JPS6232462B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a high speed rotary shutter system.

In order to record high-speed moving objects on photographic film without blur, there is a strong demand for the development of a shutter with a shutter speed of 1/1000 seconds or more. It is possible to obtain a shutter speed of 1/1000 or more with a sector shutter that rotates continuously at high speed, but it is difficult to obtain a shutter speed of 1/1000 or more seconds with a shutter that records one sheet at a time. It is. This is because the sector blade and its drive mechanism have inertia, and the motor itself also has inertia, making it impossible to instantaneously obtain the desired rotational speed. Also, even if the opening part of the sector reaches the desired speed, it must be slowed down and stopped, so the rotation angle until it opens is increased and the rotation angle until it stops is decreased. It is difficult. Therefore, the opening part of the sector is accelerated from 180° in front of the film aperture,
A method is adopted in which the film decelerates when it reaches the film aperture, rotates an additional 180 degrees, and then comes to a standstill to complete one operation. 1/1000～1/20
When attempting to configure a shutter system capable of obtaining a shutter speed of 0.00 seconds, problems arise in that the acceleration/deceleration method described above may not provide a sufficient sector speed or force the shutter to come to a stop.

An object of the present invention is to provide a control method for a rotary shutter system in which one photograph is taken at a time using a sector shutter having a constant opening angle, which can provide good acceleration and constitute a durable system. Our goal is to provide the following.

The present invention will be described in more detail below with reference to the drawings and the like.

The conventional sector running and the sector running according to the present invention will be explained while comparing them with reference to FIGS. 1 and 2. FIG. 1A shows a conventional sector in which the film section is opened by traveling 180 degrees, and one cycle is completed by traveling another 180 degrees. FIG. 1B is a graph showing running characteristics. Sector s is accelerated clockwise from x where the opening angle portion that fully opens film aperture F is at the position indicated by the dotted line, and rotates 180 degrees to expose film aperture F at y. Once this exposure is done, it is then rotated another 180 degrees while being decelerated, returning to its original position z.
When it reaches this point, it is brought to a standstill and the first photographing is completed.
The angular velocity of sector s is obtained by differentiating the curve shown in FIG. 1B. At the beginning of the run, the speed is extremely slow, but it is gradually accelerated, and when it reaches the aperture portion y, it reaches the maximum angular speed, and is gradually decelerated to complete one cycle.

Generally speaking, the slope d of the curve at time y
It is preferable that ω/dt be large and that the slope in z be small. However, it is difficult to create ideal conditions within a limited rotation angle.

FIG. 2 is an explanatory diagram for explaining the sector driving method according to the present invention. In the driving method according to the present invention, as shown in FIG.
The opening portion of the sector s, which is fully opened, is rotated from a position a at an angle α, which is more than 180 degrees in front of the film aperture F. If the opening degree of sector s is θ, this angle α cannot exceed 2π−θ. From point a to aperture center b
From point b, it is decelerated, rotated by an angle β, and then stopped once. This β also cannot exceed (2π-θ). Next, it is rotated counterclockwise from position c and returned to position d (d=a), completing one photographing cycle.

FIG. 2B is a diagram showing this operating characteristic. Sector s is accelerated from point a, which is α (=3π/2) before aperture F, and reaches point b. Since the acceleration time is π/2 longer than the case explained in Fig. 1, if the conditions such as inertia and acceleration are the same, the acceleration dω/dt at point b is lower than the velocity at point y in Fig. 1A. growing. When the sector s reaches point b and the film aperture F is fully opened, the sector s is decelerated and reaches point c while gradually decreasing the speed. The angular velocity dω/dt at point c becomes zero. This means that the sector has been temporarily stopped. Subsequently, it is rotated in the opposite direction and reaches point d, completing one imaging cycle.

According to such a control method, sufficient acceleration can be obtained at point b of the aperture portion, and it is also possible to decelerate easily and return to the next starting position.

Next, a driving device that can implement the above control method will be described.

FIG. 3 is a block diagram showing an example of the configuration of a control circuit for driving the sector shutter, and FIG. 4 is an operational characteristic diagram for explaining the operation of the circuit.

A pair of photocoupler PC ₁ is used to detect the position angle of sector s and form a control timing signal.
A PC ₂ is provided in association with sector s. Photocoupler PC ₁ is a photocoupler for detecting when sector s has reached the fully open position of aperture F, and PC ₂ detects when an open angle exists at point a shown in Figure 2 A. It is a photocoupler for

The sector s is adapted to be driven by a print motor M of low inertia. This motor has low inertia and can rotate in forward and reverse directions, and the steady rotation speed can be controlled by voltage. The timing generation circuit 1 is configured to receive a signal instructing the start of imaging and the signals from the photocouplers PC ₁ and PC ₂ described above, and the timing generation circuit 1 receives the next signal in accordance with the order of these inputs. The acceleration signal generation circuit 2, deceleration signal generation circuit 3, and inversion signal generation circuit 4 connected to each stage are sequentially driven to sequentially generate an acceleration signal V _A , a deceleration signal V _B , and an inversion signal V _C . These outputs are summed by a summing amplifier 5 and applied to a motor control circuit 6 to form a motor drive voltage and applied to the motor M.

Next, the operation of the control circuit will be explained in detail with reference to the time chart of FIG. 4.

When a start signal is applied to the timing generation circuit 1 when the sector opening is at the start position a indicated by the dotted line in FIG. The accelerating voltage is applied to the motor control circuit 6 and the motor M. This voltage gradually accelerates the sector s, and when it reaches point b shown in FIG. 2A, the photocoupler PC ₁ generates an output. The timing generation circuit 1 stops the operation of the acceleration signal generation circuit 2 and activates the deceleration signal generation circuit 3 according to the trailing edge of the output of PC ₁ . The output of the deceleration signal generating circuit 3 is converted into a decreasing voltage by the summing amplifier 5 and applied to the motor control circuit 6, and a gradually decreasing decelerating voltage is applied to the motor M. After decelerating for a predetermined period, the inversion signal generation circuit 4 is activated to generate an inversion signal. This signal causes the motor M to reverse from the position c shown in FIG. 2A and slowly move in the direction d. The opening angle part is d (=
When the position a) is reached, the photocoupler PC ₂ outputs an output, which causes the reversal signal to stop and the motor M to stop as well. As shown in FIG. 4, PC ₂ sends out an output three times during one operation, and the timing generation circuit sets the trailing edge of the third output as the point of stop.

FIG. 5 is a graph showing the relationship between motor control voltage and motor speed in comparison with a conventional device. Fifth
Figure A is a graph showing the relationship between motor speed and control voltage for 180° acceleration and 180° deceleration shown in Figure 1A. Even if voltage V is instantaneously applied, the motor will speed up according to its own startup characteristics, and will not stop instantaneously even if it accelerates 180 degrees and the voltage becomes zero. FIG. 5B is a diagram showing the relationship between control voltage and motor speed when using the control method according to the present invention described in detail above.
Section a→b (π<α<2π−θ) shown in Figure 2A
Acceleration voltage V _A is applied only by V A . Since this section is substantially longer than in the conventional method, the motor can be smoothly increased to a predetermined rotational speed. In the section b→c, the motor rotates by β (π<β<2π−θ) while being decelerated by the gradually decreasing voltage, and the speed becomes zero. Then the inversion voltage (-V _C )
is added and returned to the position d (=a), that is, the starting position.

FIG. 6 is a graph showing the mode of deceleration voltage.
As shown in FIG. 6A, if the control voltage is instantaneously changed from V _A to V _B =0, the deceleration effect is large. However, in general, during deceleration, a force acts in the opposite direction to the acceleration direction, so a sudden voltage change will give an impactful force to the motor and mechanical system. As a result, mechanical noise is generated, and there is a possibility that the device cannot withstand repeated use.

FIG. 6B is a graph showing the aspect of the control voltage explained in FIG. 5B. Such a control voltage can be obtained by providing an integrating circuit using an operational amplifier in the deceleration signal generating circuit 3 shown in FIG. This uniform acceleration deceleration largely eliminates the motor and mechanical problems described in connection with FIG. 6A. However, even with this control method, a rather large change in acceleration can be seen at the shoulder section where the transition from V _A to V _B occurs. Although it is possible to operate the mechanical system without difficulty using this control method, it is also possible to use a deceleration voltage as shown in FIG. 6C. By providing a function generator in the deceleration signal generation circuit, a voltage change that approximates an ideal deceleration curve is given by a broken line. In this way, damage and noise caused by impact on the motor and mechanical system are completely eliminated.

Such voltage control can also be applied to control of the reversal voltage, but there is no need to take such consideration since the speed is decelerated and stopped for a while before being reversed. However, it is effective when shortening the inversion time.

As explained in detail above, according to the method of the present invention, rotary shutters can be effectively controlled,
The apparatus for carrying out the method of the invention can reasonably achieve high shutter speeds. Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

The scope of the present invention extends to all of the claims, including any modifications thereof.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram and a running characteristic diagram for explaining conventional sector running, and FIG. 2 is a schematic diagram and a running characteristic diagram for explaining sector running according to the method of the present invention. FIG. 3 is a block diagram showing an embodiment of a control circuit for carrying out the method of the present invention, and FIG. 4 is a graph for explaining the operation of the circuit. Fifth
The figure is a graph showing the relationship between the voltage applied to the motor and the rotational speed of the motor, and FIG. 6 is a graph for explaining the types of deceleration voltages applied to the motor. s...Sector, F...Film aperture, 1
...timing generation circuit, 2 ... acceleration signal generation circuit, 3 ... deceleration signal generation circuit, 4 ... inversion signal generation circuit, 5 ... summing amplifier, 6 ... motor control circuit, M ... motor, L ... …lens.

Claims (1)

[Claims] 1. A rotary shutter system in which a sector shutter having an opening angle θ that fully opens the film aperture is rotated by a motor so as to pass over the film aperture only once per photograph, thereby exposing the film one time at a time. In the control method, α from the center of the sector opening angle when the sector is fully opened
The steps include applying an accelerating voltage to the motor to rotate the sector at an increased speed from a starting position earlier than (π<α<2π−θ) toward the shutter open position; and While gradually lowering the applied voltage and decelerating the sector speed, further β(π<
(beta < 2π - θ) to bring the speed to zero; and applying a reversal voltage to the motor from the β position to rotate the motor in the opposite direction to the traveling rotation direction to bring it to the α position. A method of controlling a rotary shutter, including: