JP2717651B2 - Electromagnetic drive shutter control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exposure amount (hereinafter, to be exact, a change in power supply voltage level of a camera shutter that is opened and / or closed by a direct electromagnetic driving force. The present invention relates to an electromagnetically driven shutter control device that compensates for variations in the integral aperture of the shutter. "Prior art" Many devices have been proposed which directly drive the opening and closing of a camera shutter by electromagnetic force. These shutter driving devices are driven by small batteries built into the camera, and the voltage of these batteries usually decreases over time. Therefore, conventionally, the output of the battery has been supplied to those devices through a constant voltage circuit. "Problems to be Solved by the Invention" However, since passing through a constant voltage circuit involves power loss, there is a problem in terms of energy saving as a power supply for a small device such as a camera. Means for Solving the Problem The present invention detects a power supply voltage level of an electromagnetic drive device in a camera shutter that is opened and / or closed by an electromagnetic drive force, and detects a power supply voltage change in advance. A shutter time for measuring and analyzing the aperture characteristic of the applicable shutter and correcting the integrated aperture for a regular power supply voltage and the integrated aperture for a reduced power supply voltage to be substantially equal in the aperture characteristic diagram of the shutter with respect to time. Is determined in advance, and this is recorded in advance as a data table, and when the electromagnetically driven shutter is activated, the correction time corresponding to the battery voltage is taken out of the data table based on the battery voltage information and arithmetically processed, whereby the opening is mechanically closed. Is electromagnetically performed, the approximate middle point of the change in the integral opening amount of the closing operation of the shutter due to the decrease in the power supply voltage is the normal value. The start time of the shutter closing operation is shortened and corrected so as to coincide with the midpoint of the change in the integral opening amount of the shutter closing operation in the case of the source voltage. The power supply voltage is reduced by shortening or extending the shutter time so that the amount of decrease in the integral aperture due to the delay in the opening operation of the shutter due to the voltage drop and the amount of increase in the integral opening due to the delay in the closing operation become equal. An electromagnetically driven shutter control device characterized in that the shutter time is corrected so that the integrated opening amount when the voltage is lowered is substantially equal to the integrated opening amount when the power supply voltage is normal. [Operation] According to the configuration of the present invention, the device of the present invention operates as follows. That is, in an electromagnetically driven shutter in which shutter closing drive is performed electromagnetically and opening drive is performed electromagnetically or mechanically with a spring or the like, for example, the power switch S
When the release button is depressed at the start of shooting, the photometry data from the photometry unit, the photo information data from the photo information unit, and the battery voltage information data from the power supply voltage level detection unit are linked to the operation unit. Is entered into
In advance, the opening characteristics of the applied shutter with respect to a change in the power supply voltage are measured and analyzed, and the integrated opening amount when the power supply voltage is reduced is substantially equal to the integrated opening amount when the power supply voltage is normal in the shutter opening characteristic diagram with respect to time. The shutter time to be corrected is determined so that the corrected shutter time is calculated using the recorded data table, and this output is sent to the shutter control unit to open and close the electromagnetically driven shutter. According to the above configuration, a change in the integral aperture (exposure light amount) due to a decrease in the power supply voltage is prevented by correcting the shutter time. Example An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a control device according to the present invention, and FIGS. 2 and 3 are explanatory diagrams showing the opening characteristics of a shutter of a type that electromagnetically drives a closing. FIG. The figure shows the case where it is not fully opened. 4 (a) and 4 (b) are explanatory diagrams showing the opening characteristics of a shutter of a type which electromagnetically drives the opening and closing, and FIG. 5 is a schematic view showing an example of a type of a shutter which electromagnetically drives the closing. In FIG. 5, reference numerals 1 and 2 denote shutter blades, and the drawing shows a closed state. 1a and 2a are long grooves for opening and closing the shutter blades 1 and 2, and 3 is a pin inserted in the long grooves 1a and 2a. The shutter blades 1 and 2 are moved upward in the drawing to move the shutter blades 1 and 2 around the rotation shaft 4. A shutter opening is formed by the portions 1b and 2b that open left and right. 2c is a stopper portion for rotating the shutter blade 2 in the opening direction. 5 is a spring for moving the pin 3 to rotate the shutter blades 1 and 2 in the opening direction. 6 is a pin for moving the pin 3 in the shutter blade closing direction. A driving unit 7 schematically represents an electromagnetic driving mechanism for driving. Reference numeral 7 denotes a separation type electromagnet. When energization is stopped, the contact piece 9 is separated from the stopper 2c by a spring 8. Next, the operation of the shutter shown in FIG. 5 will be described. The figure shows a shutter closed state. Here, when energization of the electromagnet 7 is stopped by the shutter open signal, the contact piece 9 is moved by the spring 8 to the stopper portion.
2c, the pin 3 is moved upward by the spring 5 to rotate the shutter blades 1 and 2 in the opening direction. Next, when a current flows through the electromagnetic drive unit 6 in response to a shutter closing signal, the pin 3 moves the shutter blades 1 and 2 against the force of the spring 5 by the driving force.
In the closing direction. 2 and 3 show shutter opening characteristics. FIG. 2 shows a case where the shutter is fully opened. In FIG. 2, the shutter starts opening from a point A by the force of the spring 5 shown in FIG. At the point C, the closing is directly started by the electromagnetic force of the driving unit 6 in FIG. 5, and at the point D, the closing is completed. Here, when the battery voltage decreases, as shown by C to D ', it takes a long time to close, and the exposure is overexposed by an area corresponding to the area surrounded by the triangle CDD'. Therefore, it is understood that proper exposure can be obtained by closing the shutter at C'D "passing through the midpoint E of CD and parallel to CD '. FIG. 3 shows that the shutter is closed before the shutter is fully opened. In the same manner as in FIG. 2, the opening is started with the spring 5 from A, the closing is started with the force of the drive unit 6 from the point B ', and the closing is performed with D. Here, when the battery voltage decreases, the closing is performed. The characteristics are as follows: B'D 'Also in this case, it is easy to obtain a proper exposure by closing the shutter with a line B "D" passing through the midpoint E of B'D and parallel to B'D'. understandable in. FIG. 1 is a block diagram circuit diagram for performing such correction of the shutter closing characteristic, E is the power supply battery, S is a switch, R ₁ and R ₂
Is a voltage-dividing resistor for detecting the voltage of the power supply battery, 11 is an AD converter that converts the battery voltage detected by the voltage-dividing resistors R ₁ and R ₂ to AD, and 12 is photometric measurement of the brightness of the subject, logarithmically compressed and Apex. Photometric unit that converts to exponent, then encodes and outputs, 13
Is a photographic information section that converts photographic information such as film sensitivity and exposure compensation into an apex index and then outputs the coded information, and an arithmetic section 14 inputs the outputs from the photometric section 12 and the information section 13 and outputs an AD.
After correcting these values with the output from the converter 11 as described in FIGS. 2 and 3, a signal is sent to the shutter control unit 15 to control the shutter drive so as to obtain an appropriate exposure. Actually, the shutter closing characteristic is not linear,
Further, if the correction when the shutter is not fully opened is simply performed as shown in FIG. 3, a slight correction error occurs. It is clear that a high-precision correction can be performed by analyzing the characteristics of these and preparing a data table in advance and performing correction in accordance with the data table. FIG. 4 shows the shutter characteristics when both the opening and closing of the shutter are operated by the electromagnetic driving force. When the shutter shown in FIG. 4A is fully opened, the area of the opening delay S and the closing delay S 'are shown. Are almost equal, so the necessity of correction is small. When correction is performed, S and S 'may be made equal. If the shutter shown in FIG. 2B is not fully opened, a large error occurs in the exposure. For example, the area of the triangle AB'D 'corresponding to the exposure amount when the battery voltage is normal and the exposure amount when the battery voltage decreases Is compared with the triangle AB'D 'corresponding to the above equation, and correction is performed so that ΔAB "D" = ΔABD. [Effects of the Invention] According to the present invention, in a camera shutter that is opened and closed directly by an electromagnetic driving force, even when the power supply battery is reduced, the exposure amount can be corrected with high accuracy without causing a power supply loss. Can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block circuit diagram of a control device. FIGS. 2 and 3 show opening characteristics of a shutter of a type which performs a closing operation electromagnetically. FIG. 2 shows a case where the shutter is fully opened, and FIG. 3 shows a case where the shutter is not fully opened. 4th
FIGS. 7A and 7B are explanatory diagrams showing the opening characteristics of a shutter of a type that is electromagnetically driven for both opening and closing, and FIG. 5 is a schematic diagram showing an example of a shutter that is electromagnetically driven for closing. 1, 2, shutter blades 3, pin 4, rotating shaft 5, spring 6, driving unit 7, electromagnet 8, spring 9, contact piece 11, AD converter 12, ... Distance measuring unit 13 ... Photo information unit 14 ... Calculating unit 15 ... Shutter control unit

Claims (1)

(57) [Claims] In a camera shutter that is opened and / or closed by an electromagnetic driving force, a level of a power supply voltage of an electromagnetic drive is detected, an aperture characteristic of an applicable shutter with respect to a change in a power supply voltage is measured and analyzed in advance, and a time is measured. A shutter time to be corrected is determined so that the integral opening amount in the case of a normal power supply voltage in the shutter opening characteristic diagram and the integral opening amount in the case of a decrease in the power supply voltage are substantially equal, and this is recorded in advance as a data table. When the electromagnetically driven shutter is activated, a correction time corresponding to the battery voltage is taken out of the data table based on the battery voltage information and subjected to arithmetic processing.
The shutter closing operation is performed so that the approximate middle point of the change in the integral opening amount of the shutter closing operation due to the decrease in the power supply voltage coincides with the middle point of the change in the integral opening amount of the shutter closing operation in the case of the normal power supply voltage. In a shutter in which the start time is shortened and corrected so that both opening and closing are performed electromagnetically, a decrease in the integral opening due to a delay in the opening operation of the shutter due to a drop in the power supply voltage and a decrease in the integral opening due to a delay in the closing operation. By shortening or extending the shutter time so that the increment is equal to the shutter time, the shutter time is corrected so that the integral aperture when the power supply voltage decreases is approximately equal to the integral aperture when the power supply voltage is normal. An electromagnetically driven shutter control device.