JP2585003B2 - Multi-program shutter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor-driven multi-program shutter capable of switching an opening / closing speed of a sector according to a shooting mode.

[Prior art] Generally, a high-speed program is required when using a lens with a long focal length or when shooting a moving subject, and a low-speed program is required when using a lens with a short focal length or when you want to increase the depth of field. Become. As for a multi-program shutter having a high-speed program and a low-speed program, as has been proposed by the present applicant as Japanese Patent Application No. 61-2796 (Japanese Patent Application Laid-Open No. 62-160430), the rotational speed of the motor is switched. To control.

In addition, a relatively inexpensive step motor capable of normal and reverse rotation is used as the above-mentioned motor, and it is general to change only the pulse energizing time in order to switch the rotation speed of the step motor.

However, as shown in FIG. 7, when a driving condition in which the relationship between the rotor rotation angle of the stepping motor and the pulse is linear at a high speed is set and only the energization time of the pulse is changed at a low speed, the rotor rotation angle and the pulse are changed. Is disturbed as indicated by the dotted line. This is because the balance between the output of the step motor and the load is lost, and as a result of this disturbance, the change in the sector opening diameter with the passage of time becomes non-uniform as shown by the dotted line in FIG. Has disadvantages. Conversely, if an appropriate motor drive condition is set at low speed, the rotor of the step motor will not follow the pulse at high speed, and the shutter will not operate normally.

[Purpose] The present invention has been made in order to solve the above-mentioned drawbacks, and it is an object of the present invention to provide a multi-program shutter capable of performing a smooth motor operation in accordance with each program and enabling accurate exposure control. Is to do.

[Means for Achieving the Object] That is, in order to achieve the above object, the present invention has a high-speed program and a low-speed program in which a shutter is operated by a motor and a shutter speed is relatively high and low, In a multi-program shutter in which one of a high-speed program and a low-speed program can be selected by a switching unit, a drive for supplying power to the motor so that the motor operates smoothly regardless of which of the high-speed program and the low-speed program is selected. A multi-program shutter is characterized in that one of a pulse driving voltage or a driving current and a pulse time are made different according to a high-speed program and a low-speed program.

[Embodiment] Therefore, details of the present invention will be described below based on an illustrated embodiment.

FIGS. 1 and 2 show an example of a shutter mechanism to which the present invention is applied. In the drawings, reference numeral 1 denotes a base plate on which a base plate 2 for positioning a lens is mounted. A chamber 3 is formed in which two sectors 4, 4 symmetrically pivoted to determine the lens aperture are pivotally provided by pins 5. Reference numeral 6 denotes a sector drive lever, which is rotatably supported by a shaft 7 implanted in the base plate 1, and which is rotatably provided on the shaft 7 through a groove 6a formed at one end of a sector drive wheel 9 described later. 9a, and is engaged with the sectors 4, 4 by the sector pins 10 implanted on the base plate side. Reference numeral 9 denotes the above-mentioned sector drive vehicle, which is rotatably supported by a shaft 7 so as to be regulated to a reference position at rest by a spring 8 for imparting left-turning, and which is formed at one end, by means of degree determining portions 9b, 9b formed on the outer periphery. The toothed portion 9c is connected to a drive shaft 13a of a step motor 12, which will be described later, via a wheel train.

In the figure, reference numeral 11 denotes a degree determination unit 9b of the sector drive vehicle 9,
9B shows a pin that engages with 9b to regulate the rotation range.

FIGS. 3 and 4 show one embodiment of the above-described step motor 12. In the drawings, reference numeral 13 denotes a four-pole rotor made of a permanent magnet, and one end of a rotor shaft 13a is protruded so that an upper plate 14 is formed. And the lower plate 15 is rotatably mounted, and the sector drive wheel 9 of the shutter mechanism is driven by the pinion 16 mounted on the shaft 13a. Reference numerals 17 and 18 denote stators made of a U-shaped magnetic material each having two legs formed thereon, and the exciting coils L1 and L2 are wound around one of the legs, respectively. Magnetic pole 17 at 90 °
a, 17b, 18a and 18b are formed. These stators 17 and 18 are positioned in a “C” shape by positioning with guide pins 19 such that one of the magnetic pole portions 17b and 18b takes a position of 45 ° with respect to the rotor 13, and is disposed at 90 ° for one step. The rotor 13 is configured to be able to rotate in the forward and reverse directions.

On the other hand, in FIG. 1, a control circuit 22 is connected to the above-described step motor 12 via a drive circuit 21 to which a constant voltage circuit 20 described later is connected.
The selector switch 23 and the constant voltage circuit 20, which can select a high-speed program and a low-speed program described later, are connected to the switch. The drive circuit 21 amplifies and converts the output signal of the control circuit 22 and supplies power to the excitation coils L1 and L2 of the step motor. The constant voltage circuit 22 can control two kinds of high and low supply voltages. Drive circuit 21
Output to The control circuit 22 obtains two types of programs, a high-speed program and a low-speed program, which will be described later, with reference to FIG. 5, based on the brightness information of the subject from a photometry unit (not shown) and the opening / closing information of the switch. As described above, the number of pulses, the pulse time, and the applied voltage, which are the driving conditions of the step motor 12, are set in advance. In the above-described motor driving conditions, the pulse time and the applied voltage
For example, if the changeover switch 23 is in the open state as a high-speed program, a preset short pulse time and a high applied voltage are selected,
When the changeover switch 23 is in the closed state, a preset long pulse and a low applied voltage are selected. In general, the response of a step motor increases as the applied voltage increases,
Since the response becomes worse when the applied voltage is reduced, the applied voltage and the pulse time are set so that the relationship between the rotor and the pulse of the step motor is linear at both high and low speeds as shown in FIG. Thus, the change of the sector opening diameter with the passage of time becomes linear as shown in FIG.

In program diagram according to an embodiment of Figure 5 is the present invention, the vertical axis represents aperture value (FNo.), Horizontal axis represents the shutter speed (T), Oblique is E _V value. The high-speed program is a program with a high shutter speed that is suitable when using a telephoto lens or shooting a moving subject. The low-speed program is a program with a low shutter speed that is suitable when using a wide lens or when you want to increase the depth of field due to the aperture effect. is there.

Next, the operation of the shutter configured as described above will be described.

First, for example, to use a lens with a long focal length,
Switch 23 for high-speed programs that are less affected by camera shake
Shall be selected by By operating a release button of a camera (not shown), a power switch (not shown) is turned on, and luminance information of the subject and information of a changeover switch 23 are input to the control circuit 22.
The control circuit 22 selects the high-speed program in FIG.
Determine the 12 applied voltages and pulse times. Further, the control circuit 22 determines the number of pulses of the step motor under the condition that the relationship between the aperture and the shutter speed becomes a diagram of a high-speed program from the luminance information, and outputs the pulse number to the constant voltage circuit 20 and the drive circuit 21. The constant voltage circuit 20 outputs a higher supply voltage to the driver circuit 21 by a signal from the control circuit 22.The driver circuit 21 outputs a higher applied voltage and a shorter pulse time and a predetermined time by the output from the control circuit 22 and the constant voltage circuit 20. The number of pulses is output to the step motor 12. Then, when the output of the drive circuit 21 is supplied to the exciting coils L1 and L2 of the step motor 12, the stators 17 and 18 are excited, respectively, and the rotor 13 rotates forward and backward by a predetermined number of pulses under the above-described driving conditions. The rotation of the rotor 13 is transmitted to the sector driving vehicle 9 via the pinion 16 against the load of the spring 8, and the rotation of the driving vehicle 9 is transmitted to the sector 4 via the sector driving lever 6. Thus, the sector opening operation at the time of high speed shown in FIG. 4 is performed.

On the other hand, when the low-speed program is selected by the changeover switch, the low-speed program in FIG. 5 is selected, and the driving condition of the step motor is determined based on each information, and the sector opening operation at low speed in FIG. 4 is performed. Things.

In the above embodiment, two programs, high speed and low speed, were used. However, even when the number of programs exceeds two, the number of changeover switches is increased, and an appropriate pulse time and applied voltage are set for each program. It can be easily implemented. Further, in the above-described embodiment, the description is made such that an appropriate pulse time and an applied voltage are set for each program. However, a similar effect can be obtained by setting an appropriate pulse time and a motor drive current for each program. be able to.

Although the embodiment using the step motor has been described, any motor that controls forward and reverse rotation can be applied based on the concept of the present invention.

Further, in the above embodiment, the changeover switch is selectively operated. However, in a camera having a lens having a plurality of focal lengths such as telephoto and wide-angle, the use of the telephoto lens is enabled by interlocking the changeover switch with the lens selection means. Sometimes it is possible to automatically select a high-speed program and a low-speed program when using a wide-angle lens.

[Effects] As described above, according to the present invention, the length of the pulse supplied to the motor is changed according to the selected program,
Since the voltage or current supplied to the motor is changed according to the pulse length, the motor can be operated smoothly in each program, and the change in the aperture diameter over time becomes uniform, so high-precision exposure control is achieved. Not only becomes possible, but also in flash photography, it is possible to improve the precision of flash tuning with an appropriate aperture diameter corresponding to the distance.

[Brief description of the drawings]

1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is a plan view of a known step motor used in the present invention, and FIG. FIG. 5 is a program diagram showing a program of the shutter speed and aperture according to the present invention, FIG. 6 is a sector open diagram showing changes in the sector opening diameter at high speed and low speed, and FIG. FIG. 6 is an operation diagram showing the movement of the rotor of the step motor at low speed and at low speed. 4 ... Sector, 12 ... Step motor, 20 ... Constant voltage circuit, 21 ... Drive circuit, 22 ... Control circuit, 23 ... Switch.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuhito Niwa 934-13 Kadawa, Yokkaido, Chiba Prefecture Inside of Seikosha Chiba Office (72) Inventor Michitaka Nakazawa 934-13, Kadawa, Yokkaido, Chiba Prefecture Shachiba Works (56) References JP-A-60-225122 (JP, A)

Claims (1)

(57) [Claims] A high-speed program and a low-speed program in which a shutter is operated by a motor and a shutter speed is relatively high and low, and one of the high-speed program and the low-speed program is switched by switching means. In the selectable multi-program shutter, one of the driving voltage or the driving current of the driving pulse for supplying power to the motor so that the motor operates smoothly regardless of whether the high-speed program or the low-speed program is selected. A multi-program shutter, wherein the time is made different according to the high-speed program and the low-speed program.