JP3110179B2 - Signal detection device for camera shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a position by an optical sensor in a camera shutter having a lens extension mechanism or an aperture mechanism.

[0002]

2. Description of the Related Art Conventionally, a lens extension mechanism for automatically adjusting the focus by providing a lens barrel integrally with a shutter block, and an aperture mechanism for adjusting the position of aperture blades to obtain an appropriate exposure value. In order to reduce the number of sensors for position detection and reduce the size of the device, the shutter blades are configured to interlock with the shutter blades at the beginning of the operation of the lens drive ring and the aperture ring, and the initial position detection is performed at the shutter blade position. A detection sensor used in combination with one sensor is used. In these types, only the initial position is detected, but not performed in each set stage (extending amount, aperture value).

In addition, a stepping motor, an iris motor, a DC motor, or the like is used as a driving source for these mechanisms. When a stepping motor is used as the driving source, the position of each set stage is set by open loop control. However, when an iris motor or a DC motor is used, open-loop control cannot be performed, so that the lens extension and aperture operation are intermittently operated using, for example, a stepping mechanism to determine the position of each set stage. It was necessary to make settings.

[0004]

In the case of the above-mentioned conventional example, it is necessary to detect that the lens or the aperture blade is at the initial position.
An operation sequence for position confirmation was required before the shutter operation. That is, all shutter operations have to be performed from the state where the lens and the aperture blade are at the initial position. Further, in a shutter using an iris motor or a DC motor as a drive source, a mechanism for intermittently operating the shutter is required, which causes a problem that the structure and operation sequence of the shutter are complicated.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a shutter having a lens feeding mechanism or a diaphragm mechanism, and An object of the present invention is to provide a signal detection device which can perform position detection in real time and can form a shutter with a simple structure and an operation sequence even when a motor which cannot perform open loop control is used as a driving source.

[0006]

SUMMARY OF THE INVENTION According to the present invention,
The signal detection device of the camera shutter is a lens extension mechanism
Or at least a camera shutter having an aperture mechanism
Also has a light emitting element and a light receiving element
Position of the member operating on the optical path due to the change of light
Optical detection means for detecting the lens extension position or
It has a continuous slit corresponding to the aperture position and
A first slit member for operating a slit on the optical path;
It has a slit for detecting the predetermined operating position of the shutter blade.
The slit is operated on the optical path.
Second slit portion interlocking with the shutter blade or the shutter blade
And an absolute value signal level detection circuit is provided.
Detecting by the detecting means from the slit of the first slit member
Lens extension position or aperture position based on the absolute value of the signal level
And the change signal level detection circuit detects the shutter position.
Detecting means from the blade or the slit of the second slit member
The predetermined amount of change of the signal level detected by
Characterized in that the position is detected.
You.

The principle of the present invention will be described with reference to FIG.
In the figure, 1a is the light projecting unit, 1b is receiving unit, 2 a slit 2a of varying the width continuously formed slit
The slit member 3 is a comb-shaped slit member . The slit members 2 and 3 are movably disposed between the light emitting unit 1a and the light receiving unit 1b.
By changing the position of the slit members 2 and 3, the amount of light emitted from the light emitting unit 1a and received by the light receiving unit 1b is changed. The light receiving unit 1b photoelectrically converts and outputs a current i having a magnitude corresponding to the amount of received light, and the detected current i is input to a circuit (not shown) for determining the absolute value of the current and a circuit for determining the amount of change in the current. It has become so.

[0008] In FIG. 1, a slit originating from the position i.e. the light projecting units 1a shows a slit member 2 in solid line in the drawing 2
from the narrowest position the width of the slit 2a is to light passing through a, to the position i.e. widest a position indicated by a dotted line, when moved over time t _1, the current output from the light receiving unit 1b i changes as shown in FIG. 2A corresponding to the change in the amount of received light accompanying the movement of the slit 2a. That is, in FIG. 2 (A), the during the up 0 to t ₁ the absolute value of the current signal | i | By measuring the value, the position of the slit 2a that contain changed to the amount corresponding to the value, in other words For example, the position of the slit member 2 can be detected.

Furthermore, in FIGS. 1 and FIG. 2 (A), the scan
With the movement of the slit member 3, after the light received by the light receiving unit 1b is temporarily shielded by the time t _2, the light quantity is changed to again received at time t _3. Then, [d | i
| / Variation of the current i, represented by dt] is as shown in FIG. 2 (B), the amount of change per unit time at time t ₂ ~t ₃ becomes considerably large value. That is, for example pre-sets the current i of the variation of the reference value b (see FIG.), If to detect only the change amount exceeds the reference value b, the variation in the amount of variation of the slit member 3 The position can be detected.

Accordingly, it provided as a movable member for detecting the slit member 2 lens extension position or stop position and, when providing the slit member 3 as a movable member for detecting the position of the shutter blade, the real-time
It is the position detection of the variable rotary members, since the single photosensor can detect the position of the two movable members, a camera shutter with a simple structure and operation sequence
This makes it possible to configure a signal detection device for the data .

[0011]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 3 shows the present invention suitable for a camera shutter having an aperture mechanism.
In the figure, reference numeral 11 denotes an opening 11
a, an aperture driving ring in which a cam portion 11b for the aperture blade and a slit 11c having a continuously changed width are formed; It is. Diaphragm blade 12 is being rotatably supported by the other members (not shown) by dowels 12b, also dowel 12a is the cam portion 11b
And mounted on the aperture drive ring 11. Soshi
Thus, such an aperture blade 12 is formed from the number of the cam portions 11b.
As can be seen, actually five are provided. 13,1
Reference numeral 4 denotes a shutter blade for opening and closing the opening 11a, and reference numeral 15 denotes a shutter blade 1 connected to a drive source (not shown) such as a DC motor or a stepping motor via a dowel 15a.
An opening / closing lever for operating the light emitting units 3 and 14 and an optical sensor unit 16 having a built-in light emitting unit 16a and a light receiving unit 16b.

[0012] diaphragm blades 12, by the dowel 12a is being apparatus to the drive ring 11 stop engages with the cam portion 11 b, the diaphragm drive ring 11 is rotated counterclockwise in FIG. 3, dowel 12b 11 as a fixed axis
a is squeezed. The slit 11c also moves with the rotation of the aperture driving ring 11.
A comb-shaped slit 14a is formed at one end of the shutter blade 14 along a line along which the 1c moves. The light projecting unit 16a and the light receiving unit 16b of the optical sensor unit are connected to the slit 14a and the slit 11
The slits 11c and 14a are arranged so as to sandwich these slits on the movement line of c. The light receiving amount in the light receiving unit 16b is changed by changing the positions of the slits 11c and 14a, and the light receiving unit 16b has a size corresponding to the light receiving amount. The current i is photoelectrically converted and output.

FIG. 4 shows a circuit block for detecting and controlling the position of the aperture driving ring 11 in response to the detection current i output from the light receiving unit 16b. In the figure, reference numeral 17 denotes an absolute value signal level detection circuit for detecting and outputting the magnitude of the absolute value of the detection current i, and reference numeral 18 denotes a preset absolute value signal of the target rotation amount of the aperture drive ring 11 and a signal from the detection circuit 17. An operation control circuit for detecting the position of the aperture drive ring 11 by comparing the magnitude of the signal with the signal and controlling the position at the same time, and a change signal level detector 19 for detecting a change amount of the detection current i per unit time. Circuit, 20
Is a trigger circuit that detects a state in which the amount of change detected by the detection circuit 19 exceeds a certain magnitude and uses this as a shutter trigger. 21 is a circuit for controlling the exposure amount after a trigger signal from the trigger circuit 20 is input. This is the exposure amount control circuit to be performed.

Next, the operation sequence of this embodiment will be described. Before performing the exposure amount control, the aperture blade control is performed.
First, a target rotation amount of the aperture drive ring 11 is set in the operation control circuit 18 in advance. The aperture blade 12 narrows the opening 11a with the rotation of the aperture drive ring 11, and at the same time, the slit 11c changes its position, so that the amount of light received by the light receiving unit 16b changes. That is, the aperture blade 1
2 is a detection current i having a magnitude corresponding to the amount by which the opening 11a is narrowed.
Is input to the detection circuit 17. The detection circuit 17 detects the magnitude | i | of the absolute value of the detection current i and detects the operation control circuit 1
8 is output. The operation control circuit 18 compares the signal from the detection circuit 17 with the absolute value signal of the target rotation amount of the aperture driving ring 11 and determines that the magnitude of the signal from the detection circuit 17 is the magnitude of the absolute value signal of the target rotation amount. Then, the diaphragm drive ring 11 is rotated until the position becomes the same as that described above, and the position is controlled.

After setting the position of the aperture blade 12, the sequence proceeds to a sequence for detecting the amount of change in the detection current i in order to detect the position of the shutter trigger. In this case, the detection circuit 19 changes the detection current i per unit time [d | i | / d
the detection of t], but changes its position shutter blades 3 and 4 is actuated, the slit 14 a is shielded once the light has been received by the light receiving unit 16b, the change amount becomes extremely large. The value of the amount of change at this time is detected by the trigger circuit 20, and the control timing signal S is sent to the exposure amount control circuit 21.
Output t. The exposure control circuit 21 starts exposure control using an input signal from the trigger circuit 20 as a trigger.

Since the present embodiment is constructed as described above, the position of the aperture drive ring 11 can always be detected in real time, and the sequence can be controlled by open loop control regardless of the type of motor driving the aperture drive ring 11. Can be activated. Further, since the position of the two movable members can be detected by one photosensor, the shutter can be configured with a simple structure and an operation sequence.

FIG. 5 shows the present invention having a lens feeding mechanism .
1 shows an embodiment applied to a camera shutter . In this case, the slit 31 of the lens feeding cam 31
a has a continuously changing width similarly to the slit 11c of the aperture driving ring 11 described above, and the slit 14a formed in the shutter blade 14 passes through the inside of the optical sensor unit. A similar operation and effect can be obtained with a similar operation sequence. In the above-described embodiment, an example is described in which only the position of the shutter trigger is detected. However, the number of slits may be increased to detect the position of the blade for detecting the aperture F value during flash synchronization.

[0018]

As described above, according to the present invention, in a shutter having a lens extension mechanism or an aperture blade mechanism, the position of the lens extension or aperture position can be detected in real time, and an iris motor or a DC motor is used as a drive source. In this case, the sequence can be operated by the open loop control. In addition, since the position of the two movable members can be detected by one photo sensor, the shutter can be configured with a simple structure and an operation sequence.

[Brief description of the drawings]

1 is a diagram for explaining the principle of the present invention.

[2] FIG. 2 (A), Ri FIG der showing changes of a signal obtained from the circuit for determining the absolute value of the current by moving the slit member 2 of FIG. 1, and FIG. 2 (B) Figure 1
By moving the slit member 2 of FIG.
FIG. 7 is a diagram showing a state of a change in a signal obtained from a determination circuit;
is there.

FIG. 3 illustrates a camera shutter having an aperture mechanism according to the present invention .
FIG. 3 is an exploded perspective view of the embodiment applied to FIG.

FIG. 4 illustrates a detection signal processing circuit in the embodiment of FIG . 3;
It is a block diagram for clarification.

FIG. 5 shows a camera having a lens extension mechanism according to the present invention .
FIG. 4 is an exploded perspective view of an embodiment applied to a shutter for use in the present invention.

[Explanation of symbols]

1a, 16a ... Light emitting unit 1b, 16b ...
Light receiving units 2, 3 Slit member 11 Aperture drive ring 12 Aperture blades 13, 14 Shutter blades 15 Opening / closing lever 16 Optical sensor unit 31 Lens extension cam

Claims (1)

(57) [Claims] 1. A lens extension mechanism or a diaphragm mechanism is provided.
At least a light emitting element and a light receiving element
The light incident on the light receiving element
Optical detection to detect the position of a member operating on the optical path
Means and a link corresponding to the lens extension position or the aperture position.
Having a continuous slit and forming the slit on the optical path.
A first slit member to be moved, and a predetermined operation of a shutter blade.
It has a slit for detecting a moving position, and the slit is
Shutter blades or shutters
A second slit member interlocked with the blade,
An absolute value signal level detection circuit is provided for detecting the position of the first slit member.
Absolute value of the signal level detected by the detection means from the lit
To detect the lens extension position or aperture position, and
Signal level detection circuit is the shutter blade or the second slit
The signal level detected by the detecting means from the slit of the member
To detect the predetermined position of the shutter blade based on the amount of change
Signal detection device for camera shutter
Place.