JPH01251012A - Electronic shutter with diaphragm - Google Patents

Abstract

PURPOSE:To automatically execute an opening/closing control of a diaphragm in accordance with brightness at the time of photographing by providing a polarization angle changing part which is provided between a first polarizing plate and a second polarizing plate, and formed by providing like concentric circles plural pieces of polarizing elements for polarizing a transmission light by a prescribed angle in accordance with a prescribed input signal. CONSTITUTION:The title electronic shutter is provided with a polarization angle changing part 3 which is provided between the first polarizing plate 2, and the second polarizing plate 4 whose polarization angle is different by a prescribed angle from that of said first polarizing plate 2, and formed by providing like concentric circles plural pieces of polarizing elements 5, 7 and 9 for polarizing the transmission light by a prescribed angle in accordance with a prescribed input signal. Among the polarizing elements 5, 7 and 9 of the polarization angle changing part 3, that which has received an input signal is driven, therefore, only a light beam whose polarization angle is changed by the polarizing element which is driven in accordance with the input signal can transmit through the second polarizing plate 4. In such a way, in accordance with the input signal, the transmission light quantity can be adjusted, and such a problem as the depth of field is made constant is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electronic shutter with an aperture for use in cameras and the like.

(Prior Art) Conventionally, a shutter device of a camera or the like has been constructed mechanically. Such a mechanically constructed shutter device has problems such as slow response speed and poor operability.

In view of these problems, an electronic shutter as shown in FIG. 4 was devised. As shown in the figure, in this electronic shutter, polarizing plates 61 and 63 are disposed before and after the polarization angle changing section 51. The polarizing plates 61 and 63 are arranged so that the polarization angles of the polarizing plates 61 and 63 differ by 90 degrees.

As shown in FIG. 3, the polarization angle changing section 51 consists of a frame 53 and a polarizing element 55 such as a liquid crystal.

A lead wire 57 is connected to an electrode 59 of the polarizing element 55 via the frame 53.

When a voltage is applied to the electrode 59 via the lead wire 57, the polarization angle of the light transmitted through the polarizing element 55 is converted by 90 degrees. Further, when no voltage is applied to the electrode 59, the light that passes through the polarizing element 55 is transmitted as is without being polarized.

When the switch 67 is off, the light that has passed through the polarizing plate 61 passes through the polarization angle changing section 51 as it is, so the polarizing plate 6
3 cannot be passed through. When the switch 67 is turned on, a voltage is applied to the polarization angle changing section 51 from the power source 65. Therefore, the polarization angle of the light transmitted through the polarizing plate 61 is polarized by 90 degrees by the polarization angle changing section 51, so that the light can be transmitted through the polarizing plate 63.

By interlocking the switch 67 with the release button, the electronic shutter opens when the release button is pressed.

However, such an electronic shutter has a problem in that since there is no change in the amount of light on one surface of the polarization angle changing section 51, the depth of field is constant and it is not possible to take advantage of the blur characteristic unique to cameras.

(Problems to be Solved by the Invention) As described above, the conventional electronic shutter has a problem in that the depth of field is constant.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electronic shutter having an aperture function.

[Configuration of the Invention (Means for Solving the Problems) To achieve the above object, the present invention comprises a first polarizing plate,
a second polarizing plate having a polarization angle different from the first polarizing plate by a predetermined angle;
a polarizing plate, and a plurality of polarizing elements arranged concentrically between the first polarizing plate and the second polarizing plate and polarizing the transmitted light by the predetermined angle according to a predetermined input signal. and a polarization angle changing section.

(Function) In the present invention, among the polarization elements of the polarization angle changing section, only those that receive an input signal are driven. Therefore, only the light whose polarization angle has been changed by the polarizing element driven according to the input signal can pass through the second polarizing plate. Therefore, the amount of transmitted light can be adjusted according to the input signal.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. FIG. 2 is a schematic configuration diagram of a camera using an electronic shutter with an aperture according to an embodiment of the present invention.

Light transmitted through lens 1 is incident on polarizing plate 2 . The polarizing plate 2 transmits only vertically polarized light and makes it enter the polarization angle changing section 3 .

FIG. 1 is a plan view of the polarization angle changing section 3, in which polarizing elements 5, 7.9, such as liquid crystals, are arranged concentrically. The polarizing element 5 polarizes the light by 90 degrees when a voltage is applied to the electrodes 11a and 11b, and when no voltage is applied, the light is transmitted without changing the polarization angle. Similarly, the polarizing element 7 changes the polarization angle by 90 degrees only when a voltage is applied to the electrodes 13a and 13b, and the polarizing element 9 changes the polarization angle by 90 degrees only when a voltage is applied to the electrodes 15a and 15b. change.

The transmitted light of the polarization angle changing section 3 is taken into a solid-state imaging device (CCD) 17 via a polarizing plate 4. The polarizing plate 4 is arranged so that the polarization angle differs from that of the polarizing plate 2 by 90 degrees. That is, the polarizing plate 4 transmits only horizontally polarized light.

The oscillator 19 oscillates by the voltage sent from the power supply 18. The transformer 21 changes the voltage generated by the oscillator 19 to a predetermined value. Capacitor 25 stores the voltage sent from transformer 21. The switches 27, 29, and 31 are turned on and off according to commands sent from the central processing unit (CPU) 35, and when turned on, send the voltage accumulated in the capacitor 25 to each electrode. That is, when the switch 29 is turned on, a voltage is applied from the capacitor 25 between the electrodes 11a and llb, and the polarizing element 5 operates to change the polarization angle by 90 degrees. When the switch 27 is turned on, the electrodes 13a, 13
A voltage is applied from the capacitor 25 between b, and the polarizing element 7
operates to change the polarization angle by 90 degrees. Similarly, when the switch 31 is turned on, the polarizing element 9 operates to change the polarization angle by 90 degrees. The photometry circuit 33 measures the brightness of the shooting location and sends a signal corresponding to the measured brightness to the CPU.
Send to 35. A read-only memory (ROM) 37 stores the F value for the signal sent from the photometry circuit 33. When the CPU 35 receives a signal from the photometry circuit 33, the R
The F value corresponding to the signal is read from the OM 37, and the opening/closing control of the switches 27, 29, and 31 is performed in accordance with the F value.

When the shooting condition is bright, the CPU 35 reads the F value in the ROM 37 in accordance with the signal sent from the photometry circuit 33,
Only switch 29 is turned on.

Therefore, only the polarizing element 5 is driven, and only the light that has passed through the polarizing element 5 out of the light that has passed through the lens 1 is taken into the CCD 17.

In a slightly darker state than the above-mentioned state, the photometry circuit 3
According to the signal sent from 3, the CPU 35 reads the F value of the ROM 37 and turns on the switch 29 and the switch 31. Therefore, among the light incident through the lens 1, the light that has passed through the polarizing elements 5 and 7 is taken into the CCD 17.

When it is dark, the CPU 35 switches switches 27, 29.31.
are all turned on. In this case polarizing elements 5, 7.9
are all driven, so that out of the light incident through lens 1, the light that has passed through the polarizing elements 5 and 7.9 is reflected by the CCD.
Incorporated into 17th.

Thus, in this embodiment, the opening and closing of the aperture can be controlled automatically according to the brightness at the time of photographing.

In this embodiment, the aperture value can be changed in three steps using the polarizing elements 5, 7.9, but it goes without saying that the number is not limited to three steps.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide an electronic shutter having an aperture function.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a polarization angle changing section 3 of an electronic shutter according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a camera using an electronic shutter, and FIG. 3 is a diagram of a conventional polarization angle changing section. FIG. 4 is a schematic diagram of a conventional electronic shutter. 2.4...Polarizing plate 3...Polarization angle changing unit 5.
7.9...Polarizing element applicant Toshiba Corporation Representative Patent attorney Suyama Sa - Figure 1 Figure 2

Claims (1)

[Claims] A first polarizing plate, and a second polarizing plate having a polarization angle different from the first polarizing plate by a predetermined angle.
a polarizing plate, and a plurality of polarizing elements arranged concentrically between the first polarizing plate and the second polarizing plate and polarizing transmitted light by the predetermined angle according to a predetermined input signal. What is claimed is: 1. An electronic shutter with an aperture, comprising: a polarization angle changing section;