JPH09222602A - Liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device with which the setting of the color temp. of a liquid crystal panel and the change of the setting are possible. SOLUTION: Images are displayed by irradiating the liquid crystal panel 1A by an irradiation device 6A having a first irradiation means 7 having light emission spectra of three primary colors and a second irradiation means 8 having light emission spectra of single color or two colors among the three primary colors. The liquid crystal panel 1A is irradiated with the first irradiation means 7 and the second irradiation means 8 in such a manner, by which the color temp. of the liquid crystal panel 1A is set. Further, the liquid quantity for irradiation of the second irradiation means 8 is changed by a light quantity changing means, by which the setting of the color temp. of the liquid crystal panel 1A is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device for illuminating a liquid crystal panel from the back side to display an image, and more particularly to an illuminating device for illuminating a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, there has been a liquid crystal device which displays an image by illuminating a liquid crystal panel from the back with an illuminating device. One example of such a liquid crystal device is a color liquid crystal finder of a video tape recorder with a built-in camera. .

FIG. 16 is a view showing the basic structure of such a color liquid crystal finder. In FIG. 16, 1 is a transmissive and normally white type TFT active liquid crystal display panel (hereinafter referred to as a liquid crystal panel), 2 Is an eyepiece optical lens for magnifying the liquid crystal panel 1, and 3 is a backlight which is an irradiation means for irradiating the liquid crystal panel 1 from the back side,
Reference numeral 4 is a diffusion plate, and 5 is a reflection plate for condensing the light from the backlight 3 on the liquid crystal panel 1 on the front surface. The backlight 3, the diffusion plate 4, and the reflection plate 5 constitute an irradiation device 6.

Here, as shown in FIG. 17, the liquid crystal panel 1 has three color filters of red (R), green (G), and blue (B) alternately arranged two-dimensionally. It is equipped with a filter part that did, red from this filter part,
Each dot that emits green and blue light is a pixel cell of the liquid crystal panel. The pixel cell is minute and has a size that does not hinder the image display of the liquid crystal panel.

By the way, since the characteristics of the drive voltage and the transmittance of each pixel are as shown in FIG. 18, when displaying black on the liquid crystal panel 1, the pixels of each color are shown in FIG. As shown, a voltage of 80 to 100 (%) of the driving voltage is applied. Further, when displaying white, the driving voltage of each color pixel is set to 0 to maximize the transmittance of the liquid crystal panel, thereby maximizing the white light of the backlight 3 and transmitting all three primary colors. I will let you.

[0006]

In such a conventional liquid crystal device, the color temperature of the white image of the liquid crystal panel 1 is the color temperature of the backlight 3 and the spectral transmission characteristics of the liquid crystal panel 1 in the normally white state. Is determined by the overall characteristics of. Therefore, when the driving voltage of the three-color pixels of the liquid crystal panel 1 is 0 (V) or close to 0 (V), that is, in the high-luminance image, the color temperature is set while driving the liquid crystal panel 1 while maintaining the gradation. It is extremely difficult to do by.

When it becomes difficult to set the color temperature in this way, there is a problem that it is not possible to satisfy various preferences of the photographer regarding the color temperature and the white balance particularly during white display. Further, there is a problem that the color temperature and white balance corresponding to the color temperature of the surrounding environment of the liquid crystal device cannot be adjusted.

Therefore, the present invention has been made in order to solve such a problem, and an object thereof is to provide a liquid crystal device capable of setting the color temperature of a liquid crystal panel. Another object of the present invention is to provide a liquid crystal device capable of changing the color temperature setting of the liquid crystal panel.

[0009]

According to the present invention, in a liquid crystal device in which a liquid crystal panel is illuminated from the back by an illuminating device to display an image, the illuminating device includes first illuminating means for illuminating the liquid crystal panel. Second irradiation means for irradiating the liquid crystal panel and setting the color temperature of the liquid crystal panel are provided.

Further, in the invention, the first irradiating means has emission spectra of three primary colors, and the second irradiating means has the above-mentioned three.
It is characterized by having an emission spectrum of a single color or two colors of the primary colors.

Further, the present invention is characterized in that the first and second irradiation means are fluorescent lamps.

Further, the present invention is characterized in that one of the first and second irradiation means is a flat-emission fluorescent lamp, and the other is arranged below the flat-emission fluorescent lamp. is there.

Further, the present invention is characterized in that the flat emission type fluorescent lamp is provided with a light amount changing means, and the color temperature setting can be changed by changing the irradiation light amount by the light amount changing means. is there.

Further, the present invention is characterized in that one of the first and second irradiating means is the planar emission type fluorescent lamp and the other is a light emitting diode.

The present invention is also characterized in that one of the first and second irradiating means is the planar light emitting type fluorescent lamp and the other is an electroluminescent light emitting body.

Further, the present invention is characterized in that one of the first and second irradiating means is the plane emission type fluorescent lamp and the other is a colored light bulb.

The present invention is also characterized in that one of the first and second irradiating means is the planar light emitting type fluorescent lamp and the other one is various discharge tube type light emitting bodies.

The present invention is also characterized in that the liquid crystal panel is a transmissive type and a normally white type.

Further, with this structure, the irradiation device having the first irradiation means having the emission spectra of the three primary colors and the second irradiation means having the emission spectrum of a single color or two colors of the three primary colors is used as a liquid crystal panel. Can be illuminated from the back to display an image. Further, by irradiating the liquid crystal panel with the first irradiating means and the second irradiating means in this way, the color temperature of the liquid crystal panel can be set. Further, the color temperature setting of the liquid crystal panel can be changed by changing the irradiation light quantity of the second irradiation means by the light quantity changing means.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic structure of a color liquid crystal finder portion of a camera-integrated VTR which is an example of a liquid crystal device according to a first embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 16 indicate the same or corresponding parts.

In the figure, 1A is a transmissive and normally white color liquid crystal panel, and 7 and 8 are first fluorescent lamps and second irradiation which are first irradiation means for irradiating the color liquid crystal panel 1A from the back side. It is a second fluorescent lamp which is a means. Here, the color liquid crystal panel 1A is driven by an active matrix driving method (TFT), and red, green, and blue color filters are arranged for each pixel (see FIG. 17). The spectral characteristics of this color filter are as shown in FIG.

A pixel transistor 16 is connected to each pixel 9 of the color liquid crystal panel 1A as shown in FIG. 3, and the video signal applied to the X electrode 14 is Y.
It is adapted to be applied to each pixel 9 by turning on the pixel transistor 16 with the drive pulse applied to the electrode 15. The relationship between the video signal voltage and the light transmittance of the driving pixel in the liquid crystal panel 1, that is, the so-called voltage-transmission characteristic is the same as that in FIG.

On the other hand, the first fluorescent lamp 7 is a fluorescent lamp having an emission spectrum of three primary colors as shown in FIG. 4, and its color temperature is indicated by point A in the CIE chromaticity diagram shown in FIG. . The second fluorescent lamp 8 is a lamp having a monochromatic or bicolor emission spectrum. In this embodiment, as shown in FIG. 6, it has a monochromatic red emission spectrum, and its color temperature is indicated by point B in FIG.

By the way, these first fluorescent lamp 7 and second fluorescent lamp
Irradiation device 6 with fluorescent lamp 8, diffusing plate 4 and reflecting plate 5.
In this irradiation device 6A, the light from the first fluorescent lamp 7 and the second fluorescent lamp 8 is reflected and condensed by the reflector 5 and then diffused by the diffuser 4 to form a color liquid crystal panel. It is designed to be incident on 1A.

In the present embodiment, in the visible light range, the spectral reflectance of the reflector 5 and the spectral transmittance of the diffuser 4 are made uniform, and the white display state of the color liquid crystal panel 1A, that is, red, green, The driving video signal voltage of each pixel of three colors of blue is 0
The spectral transmission characteristics of the entire liquid crystal panel and the spectral transmission characteristics of the eyepiece optical lens 2 at the time of (V) are also made uniform.

When the color liquid crystal panel 1A is illuminated by the first fluorescent lamp 7 having the emission spectra of the three primary colors and the second fluorescent lamp 8 having the emission spectrum of a single color or two colors in this way, each pixel of the three colors is illuminated. When the white is displayed with the driving video signal voltage of 0 (V), the color temperature of the color liquid crystal panel 1A becomes red in the chromaticity diagram of FIG. 5 due to the combined spectrum of the first fluorescent lamp 7 and the second fluorescent lamp 8. It is the color temperature displayed at the enhanced point C.

That is, the conventional liquid crystal panel is controlled by irradiating the color liquid crystal panel 1A with the first fluorescent lamp 7 having the emission spectra of the three primary colors and the second fluorescent lamp 8 having the emission spectrum of a single color or two colors. Color temperature in white display (normally open) that could not be
It is possible to set the desired value. Note that with this configuration, white display (normally open state)
It is possible to set the color temperature of the video other than the following.

On the other hand, FIG. 7 shows the brightness provided in the color liquid crystal finder part which is an example of the liquid crystal device according to the second embodiment of the present invention in which the brightness of the second fluorescent lamp is made variable. It is a circuit diagram of an adjustment circuit.

In the figure, 22 is a step-up type high voltage transformer, 23 is a MOS switching transistor,
Reference numeral 24 is a variable voltage power supply which is a light quantity changing means for changing the irradiation light quantity of the second fluorescent lamp 8, and A1 is a pulse input terminal for pulse-driving the MOS switching transistor 23. When a drive pulse is input to the pulse input terminal A1, the MOS switching transistor 23 is turned on, and the source and drain of the transistor 23 are brought into conduction.

Now, let the output voltage of the variable voltage power supply 24 be E
(V), in the step-up transformer 22, the primary winding 22a formed between points A and B has a pulse period of 63.5 μm as shown in FIG.
A pulse whose voltage is E (V) is applied at s.

Here, this step-up transformer 22
Is formed between the primary winding 22a and the points b and c.
The winding ratio with the next winding 22b is set to be very large, so that a high voltage pulse having a waveform as shown in FIG. 8B is generated at the output end of the step-up transformer 22 shown by point C. Has become. Then, by applying this high-voltage pulse to the cold cathode type red fluorescent lamp 8 shown in FIG. 7, the cold cathode type red fluorescent lamp 8 discharges and emits light.

By the way, when the voltage of the variable voltage power supply 24 is increased, the primary winding 22a of the step-up transformer 22 is increased.
The switching pulse voltage applied to the secondary winding 22b rises, and the voltage generated in the secondary winding 22b accordingly rises in proportion to the turn ratio between the primary winding 22a and the secondary winding 22b.
As a result, the current flowing through the fluorescent lamp 8 increases, and the amount of light emitted from the fluorescent lamp 8 (the amount of irradiation light) increases.

By increasing the amount of light emitted from the second fluorescent lamp 8 in this way, the display color temperature of the liquid crystal panel 1 at the time of normally opening is increased from red, and the display color temperature changes from point C to point D in FIG. It came to move, and liquid crystal panel 1
Can be controlled to a low color temperature. The color temperature can be changed between points C and D in FIG. 7 by changing the output of the variable voltage power supply 24.

In this way, the setting of the color temperature can be changed by changing the irradiation light amount of the second fluorescent lamp 8 by the variable voltage power supply 24, whereby the white balance of the color liquid crystal panel 1A can be adjusted. Becomes

By the way, in the above description, the second fluorescent lamp 8 has been described as an ordinary cylindrical type, but the present invention is not limited to this, and may be a plane emission type.

FIG. 9 shows a basic structure of a color liquid crystal finder section using the flat emission type fluorescent lamp according to the third embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

In the figure, reference numeral 10 is a flat fluorescent lamp. As shown in FIG. 10, the flat fluorescent lamp 10 is generally made of a flat transparent glass 33 having a two-dimensional light emitting surface 10a. It is covered with a pair of discharge electrodes 31, 31, a phosphor 32, a gas (not shown), and the like. Incidentally, 34 is a back cover. In addition, FIG.
In the above, the diffusing plate 4 and the reflecting plate 5 are designed so that the entire surface of the liquid crystal panel 6A is irradiated with the irradiation light evenly, and the effect of the present invention is the same even if they are not provided.

Further, the positional relationship between the first fluorescent lamp 7 and the second fluorescent lamp 10 is the positional relationship shown in FIG. 11 which is a sectional view taken along the line NM of FIG. 9 in the present embodiment. That is, the reflection plate 5 of the first fluorescent lamp 7 and the reflection plate 5 ′ of the second fluorescent lamp 10 are connected to the glass 3 of the second fluorescent lamp 7.
The structure is arranged above and below 3.

By the way, in the above description, as the irradiation means, the fluorescent lamp 7 having a monochromatic color or two luminescent colors,
However, the present invention is not limited to this, and a single or a plurality of light emitting diodes having a single color or two colors of light emitting colors may be used, or an array form may be used. Light-emitting diodes are generally compact and low-priced, and can be installed relatively reasonably. The light-emitting diode lighting circuit can be lighted with a relatively simple circuit, without the need for a high-voltage transformer required for a discharge tube. Is. In the case of a light emitting diode, the brightness can be of course controlled by controlling the current.

Incidentally, FIG. 12 shows the basic structure of a color liquid crystal finder section according to the fourth embodiment of the present invention using such a light emitting diode.
Is a red light emitting diode arranged below the flat fluorescent lamp 10, and 51 is a transparent light guide formed of a transparent resin such as acrylic.

FIG. 13 is a view of the red light emitting diode 71 and the light guide body 51 as seen from the emission side of the light guide body 51, and FIG. 14 is a side view thereof. FIG.
In FIGS. 3 and 14, 51a is a reflection film, and the red light emitted from the red light emitting diode 71 is guided to the inside of the light guide body 51, then reflected by the reflection film 51a, and diffused linearly. The red light is guided to the front glass of the three-wavelength flat fluorescent lamp 10 and the diffusing plate 4, diffused by the diffusing plate 4, and applied to the liquid crystal panel 6A.

Further, instead of the fluorescent lamps 8 and 10, the same effect can be obtained with an electroluminescent light emitter which can be structurally thinly arranged, or an inexpensive and affordable colored light bulb or various discharge tube type light emitters such as a plasma discharge tube. To be

FIG. 15 shows the basic structure of a color liquid crystal finder section according to the fifth embodiment of the present invention using, for example, an electroluminescent light-emitting body. In FIG. 15, 52 is a flat fluorescent lamp 10. The red light emitted from the red electroluminescence light-emitting body disposed below, and the red light from the red electroluminescence light-emitting body 52 is guided to the front glass of the three-wavelength flat fluorescent lamp 10 and the diffusing plate 4, and then radiated to the liquid crystal panel 6A. It is supposed to be done.

[0045]

As described above, according to the present invention, 3
The color temperature of the liquid crystal panel can be set by irradiating the liquid crystal panel with the first irradiation unit having the emission spectrum of the primary color and the second irradiation unit having the emission spectrum of one of the three primary colors or two colors. . Further, the color temperature setting can be changed by changing the irradiation light quantity of the second irradiation means by the light quantity changing means. Accordingly, it is possible to satisfy various tastes of the user with respect to the color temperature and the white balance, and it is also possible to adjust the color temperature and the white balance corresponding to the color temperature of the surrounding environment of the liquid crystal device.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure of a color liquid crystal finder portion of a camera-integrated VTR which is an example of a liquid crystal device according to a first embodiment of the invention.

FIG. 2 is a diagram showing a spectral transmission characteristic of a color filter of a color liquid crystal panel which constitutes the color liquid crystal finder section.

FIG. 3 is a diagram showing a part of an equivalent circuit of the color liquid crystal panel.

FIG. 4 is a diagram showing an emission spectrum of a first fluorescent lamp that illuminates the color liquid crystal panel.

FIG. 5 is a CIE chromaticity diagram.

FIG. 6 is a diagram showing an emission spectrum of a second fluorescent lamp that illuminates the color liquid crystal panel.

FIG. 7 is a circuit diagram of a brightness adjustment circuit provided in a color liquid crystal viewfinder section according to a second embodiment of the present invention.

FIG. 8 is a diagram showing input / output signals of the brightness adjustment circuit.

FIG. 9 is a diagram showing a basic structure of a color liquid crystal finder section according to a third embodiment of the present invention.

FIG. 10 is a structural diagram of a flat fluorescent lamp provided in the color liquid crystal finder section.

11 is a sectional view taken along line NM of FIG.

FIG. 12 is a diagram showing a basic structure of a color liquid crystal finder section according to a fourth embodiment of the present invention.

FIG. 13 is a diagram of a red light emitting diode and a light guide body provided in the color liquid crystal finder section as viewed from the exit side of the light guide body.

FIG. 14 is a side sectional view of the red light emitting diode and the light guide body.

FIG. 15 is a diagram showing a basic structure of a color liquid crystal finder section according to a fifth embodiment of the present invention.

FIG. 16 is a diagram showing a basic structure of a conventional color liquid crystal finder.

FIG. 17 is a diagram showing a color filter array of the conventional color liquid crystal panel.

FIG. 18 is a chart showing drive voltage vs. transmission characteristics of a normally white liquid crystal panel.

[Explanation of symbols]

 1, 1A Liquid crystal display panel 6, 6A Irradiation device 7 First fluorescent lamp 8 Second fluorescent lamp 10 Flat fluorescent lamp 24 Variable voltage power source 52 Red electroluminescence 71 Red light emitting diode

Claims (10)

[Claims] 1. A liquid crystal device in which an image is displayed by irradiating a liquid crystal panel from the backside with an irradiating device, wherein the irradiating device irradiates the liquid crystal panel with first irradiating means, and A liquid crystal device, comprising: a second irradiation unit that sets a color temperature of the liquid crystal panel. 2. The first irradiation means has an emission spectrum of three primary colors, and the second irradiation means has an emission spectrum of a single color or two colors of the three primary colors. Liquid crystal device. 3. The liquid crystal device according to claim 1, wherein the first and second irradiation means are fluorescent lamps. 4. One of the first and second irradiation means is a flat-emission fluorescent lamp, and the other is arranged below the flat-emission fluorescent lamp. The liquid crystal device described. 5. The flat-emission fluorescent lamp is provided with a light quantity changing means, and the color temperature setting can be changed by changing the irradiation light quantity by the light quantity changing means. The liquid crystal device described. 6. The liquid crystal device according to claim 1, wherein one of the first and second irradiation means is the flat emission type fluorescent lamp and the other is a light emitting diode. 7. One of the first and second irradiation means is the planar emission type fluorescent lamp, and the other is an electroluminescence light-emitting body.
The liquid crystal device according to the above. 8. The liquid crystal device according to claim 1, wherein one of the first and second irradiation means is the planar emission type fluorescent lamp and the other is a colored light bulb. 9. The liquid crystal device according to claim 1, wherein one of the first and second irradiating means is the planar light emitting type fluorescent lamp, and the other one is various discharge tube type light emitting bodies. 10. The liquid crystal device according to claim 1, wherein the liquid crystal panel is a transmissive type and a normally white type.