JPS63110431A - Controller for electromagnetically driven shutter - Google Patents

Abstract

PURPOSE:To maintain a correct exposure, by compensating a decline in the opening/closing speed of a shutter caused by a decline in an electromagnetically driving force resulting from a drop in a battery voltage by correcting the shutter speed in accordance with the level of the battery voltage. CONSTITUTION:Since the time required for closing a shutter becomes longer as shown by the segment CD' of the graph when a battery voltage drops, the shutter is closed at the segment C'D'' which passes the midpoint E of the segment CD and is parallel to the segment CD' in order to obtain a correct exposure. For making such shutter closing characteristic correction, voltage dividing resistances R1 and R2 for detecting the voltage of a power supply battery, AD converter 11 which AD-converts the battery voltage detected by the resistances, and arithmetic section 14 are provided. The arithmetic section 14 inputs the outputs of a photometric section 12 and information section 13 and controls the drive of the shutter by sending a signal to a shutter controlling circuit 15 after the section 14 corrects the values by using the output of the AD converter 11. Therefore, no loss is produced in the electric power of the power source even if the supply voltage of the battery drops and correction of the exposure quantity can be made with high accuracy.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to an electromagnetic drive shutter that compensates for exposure variations due to changes in the power supply voltage level of a camera shutter whose opening and/or closing operations are performed by direct electromagnetic drive force. Regarding a control device.

"Prior Art" Many devices have been proposed that directly drive the opening and closing of camera shutters using electromagnetic force. These shutter drive devices are driven by a small battery built into the camera, and the voltage of these batteries usually decreases over time. equipment.

``Problems to be solved by the invention'' However, since passing through a constant voltage circuit involves power loss,
As a power source for small devices such as cameras, there was a problem in terms of energy conservation.

"Means for Solving the Problem" The present invention has a configuration in which the shutter time is corrected based on the level of the power supply voltage of an electromagnetic drive device for a camera shutter that is directly driven to open and close by an electromagnetic drive force.

1. Proper exposure is maintained by correcting the shutter time in accordance with the level of battery voltage to compensate for the decrease in shutter opening/closing speed caused by the decrease in electromagnetic driving force accompanying the decrease in battery voltage.

"Example" The present invention will be described in detail below using the drawings.

Fig. 1 is a block circuit diagram of the control device of the present invention, Figs. 2 and 3 are explanatory diagrams showing the opening characteristics of a type of shutter whose closing is electromagnetically driven, and Fig. 2 shows a case with a full opening time; Figure 3 shows the case where the valve is not fully opened. Figure 4(a), (
b) is an explanatory diagram showing the opening characteristics of a shutter of a type in which opening and closing are driven electromagnetically, and FIG. 5 is a schematic diagram showing an example of a shutter of a type in which closing is driven electromagnetically.

In FIG. 5, 1 and 2 are shutter blades, and the figure shows the closed state. 1a and 2a are long grooves for opening and closing the shutter blades 1 and 2, and 3 is a pin inserted into the long grooves 1a and 2a, and by moving upward in the drawing, the shutter blade 1 is opened.
, 2 are opened left and right about the rotating shaft 4 to form a shirt opening at portions 1b and 21). 2C is a stopper portion for rotating the shutter blade 2 in the opening direction; 5 is a shutter blade 1, 2;
a spring for moving the pin 3 in order to rotate the pin 3 in the opening direction;
6 is a drive unit schematically representing an electromagnetic drive mechanism that drives the pin 3 in the shutter blade closing direction, 7 is a separation type electromagnet, and the contact piece 9 is moved from the stopper part 2C by the barb 8 that stops energization. make them leave.

Next, the operation of the shutter shown in FIG. 5 will be explained. The figure shows the shutter closed state. Here, when the electromagnet 70 is de-energized by the shutter open signal, the contact piece 9 is moved to the stopper part 2 by the spring 8.
C, the pin 3 is moved upward in the figure by the spring 5, and the shutter blades 1 and 2 are rotated in the opening direction. Next, when a current flows through the electromagnetic drive unit 6 due to the shack closing signal, the driving force resists the force of the spring 5 and moves the pin 3 to the shutter blade 1.
Move in the closing direction of °2. Figures 2 and 3 show the shutter opening characteristics. Figure 2 shows the case where the shutter is fully opened. In the figure, the shutter starts opening from point A under the force of spring 5 in Figure 5, and fully opens at point B. , Direct closing is started at point C by the electromagnetic force of the drive unit 6 shown in FIG. 5, and closing is completed at point C. At this point, the battery voltage decreases, and as shown by C to D', it takes time to close, resulting in overexposure by an amount equivalent to the area surrounded by triangle CDD'. Therefore, it is understood that proper exposure can be obtained by closing the shutter at C'D'', which passes through the midpoint E of CD and is parallel to CD'.

Figure 3 shows an example in which the shutter starts to close before it is fully open; similarly to Figure 2, it starts opening from A with the help of the spring 5, starts closing with the force of the drive unit 6 from point B1, and closes at D. do. Here, when the battery voltage decreases, the closing characteristic becomes B/D/. In this case as well, the line C/D passes through the midpoint E of B/D and is parallel to CD'.
It is easy to understand that proper exposure can be obtained by closing the shutter at ".

Figure 1 is a block circuit diagram for correcting the shutter closing characteristics, where E is the power battery, S is the switch, and R1 and R
1 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 voltage dividing resistors R, R, 2, and 12 is a logarithmic compression that measures the brightness of the subject. A photometric section 13 converts photographic information such as film sensitivity and exposure compensation into an Apex index, encodes it and outputs it, and numeral 14 denotes a photometric section 12 and the information. After inputting the output from section 13 and correcting these values using the output from AD converter 11 as explained in FIGS. 2 and 3, a signal is sent to the shutter control circuit 15 to obtain the appropriate exposure. Control the shutter drive to get the desired results.

In reality, the shutter closing characteristic is not linear, and if the correction when the shutter is not fully opened is simply performed as shown in FIG. 3, some correction error will occur. It is clear that highly accurate correction can be made for these by analyzing their characteristics, creating a data table in advance, and making corrections in accordance with this data table.

Figure 4 shows the shutter characteristics when both opening and closing of the shutter are operated by electromagnetic driving force. When the shutter in Figure (a) is fully opened, the area of the opening delay S and the closing delay S' Since the areas of are almost equal, there is little need for correction (
, in the case of correction, it is sufficient to make the correction so that S and S' become equal. If the shutter in figure (b) does not open fully, a large error in exposure will occur, so for example, the area of triangle AB'D' corresponding to the exposure amount when the battery voltage is normal and the exposure amount when the battery voltage drops. Triangle AB//D “corresponding to
and is corrected so that ΔA B'D'=ΔAB"'D'''.

"Effects of the Invention" According to the present invention, in a camera shutter that is opened and closed by direct electromagnetic driving force, the exposure amount can be corrected with high precision without causing loss of power even when the power supply battery is low. I can do it.

[Brief explanation of the drawing]

The figures show 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 type of shutter whose closing operation is performed electromagnetically, and Fig. In the case where there is a full opening time, FIG. 3 shows a case where the opening is not fully opened. Fourth
Figures (a) and (b) are explanatory diagrams showing the opening characteristics of a shutter of the 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 blade 3...Pin 4...Rotating shaft 5...Spring 6...Drive unit
7...Electromagnet 8...Spring 9...
Contact piece 11...AD converter 12...Distance measuring section 13
...Photo information section]4...Calculation section 15...Shutter control circuit

Claims (1)

[Claims] An electromagnetic drive shutter control device, in a camera shutter driven to open and/or close by an electromagnetic drive force, wherein the shutter time is corrected depending on the level of the power supply voltage of the electromagnetic drive device.