JPS62100732A - lcd dimmer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light control device for a television camera.

[Summary of the invention]

The present invention is placed on the optical path of an imaging element of a television camera,
I In a liquid crystal light control device that adjusts the amount of light reaching the most image element, the first polarizing plate has a transmission axis that is concentric or spiral shaped with the optical axis as the center, and the second polarizing plate has a transmission axis that is concentric or spiral shaped. , the transmission axis is radial with the optical axis as the center, and the upper glass and the second polarizing plate are rubbed in the direction of the transmission axis of the first polarizing plate between the first polarizing plate and the second polarizing plate. Image shading is reduced by disposing a liquid crystal panel in which a liquid crystal material is sealed with a lower glass rubbed in the direction of the transmission axis.

[Conventional technology]

A conceptual diagram of a conventional liquid crystal light control device is shown in FIG.

3 is the first polarizing plate, and the polarized light transmission axis 5 is in a constant linear direction. 2 is a second polarizing plate, polarization 12iii
1! The axis is a constant linear direction that is substantially orthogonal to the polarized light transmission axis 5 of the first polarizing plate 1. 3 is an upper glass 4 and a lower glass, and a liquid crystal material is sealed in the gap thereof to form a liquid crystal panel.

FIG. 5 is a conceptual diagram when the liquid crystal is turned off.

7 is a liquid crystal molecule sandwiched between an upper glass 3 and a lower glass 4. 8 is the rubbing direction applied to the upper and lower glasses.

Rubbing refers to rubbing the glass surface with a soft cloth in order to give directionality to liquid crystal molecules.Rubbing direction 8
is parallel to the polarized light transmission axis 5 of the first polarizing plate 1 in FIG. After being polarized by the first polarizing plate 1 , the light is rotated by 90° by the liquid crystal molecules 7 and passes through the second polarizing plate 2 . Therefore, when the liquid crystal is OFF, light is transmitted.

FIG. 6 shows a conceptual diagram when the liquid crystal is turned on. At this time, the liquid crystal molecules 7 stand upright with respect to the upper and lower glasses 3.4, so
The rotation of light is lost and no light is transmitted.

As mentioned above, the liquid crystal dimmer is
The amount of transmitted light is adjusted by utilizing the change in light transmittance up to the N time.

[Problems and Objectives to be Solved by the Invention] However, the above-mentioned prior art has the following problems. The light that enters the liquid crystal light control device is not limited to the normal direction to the glass, and may also be incident obliquely. FIG. 7 shows a conceptual diagram of the angle of incidence.

9 is incident light.

Looking at the transmittance of the liquid crystal light control device in all directions for incident light tilted by ψ from the normal direction, we find that
As shown in the figure, the dependence of transmittance on the conventional incident direction, there is a large difference depending on the direction. This is a problem in that when a video signal from a television camera is input to a monitor television and viewed as 11 images, a portion of the screen becomes dark (hereinafter referred to as shading). This incident direction dependence occurs in a certain direction from the rubbing direction 8 of the upper glass 3 and lower glass 4.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and an object of the present invention is to provide a liquid crystal light control device that can provide images with less shading.

Means for Solving Problem c] The liquid crystal light control device of the present invention includes a first polarizing plate having a transmission axis concentrically or spirally with the optical axis as the center; A second polarizing plate having a radial transmission axis is located between the first polarizing plate and the second polarizing plate, the upper glass is rubbed in the direction of the transmission axis of the first polarizing plate, and the lower glass is rubbed in the direction of the transmission axis of the first polarizing plate. The liquid crystal panel is arranged in the transmission axis direction of the polarizing plate, and includes a liquid crystal panel in which a liquid crystal material is sealed between an upper glass and a lower glass.

[Effect]

The way in which light enters a television camera is that it enters in concentric circles around the optical axis of the lens, so according to the above configuration of the present invention, the rubbing direction of the upper and lower panels for the incident light in each direction can be adjusted. Since is constant, the transmittance of the liquid crystal light control device for incident light in each direction is constant, and shading does not occur.

(Example) FIG. 1 is a sectional view of a liquid crystal light control device in an example of the present invention, in which 1 is a first polarizing plate, which is arranged concentrically or spirally around the optical axis. 2 is a second polarizing plate, which has a transmission axis radially centered on the optical axis. 3 is an upper glass, on which a transparent electrode is arranged on the surface facing the liquid crystal 10; It is rubbed in the direction of the transmission axis of the first polarizing plate 1. 4 is a lower glass, which has a transparent electrode on the surface facing the liquid crystal 10, and is rubbed in the direction of the transmission axis of the second polarizing plate 2. 10 is a liquid crystal, which is sandwiched between an upper glass 3 and a lower glass 4, and whose molecular arrangement changes by applying an electric field between the transparent electrodes of the upper and lower glasses. Twist type liquid crystal (TN type liquid crystal) used for displaying characters on computers and calculators
is typical. 11 is the liquid crystal 10 with upper and lower glass 3.4
This is a sealing material that is inserted between the two.

FIG. 2 is a schematic diagram of the first polarizing plate. FIG. 3 is a schematic diagram of the second polarizing plate.

Next, the operation of this embodiment will be explained. As mentioned above, light enters the television camera in concentric circles centered on the optical axis of the lens. Further, the transmittance of the liquid crystal light control device depending on the incident direction of light is determined by the angle with the rubbing direction 8 of the upper and lower glasses 3.4. According to this embodiment,
The relationship between the incident direction of light and the rubbing direction of the upper and lower panels 3.4 (or the transmission axis direction of the first and second polarizing plates) is such that the direction is tilted by a certain angle ψ from the normal direction with the lens optical axis as the center. A constant relationship can be obtained for incident light in any direction. (Refer to Figure 7, a conceptual diagram of the angle of incidence.) In other words, there is no difference in transmittance depending on the direction of incidence at the center of the optical axis. This situation is shown in FIG. 9, which shows the dependence of transmittance on the direction of incidence.

C. Effects of the Invention] As described above, according to the present invention, centering on the optical axis,
a first polarizing plate with concentric or spiral transmission axes;
A second polarizing plate having a transmission axis radially centered around the optical axis, an upper glass that is rubbed in the direction of the transmission axis of the first polarizing plate, and a top glass that is rubbed in the direction of the transmission axis of the second polarizing plate. This is a liquid crystal light control device that uses a lower glass and seals liquid crystal material between the upper and lower glasses, so the transmittance depending on the direction of light incidence is constant in any direction, so images without shading can be created. is obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the liquid crystal light control device of the present invention. Figure 2 is a schematic diagram of the first polarizing plate. Figure 3 is a schematic diagram of the second polarizing plate. FIG. 4 is a conceptual diagram of a conventional liquid crystal light control device. Figure 5 is a conceptual diagram when the liquid crystal is turned off. Figure 6 is a conceptual diagram when the liquid crystal is turned on. Figure 7 is a conceptual diagram of the angle of incidence. FIG. 8 is a diagram showing the dependence of the transmittance on the incident direction according to the conventional method. FIG. 9 is a diagram showing the dependence of the transmittance on the incident direction according to the present invention. l...First polarizing plate 2...Second polarizing plate 3...Upper glass 4...Lower glass 5...Polarized light transmission axis 6...Polarized light transmission axis 7...Liquid crystal molecules 8...Rubbing direction 9...More than incident light

Claims (1)

[Claims] (1) a) In a liquid crystal light control device that is located on the optical path of an image sensor and adjusts the amount of light reaching the image sensor, b) a first light control device that has a transmission axis concentrically or spirally around the optical axis; Polarizer. c) A second polarizing plate having a transmission axis radial around the optical axis. d) Located between the first polarizing plate and the second polarizing plate, the upper glass is rubbed in the transmission axis direction of the first polarizing plate, and the lower glass is rubbed in the transmission axis direction of the second polarizing plate. 1. A liquid crystal light control device comprising a liquid crystal panel which is rubbed in the direction of the glass and has a liquid crystal material sealed between the upper glass and the lower glass.