JPS6321633A - Varying device for irradiation angle of projector - Google Patents

Abstract

PURPOSE:To switch an irradiation angle according to telephotography and wide-angle photography by arranging a liquid crystal member in the optical path of a projector, and applying a voltage or varying the voltage and varying the irradiation angle of light projection transmitted through the liquid crystal member. CONSTITUTION:The liquid crystal member 13 has dynamic scattering structure and also has dynamic light scattering effect when applied with an AC voltage and transparency like plane glass when not. Namely, when the liquid crystal member 13 is fed with electricity, reflected light from a reflecting mirror 12 is scattered by the member 13 and projected. The degree of the light scattering is determined by the voltage value and increases when the voltage is raised. When no electricity is fed, light emitted by a xenon discharge tube 11 is transmitted through the member 13 by the reflecting mirror 12 and projected. For the purpose, the member 13 is stopped from being fed electrically and the irradiation light is converged to obtain a normal irradiation angle, so illumination light for standard photography is obtained; when the member 13 is fed electrically, the illumination light is scattered to obtain a wide irradiation angle, thereby obtaining the illumination light for wide-angle photography.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable illumination angle device provided in various kinds of projectors, for example, projectors used as light emitters of flash discharge light emitters for photography.

``Prior Art'' A flash discharge light emitting device used for photography is configured to emit light from a xenon discharge tube through a light emitting window provided in the front of the flash discharge light emitting device.

In such a light emitter, the irradiation angle is kept constant by a reflector with an almost parabolic cross section that has a xenon discharge tube fixed inside, but the irradiation angle is changed depending on telephoto shooting or wide-angle shooting. There is a structure in which a lens is provided in front of a light emitting window.

7 and 8 are cross-sectional views showing the configuration of the light emitting part of this type of flash discharge light emitting device. In these figures, 1 is a body, 2 is a xenon discharge tube, 3 is a reflector, and 4 is a This is a lens that forms a light emitting window.

In the conventional example shown in FIG. 7, the illumination angle changing lens 5 (telephoto illumination lens or wide-angle illumination lens) is removably provided in front of the light emitting window.In the conventional example shown in FIG.
A lens 6 for changing the illumination angle is slidably provided on the body 1 so as to move forward and backward in front of the light emitting window.

``Problems to be Solved by the Invention'' In the case of the conventional example shown in FIG. There is the inconvenience of having to carry it with you.

In the conventional example shown in FIG. 8, the lens 6 for changing the illumination angle can be moved forward or backward according to telephoto shooting or wide-angle shooting, and there is no inconvenience as described above. However, since this lens 6 has a zoom structure, it is compact. This makes it difficult to equip a flash discharge light emitting device.

Furthermore, in the conventional examples shown in FIGS. 7 and 8, the illumination angle changing lenses (5, 6) cannot be used for interchangeable lenses of a compact camera.

"Means for Solving the Problems" The present invention was developed with the aim of solving the above problems, and includes disposing a liquid crystal member having a dynamic light scattering effect in the optical path of a projector. We propose a variable irradiation angle device for a projector, which is characterized by applying an electric voltage to or changing the applied electric voltage to change the irradiation angle of light transmitted through a liquid/crystal member.

Currently, small cameras have been developed that have a built-in flash discharge light emitting device and can switch the photographing lens to telephoto shooting or wide-angle shooting. You can switch the illumination angle for telephoto shooting or wide-angle shooting.

Note that the present invention is not limited to being implemented in the light emitting part of a flash discharge light emitting device, but is effective in being implemented in various types of floodlights.

``Example'' Next, examples in which the present invention is implemented as a light emitting part of a flash discharge light emitting device will be described with reference to the drawings.

FIG. 1 is a perspective view of the light emitting section, in which 11 is a xenon discharge tube, 12 is a reflecting mirror, and as is well known,
A xenon discharge tube 11 lies deep inside a reflecting mirror 12 having a substantially parabolic cross section, and its both ends are fixed to the sides of the reflecting mirror 12 via bushings.

13 is a liquid crystal member provided near the front of the reflecting mirror 12;
- This is a structure in which a liquid crystal is sandwiched between glass substrates, and an alternating current voltage is applied to the liquid crystal via electrodes. AC power supply 14 and power switch 1 illustrated
5 shows a simplified circuit for powering the liquid crystal.

There are various types of liquid crystal materials, such as guest host type (GSH) and twisted nemastic (TSN).
, phase change (P, C), dynamic scattering (D, S), etc.
The liquid crystal member 13 described above uses dynamic scattering (dynamic scattering).
It has a structure called g).

In this liquid crystal member 13, when an alternating current voltage is applied to the liquid crystal, the domains that have remained balanced and stationary due to the anisotropy of the dielectric constant and the anisotropy of the ion mobility are gradually deformed and segmented. Along with this, it has the property of scattering light incident perpendicularly to the liquid crystal molecular layer at a wide angle. This phenomenon is generally called the dynamic light scattering effect.

Further, this liquid crystal member 13 has the same light transmittance as ordinary flat glass when power is not supplied.

In this embodiment, which includes the liquid crystal member 13 as described above, when power is not supplied to the liquid crystal member 13, the light emitted from the xenon discharge tube 11 reflected by the reflecting mirror 12 is is irradiated through the liquid crystal member 13 without being equally scattered.

When power is supplied to the liquid crystal member 13, the reflected light from the reflecting mirror 12 is scattered by the liquid crystal member 13 and irradiated, as shown in FIG. 2(b). The degree of light scattering is determined by the voltage value of the power supply, and generally, as the voltage is increased, light scattering increases.

Therefore, if the power supply to the liquid crystal member 13 is cut off and the irradiated light is focused, the irradiation angle becomes the normal irradiation angle, and the illumination light passes through standard photography.If the power is supplied to the liquid crystal member 13 and the irradiated light is scattered, Since the illumination angle is the same, the illumination light is suitable for wide-angle photography.

FIG. 3 shows an embodiment in which the transparent surface of a liquid crystal member 16 similar to the liquid crystal member 13 is electrically divided into multiple parts, and the irradiation angle is changed into three stages.

In this embodiment, 16a to 16f are provided on the transparent surface of the liquid crystal member 16.
In addition to configuring the band-shaped divided portions of
The configuration is such that the changeover switch 17 is switched to each of the liquid crystals 6c and 16e, and the switch 18 is switched to supply power from the alternating current power source 14 to each of the liquid crystals at the divided portions 16b, 16d, and 16f.

That is, when the changeover switches 17 and 18 are respectively turned on to the terminal a, the liquid crystal member 16 becomes non-voltage, and the reflected light from the reflecting mirror 12 directly passes through the liquid crystal member 16 and becomes focused illumination light.

When the changeover switches 17 and 18 are turned on to the respective terminals, only the liquid crystals in the divided portions 16b, 16d, and 16f are supplied with power.
The reflected light of the reflecting mirror 12 that passes through these divided portions is scattered, and the reflected light that passes through the divided portions 16a, 16C1, and 16e is not subjected to the light scattering effect.

Therefore, the illumination light is a combination of focused light and scattered light.

When the changeover switches 17 and 18 are respectively turned on to the terminals C, the liquid crystals of the respective divided portions are supplied with power, and all the reflected light from the reflecting mirror 12 is scattered to become irradiated light with a wide irradiation angle.

Therefore, the changeover switches 17 and 18 are connected to terminal a to provide illumination light suitable for telephoto shooting, to terminal A to emit illumination light for standard photography, and to terminal C to emit illumination light for wide-angle photography. be able to.

FIG. 4 shows an embodiment in which the power supply voltage applied to the liquid crystal member 13 is continuously changed using a potentiometer 19.

The light scattering of the liquid crystal member 13 increases as the applied AC voltage increases, and the relationship between the diffusion rate and the AC voltage has characteristics as shown in FIG.

Therefore, by continuously changing the power supply voltage as in this embodiment, the illumination light can be changed steplessly from the focused state shown in Fig. 2(a) to the light scattering state shown in Fig. 2(b). It can be changed. As a result, there are practical benefits such as being able to change the illumination light in accordance with the zoom lens of the camera.

FIG. 6 shows an embodiment in which illumination light is obtained by combining a liquid crystal member 20 having a divided portion similar to the liquid crystal member 16 described above and an optical member 21 such as a lens or prism.

In this embodiment, various variations of illumination light can be obtained by supplying power to the liquid crystal member 20 and cutting off the power supply.

As shown in the above embodiment, the present invention allows the illumination angle to be changed with a simple configuration, and when performing flash photography using a photographing lens with a fixed angle of view, the aperture is opened and the illumination angle is changed at short distances. When photographing, overexposure occurs, but since the illumination angle variable device of the present invention can reduce illumination light by light scattering, this problem can also be addressed.

Note that exposure factors such as film sensitivity can also be dealt with in the same way.

In addition, in the embodiment shown in FIG. 4, the divided portions are provided in a striped pattern, but these divided portions may be configured in accordance with the needs of the light distribution characteristics, such as a base pattern mosaic or a random pattern. .

In the above embodiment, the configuration is such that an AC voltage is applied to the liquid crystal member by an AC type #14, but in reality, the configuration is often such that the DC voltage of the battery is converted to an AC voltage and this AC voltage is applied. Furthermore, for a liquid crystal member that can obtain a dynamic light scattering effect by applying a DC voltage, the structure is such that the DC voltage is directly applied.

"Effect of the invention" As described above, the variable illumination angle device according to the present invention arranges a liquid crystal member having a dynamic light scattering effect in the optical path of the projector,
The configuration is such that the irradiation angle of the light transmitted through the liquid crystal member is changed by applying an electric voltage to the liquid crystal member or by changing the applied electric voltage, so the irradiation angle can be easily changed by electrical control. In addition, since it is an electric control mechanism,
Since the installation space of the device can be saved, even a small floodlight can be satisfactorily implemented.

In particular, it can be implemented as a light emitting part of a flash discharge light emitting device built into a camera, and is advantageous in that the irradiation area can be switched depending on telephoto shooting, standard shooting, or wide-angle shooting.

[Brief explanation of the drawing]

The drawings show an example in which the present invention is implemented as a light emitting part of a flash discharge light emitting device used for photography. Fig. 1 is a perspective view of the light emitting part and the liquid crystal member, and Fig. 2 (a>, (b) shows the illumination angle. 3 is a front view and a power supply circuit diagram of the liquid crystal member showing an embodiment in which a multi-divided portion is provided in the liquid crystal member to switch the illumination angle, and FIG. 4 is a simplified diagram of the light emitting unit showing the switching state of the liquid crystal member. A front view and a power supply circuit diagram of a liquid crystal member showing an example of changing the illumination angle by steplessly changing the light scattering of the liquid crystal member, Fig. 5 is a diagram showing the light diffusion characteristics of the liquid crystal member, and Fig. 6 is a diagram showing the light diffusion characteristics of the liquid crystal member. A simplified diagram showing an embodiment in which an optical member having an optical effect that synergizes with the scattering effect is provided. FIG. 7 shows the light emitting part of a conventional flash discharge light emitting device equipped with a lens for changing the irradiation angle that can be attached freely. Sectional view, No. 8
This figure is a top view of a light emitting part similar to that shown in FIG. 7, which is equipped with a slidable lens for changing the irradiation angle. 11... Xenon discharge tube 12... Reflector 13.16.20... Liquid crystal member 17.18... Changeover switch 19... Potentiometer. 7th vIA M2F! IJ Figure 3 Figure 4 MS diagram System: Nno h, 1 to FL (1/) Figure 1 Figure 6 FIIJ MS diagram

Claims (6)

[Claims] (1) A liquid crystal member having a dynamic light scattering effect is placed in the optical path of the projector, and an electric voltage is applied to the liquid crystal member, or the applied electric voltage is changed to emit light that passes through the liquid crystal member. A variable illumination angle device for a floodlight that is characterized by changing the angle. (2) The liquid crystal member is electrically divided into multiple parts, and the irradiation angle of the light is changed by selectively supplying power to the entire liquid crystal member and the divided parts. The illumination angle variable device for the projector described in item (1). (3) Create electrically multi-divided parts in the liquid crystal member, selectively supply power to the entire liquid crystal member and the divided parts to change the illumination angle of light, and The illumination angle variable device for a projector as set forth in claim (1), characterized in that an optical member having an optical effect synergistic with the light scattering effect of is disposed in the optical path of the projector together with a liquid crystal member. (4) Claim (1) characterized in that the power supply voltage of the liquid crystal member is changed in accordance with the adjustment of the photographing angle of view of the photographing lens, and is implemented as an illuminator for camera photography.
The illumination angle variable device for the floodlight described in Section 1. (5) A structure is created in which the liquid crystal member is electrically divided into multiple parts, and power is selectively supplied to the entire liquid crystal member and the divided parts in accordance with the adjustment of the shooting angle of view of the photographic lens, and the lighting for camera photography is Claim No. (2) characterized in that it is implemented as a device
The illumination angle variable device for the floodlight described in item 1). (6) A floodlight according to claim (1), characterized in that the power supply voltage of the liquid crystal member is linked to an exposure factor such as a camera aperture, and is implemented as an illuminator for camera photography. Variable beam angle device.