JPS6161092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a standard shutter device for calibrating a focal plane shutter tester to maintain high accuracy at all times.

A focal plane shutter in a camera, etc. is installed just in front of the film surface of the camera, and runs through the aperture with the front and rear curtains of the shutter, and changes the width of the slit between these shutter curtains to achieve the desired shutter speed, that is, exposure. The shutter curtain is configured to run through the opening at a constant speed, especially during high-speed shutter operation. Various types of testers are used to test the shutter speed of the focal plane shutter of such cameras, and one type of tester measures the exposure amount by electrically detecting the amount of light passing through the shutter aperture. What is being measured is being used.
In this case, a method is generally used in which a certain amount of diffused light is incident through a lens of a certain diameter, and the output of a light receiving element provided at a position corresponding to the surface of the photosensitive material is integrated and displayed.

In order to maintain high accuracy of the above-mentioned shutter tester, it is conceivable to use a standard shutter device to easily calibrate the tester. In other words, by attaching a standard shutter device that passes a standard amount of light in place of the camera shutter to the shutter tester, displaying its output, and adjusting the light source and shutter tester to keep it at a constant value, the shutter tester can be used. It is possible to perform a calibration of

The object of the present invention is to provide a standard shutter device for calibrating the focal plane shutter tester as described above. In order to obtain such a standard shutter speed, a shutter device must be equipped with a mechanism that allows a shutter curtain with a constant slit width to run at an accurate constant speed, and the amount of light passing through the shutter curtain depends on the slit width. The slit width can be determined geometrically accurately, so if a standard shutter device has a structure that makes the curtain speed extremely accurate, It is often possible to calibrate the tester by attaching such a standard shutter to a shutter tester instead of the camera shutter and measuring the output of the tester.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a front view and a side view showing an embodiment of a standard shutter device according to the present invention. In the figure, a is a front view, b is a diagram showing the structure of the drive side, and c is a diagram showing the structure of the brake side. 1 is a shutter curtain drive motor that can rotate at a constant speed, such as a synchronous motor or a pulse motor, and 2 is an electromagnetic motor. The clutch transmits the rotation of motor 1 to the shutter curtain drive section. 3 is a roller for driving the curtain, 4 is a rotatable roller,
3 and 4 sandwich the shutter curtain, and the rotation of 3 moves the shutter curtain. 5 is a shutter curtain. As one embodiment of the shutter curtain 5 is shown in FIG.
4 and a row of small holes 15 for measuring curtain speed. Reference numerals 6 and 8 designate plates for preventing the shutter curtain from wobbling laterally as it runs, and a photo coupler comprising a light source and a light receiving element is attached to the plate 6 with the shutter curtain 5 in between. 7 is a camera body having an opening 13; 9 is an electromagnetic brake; 1
A roller 0 is attached to the shaft of the brake 9, and together with a guide roller 11, guides the movement of the shutter by sandwiching the shutter curtain 5, and also stops the movement of the shutter curtain by operating an electromagnetic brake. 12
is the control mechanism. FIG. 3 is a perspective view showing an arrangement for calibrating a shutter tester using the standard shutter shown in FIGS. 1 and 2, in which the same parts as in FIG. 1 are designated by the same reference numerals. In addition, 16 is a light source,
17 is a lens, and 18 is a light receiving section of the shutter tester.

Next, the operation of the standard shutter shown in FIGS. 1 and 2 will be explained. The shutter curtain 5 is inserted between the drive-side rollers 3, 4 and the brake-side rollers 10, 11, as shown in the figure, and the slit 13 and small hole 15 portion of the shutter curtain is initially an accumulation part (absence) on the brake side. (shown). In this state, the opening 13 of the tester is shielded from light by the shutter curtain 5. Further, the shutter curtain is set in advance so that it has a sufficient run-up distance before the small hole for measuring the curtain speed reaches the sensor 6. In this state, attach the standard shutter device to the tester,
Turn on the power switch (not shown) and rotate the motor 1. After the motor rotates at a specified speed, an operating switch (not shown) is turned on to connect the electromagnetic clutch 2 and transmit the rotation of the motor 1 to the roller 3. As a result, the shutter curtain starts running and moves in the direction of the arrow. The running speed of the shutter curtain becomes constant after running the run-up distance, and the row of small holes provided in the curtain passes between the light source LED of the photo coupler provided at 6 and the light receiving element SPD. The small holes have the same diameter and are arranged in a straight line in the curtain running direction so that the intervals are constant, and when these pass through the surface of the photo coupler, a pulse signal with a constant period is sent to the output of the light receiving element SPD. occurs. Based on this signal, it is determined whether the shutter curtain speed satisfies the set conditions. The slit 13 in the shutter curtain then passes through the opening in the tester, and light from the standard light source passes through the opening and the slit. This is detected electrically and the shutter time is measured. When the rear slit passes the photo coupler position, the electromagnetic brake 9 is activated by a signal from the detection circuit described later.
At the same time, power to the electromagnetic clutch 2 and motor 1 is cut off, and the movement of the shutter curtain 5 is stopped. In this state, the opening is completely blocked by the shutter curtain.

With the above operation, the shutter curtain slit 14
Since the aperture is scanned at a constant speed during exposure, the exact exposure time is determined from the slit width and curtain speed. If the curtain speed changes for some reason, the period of the pulse signal that passes through the small hole for measuring the curtain speed changes, and from this it is possible to know if there is an abnormality in the curtain speed.

When calibrating a tester that tests focal plane shutter using the standard shutter of the present invention, a lens of a fixed diameter is attached to the mount of the tester, and the diffused light passing through this is used. Furthermore, by using this device and using a standard lens with an accurate F number, it is possible to calibrate an image plane light meter.

Next, FIG. 4 is a block circuit diagram showing one embodiment of the drive circuit for the standard shutter device of the present invention. In the figure, LED is the light emitting diode of the light source lamp, and S is the shutter curtain, which has the structure shown in the second figure. SPD is a light receiving element, and LED and SPD
and make up the photo cutlet. A waveform shaping circuit 102 shapes the output signal of the SPD to obtain a pulse signal (FIG. 5a). FIG. 5 is a timing chart showing waveforms of various parts of the circuit of FIG. 4. 1
03 is a one-shot circuit which is excited by the pulse signal shown in FIG. 5a and generates a pulse of a constant width as shown in FIG. 5b. 104 is a comparison circuit, and 105 is a detection circuit that determines whether the output signal from the SPD is a curtain speed measurement pulse or a shutter slit signal, and detects the fall of the slit signal at a time corresponding to the phase. Outputs a single pulse as shown in Figure 5c. 10
7 is a gate control circuit, and 108 is a gate circuit which ANDs the pulse signal (FIG. 5a) and the output of the gate control circuit (FIG. 5d). 109 is a counter that counts the pulses that have passed through the AND gate 108, and 110 is a comparison circuit that determines whether the count number 109 is within the error tolerance range or outside the range. 111 is a circuit that generates signals indicating the upper and lower limits of error tolerance, and 112 is a display circuit.

Next, the operation of the circuit shown in FIG. 4 will be explained. When a start switch (not shown) is turned on, the motor 1 rotates, the electromagnetic clutch 2 is brought into contact, and the shutter curtain 5 starts traveling in the direction of the arrow, as explained in FIG. As the shutter curtain runs, the small hole 15 for measuring the curtain speed passes through the photo coupler surface, and a pulse signal as shown in FIG. 5a is output from the SPD. Now, if the shutter speed is υ, the diameter of the small hole is Φ, the distance between the small holes is L, and the width of the shutter slit is _L0 , then the time T ₁ of light passing through one of the small holes 15 is T ₁ =Φ/υ ………(1) Time required for the curtain to travel the distance between the small holes
T ₂ is T ₂ =L/υ (2) and the opening time T ₀ of the shutter slit is T ₀ =L ₀ /υ (3). Further, if the pulse width generated at the output of the one-shot circuit triggered by the pulse signal (Fig. 5a) is _T3 , and this _T3 is selected as _T1 < _T3 < _T0 (4), The output of the comparator 104 is at a low level L while the small hole passes through the photocoupler surface, and is reversed to a high level H at time _t3 delayed by a time _T3 from the rise of the shutter opening pulse. Further, as shown in FIG. 5c, the output of 104 is inverted again to the L level at time _t4 when the rear end of the shutter slit passes through the photo coupler surface. At this time _t4 the detection circuit 105 generates a single pulse (FIG. 5d). That is, when the pulse d occurs, it means that the shutter slit has passed through the opening, and this signal becomes the output 106, which turns off the motor and electromagnetic clutch, and at the same time activates the electromagnetic brake to stop the shutter curtain from moving. let

The output pulse of the pulse shaping circuit 102 in the figure is
Input to AND gate 108, gate control circuit 1
07 (FIG. 5e), and its output pulses are counted by a counter 107. The output of the counter 109 is input to a comparator circuit 110 and compared with the error tolerance upper and lower limit signals applied to one input of the comparator circuit 110 . That is, it is determined whether the count number 110 is within the range of the allowable value generated by the circuit 111 or outside the range, and this is displayed on the display circuit 112.
This allows it to be determined whether the calibration using the standard shutter is accurate or not.

As described above, the standard shutter device according to the present invention can operate while accurately measuring the curtain speed, and can be used to easily calibrate the shutter tester, ensuring that the tester always has high accuracy. This can be highly effective in improving the accuracy of product inspection. In addition, in the above embodiment, a photocoupler is used to measure the curtain speed, but this measurement is not limited to photoelectric means, and it is also possible to measure using a magnetic recording medium and a head, for example. Needless to say.

[Brief explanation of the drawing]

FIG. 1 is a top view and side view showing an embodiment of the standard shutter device according to the present invention, FIG. 2 is a plan view showing the structure of the shutter curtain, and FIG. 3 is a shutter tester calibration using the standard shutter shown in FIG. 1. FIG. 4 is a block circuit diagram showing an embodiment of the drive circuit of the standard shutter device shown in FIG. 1, and FIG. 5 is a timing chart showing waveforms of various parts of the circuit shown in FIG. 4. be. 1... Drive motor, 2... Electromagnetic clutch,
3, 4... Drive side roller, 5... Shutter curtain, 14... Shutter slit, 15... Small hole row for curtain speed measurement, 6, 8... Shutter curtain guide plate, 7... Tester opening , 9...electromagnetic brake,
10, 11...braking side roller, 12...braking mechanism, 13...opening, 14...slit, 15...
...Small hole row, 16...Light source, 17...Lens, 18
... Tester light receiving section.

Claims (1)

[Claims] 1. In a standard shutter device that is attached to a shutter tester for testing the shutter operating characteristics of a focal plane shutter to calibrate the shutter tester, a focal plane shutter is provided with a slit that forms a shutter opening of the standard shutter device. A shutter curtain, a drive means and a control means for running the shutter curtain at a constant speed, and a row of small holes of the same size arranged at equal intervals on the running direction side of the slit of the shutter curtain, and the row of small holes. A photo coupler that detects transmitted light and converts it into an electrical signal, a counter that counts output signals of the photo coupler, and a determination that determines whether the counted value of the counter is within a permissible range. A standard shutter for calibrating a shutter tester, characterized in that it has a means for calibrating a shutter tester.