JPS61113041A - Exposure controller of camera - Google Patents

Abstract

PURPOSE:To shorten a stop-down time by driving a motor which performs stopping-down operation at a speed corresponding to the latitude width of a film. CONSTITUTION:A detecting means detects latitude signals 21 and 22 provided on the cartridge of a film, a motor driving signal generating means 1 outputs a motor driving signal (a) for driving the motor M at the speed corresponding to the latitude width of a detected latitude signal, and a motor control means 2 inhibits the motor from being driven with the motor driving signal associatively with releasing operation when the motor is driven with the motor driving signal and a specific aperture value is obtained. Consequently, the lens is stopped down to the specific aperture value and when a film having wide latitude width is used, the stopping-down time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an exposure control device for a camera that performs aperture control, and more particularly to an exposure control device for a camera that uses a motor to narrow down the aperture.

(Background of the invention) Conventionally, shutter speed priority AE cameras and program AE
A camera's exposure control device determines the aperture value that will give an appropriate exposure when the lens aperture is open, depending on the subject mode, etc., and then adjusts the aperture value in relation to the release operation (hereinafter referred to as the predetermined aperture value). Generally, the shutter front curtain starts running after the narrowing down operation is completed.

However, with such conventional camera exposure control devices, a certain amount of aperture time is required in order to accurately narrow down the aperture to a predetermined aperture value. In the case of a device, the aperture time is considerably longer than in normal manual shooting, so the time from the release operation to the shutter front curtain starting to move is longer, making it difficult for sports photography, especially for automobile races. When photographing a fast-moving subject like this, there is a problem in that a large discrepancy occurs between the composition intended by the photographer and the actual photograph.

(Objective of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and the amount of error in the stop position of the aperture deviates from the predetermined aperture value is determined by the latitude of the loaded film. The purpose of the present invention is to solve Problem 1j by driving a motor that performs a stop-down operation at a speed corresponding to the latitude width, focusing on the fact that proper exposure can be obtained if the latitude width is within the range.

(Summary of the invention) The gist of the present invention to achieve this object is as follows.

In an exposure control device for a camera in which the aperture narrowing operation is performed by a motor, there is provided a detection means for detecting a latitude signal provided on a film cartridge, and the motor is driven at a speed corresponding to the latitude width of the detected latitude signal. a motor drive signal generating means for outputting a motor drive signal to drive the motor by the motor drive signal in connection with a release operation, and a motor drive signal for driving the motor by the motor drive signal when the aperture reaches a predetermined aperture value; The present invention relates to an exposure control device for a camera, comprising a motor control means for stopping the motor from being driven.

In the camera exposure control device, the motor drive signal generating means generates a fast motor drive signal when the latitude width of the loaded film is wide, and generates a slow motor drive signal when the latitude width is narrow. The motor control means drives the motor using the motor drive signal until the aperture reaches a predetermined aperture value.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 to 6 show embodiments of the present invention, and FIG. 1 is a circuit diagram showing an exposure control device for a camera according to this embodiment.

As shown in Fig. 6, when a film A F is loaded onto the Hatrone P, which is provided with a signal section 1o indicating film characteristics such as film sensitivity, number of films, latitude, etc., the film information is transmitted. It can be read from the signal section 10.

As shown in FIG. 6, the signal section 10 provided in the cartridge P1- includes film sensitivity signal sections 12-16, film number signal sections 18-20, latitude signal section 21.
22, and a common electrode contact 11. +7.

As shown in FIG. 1, the camera's exposure control device consists of a motor M that performs an aperture narrowing operation, contacts provided on the camera body, and a film cartridge.
Detecting means 3 for reading the latitude signal from the latitude signal section 21 and 22 of 1-, and a motor drive for outputting a motor drive signal a for driving the motor at a speed corresponding to the latitude width of the latitude signal output from the detecting means 3. The signal-3 generating means 1 drives the motor M with the motor drive signal a in connection with the release operation, and generates the motor drive signal a when the aperture reaches the predetermined aperture value.
A motor control means 2 is provided for preventing the motor X from being driven by the motor.

The detection means 3 includes a first detection section 31 that reads and outputs latitude signals from the latitude signal section 21, and a second detection section 32 that reads and outputs latitude signals from the latitude signal section 22. .

Then, the latitude signal output from the first detection section 31.32 of the detection means 3 is H, Hl when the latitude width is the narrowest, Hl then H, L, and when the latitude width is the widest. There are four types: Niri and L.

The motor drive signal generating means 1 includes an inverter G1.
G2. A N D gate 03-G8. OR gate GIO
and a pulse generating circuit A2.

The latitude signals from the first detection section 31 and the second detection section 32 are input to the re-input terminal of the AND game hG3, and the AN
D game) The latitude signal from the first detection section 31 is inputted to one input terminal of G4 and G6 via the in/hater Gl, and the latitude signal from the second detection section 32 is inputted to the other input terminal of the AND gate G4. The latitude signal from A is input, and
The latitude signal from the first detection section 31 is input to one input terminal of the ND gate G5, and the latitude signal from the second detection section 32 is input to the other input terminals of the AND gates G5 and G6 via the inverter G2. is input.

Then, inverters Gl, G2 and AND gate 03
~G6 constitutes a line decoder, and the first detection unit 31
．． AN depending on the latitude signal from the second detection section 32
D game) One of G3 to G6 outputs H.

As shown in FIG. 2, the pulse generating circuit A2 generates three types of pulse signals u, v, with different pulse widths and duty ratios.
The pulse signal U is input to an AND gate G7, the pulse signal V is input to an AND gate G8, and the pulse signal W is input to an iND gate G9.

Also, AND gate G7. Each input terminal of G8 and G8 is connected to an AND gate G3. G4. They are respectively connected to the output terminals of G5. The input terminal of OR gate GIO is AN
D game) is connected to the output terminals of 08 to G9, and the OR
A motor drive signal a as shown in FIG. 3 is output from the gate GIO.

The motor control means 2 is composed of an AND gate G11° transistor Q1 and a motor control circuit A1.

As shown in FIG. 4, the motor control circuit A1 generates an output signal that becomes H at time ta related to the release operation and becomes L when the aperture reaches a predetermined aperture value (time tb). Output to. Further, the motor drive signal a from the OR gate GIO is input to the other input terminal of the AND gate Gll, and a control signal C for controlling on/off of the transistor Q1 is sent from the AND gate Gll to the transistor Ql.

The motor X rotates when the l transistor Q1 is turned on.

The operation of the camera exposure control device having the above configuration will be described below.

When the film with the narrowest latitude width is loaded into the camera, the first detection unit 31. The latitude signals from the second detection section 32 are H and H, respectively, and the output of the AND gate G3 becomes H. At this time, AND game I・04~
Each output of G6 is shown.

AND gate G3 is connected to one input terminal of AND gate G7.
By inputting the H signal from the AND gate G7, the motor drive signal a3 having the same waveform as the pulse signal piece input to the other input terminal of the AND gate G7 is input to the OR gate GI.
0 to one input terminal of AND gate G11. At this time, the output signal from the motor control circuit A1 is input to the other input terminal of the AND gate G11.

Since this output signal S goes to H level at the time of ta in relation to the release operation, the AND gate Gll outputs the control signal C3 from taBI, and this control signal C3 causes the transistor Q to repeat on and off, and the motor N to the highest level. It is pulse driven at a slow speed, and the rotation of this motor M starts the narrowing operation of the aperture.

Then, when the aperture reaches a predetermined aperture value, the output signal S becomes L level, so the AND gate G11 outputs tb
At 4 o'clock, the output of the control signal C3 is stopped, and the motor X is stopped.

In this way, when the latitude width is the narrowest, the narrowing down time is the longest, from time t1 to time tbd, and narrowing down is performed with high accuracy.

When using a film whose latitude width is the second widest after the double continuous film, the latitude signals from the first detection section 31 and the second detection section 32 are respectively H.
The output of AND gate G4 becomes H, and AND gate G3
, G5, and G13 are L.

In this case, the OR game) GIO outputs the motor drive signal a4, and the AND game) Gll outputs the control signal C4 from time ta, and the motor X is pulse-driven via the transistor 0 by this control signal C4. ,A
The ND gate Gll stops outputting the control signal G4 at tb3.

The narrowing down time in this case is from time ta to time tb3.

When a film with a wider latitude width is used, the first detection section 31. The latitude signal from the second detection section 32 is H and L, and only the output of the AND gate G5 becomes H. In this case, the motor drive signal a5 is output from the ○R game) GIO, and the AND gate Gll is
A control signal C5 from time ta to time tb2 is output.

The narrowing down time in this case is from time ta to time tb2.

Next, when a film with the widest latitude width is used, the first detection section 31. The current signal from the second detection section 32 is low, and only the output of the AND gate 1G6 is high. Therefore, the motor drive signal a6 is output from the OR game (GIO). Therefore, A.N.
D game) Gll continues to output an H level control signal C6 from time ta to time tb1, and this control signal C6 causes the transistor Q to continue to be turned on and the motor X to continue rotating. In this case, motor X is not pulse driven;
The narrowing down time is the shortest, from time ta to time tb1.

In this way, the narrowing time of the aperture becomes shorter as the latitude width becomes wider.

In addition to the pulse drive method described in the above embodiment, to change the rotational speed of the motor, there are also methods of applying a drive voltage to the motor according to the latitude width, and a method of using these methods in combination.

(Effects of the Invention) The camera exposure control device according to the present invention drives the motor that performs the aperture narrowing operation at a speed corresponding to the latitude width of the latitude signal, so the aperture can be narrowed down to a predetermined aperture value with high precision. In addition, when using a film with a wide latitude width, the time for closing the aperture can be shortened, thereby shortening the time from when the lens is activated until the front curtain of the shutter starts moving. Therefore, even when photographing a fast-moving subject such as a sports photograph, particularly an automobile race, a photograph with a composition extremely close to the composition intended by the photographer can be obtained.

[Brief explanation of drawings]

1 to 6 show one embodiment of the present invention, and the first embodiment is shown in FIG.
The figure is a circuit diagram, Figure 2 is a time chart of the output of pulse generation circuit A2, Figure 3 is a time chart of the output of OR gate GIO, Figure 4 is a time chart of the output of motor control circuit AI, and Figure 5 is a time chart of the output of motor control circuit AI. FIG. 6 is a perspective view of the film cartridge.

Claims (1)

[Claims] In an exposure control device for a camera in which the aperture narrowing operation is performed by a motor, there is provided a detection means for detecting a latitude signal provided on a film cartridge, and the motor is driven at a speed corresponding to the latitude width of the detected latitude signal. a motor drive signal generating means for outputting a motor drive signal to drive the motor by the motor drive signal in connection with a release operation, and a motor drive signal for driving the motor by the motor drive signal when the aperture reaches a predetermined aperture value; An exposure control device for a camera, comprising a motor control means for preventing the motor from being driven.