JPS6079341A - Camera - Google Patents

Abstract

PURPOSE:To prevent an accident of a comparatively weak shutter curtain of a camera having a focal-plane shutter by running only a shutter front curtain automatically by an operation for opening a rear cover, and setting the camera to a shutter opened state. CONSTITUTION:In case of opening a rear cover, a shutter button is not pressed, and a rewinding knob 5 is drawn upward from the state that switches 11, 26 are all off, by which the switch 12 becomes on, and accordingly, an output of an AND gate 27 becomes a low level, therefore, a transistor 24 electrically conducts and a power source 25 is supplied to each prescribed part. Also, since the switch 12 is on and 11 is off, an output of an OR gate 28 becomes a high level, a transistor 30 is in an on-state, therefore, a rear curtain control magnet 41 is not energized. However, since the switch 12 is on, a NAND gate 15 becomes a high level, a front curtain control magnet 21 is energized, and a front curtain runs. That is to say, only the front curtain runs and the rear curtain does not run and becomes what is called the state that the curtain remains opened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a camera having a focal plane shutter.

Cameras that use a 7-ocal-grain shutter like the commonly used single-lens reflex camera, the shutter curtain is placed just in front of the exposure aperture, so when the user of camera 2 is loading or unloading film, etc. There are times when I accidentally touch the shirt curtain. In such cases, there would not be much of a problem if flexible materials such as conventional cloth curtains or rigid materials such as titanium blades were used, but light alloys such as aluminum or plastics In the case of a shutter having split blades made of wood, accidents may occur when the curtain or blade itself becomes deformed or the blades fly out and the shutter does not operate.

In addition, in recent years, focal plane shutters have been required to increase the shutter curtain speed and reduce the driving force during charging due to the automatic winding by the motor.
For this purpose, it is desirable to use light alloy or plastic blades that have light overlap.

The purpose of the present invention is to prevent the above-mentioned accidents in cameras using relatively weak shutter curtains. Focusing on the fact that accidents are likely to occur when the back cover is open, we created a system that automatically moves only the front curtain of the shutter to open the shutter when the back cover is open. I made it impossible to touch the shatter curtain.

The present invention will be described in detail below with reference to the figures.0 Figure 1 schematically shows the back cover opening/closing operation part, for example,
As shown in Japanese Patent No. 4755, the back cover can be opened and closed by pulling up the film rewind knob.

In the figure, 1 is the camera body, 2 is the upper cover, and 3 is the main body 1
The rewind shaft 4 is rotatably and slidably supported by an unwind bearing fixed to the rewind bearing.

5 is a rewinding knob attached to the upper end of the rewinding shaft.

Reference numeral 6 denotes a back cover opening/closing plate slidably attached to the side of the camera body, which has a claw portion that engages with a claw or bottle (not shown) fixed to the back cover, and is pressed downward by a spring 8. The back cover is locked in the closed position. When opening the back cover, when the rewinding knob 5 is pulled upward, the shoulder 4I of the rewinding fork provided at the lower end of the shaft 4 engages with the bent portion 6I of the opening/closing plate B, resisting the spring 8. By moving the plate 6 upward, the locking of the claw portion (not shown) is released, and the back cover is rotated around a hinge attached to the side opposite to the opening/closing plate 6. You will be able to open it by hand. 12 is a switch for running the front shutter curtain, which is open when the rewind knob 5 is in the normal operating position shown in FIG. The position where the switch 12 closes is not limited to the same time as the opening of the back cover. By closing the shutter in the raised position, the user can arbitrarily select whether or not to run the front shutter curtain.

FIG. 4 is a circuit diagram showing an embodiment of the present invention.

In the figure, 11 is a switch that is turned on when the second stroke of the release button (not shown) is suppressed, 12 is a switch that is turned on when the back cover is opened, 13° and 14 are pull-up resistors for each switch 11 and 12, and 15 is a switch that is turned on when the second stroke of the release button (not shown) is suppressed. Nant gate 16 is an inverter gate. 17 is a flip frog, 18 is an AND gate, and s 17.18 constitutes a one-shot multivibrator. 19 is resistance,
21 is a magnet that controls the movement of the shutter front curtain.

22°23Fi resistor, 24 a transistor, and 25 a power supply battery. 26 is the first release button (not shown)
This is a switch that is turned on by stroke suppression. 2
7 is an AND gate, 28 is an OR gate, 29 is a resistor, 6
0 is a transistor. 61 is a constant current source, 32 operational amplifier, and 33 electric capacitor, and 31, 32, and 33 constitute an integrating circuit.

Reference numeral 34 denotes a voltage source which outputs a negative voltage corresponding to the shutter speed to be controlled by the output of a shutter speed calculating circuit (not shown). 65 is a comparator, 36 is a flip-flop, 67-way AND gate, and 36.37 constitutes a one-shot multivibrator. A clock pulse oscillator 68 supplies reference clock pulses to the flip-flops 17.36. 69 is resistance, 40u
)2 register, 41 is a trailing curtain control magnet.

Using the circuit configuration described above, the operation in normal photographing will first be explained.

When the shutter is charged and a release button (not shown) is pressed while the switch 12 is open, the switch 26 is turned on with the first stroke.
Since the output of the transistor 7 becomes low level, the transistor 24 becomes conductive, and the power supply 25 is supplied to each predetermined part, and the circuit is activated.

Next, by suppressing the second stroke, the switch 11 is turned on, and a predetermined pulse is output from the one-shot multi-pipe lakes 17 and 18. When the pulse is supplied to the base of the transistor 20 through the resistor 19, the transistor is turned on.
is excited.

Accordingly, the leading curtain (not shown) is unlocked and runs. Furthermore, before the switch 11 is turned on, the output of the OR gate 28 is at a high level, so the transistor 30 is turned on and the capacitor 63 is short-circuited. Therefore, the output of the operational amplifier 32 is the same as the ground level, and the voltage source 3
4 is at a negative potential, the output of the comparator 35 is at a low level, and no output is output from the one-shot multivibrator composed of the flip-flop 36 and the AND gate 67.)

Then, when the switch 11 is turned on, the output of the OR gate 28 changes to low level.) The transistor 30a is turned off, and the current of 31 is transferred to the capacitor 63 by the integrating circuit composed of the constant current source 31, the operational amplifier 32, and the capacitor 36.
When the output of the operational amplifier 62 becomes lower than the output voltage of the voltage source 34 corresponding to the shutter time, the output of the comparator 35 becomes high level, and a predetermined pulse is generated as a one-shot multi-by-break composed of 36.37. is output, and the pulse is supplied to the base of the transistor 40 via the resistor 69, the transistor 40 is turned on, and the trailing curtain control magnet 41 is excited. As a result, the shutter trailing curtain is released and runs, and the exposure is completed.

Next, to open the back cover, do not press the shutter button and switch 11.2<S by pulling up the rewind knob 5 from the off state.
Since the output of the AND gate 27 becomes low level, the transistor 24 becomes conductive and the power supply 25 is supplied to each predetermined part. Further, since the switch 12 is on and the switch 11 is off, the output of the OR gate 28 is at a high level, and the transistor 30 is on, so the trailing curtain control magnet 41 is not excited as described above. However, when the switch 12 is turned on, the Nantes gate 15
becomes high level, the leading curtain control magnet 21 is excited and the leading curtain runs in the same manner as described above. That is, only the leading curtain runs and the trailing curtain does not run, resulting in a so-called state where the curtain is left open.

Even if the second stroke of the shutter button is pressed and the switch 11 is turned on when the back cover is open, that is, the switch 12 is on, the output of the OR gate 28 is still high, so the rear curtain will not run. do not have.

In order to close the shutter, the next winding operation is forced while the rear curtain remains inactive. As a result, the shutter is charged and the front curtain covers the opening, and the next photograph is taken by pressing the shutter button.

Because the present invention has the above-described structure, there is no chance for the user to unconsciously touch the curtain or blade of the focal plane shutter with his or her finger (this prevents accidents such as blade deformation, breakage, and flying out). This also eliminates the possibility of fingerprints adhering to the metal blades.Also, by electromagnetically controlling the front curtain and the rear curtain, the rear curtain can be turned off if an inconvenience occurs with the shutter open. Winding can be carried out as is without running the camera, and unlike conventional cameras, where the next winding operation cannot be performed unless the rear shutter curtain moves, it is possible to check the performance of the shutter, etc. Even if it is necessary to operate the shutter in the open state, no problem will occur.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the back cover opening operation part, Figure 2 is a cross-sectional view showing the switch for running the front curtain is closed, and Figure 3 is a cross-sectional view of the back cover opening operation section.
The figure is a sectional view showing a modification, and FIG. 4 is a circuit diagram. 1: Camera 2 body, 2: Camera top cover, 6: Rewind bearing, 4: Rewind shaft, 5: Rewind knob, 6: Back cover opening/closing plate, 1
2: Switch to run the first curtain.

Claims (1)

[Claims] (1) A camera comprising a focal plane shutter and a switch that is linked to the opening operation of the first back cover, and when the first back cover is opened, the switch causes only the shutter front curtain to run, thereby opening the shutter. (2) Claim 1 (1) characterized in that the open state of the shutter is released by the next hoisting operation.
) Cameras listed in section.