US 4,053,907 A · Program-controlled shutter

Abstract

In exposure means comprising, in combination, two shutter blades which also function as the aperture setting blades, a step-motor for displacing the shutter blades stepwise in response to the driving pulse or pulses, and a driving circuit for the step-motor. Slits are cut through the shutter blades so that the relative displacement between the shutter blades may be optically detected in order to control the stepwise rotation of the step-motor, thereby displacing the shutter blades to define the main aperture stepwise; and when the light from a subject reaches a predetermined level, detecting means causes the step-motor to reverse its rotation, thereby closing the shutter blades. The program-controlled shutter in accordance with the present invention is very simple in construction and is free from any erratic operations.

Drawings

Drawings are temporarily unavailable. Open the PDF at USPTO

Drawings

Claims9

Dependent claims

A program-controlled shutter comprising

a. aperture setting means including a plurality of shutter
blades adapted to be used as the aperture setting blades,
a step-motor drivingly coupled to said plurality of shutter blades for displacing them stepwise, and a driving circuit adapted to control the rotation of said step-motor in response to the input driving pulse or pulses;
b. shutter-blade-displacement detecting means for providing a series of output pulses each corresponding to an incremental motion of said shutter blades during the displacement of said shutter blades;
c. driving pulse generating means adapted to generate said driving pulse or pulses to be applied to said step-motor in response to the output pulses from said shutter-blade-displacement detecting means;
and
d. photometric means for detecting the brightness of a subject and for generating a brightness detection signal corresponding to the amount of said brightness from said subject that passes through said shutter blades during the time when said shutter blades are so displaced to define an aperture and to generate a shutter closing signal to be applied to said driving circuit and said driving pulse generating means when the integrated value of the brightness detection signal reaches a predetermined level, whereby said shutter blades are displaced to define the optimum aperture depending upon the brightness of the subject and to close said aperture after a predetermined time depending upon the brightness of the subject, thereby attaining the optimum exposure.

4 more elements

A program-controlled shutter comprising:

a. aperture setting means including a plurality of shutter blades adapted to be used also as the aperture setting blades, a step-motor drivingly coupled to said shutter blades for displacing them stepwise, and a driving circuit adapted to control the rotation of said step-motor in response to the input driving pulse or pulses;
b. shutter-blade-displacement detecting means adapted to detect the displacement of said shutter blades, said shutter-blade-displacement detecting means comprising
i. a plurality of permanent magnets attached on one of said shutter blades and arrayed in such a way that the opposite polarity poles may be alternately located in side-by-side relation, and
ii. detecting means so arranged as to detect the polarity of the pole brought in opposed relation therewith as said shutter blades are displaced;
c. driving pulse generating means adapted to generate said driving pulse or pulses to be applied to said step-motor in response to the output from said shutter-blade-displacement detecting means;
d. a first photometric circuit means adapted to detect the brightness of a subject and to actuate said driving pulse generating means for a period determined by the brightness detected and to generate the shutter opening pulse signal which is applied to said driving circuit for driving said step-motor in the direction in which said shutter blades define an aperture;
and
e. a second photometric circuit means adapted to detect the brightness of the subject and to provide a voltage corresponding to the amount of said brightness that passes through said aperture and to generate a signal when the detected brightness voltage reaches a predetermined level so that in response to said signal said driving pulse generating means is actuated to cause said step-motor to rotate in the direction in which said aperture defined by said shutter blades is closed, and to generate the shutter closing signal to be applied to said driving circuit, whereby the aperture may be set by said first photometric circuit means while the shutter opening time or shutter speed may be determined by said second photometric circuit means, thereby attaining the optimum exposure depending upon the brightness of the subject.

5 more elements

A program-controlled shutter comprising:

a. aperture setting means including a plurality of shutter blades adapted to be used also as the aperture setting blades, a step-motor drivingly coupled to said shutter blades for displacing them stepwise, and a driving circuit adapted to control the rotation of said step-motor in response to the input driving pulse or pulses;
b. shutter-blade-displacement detecting means adapted to detect the displacement of said shutter blades, said shutter-blade-displacement detecting means comprising
i. a plurality of electrical contacts attached and arrayed on one of said shutter blades in equidistantly spaced apart relation, and
ii. a wiper means so positioned as to make electrical contacts as said shutter blades are displaced;
c. driving pulse generating means adapted to generate said driving pulse or pulses to be applied to said step-motor in response to the output from said shutter-blade-displacement detecting means;
d. a first photometric circuit means adapted to detect the brightness of a subject and to actuate said driving pulse generating means for a period determined by the brightness detected and to generate the shutter opening pulse signal which is applied to said driving circuit for driving said step-motor in the direction in which said shutter blades define an aperture;
and
e. a second photometric circuit means adapted to detect the brightness of the subject and to provide a voltage corresponding to the amount of said brightness that passes through said aperture and to generate a signal when the detected brightness voltage reaches a predetermined level so that in response to said signal said driving pulse generating means is actuated to cause said step-motor to rotate in the direction in which said aperture defined by said shutter blades is closed, and to generate the shutter closing signal to be applied to said driving circuit, whereby the aperture may be set by said first photometric circuit means while the shutter opening time or shutter speed may be determined by said second photometric circuit means, thereby attaining the optimum exposure depending upon the brightness of of the subject.

5 more elements

A program-controlled shutter comprising:

a. aperture setting means including a plurality of shutter blades adapted to be used also as the aperture setting blades, a step-motor drivingly coupled to said shutter blades for displacing them stepwise, and a driving circuit adapted to control the rotation of said step-motor in response to the input driving pulse or pulses;
b. shutter-blade-displacement detecting means adapted to detect the displacement of said shutter blades, said shutter-blade-displacement detecting means comprising
i. a grating with a suitable number of equidistantly spaced apart slits cut in through said shutter blades;
ii. light emitting means;
and
iii. photocell means so positioned as to intercept the light from said light emitting means through the slits;
c. driving pulse generating means adapted to generate said driving pulse or pulses to be applied to said step-motor in response to the output from said shutter-blade-displacement detecting means;
d. a first photometric circuit means adapted to detect the brightness of a subject and to actuate said driving pulse generating means for a period determined by the brightness detected and to generate the shutter opening pulse signal which is applied to said driving circuit for driving said step-motor in the direction in which said shutter blades define an aperture;
and
e. a second photometric circuit means adapted to detect the brightness of the subject and to provide a voltage corresponding to the amount of said brightness that passes through said aperture and to generate a signal when the detected brightness voltage reaches a predetermined level so that in response to said signal said driving pulse generating means is actuated to cause said step-motor to rotate in the direction in which said aperture defined by said shutter blades is closed, and to generate the shutter closing signal to be applied to said driving circuit, whereby the aperture may be set by said first photometric circuit means while the shutter opening time or shutter speed may be determined by said second photometric circuit means, thereby attaining the optimum exposure depending upon the brightness of the subject.

7 more elements

Dependencies are inferred from the claim text.

Description4,386 words

Summary425 words

#The present invention relates generally to a program-controlled shutter adapted to attain the optimum exposure depending upon the brightness of a subject, and more particularly a program-controlled shutter of the type in which a plurality of shutter blades which also function as the aperture setting blades are driven stepwise by a step-motor so that the optimum aperture may be set for the optimum time interval depending upon the brightness of a subject.

#The program-controlled shutters of the type described above have been disclosed, for instance, in U.S. Pat. No. 3,882,522, U.S. Pat. No. 3,813,680 and the copending applications filed by the same inventors, Ser. Nos. 550,367 filed on Feb. 18th, 1975, 567,231 filed on Apr. 11th, 1975, and 569,006 filed on Apr. 17th, 1975. These prior art program-controlled shutters were devised in order to overcome the defects encountered in the prior art program-controlled shutters of the type using a moving coil or governor for controlling the shutter or aperture setting blades or diaphragms. That is, the prior art program-controlled shutters use a step-motor for driving stepwise the shutter or aperture setting blades or diaphragms. The common underlying principle of these program-controlled shutters is that the step-motor is rotated stepwise in response to the number of pulses which in turn are generated by a pulse generator in response to the brightness of a subject, whereby the aperture and shutter speed may be selected. Therefore if the shutter or aperture setting blades or diaphragms are not coupled to the step-motor with suitable mechanical coupling means which permits the smooth transmission of the driving power from the step-motor to the shutter or aperture setting blades or diaphragms or when the step-motor's response to the driving pulse is slow, the number of stepwise angular rotations of the steo-motor is different from the number of driving pulses applied thereto, resulting in the erratic exposure; that is, under- or over-exposure. Furthermore, since the prior art program-controlled shutters of the type described above must incorporate a control circuit for controlling the pulse generator, they are relatively complex in construction.

#One of the objects of the present invention is therefore to provide a program-controlled shutter of the type in which exposure means consisting of a step-motor and shutter and aperture setting blades may be actuated in a very reliable and dependable manner without any erratic functions even without the use of a pulse generator.

Brief description of the drawings7 figures

#The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof taken in conjunction with the accompanying drawing.

#FIG. 1A is a schematic top view of exposure means consisting of a step-motor and two shutter aperture setting blades;

#FIG. 1B is a schematic front view thereof showing the shutter and aperture setting blades in closed position;

Detailed description3,813 words

#Referring to FIGS. 1A, 1B and 1C, a step-motor 1 is of the conventional type and rotates through an angle in proportion to the number of driving pulses received. Two driving pins 2 and 3 extend in parallel with the driving shaft of the step-motor 1 from a disk 1a attached to the shaft, and are loosely fitted into guide slots 6 and 7, respectively, of shutter blades 4 and 5. The shutter blades 4 and 5 have main openings 8 and 9 which define a main aperture 10 as will be described in detail hereinafter, auxiliary openings 13 and 14 which define the auxiliary aperture 15 (See FIG. 1C) as will be described in detail hereinafter, and gratings 17 each with a plurality of slits a and opaque or light shielding spaces b therebetween.

#FIG. 1B shows the shutter blades 4 and 5 in the inoperative position; that is, when the shutter button (not shown) is not depressed, but when the step-motor 1 is rotated in the direction indicated by the arrow in FIG. 1B in response to the driving pulse or pulses applied thereto in a manner to be described in detail hereinafter, the shutter blades 4 and 5 are displaced in the opposite directions relative to each other as indicated by the arrows A and B in FIG. 1C so that the main and auxiliary openings 8 and 9 and 13 and 14 overlap to define the main and auxiliary apertures 10 and 15, respectively. As a result, a subject 12 is focused through a lens 11 and the main aperture 10 on a film 20 (See FIG. 1A), and the light from the subject 12 is intercepted through the auxiliary aperture 15 by a photocell 16 for the purpose to be described hereinafter. Since the step-motor 1 rotates through a predetermined angle in response to one driving pulse, the opening area of the main aperture 10 is increased stepwise. The increase in the opening area of the main aperture 10 in response to one driving pulse may be arbitrarily selected by suitably selecting the configuration of the main openings 8 and 9 and the configuration and position of the guide slots 6 and 7. In the instant embodiment, it is assumed that in response to one, two and three driving pulses applied to the step-motor 1, the shutter blades 4 and 5 are so displaced as to define the opening areas of the main aperture 10 corresponding to stopping down the lens to f-16, f-8 and f-4, respectively.

#In like manner, the opening area of the auxiliary aperture 15 defined by the auxiliary openings 14 and 15 changes stepwise. That is, in the instant embodiment, the opening area is minimum when the main aperture 10 is closed while it is maximum when the main aperture 10 is wide open. The auxiliary aperture 15 is therefore provided in order to control the quantity of the light from the subject 12 to be intercepted by the photocell 16 in proportion to the opening area of the main aperture 10. As a result, the time of a photometric circuit including the photocell 16 to be described in detail hereinafter may be changed in response to the brightness of the subject 12.

Facts

Application

05/621,819Filed 14 Oct 1975

Priority

JA 49-12090318 Oct 1974

Granted

11 Oct 1977

Term ended

11 Oct 1994

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

G03B 7/097
Digital circuits: for control of both exposure time and aperture
G03B 7/085
Analogue circuits: for control of aperture
G03B
Apparatus or arrangements for taking photographs or for projecting or viewing them

Program-controlled shutter

Life of this patent

Program-controlled shutter

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims9

Description4,386 words

Drawings

Classification3 codes

Life of this patent

Description4,386 words