JP2997953B2 - Camera shutter control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shutter control device for a camera, and more particularly to a shutter control device for controlling an exposure amount of a camera in an aperture priority system.

[0002]

2. Description of the Related Art Generally, the exposure amount (E _v ) of a camera is a waveform (FIG. 2) showing the operation from the start of opening of a shutter to a predetermined aperture to the end of closing until the shutter is completely closed. In the so-called trapezoidal control in which the exposure time is controlled based on a preset aperture value, the time between the AE pulse data and the pulse is determined in order to open a shutter with a predetermined aperture. The analog time data to be determined must be determined. For this reason, a data table of the number of AE pulses and a data table of the analog time are previously stored in the storage means in the conventional camera for each exposure amount (Ev) according to the aperture, and the exposure amount is controlled by this. ing.

However, in such conventional AE control, a data table must be prepared for each exposure amount corresponding to all apertures, and the number of data tables must be enormous. In addition, although the linearity of the trapezoid indicating the open / close waveform varies depending on the camera shutter, it is very difficult to correct the trapezoidal linearity.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera shutter control device capable of easily performing various program controls with a small amount of data memory. With the goal.

[0005]

According to the present invention, there is provided a camera shutter control apparatus for measuring a subject brightness and a distance, a setting means for setting an aperture value of a shutter, and the like. In a control device for a camera shutter, comprising a control means for calculating the outputs of the measuring means and the setting means to control the shutter, the control means comprises an effective exposure time calculated based on the outputs of the measuring means and the setting means ( T _v ) and a storage means for storing a conversion coefficient between the shutter opening time (T) and an effective exposure time (T _v ) based on the value set by the measurement means and the setting means. The opening time (T) is calculated based on the stored conversion coefficient. Preferably, the shutter-specific correction value (β) is stored in advance in a storage unit provided in the control unit, and based on the correction value (β),
The opening time (T) is calculated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera shutter control device according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a control device for a camera shutter includes a photometric unit 1 for measuring the luminance of a subject as a measuring unit, a distance measuring unit 2 for measuring a distance to the subject, and film sensitivity information as a setting unit. ISO setting means 3 for setting, and aperture value setting means 4 for setting an aperture value, and shutter 5 for calculating outputs from these measuring means and setting means.
Control means 6 for controlling the opening time of the shutter, and shutter driving means 7 for driving the shutter 5 by an output from the control means 6.
And storage means 8 for storing predetermined data required for the calculation.

The shutter 5 is a lens shutter that also serves as an aperture, and is composed of a plurality of sectors which are opened and closed by forward / reverse rotation of a motor as a shutter driving means 7, and is opened for a predetermined time and a predetermined aperture, so that the shutter 5 is opened. And the aperture operation is performed.

The photometric means 1 measures the brightness (B _v ) of the subject by means of a light receiving element. The distance measuring means 2 includes a light emitting element such as an infrared ray and a light receiving element, and measures the distance (Dv) to the subject. The ISO setting means 3 reads the manual setting switch or the DX code of the film cartridge and sets film sensitivity information ( _Sv ).

The aperture setting means 4 manually sets the aperture value based on the measured value of the distance measuring means 2 and the set value of the ISO setting means 3, and outputs a signal corresponding to the aperture value to the control means 6. I do. The aperture value setting means 4 may be included in the control means 6 when it automatically sets the aperture value.

The control means 6 includes a photometric means 1, a distance measuring means 2,
The outputs from the ISO setting means 3 and the aperture value setting means 4 are calculated as described later, the opening time at the set aperture value and exposure amount is determined, and a signal corresponding thereto is output to the shutter driving means 7.

The storage means 8 preferably comprises a non-volatile ROM such as an EEPROM, and is used for calculating analog time in addition to shutter opening pulses (AE pulses) corresponding to respective apertures as data necessary for calculation. , For example, the difference (α) between the calculated effective exposure time (T _v ) and the shutter opening time (T) for each aperture, the shutter opening slope (k), and the shutter opening slope correction value (β) Etc. The shutter driving unit 7 includes a motor such as a DC motor and a step motor and a motor driver, and performs opening and closing driving of the shutter sector controlled by the control unit 6.

Next, the calculation of the analog opening time (T) of the shutter by the control means 6 will be described with reference to FIGS. In the drawing, the horizontal axis represents time, and the vertical axis represents the aperture (A _v ) of the shutter.

First, an output corresponding to the subject luminance (B _v ) from the photometric means 1 and an output corresponding to the film sensitivity information (S _v ) from the ISO setting means 3 are calculated, and the exposure amount (E _v ) is calculated. Ask for. That is, _Ev = _Bv + _Sv Then, the output corresponding to the subject distance ( _Dv ) from the distance measuring means 2 and the output corresponding to the film sensitivity information ( _Sv ) are calculated, and the aperture ( _Av ) is calculated. Ask for. That is, where _{A v = D v + S v} , when the diameter is not based on the measurement result is determined from the set aperture value regardless of the operation. Further the amount of exposure determined in this manner (E _v) and diameter (A _v), effective exposure amount (T _v) is calculated. That, T _v = E _v -A _v Incidentally, if in the isosceles trapezoid as shown in FIG. 2 constant shutter aperture (A _v) are effective exposure amount and (T _v) an analog opening time (T) Is constant.

T = T _v -2α Therefore, α corresponding to each aperture as shown in FIG. 4 (Table 1)
By storing the data table in the storage unit 8, the analog opening time (T) can be obtained by reading out α and performing the above calculation (FIG. 5). On the other hand, AE pulse data corresponding to each aperture (A _v ) is shown in FIG. 4 (Table 2).
As shown in (1), trapezoidal control can be performed based on the analog aperture time (T) and the AE pulse calculated as described above, since they are stored in the storage means 8 in advance. The difference (α) between the effective exposure amount (T _v ) and the analog opening time (T) is proportional to the aperture (A _v ) when the shutter opening slope is constant (FIG. 3). The constant (k), that is, the slope of the opening is stored in the storage means 8, and by reading out this, the calculation of T = T _v -2 kA _v is performed to obtain the analog opening time (T). Good.

The above case is the case where the shutter operation is ideal. However, in the actual shutter, the inclination of the opening of the shutter may not be uniform (FIG. 6). In such a case, it is necessary to perform a shutter-specific correction corresponding to the aperture. Therefore, advance correction value corresponding to the diameter data (beta) as shown in FIG. 4 (Table 3), may be stored in the storage means 8, T = T _v -2βα or, T = T _v -2βkA _v The analog opening time (T) is obtained by the calculation of FIG.
(A) or (b)).

Next, the operation of the shutter in such control will be described.

First, the shutter motor is driven in the forward rotation direction based on the signal from the control means 6, and the shutter sector starts to open. Here, the aperture (A _v ) of the shutter is determined by the number of AE pulses stored in the storage means 8. When the shutter sector is opened until the calculated Av value is obtained by rotating the motor by a predetermined rotation amount, the rotation driving of the motor is stopped, and then the calculated analog opening time (T)
Will be retained. Next, the shutter motor is again rotated in the reverse direction to close the shutter.

[0019]

As is clear from the above embodiments, according to the camera shutter control device of the present invention, trapezoidal control can be performed with fixed data of only the AE pulse, and a small-capacity data ROM is used. be able to. Further, according to the present invention, by storing the correction amount specific to the shutter in an EEPROM or the like in advance, it is possible to easily correct the inclination error of the opening of each shutter, and always perform appropriate shutter control. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a camera shutter control device according to the present invention.

FIG. 2 is a diagram showing an operation of a shutter.

FIG. 3 is a diagram showing an operation of a shutter.

FIG. 4 is a diagram showing an example of a data table according to the present invention.

FIG. 5 is a flowchart illustrating shutter control according to the present invention.

FIG. 6 is a diagram showing an operation of a shutter requiring correction.

FIG. 7 is a flowchart illustrating shutter control according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photometry means 2 ... Distance measurement means 3 ... ISO setting means 4 ... Aperture value setting means 5 ... Aperture time control means 6 ... Control means 7 ... Shutter drive means 8 ... Storage means

Continued on the front page (72) Inventor Isamu Ishii 934-13 Shikato, Yokkaido, Chiba Pref. Inside Seikosha Chiba Works (72) Inventor Noriyuki Osato 934-13, Shikato, Yotsukaido-shi Chiba Pref. (56) References JP-A-57-19720 (JP, A) JP-A-63-259524 (JP, A) JP-A-60-164727 (JP, A) JP-A-2-188731 (JP, A) Kaihei 3-62325 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B ^7/ 00-7/28

Claims (2)

(57) [Claims] A measuring means for measuring a luminance and a distance of a subject; a setting means for setting an aperture value of a shutter; and a control means for calculating outputs of the measuring means and the setting means to control a shutter. In the camera shutter control device, the control means includes a storage means for storing a conversion coefficient between an effective exposure time calculated based on outputs of the measurement means and the setting means and an analog opening time of the shutter, A control device for a camera shutter for calculating an effective exposure time and calculating an analog opening time based on the conversion coefficient. 2. The camera shutter control device according to claim 1, wherein the storage device has a shutter-specific correction value as stored data.