22B for red, green, and blue.

Further, in the embodiment of FIG. 1, the microcomputer 71 of the control circuit interlocks with the HID
The amount of light of the lamp 41, the number of rotations of the cooling fan 75, red, green,
Although all the settings of the blue liquid crystal panels 22R, 22G, and 22B are changed, the microcomputer 71 determines the light amount of the HID lamp 41, the rotation speed of the cooling fan 75, the red, green, and blue liquid crystal panels 22R, 22R. The drive setting of at least one of 22G and 22B may be changed.

[0040]

As described above, according to the present invention, a projected image can be switched between a state where priority is given to brightness and a state where priority is given to color purity, and image display suitable for various uses can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a projection type liquid crystal display device according to the present invention.

FIG. 2 is a block diagram showing a circuit in the projection type liquid crystal display device of FIG.

FIG. 3 is a graph showing wavelength characteristics of incident light of the green liquid crystal panel of FIG. 2;

FIG. 4 is a graph showing gamma characteristics of the liquid crystal drive circuit of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Projection liquid crystal display device 12 Housing 13 White light source part 14 UV-IR filter 15R, 15G Dichroic mirror 18, 19, 20 Reflection mirror 22R, 22G, 22B Liquid crystal panel for red, green, and blue 23 Dichroic prism 24 Projection lens 31G Green filter 32 Mode switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 9/30 H04N 9/30 F term (Reference) 2H088 EA14 EA15 HA12 HA13 HA21 HA24 HA28 MA05 MA06 2H091 FA02Z FA05X FA05Z FA14X FA26X FA26Z FA41Z FD24 FD26 LA15 LA16 MA07 5C060 BC01 EA01 HC10 HC11 HC12 HC14 HC19 HD05 JA11 JA18 JB06

Claims (2)

[Claims] 1. A white light source, spectral means for separating the light of the white light source into red, green, and blue light, and the spectral means are arranged on the optical paths of the separated red, green, and blue light, respectively. A liquid crystal panel for red, green, and blue, a synthesizing means for synthesizing the red, green, and blue light passing through the liquid crystal panels for red, green, and blue, respectively, and projecting the light synthesized by the synthesizing means. A projection optical unit, a narrow-band green filter that is removably inserted on the optical path of the green light and cuts low- and high-frequency components of a wavelength band of the green light, and And a mode switching means for switching an operation mode by using a projection type liquid crystal display device. 2. The method according to claim 1, wherein the mode switching unit sets at least one of a light amount of the white light source, a rotation speed of a cooling fan for cooling the inside of the device, and a drive amount of the red, green, and blue liquid crystal panels. 2. The projection-type liquid crystal display device according to claim 1, wherein when the green filter is inserted, the operation mode is switched to an operation mode that emphasizes color reproducibility.