JPH08201736A - Automatic light shielding spectacles - Google Patents

Abstract

PURPOSE: To automatically shield light when the light having higher intensity than a specified level is outputted and to protect eyes from the strong light by providing a photosensor generating an output signal when the intensity of incident light exceeds the specified level higher than ambient light and a control circuit receiving the output signal and generating control voltage so that a light shutter means decreases passing light. CONSTITUTION: The photosensor 32 is provided with a photodetector detecting the quantity of incident light on a photodetector part and supplies an output pulse signal to the control circuit 30 in the case the light quantity detected by the photodetector exceeds the specified level. When the control circuit 30 does not receive the output pulse signal from the photosensor 32, it sets liquid crystal cells 20 and 26 in a 1st control state by the control voltage so as to make the incident light pass through optical shutters 14 and 16. When the intensity of the outputted light exceeds the specified level, the photosensor 32 supplies the output pulse signal to the control circuit 30. When the control circuit 30 receives the output pulse signal, it generates the control voltage to set the liquid crystal cells 20 and 26 in a 2nd control state, so that the 1st and the 2nd light shutters 14 and 16 shield the incident light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic light blocking glasses for automatically blocking light incident on an observer's eye when light exceeding a predetermined intensity is generated.

[0002]

2. Description of the Related Art A strobe is generally used for taking photographs for commercial use in a studio. The strobe used for such shooting is
In order to take a clear picture of a subject, one or a plurality of light sources having a considerably high intensity, for example, a light source having a maximum output of 1200 W is usually used, and the intensity of the reflected light is still high. At the shooting site, photographers, assistants, etc. frequently receive such direct or reflected light from a strobe, and when they receive the reflected light, they will be dizzy and an afterimage will remain until the recovery. It may not be possible to proceed to the next procedure, and frequent intense light may cause eye strain, which may result in deterioration of visual acuity. It is conceivable to put on sunglasses in advance to avoid strong light, but it is troublesome to wear sunglasses every time it is necessary to look directly at the subject.
Therefore, an object of the present invention is to provide automatic light blocking spectacles which are normally transparent, but which automatically block passing light when light exceeding a predetermined intensity is generated.

[0003]

The automatic light-shielding glasses of the present invention include optical shutter means for passing or blocking incident light according to a control voltage, and intensity of the incident light exceeds a predetermined level higher than ambient light. And an optical sensor that produces an output signal,
It is characterized by comprising a control circuit for receiving an output signal from the optical sensor and generating a control voltage for causing the optical shutter means to reduce the passing light. According to this, when the light having the intensity higher than the predetermined level is emitted, the light can be automatically blocked and the eyes can be protected from the strong light.

[0004]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram for explaining the main structure of automatic light blocking glasses 10 of the present invention. The automatic light blocking glasses 10 have a right-eye optical shutter 14 and a left-eye optical shutter 16. The right-eye optical shutter 14 includes a first polarization filter 18, a liquid crystal cell 20 that is a first variable optical retarder, and a second polarization filter 22, which are arranged to face each other from the incident light side, and the left-eye optical shutter 16 also has the same configuration. The third polarization filter 24, the liquid crystal cell 26 that is the second variable optical retarder, and the third polarization filter 28 that are arranged are
The two optical shutters 14 and 16 form an optical shutter means. The polarization filters 18, 22, 24, and 28 are linear polarizing plates, each having a light transmission axis that allows light to pass therethrough and a light absorption axis that is orthogonal to this axis and that blocks light. Allows polarized light to pass. For example, the first and third polarization filters 18 and 24 have the vertical light transmission axis 18 respectively.
a, 24a and horizontal light absorption axes 18b, 24b, and the second and fourth polarization filters 22, 28 both have vertical light absorption axes 22a, 28a and horizontal light transmission axes 22b, 28b.

The projection of the optical axis 20a on the light transmitting surface of the liquid crystal cell 20 forms an angle of 45 degrees with respect to the vertical and horizontal axes of the polarization filters 18 and 22, and is projected onto the light transmitting surface of the liquid crystal cell 26. The optical axis 26a is projected by the polarization filters 24 and 28.
Forms a 45 degree angle with the vertical and horizontal axes of the.
The liquid crystal cells 20 and 26 are in the first control state and the second control state according to the control voltage supplied from the liquid crystal control circuit 30. In the first control state, they give a half-wave retardation to the incident light and rotate the polarization plane by 90 degrees to allow it to pass. In the second control state, the incident light does not give the retardation and passes without rotating the polarization surface. Let Therefore, in the first control state, the liquid crystal cells 20 and 26 have the polarization filter 1
The plane of polarization of the vertically polarized incident light from 8 and 24 is rotated 90 degrees, and the output light of the liquid crystal cells 20 and 26 passes through polarizing filters 22 and 28, respectively. In the second control state, the liquid crystal cells 20 and 26 do not rotate the plane of polarization of the incident light, so that the output light of the liquid crystal cells 20 and 26 are blocked by the polarization filters 22 and 28, respectively.

Optical shutters 14 and 16 used in the present invention
Requires a fast response to the control voltage.
As such a material, an optical shutter using a ferroelectric liquid crystal cell sold as Model VS2200 by Display Tech Co., USA is suitable. This liquid crystal cell has a response characteristic in which an optical delay time (0 to 10%) is 35 μsec, an optical rise time (10 to 90%) is 35 μsec, and an optical fall time is 35 μsec. This ferroelectric liquid crystal cell switches to the first or second control state, respectively, by selecting the control voltage to + 5V or -5V, for example, and consumes less power.

The strobe 12 emits light when the operator turns on the switch 34. FIG. 2 is a graph showing the time-dependent strobe light intensity when a general strobe is emitted. After turning on the switch 34, about 0.
The light intensity reaches a peak after 5 ms, and returns to 0 after about 1.0 ms.

The optical sensor 32 outputs a pulse signal to the control circuit 30 when a light receiving element such as a photodiode for detecting the amount of light incident on the light receiving portion and the light amount detected by the light receiving element exceeds a predetermined level T. Including a circuit to supply to. The predetermined level T detected by the optical sensor 32 is higher than the amount of normal room light in the shooting studio, and is set to, for example, 2 to 3 times that.

FIG. 3 is a graph showing the intensity of light passing through the automatic light blocking glasses of the present invention. When the control circuit 30 does not receive the output pulse signal from the optical sensor 32, the control voltage causes the liquid crystal cells 20 and 26 to be in the first control state, and the optical shutters 14 and 16 allow incident light to pass therethrough. When the operator turns on the switch 34 to cause the strobe 12 to emit light and the intensity of the output light exceeds a predetermined level T set by the optical sensor 32, the optical sensor 32 supplies an output pulse signal to the control circuit 30. When the control circuit 30 receives the output pulse signal,
A control voltage is generated to bring the liquid crystal cells 20 and 26 into the second control state. When the liquid crystal cells 20 and 26 are in the second control state, the first and second optical shutters 14 and 16 block the incident light. When the above-mentioned VS2200 type liquid crystal cell manufactured by Display Tech Co., Ltd. is used, the contrast ratio between the light passing state and the light blocking state is 500: 1 to 1000: 1. When the intensity of the output light of the optical strobe 12 reaches a peak and then decreases and becomes lower than a predetermined level T, the optical sensor 32 stops the output of the output pulse signal. In response to this, the control circuit 30 brings the liquid crystal cells 20 and 26 into the first control state, and the first and second optical shutters 14 and 16 allow the incident light to pass therethrough again. As described above, the automatic light-shielding glasses according to the present invention automatically shield the light when the light having the intensity higher than the predetermined level is emitted, so that the eyes can be protected from the strong light.

FIG. 4 is a diagram showing an example of the appearance of the automatic light blocking glasses of the present invention. In each of the right-eye optical shutter 14 and the left-eye optical shutter 16, two polarizing filters and one liquid crystal cell interposed between them are overlapped with each other and arranged in a frame 36 in which lenses are arranged with ordinary glasses. To be done.
The optical sensor 32 is attached to the frame 36 at the center of the optical shutters 14 and 16 in order to favorably detect the light in the direction in which the face is directed. The control circuit 30 is attached to, for example, an appropriate position of the temple of eyeglasses. The frame and temple of the spectacles are pipe-shaped, and lead wires connecting the photosensor 32, the control circuit 30, and the liquid crystal cells 20 and 26 are passed through the pipe.

Although one embodiment of the present invention has been described above, it will be apparent to those skilled in the art that various modifications can be made without departing from the gist of the present invention. For example, in each of the optical shutters 14 and 16, the two polarizing filters are arranged so that the light transmission axes thereof are at right angles to each other, but when the optical sensor generates an output pulse, the liquid crystal cells 20 and 26 are arranged.
By changing the control circuit 30 so as to bring the first control state into the first control state, similar results can be obtained even when the control circuits 30 are parallel to each other.
Further, the relationship between the two polarizing filters and the optical axis of the liquid crystal cell between them does not need to be strictly accurate, and even if it is somewhat inaccurate, the intensity of light leaked by it is within an allowable range,
For example, there is no problem if it is about ambient light. Further, as shown in FIG. 5, the optical shutter means is used for the right and left eye optical shutters 1.
It may be goggles-type glasses in which 4 and 16 are integrated.

[0012]

According to the automatic light blocking spectacles of the present invention, when the light having the intensity higher than the predetermined level is emitted, the light is automatically blocked, so that the eyes can be protected from the strong light. This is very suitable for use in a photography studio, where the high-intensity strobe is frequently exposed to high intensity light.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of automatic light blocking glasses of the present invention.

FIG. 2 is a graph showing a flash emission characteristic.

FIG. 3 is a diagram for explaining light blocking by the glasses of FIG.

FIG. 4 is a diagram showing an appearance of the glasses of FIG.

5 is a diagram showing another embodiment of the external appearance of the glasses of FIG.

[Explanation of symbols]

 14 Optical shutter for right eye 16 Optical shutter for left eye 30 Control circuit 32 Optical sensor

Claims (1)

[Claims] 1. An optical shutter means for passing or blocking an incident light as it is according to a control voltage, and an intensity of the incident light exceeding a predetermined level higher than ambient light,
An optical sensor for generating an output signal; and a control circuit for receiving the output signal from the optical sensor and generating the control voltage for causing the optical shutter means to block the passing light. Automatic light blocking glasses to.