JPS5977421A - Single-lens reflex camera using electric shutter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a single-lens reflex camera using an electric shutter, and in particular, when the shutter speed is manually set, the image plane exposure amount according to this shutter speed value is the appropriate exposure. The present invention relates to a single-lens reflex camera that displays whether the exposure amount matches the appropriate exposure amount or how much it deviates from the appropriate exposure amount.

(Prior art) A single-lens reflex camera using an electric shutter converts the photometric value into a digital signal using an analog-to-digital converter (hereinafter referred to as the "A, -D converter"), and then converts the photometric value into a digital signal based on this digital signal. There is one that operates the shutter at an appropriate shutter speed. FIG. 1 shows an example of a single-lens reflex camera using this kind of conventional electric shutter. Light P transmitted through the photographic lens is converted into a voltage signal by a photoelectric conversion element 1, and the output of this element 1 is converted into a voltage signal. The analog computing unit 2 performs corrections using the film sensitivity (ASA value) setting value and the aperture (F value) setting value, and this computing unit 2
The output is input to the A-D converter 3 via the automatic switch contact A of the automatic/manual changeover switch S. The A-D converter 3 has a memory capacity, and when the switch SF is closed, the photometric value from the arithmetic unit 2 is stored as a value converted into a digital quantity.

When the shutter is released, the switch SF is opened, and the photometric output stored in the A-D converter 3 is converted to seconds by the seconds counter 4, which activates the shutter actuating magnet 5 to set the shutter to the appropriate seconds. It is designed to be activated at certain times.

On the other hand, when setting the shutter speed manually, select the manual switch contact M of the automatic/manual changeover switch S, and then manually set the desired shutter speed using the shutter speed setting variable resistor 6. It has become.

In this case, since the system after the A-D converter 3 is in the same state as in the automatic case described above, the quasi-analog voltage generated at the variable resistor 6 is passed through the contact M of the switch S to A -
The voltage is applied to the D converter 3, and thereafter the shutter operates in the same manner as in the automatic case, and the shutter operates at a speed corresponding to the set value of the resistor 6.

By the way, according to the single-lens reflex camera using the electric shutter configured as described above, the output of the analog computing unit 2 is manually set by the variable resistor 6 with respect to the potential at point α, and A-D conversion is performed. The same A-D converter 3 guided to the device 3
If the potentials at the six input points are equal, the situation is exactly the same as in the automatic mode, and therefore the image plane exposure amount is appropriate.

However, some camera users may intentionally set the exposure amount to be under or over the value that is considered to be the appropriate image plane exposure amount required in the automatic mode.

However, the power of single-lens reflex cameras using traditional electric shutters,
The camera does not display the manually set shutter speed at all, so if you manually set the shutter speed, this setting value will not match the automatic shutter speed, which is generally considered to be an appropriate value. It is difficult to obtain a photographic image as intended by the user because it is not known at all whether the images match or not, and if they do not match, to what extent they deviate.

(Purpose) The purpose of the present invention is to check whether the manually set shutter speed matches the shutter speed that is automatically set to obtain a predetermined image plane exposure, and if there is a deviation or An object of the present invention is to provide a single-lens reflex camera using an electric shutter, which displays the amount of deviation and allows the user of the camera to obtain the desired photographic image. .

(Structure) In order to achieve the above object, the present invention compares a shutter speed value obtained based on the photometric value of light transmitted through a photographic lens with a manually set shutter speed value, and calculates the difference between the two. A logic comparator that outputs the difference in stages from each output child, an indicator that displays whether the manually set shutter speed is appropriate, over or under based on the output of the logic comparator, and a clock with a constant cycle. A frequency divider that divides and outputs the pulse in stages, and inputs each output of the logic comparator and each division ratio of the frequency divider, and displays the divided output according to the output of the logic comparator on the display. In addition, the present invention is characterized in that it is provided with a gate circuit that causes the display to blink in accordance with the frequency-divided output.

The present invention will be explained below based on the embodiment shown in FIG.

In FIG. 2, the logic comparator 7 compares the shutter speed value obtained based on the photometric value of the light transmitted through the photographing lens with the manually set shutter speed value, and calculates the difference between the two in steps of +2. ．． +1. O,-1,
-2 is output from each output terminal.

Specifically, after calculating the photometric value of the light transmitted through the photographic lens, a signal obtained by A-D conversion of this is compared with a signal obtained by A-D converting the manually set signal, and the manually set signal is set. If the signal is over 2 steps, the signal is output from the +2 terminal, if it is 1 step over, it is output from the +1 terminal, if it is correct, it is output from the 0 terminal, if it is 1 step under, it is output from the -1 terminal, and if it is 2 steps under, it is output from the -2 terminal. It is supposed to be done. The 2-stage over output signal or the 2-stage under output signal of the comparator 7 is applied to the OR circuit ORI, and the 1-stage over output signal or the 1-stage under output signal is applied to the OR circuit OR2.
The output of RI is sent to the AND circuit AND ], and the OR circuit OR2
The proper output signal of the comparator 7 is applied to the AND circuit MAND2, and the appropriate output signal of the comparator 7 is applied to the AND circuit AND3. The frequency dividing circuit 12 divides the frequency of a clock pulse of a constant period in stages and outputs the frequency. For example, a 30Hz clock pulse φ is divided into 30Hz, 20Hz,
The frequency is divided in steps such as 1.0Hz and output from the corresponding output terminals, and the 10■■Z frequency division output is sent to the AND circuit AND], the 20H7O frequency division output is sent to the AND circuit AND2, and the 30HzO frequency division output is sent to the AND circuit AND2. The output is an AND circuit AND3
can be added to. Each AND circuit ANDI
, AND2. The output of AND3 is OR circuit OR3
The output of the OR circuit OR3 is added to the transistor Tr
It can be added to the base of The transistor Tr is turned on by the output of the signal - from the OR circuit OR3, so that the display element of the display 8 can emit light only when the transistor Tr is on. The display 8 displays whether the manually set shutter speed is appropriate, over, or under based on the output of the logic comparator 7, and has a display element shaped like an arrow pointing to the left to indicate over, and a display element pointing to the left to indicate under. It has a display element in the shape of an arrow pointing to the right, and a display element A that indicates correctness. Each of the OR circuits ORI, OR2, O
R3, each AND circuit A, MDI, AND2゜AND
3 constitutes a gate circuit that adds each output of the logic converter and each frequency division output of the frequency divider 12 to the display and causes the display 8 to blink in accordance with the frequency division output.

Now, assuming that the shutter speed value automatically determined based on the photometric value and the manually set shutter speed value match, a signal is output to the logic comparator 7 from its appropriate output terminal and the AND circuit AND 3
Add to. Since the frequency divided output of 30I (Z) from the frequency divider 12 is added to the other input terminal of the AND circuit AND3, a 30Hz signal is output from the AND circuit AND3, and this signal is sent to the OR circuit OR3. The frequency of the transistor Tr is 30Hz.
It turns on and off at a relatively fast cycle according to the signal. On the other hand, in the display device 8, a signal is applied from the logic comparator 7 to its proper display element, so that the proper display element blinks at 30 Hz. Next, if the manually set shutter speed value is one step lower than the automatically determined shutter speed value, the logic comparator 7 outputs a signal from its -1 output terminal. This output signal passes through the OR circuit OR2 and the AND circuit A.
However, since the 20HzO frequency divided output from the frequency divider 12 is applied to the other input terminals of the AND circuit A and ND2, the 20HzO frequency output from the AND circuit ANT)2 is applied.
A Hz signal is output and applied to the base of the transistor Tr via the OR circuit OR3, and the transistor Tr is
Turn on/off at Hz. Therefore, on the display 8, the right-pointing arrow indicating under is blinking at 20 Hz, and this blinking period allows it to be known that the manually set value is slightly deviated from the appropriate value. Unfortunately, the manually set shutter speed value is 2 times higher than the automatically determined value.
If the stage is over, a signal is output from the +2 output terminal of the logic comparator 7, and this signal is added to the AND circuit AND ] via the OR circuit ORI, and the AND circuit ANDI receives the 10Hz signal from the frequency divider 12. Output. This 10Hz signal is applied to the base of the transistor Tγ via the OR circuit OR3, so it is turned on and off by the transistor Tr10H7, and therefore, on the display 8, the arrow indicating over is flashing at 10Hz.
This comparatively slow blinking allows us to know that the manual setting value has deviated significantly toward overexposure.

In this way, it is displayed whether or not the manually set shutter speed value is appropriate for the shutter speed value determined based on the photometric value, and the amount of deviation from the appropriate value is determined by the difference in the flashing cycle of the display element. Since the image is displayed, you can easily change the shutter speed value to obtain the desired photographic image.

(Effects) According to the present invention, a logic comparator compares a shutter speed value obtained based on a photometric value and a manually set shutter speed value, and based on this comparison signal,
In addition to displaying whether the manually set shutter speed value is appropriate, over, or under the appropriate shutter speed value based on the photometric value, there is also a frequency divider between the logic comparator and the display. By incorporating a gate circuit and a shutter speed value set manually, the deviation of the manually set shunter speed value from the appropriate shutter speed value based on photometry is displayed by changing the flashing cycle of the display element. It is possible to accurately control the exposure state in the case of a camera, and thus it is possible to easily obtain an intended photographic image by consciously changing the shutter speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an electric circuit system of a single-lens reflex camera using a conventional electric shutter, and FIG. 2 is a block diagram showing an embodiment of the present invention. 7...Logic comparator, 8...Display device, 1
2... Frequency divider, ORB, OR2, OR3, OR circuit included in the gate circuit, ANDI, AND2.
ANT) 3: AND circuit included in the gate circuit.

Claims (1)

[Claims] Photography 1: A shutter speed value determined based on the photometric value of the light transmitted through the lens is compared with a manually set shutter speed value, and the difference between the two is outputted from each output terminal in stages. , an indicator that displays whether the manually set shutter speed is appropriate, over, under, or under based on the output of the logic comparator;
A frequency divider that divides and outputs a clock pulse of a constant period in stages, and a logic comparator output and each frequency division output of the frequency divider are input, and the frequency division output according to the output of the logic comparator is displayed. A single-lens reflex camera using an electric shutter, which also has a gate circuit that causes a display to blink in accordance with the frequency-divided output.