JPH01307730A - Exposure device - Google Patents

Abstract

PURPOSE:To always control the exposure with high precision by comparing the exposure amount of a preliminary opening and closing action with a reference exposure amount, and transferring and recording to a recording circuit an exposure action or a value of a storing circuit according to a reference value derived from the repeated preliminary opening and closing, corresponding to the magnitude deviation. CONSTITUTION:In a first non-exposure opening and closing action, the detected value is stored once in the storing circuit, then the value is integrated to obtain the exposure amount, and next compared with the reference exposure amount. If there is a difference exceeding a set value, a second exposure opening and closing action is carried out taking into account the compensation derived from the value of the non-exposure opening and closing action, and when it remains within the set value, the value of the storing circuit is kept as it is, and recorded in a recording medium such as a floppy disk. Thus there is no more unnecessary taking over of photographs, and the exposure amount can be controlled with high precision, without generating any inconvenience in use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exposure device using a shutter device or an aperture device mounted on an optical device such as a camera or an observation device.

[Prior Art] There are various types of exposure devices such as shutter devices and aperture devices installed in cameras, etc., depending on the characteristics of the camera, etc. An exposure device suitable for cameras that require this has not yet been developed.

Conventionally known exposure devices such as a half-open shutter and a re-opening shutter that performs a first non-exposure opening/closing operation and a second exposure opening/closing operation have characteristics that are applicable to exposure devices for still video cameras. It was assumed that they were doing so.

[Problem to be solved by the invention]

Most of the conventional half-open type shutters described above are configured as a half-open type shutter with a sub-diaphragm, in which a sub-diaphragm that opens and closes at the same time as the aperture of the photographing lens is disposed in front of the light receiving element. In this half-open type shutter with a sub-diaphragm, the integral value of the light incident on the light receiving element is detected as the amount of light incident on the imaging surface when the sub-diaphragm is opened at the same time as the aperture is opened during the exposure operation. When the exposure amount reaches a predetermined value (the amount of exposure determined according to the photometry result), an electromagnet for closing the diaphragm is energized to close the diaphragm.

In the above known half-open shutter with a sub-diaphragm, in high-brightness shooting conditions where the aperture is in a small aperture state, an aperture closing signal is sent to the electromagnet immediately after the light passing through the sub-diaphragm enters the light receiving element. However, due to the delay in the response of the electromagnet, the diaphragm cannot close immediately, and therefore the amount of exposure always ends up being excessive.

On the other hand, in medium-brightness shooting conditions where the aperture is not fully open, the ratio of the exposure amount when the aperture is opening and the amount of exposure when it is closing is almost constant. Since a diaphragm closing signal can be given to the electromagnet,
Exposure control linearity is good and exposure control can be performed with high precision.

However, in low-brightness shooting conditions after the aperture is fully opened, the ratio of the integral exposure amount until the aperture close signal is applied to the position and the exposure amount during the aperture closing operation is not constant. It was not possible to predict the amount of exposure during the closing operation, which often resulted in underexposure or overexposure.

As a result, with the known half-open shutter with a sub-diaphragm, it is not possible to perform exposure control with linearity across high brightness areas, medium brightness areas, and low brightness areas.
"Waviness" occurs in the EV value across the three regions, and therefore, the known half-open shutter with sub-diaphragm cannot be used as an exposure device for cameras that require high-precision exposure, such as still video cameras. I couldn't do it.

Therefore, in order to eliminate the above-mentioned drawbacks of the known half-open type shutter with a sub-diaphragm, a half-open type shutter with an encoder has been proposed, which is provided with an encoder for detecting the amount of operation of the diaphragm. This encoder-equipped half-open shutter uses an encoder to detect the movement amount or position of the diaphragm, thereby detecting the sometimes separate positions of the diaphragm and the size of the exposure aperture, and based on the results, the most appropriate one for the electromagnet. The structure was such that the diaphragm closing signal could be applied at certain times.

However, this half-open shutter with encoder also
For the following reasons, it is not suitable for performing high-precision exposure control. In other words, the running characteristics of the diaphragm when it opens vary depending on the environment such as temperature and humidity, the posture of the diaphragm, and changes over time. Since the speed and speed change) are unknown, no matter how accurate the detected values of the opening movement amount and position of the diaphragm are, it is not possible to accurately control the position and timing at which the diaphragm begins to close. In addition, even if the diaphragm is configured to have a controlled movement in the opening direction by a drive source such as a motor, changes in the motor drive voltage and changes in the resistance value of the motor coil due to increases in motor temperature due to energization may occur. The running characteristics of the iris vary depending on the cause, so even if the encoder accurately detects the opening movement amount and position of the iris, the running characteristics of the iris will not be detected, making it impossible to accurately control the position at which the iris begins to close. could not. Therefore, the aperture opening i41] When the aperture position is detected at a certain time by an encoder during operation and the aperture is closed by operating an electromagnet based on the detected value, the aperture opening speed is high. Even if the detected value by the encoder is the same, the position at which the diaphragm starts to close is different from the late one, so the exposure time and the exposure amount are also different.

Figure 5 shows the fluctuations in exposure when the running characteristics of the aperture blades change due to changes in the motor drive voltage, etc., in a half-open shutter of the type described above in which the aperture blades are moved to open by motor drive. FIG.

In FIG. 5, the solid line L3 indicates the desired running characteristics, the dashed line L3 indicates the running characteristics when the opening speed of the aperture blades is too fast, and the dashed line L3 indicates the desired running characteristics. is the running characteristic when the opening speed of the aperture blades is too slow.

In addition, in FIG. 5, P l, P2. Ps represents the point in time when a closing signal is given to the electromagnet for closing the aperture blades, and PI', P2'', P,'' represent the point in time when the electromagnet actually operates and the aperture diameter at that time.

As is clear from FIG. 5, when the opening speed of the aperture blades changes, the integrated exposure amount during one opening/closing operation of the aperture blades also changes.

Therefore, in order to eliminate the drawbacks of the half-open shutter, a re-opening shutter has been proposed.

In this re-opening shutter, opening/closing members such as shutter blades or aperture blades are opened based on a value from a detection element that measures the amount of light in advance of the actual exposure opening/closing operation, and during the preliminary opening/closing operation. A reference value for the actual exposure opening/closing operation is determined based on values such as the movement amount and exposure amount detected during the preliminary opening/closing operation, and the opening/closing member is operated according to the reference value during the actual exposure opening/closing operation performed after the preliminary opening/closing operation. According to this exposure device, the exposure device is not affected by changes in the environment, the orientation of the aperture, changes over time, changes in motor drive voltage, changes in the resistance value of the motor coil due to increases in motor temperature due to energization, etc. In addition, highly accurate exposure control is possible.

However, since the shutter opens and closes twice under any conditions, it produces a double shutter sound, which is annoying when taking long exposures. There are also problems such as the need to keep the aperture fixed for a long time.

The present invention seeks to solve the problems inherent in the two types of known half-opening shutters.

In other words, the present invention enables highly accurate exposure control at all times, regardless of changes in the running characteristics of the opening/closing member that opens and closes the exposure aperture, and allows the opening/closing member to open and close twice. It is an object of the present invention to provide an exposure apparatus that can perform the process only once when it is not necessary.

[Means for Solving the Problems] In order to achieve the above object, the present invention causes an opening/closing member that opens and closes an exposure opening to perform a preliminary opening/closing operation prior to an actual exposure operation, and performs a preliminary opening/closing operation in this preliminary opening/closing operation. A reference value for the actual exposure opening/closing operation is determined based on the values of the movement amount, exposure amount, etc. detected at the time of the opening/closing operation, and the opening/closing member is adjusted according to the reference value during the actual exposure opening/closing operation performed after the preliminary opening/closing operation. an exposure apparatus that operates, a memory circuit that stores the value obtained by the preliminary opening/closing operation for a certain period of time;
and a comparison circuit that compares the value of the storage circuit with a reference light amount, and if the deviation compared with the reference light amount in the comparison circuit is greater than a certain value, the preliminary comparison is performed again. Performing an exposure operation based on the reference value obtained by opening and closing,
The device has a recording deck that transfers the value of the memory circuit to a recording circuit and records it when a difference of more than a certain value is not observed.

[Function] According to the present invention, the exposure amount of the preliminary opening/closing operation is compared with the reference exposure amount, and the data of the preliminary opening/closing operation is stored for a certain period of time.
It is stored in a memory circuit, and if the comparison value with the reference exposure amount does not deviate by more than a certain value, the value in the recording circuit is determined to be the actual exposure value, and the second exposure opening/closing operation is performed. If this is not done and a long exposure is required, the second operation will be stopped. Therefore, in the present invention, exposure control is performed in accordance with the exposure characteristics or operation characteristics in the actual exposure operation, and the second exposure opening/closing operation is performed at a long time or when the exposure amount does not deviate too much from the standard exposure amount. Since this is not carried out, the exposure device is able to take pictures without any discomfort and with no waste.

[Implementation example] 1 to 4 show one embodiment of the present invention.

Fig. 1 shows the shutter running characteristics during AE photography, Fig. 2 shows the circuit configuration, Fig. 3 shows the mechanism, and Fig. 4 shows the shutter running characteristics during AE photography.
The figure shows a flowchart.

In Figure 1, in the case of AE photography, the aperture opens little by little after the camera is released, and the number of pulses corresponding to the aperture value, which is counted in conjunction with the aperture, also increases, but the predetermined number of pulses Pn When it reaches , turn the magnet to O.
If N, then the delay time T due to the operation of the magnet, after
The shutter is declutched and closes rapidly. The value obtained at that time is stored for a certain period of time, and the exposure amount is compared with the reference exposure amount. If the value exceeds a certain value, the exposure operation amount is corrected by taking into account the amount of difference. Perform the second exposure operation.

A circuit for performing this exposure operation is shown in FIG.

In Fig. 2, 21 is a photometric block, and the photometric value obtained by this photometric block activates the shutter of 22 shutter blocks, and the value obtained by this exposure is stored in the CCD unit 23 in the memory circuit 24. Let me,
This value is compared with the standard exposure amount using the comparison circuit 25, and if it does not deviate by more than a certain value, it is recorded by the recording block 26 via the switch 25, and if it deviates by more than a certain value. performs the exposure operation again and records the value in the recording block.

In FIG. 3, 1 is a motor, 2 is a pinion gear, 3 is a reduction gear, 4 is a rack gear, 5 and 6 are rack guide shafts that guide the rack gear 4, and 7 is a return spring for the rack gear 4.

Reference numeral 8 denotes a clutch that is rotatably supported in a hole 4a of the rack gear 4, and a clutch spring 9 causes the tip 8a to be connected to the control plate 10.
The bottle 10a is biased to engage with the bottle 10a. Reference numeral 11 denotes a pulse plate bonded on the control plate 10, and is arranged so that its light-transmitting portion crosses the photointerrupter 13.

12 is a return spring for the control plate 10. Aperture blades 14 and 15 are guided by guide pins 16 and 17, respectively, and the pins 10b and 10c of the control plate 10 pass through the elongated hole 14a of the aperture blade 14 and the elongated hole 15a of the aperture blade 15, respectively. 14b and 15b are transparent parts forming an aperture. Reference numeral 18 denotes a magnetic armature, which rotates to the left around a shaft 20 when the coil 19 is energized, hits the protrusion 8b of the clutch 8 with its tip 18a, and the tip 8 of the clutch 8
a and the bottle loa of the control board 10 are disengaged.

Further, FIG. 3 will be explained. First, normal AE photography will be explained. After the release, when the motor 1 turns to the right and the reduction gear 3 turns to the left, the rack gear 4 starts sliding to the right against the spring 7. Then, since the clutch 8 attached to the rack gear 4 also slides to the right, the tip 8a of the clutch 8 pushes the bottle loa of the control plate 10, and the control plate 10 turns to the left against the spring 12. , slide the aperture blades 14 to the left, slide the aperture blades 15 to the right using the bottle 10c, and the aperture opens. At the same time, the pulse plate 11 on the control board 10 rotates to the left, and the photointerrupter 13 counts the light-transmitting portions of the pulse plate 11. When a predetermined number of pulses is reached, the coil 19 is energized, the armature 18 is attracted upward, and the protrusion 8b of the clutch 8 is used at the tip 18a.
, the engagement between the protrusion 8a and the bottle 10a is released, the control plate 10 is rotated to the right by the return spring 12, and the bottle l
Return the aperture blades 14 and 15 using Ob and loc to close the shutter.

Thereafter, the motor 1 reverses, slides the rack gear 4 back to the left, returns it to the initial position, and completes the series of operations.

In Fig. 4, the value measured by the photometric element is converted into the number of pulses corresponding to the photometric value, and the motor is operated until the number of pulses matches the number of pulses caused by the shutter opening/closing operation, and when they become the same, the motor OFF magnet is turned off. ON, the exposure operation is stopped, and the value obtained in the COD by the exposure is once transferred to the recording circuit, and while the value remains, the copied value is extracted, calculated, and compared with the reference value, and if the value exceeds a certain value. If not, record the memory of the recording circuit on a floppy disk, and if the deviation exceeds a certain value, perform the exposure operation again using the reference pulse number corrected for the amount of deviation, and transfer the obtained value to the floppy disk. Record.

[Effects of the Invention] As explained above, according to the present invention, the value detected in the first non-exposure opening/closing operation is stored in the memory circuit once, and the value is integrated to calculate the exposure amount. is calculated and compared with the standard exposure amount, and if it differs by more than a certain value, a second exposure opening/closing operation is performed taking into account the correction from the value obtained from the non-exposure opening/closing operation, and a certain value is determined. If it is within this range, by recording the values in the memory circuit as they are on a recording medium such as a floppy, it is possible to eliminate unnecessary retakes and perform high-precision exposure control without causing problems in actual use. I can do it.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the shutter running characteristics during AE photography according to the present invention, Fig. S2 is an explanatory diagram similarly showing the circuit configuration, Fig. 3 is a perspective view similarly showing the mechanism, and Fig. 4 is the same operation. FIG. 5 is an explanatory diagram showing changes in the running characteristics of the aperture blades in the prior art. 1...Motor 2...Pinion gear 3...
Reduction gear 4...Rack gear 8...Clutch
10... Control board 11... Pulse plate 13...
・Photo interrupter 14.15...Aperture blade 16.17...Guide bin 18...Magnet armature 19...Coil

Claims (1)

[Scope of Claims] 1. The opening/closing member that opens and closes the exposure opening is preliminarily opened/closed prior to the actual exposure opening/closing operation, and the operating amount, exposure amount, etc. detected during the preliminary opening/closing operation is based on,
In an exposure apparatus, a reference value for the actual exposure opening/closing operation is determined, and the opening/closing member is operated according to the reference value during the actual exposure opening/closing operation performed after the preliminary opening/closing operation. A storage circuit that stores a value for a certain period of time, and a comparison circuit that compares the value of the storage circuit with a reference light amount, and a certain value that has a deviation from the reference light amount in the comparison circuit. If there is a difference above, perform the exposure operation again using the reference value obtained by preliminary opening and closing, and if a difference of more than a certain value is not observed, transfer the value in the memory circuit to the recording circuit. An exposure apparatus characterized by having a recording deck for recording the information. 2. The exposure apparatus according to claim 1, further comprising a comparison circuit that compares the value of the storage circuit with a reference exposure amount to determine whether to perform another exposure operation.