JPS6395417A - Optical filter device - Google Patents

Abstract

PURPOSE:To obtain optional transmissivity with one piece of filter, by enclosing liquid crystal in the space formed between two glass plates facing each other so as to form transparent electrodes on the inner surfaces of the glass plates and adjusting the voltage to be impressed across the electrodes. CONSTITUTION:The optical filter device 10 of this invention is composed of two circular glass plates 11 and 12 facing each other and liquid crystal 13 enclosed in the space formed between the glass plates 11 and 12. Transparent electrodes 14 and 15 are respectively formed on the inner surfaces of the glass plates 11 and 12 and the electrodes 14 and 15 are connected with an external terminal which is connected with a DC power source 16. The power source 16 impresses a DC voltage across the terminal. Such optical filter device 10 is mounted on the end section of a camera lens barrel 17 by an appropriate means, such as screwing the filter 10 into the end section, and so forth. The intensity of the light transmitted through the liquid crystal starts to change when the impressed voltage exceeds a threshold Vth and is almost saturated at a certain voltage Vs. Therefore, optional transmissivity can be obtained when the DC voltage of the DC power source 16 is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical filter device, and relates to an optical filter device suitable for use in, for example, a camera-integrated magnetic recording device or a still camera.

[Conventional technology]

A conventional camera-integrated magnetic recording device was constructed as shown in FIG. In Figure 4, 1 is a lens, 2
3 represents an image sensor such as a CCD, and 3 represents an aperture device that adjusts the amount of light transmitted from the lens 1 to the image sensor 2. This diaphragm device 3 is driven by a diaphragm adjustment circuit 4. Reference numeral 5 indicates an electric signal from the image sensor 2, and reference numeral 6 indicates a magnetic recording device for recording an image.

Next, the operation will be explained. Light 7 enters lens l,
The amount of light is adjusted by the aperture device 3 and applied to the image sensor 2.

The light is converted into an electrical signal 5 by the image sensor 2, and then sent to the magnetic recording device f.
16 and recorded.

On the other hand, the aperture device 3 is adjusted by detecting the level 50 of the electric signal from the image sensor 2 and feeding it back to the aperture adjustment circuit 4 so that the amount of light applied to the image sensor is almost always the same. That is, the diaphragm device 3 is as shown in FIG.
As shown in (b), the area of the diaphragm is adjusted to be close to open in a dimly lit room, and to the fully diaphragm area when outdoors on a sunny day. Therefore, the amount of light was adjusted only by the aperture.

[Problem that the invention seeks to solve]

Conventional camera-integrated magnetic recording devices are configured as described above, so they are prone to overexposure in areas that are too bright, such as ski resorts on sunny days.
Neutral to N to reduce the light intensity to prevent that)
I use a filter to reduce the amount of light. Further, since the amount of light is adjusted only by the aperture device, it is necessary to use the N filter when adjusting the in-focus range (depth of field). Therefore, several N filters were required.

The purpose of the present invention was to solve these conventional problems.No matter how bright the area is, exposure will not be too high using a single filter, and the depth of field can be adjusted freely. The purpose of the present invention is to provide an optical filter device that can perform the following steps.

[Means for solving problems]

In the optical filter device of the present invention, a liquid crystal is sealed between two glass plates facing each other, a transparent electrode is formed on the inner surface of the glass plate, and the transmittance can be adjusted by adjusting the voltage applied to the electrode. It is characterized by changing.

[For production]

According to the optical filter device of the present invention, in a place that is too bright, such as a ski resort, the voltage applied to the electrodes is adjusted to reduce the transmittance of the filter, thereby reducing the amount of light. Furthermore, in a dark place or when increasing the depth of field, the voltage is similarly adjusted to increase the transmittance.

〔Example〕

Hereinafter, the optical filter device of the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.

1 and 2 show an optical filter device IO according to an embodiment of the present invention.

The optical filter device fiilO of this embodiment has two opposing
A liquid crystal 13 is sealed between circular glass plates 11.12, and transparent electrodes 14.15 are formed on the inner surface of each glass plate 11.12.
is formed, and this electrode group is connected to a column terminal, and the terminal is connected to a DC power supply 16 to apply a DC voltage.

As shown in FIG. 2, such an optical filter device 10 is attached to the end of a lens barrel 17 of a camera by suitable means such as screwing. Note that reference numeral 18 indicates a lens disposed within the lens barrel 17.

In this optical filter device IO, the intensity of light transmitted through the liquid crystal is determined by a threshold value v at a certain applied voltage as shown in FIG.
When the voltage exceeds th, it starts to change and becomes almost saturated at a certain voltage V. Therefore, any desired transmittance can be obtained by adjusting the DC voltage of the DC power supply 16, and the transmittance can be reduced to reduce the amount of light at a ski resort on a clear day, or when the depth of field is shallow. Make it smaller and open the diaphragm. Conversely, to increase the depth, increase the transmittance and close the aperture. This operation can be performed simply by changing the magnitude of the DC voltage applied to the electrodes.

The optical filter device of the present invention can be used by being attached to all kinds of cameras, such as a camera-integrated magnetic recording device or a still camera.

〔Effect of the invention〕

As explained above, since the optical filter device of the present invention is constructed using liquid crystal, any desired transmittance can be obtained with a single filter.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an optical filter device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the optical filter device of the embodiment attached to a camera lens barrel, and FIG. 3 is a perspective view showing an optical filter device according to an embodiment of the present invention. Figure 4 shows the dependence of transmitted light intensity on liquid crystal on applied voltage.
b) is a front view showing the aperture device used in the camera-integrated magnetic recording device in a dark and bright aperture state, respectively; 10... Optical filter device, 11.12... Glass plate, 13... Liquid crystal, 14.15... Transparent electrode. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] An optical system characterized by sealing a liquid crystal between two opposing glass plates, forming a transparent electrode on the inner surface of the glass plate, and changing the light transmittance by adjusting the voltage applied to the electrode. filter device.