JPS58144820A - Information display for exposure of camera - Google Patents

Abstract

PURPOSE:To announce whether the results of photographing are good or not, by displaying whether the correct exposure meeting the sensitivity of a film is obtained actually on a film plane or not at every one photographing. CONSTITUTION:When the user operates a film sensitivity setter of a camera to match the same with the film sensitivity of a film to be loaded in the camera, a film sensitivity information setting circuit 1 converts the set value of the film sensitivity to a stable voltage signal R of high reliability. On the other hand, a detecting circuit 2 for exposure on the film plane measures the exposure iteslf at which the film plane is exposed on operation of the camera and converts the value thereof to a voltage signal S which is the detected voltage. The signals R, S are discriminated with an exposure discrimintating circuit 3, and if the values of the signals R, S are equal, the circuit discriminates that the correct exposure corresponding to the film sensitivity is applied and that the cemera has operated normally. If the values are not equal, the circuit discriminates that the operation is anomalous. According to the results of the discrimination, whether the exposure is correct or incorrect is displayed 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure amount information display device for a camera, and in particular to a device that displays whether or not a proper exposure amount has actually been obtained for a film, thereby informing the quality of the shooting result. It is.

The film is coated with a photosensitive material, and the sensitivity of the film varies depending on the type of photosensitive material.

Therefore, the amount of exposure required for a film is determined according to its sensitivity, and when the film is loaded into a camera and taken, proper exposure is achieved and a high-quality photograph is obtained.

This proper exposure is determined by the film surface illuminance, aperture value, and shutter speed (timerlilI).In the case of a camera with a built-in exposure meter, the film sensitivity is first adjusted by the film sensitivity setting device, and then the aperture value or The remaining shutter speeds are determined by giving priority to one of the shutter speeds and pointing the camera at the subject. Also, if the camera has a built-in automatic exposure adjustment device.

It is automatically determined by simply adjusting the film speed and pointing the camera at the subject.

By the way, even though the proper exposure was determined and the photograph was taken, the actual amount of exposure the film received was too much or too little, and it was only after development that it was discovered that the photograph was a failure, which was disappointing. There is. This is especially true if the shooting is something that can never be reproduced again.

One of the causes of such photographic failures is malfunction of the camera, which may include malfunction of the shutter and aperture, malfunction of the exposure meter or automatic exposure control mechanism, and the like. However, in either case, the camera often appears to be operating normally from the viewpoint of shooting operations.
For this reason, the photographer does not realize that the camera is malfunctioning until he sees the development results.

In order to eliminate such shooting failures due to malfunction of the camera, this invention displays the shooting results by displaying whether or not an appropriate exposure amount corresponding to the film sensitivity has actually been obtained on the film surface for each shooting. The purpose is to provide a device that informs you of the quality of the product.

The present invention will be explained below based on the drawings.

FIG. 1 shows a block diagram of the camera exposure information display device of the present invention, in which 1 converts the required exposure amount into a reference voltage corresponding to the film sensitivity of the film used or loaded in the camera. Film sensitivity information setting circuit, 2
Reference numeral 4 designates a film surface exposure amount detection circuit that converts the exposure amount of the film surface obtained by operating the camera into a detection voltage, 3 an exposure amount determination circuit, and 4 a display circuit that displays whether the exposure amount is appropriate or inappropriate.

The film sensitivity information setting circuit 1 converts the film sensitivity setting value into a highly reliable and stable voltage signal R when the film sensitivity setting device of the camera is adjusted to match the film sensitivity of the loaded film.

On the other hand, the film surface exposure amount detection circuit 2 measures the amount of exposure to which the film surface is exposed when the camera actually operates, and converts the value into a voltage signal S of a detection voltage. These two voltage signals R and S are determined by the exposure amount determining circuit 3. If the values of both die pressure signals R and S are equal, the proper exposure amount corresponding to the film sensitivity set for the film is given, and the camera is judged to have operated normally; if they are not equal, it is assumed that there was an abnormal operation. judge. The display circuit 4 displays whether the exposure amount is appropriate (normal operation) or inappropriate (abnormal operation) in accordance with the determination result of the exposure amount determination circuit. From this display, the photographer can know in advance whether the result of the shot he just released is good or bad, that is, whether the developed and printed photo is good or bad. Therefore, if there is an inappropriate display, it is possible to immediately take another photograph and obtain the necessary records.

Next, an embodiment applied to a focal plane shutter camera will be described with reference to FIGS. 2 and 3. In the figure,
5 is an operational amplifier, 6 is a light receiving element installed inside the camera body to receive reflected light from the film surface as shown in Fig. 3, and 7 is a compressor that converts the output current of the light receiving element 6 into a detection voltage. The light receiving element 6 is a transistor, and the operational amplifier 5
The output and the positive input terminal of the operational amplifier 5 are connected to the base and collector of the compression transistor 7, respectively. 8 is an expansion transistor that generates an integral current by the compressed voltage of transistor 7;
9 is an integrating capacitor, 10 is an integration start switch that turns from on to off in connection with the start of the first curtain, and 11 is an integration stop switch that turns from on to off in connection with the start of the second curtain. transistor 7
A switch 11 is connected between the emitter of the extension transistor 8 and the ground line of one circuit.

An integrating capacitor 9 and a switch 10 are connected between the collector of the expansion transistor 8 and the positive terminal of the power supply 18. These operational amplifiers5. Light receiving element 6, transistors 7, 8
, an integrating capacitor 9, and a switch 10.degree. 11 constitute a film surface exposure amount detection circuit 2.

Reference numeral 12 denotes a display switch that switches from the a terminal to the b terminal in connection with the completion of trailing curtain travel.

Reference numeral 13 denotes a variable resistor for setting a reference voltage, which converts the required exposure amount corresponding to the film sensitivity into a reference voltage and sets it, and corresponds to the film sensitivity information setting circuit 1 in FIG. 13a and 13b are sliders for taking out the upper and lower limit voltages of the reference voltage, respectively.

14 and 15 are open collector type comparators, which constitute the exposure amount determination circuit 3.

Reference numerals 16 and 17 indicate LEDs installed in the viewfinder and each emitting light of a different color, and together with transistors 19, 20, etc., constitute the display circuit 4.

18 is a power supply, the a terminal of the switch 12 is connected to the earth line, the b terminal is connected to the collector of the transistor 8, and the common terminal is connected to the X point where the negative input of the comparator 14 and the positive input of the comparator 15 are connected. . Sliders 13a and 13b are connected to the positive input of the comparator 14 and the negative input of the comparator 15, respectively, and the output of the one-sided comparator is connected to the midpoint of the LED 16 and the resistor 23 connected in series to the power source. be done.

Further, at this midpoint, there is a transistor 19 connected in two stages.
The base of the front stage transistor 19 of 20 is connected via the resistor 21, and the collector of the front stage transistor 19 and the power supply 1
A resistor 22 is connected between the positive terminal of the transistor 8, and an LED 17 and a resistor 24 are connected in series between the collector of the subsequent transistor 2° and the positive terminal of the power source 18. Variable resistor 1
3 is linked to the film sensitivity setting member, and slider 1
3a.

The voltage across 13b corresponds to the set film sensitivity, that is, the allowable error range of the actual amount of light received on the film surface with respect to the exposure amount required by the film, and serves as a reference voltage for comparators 14 and 15.

The comparator 14.15 outputs the LED 16 according to whether the integrated voltage of the integrating capacitor 9 at point X is within or outside the above tolerance range.
Or turn on 17.

The operation of such a configuration is such that when the film is wound and the shooting preparations are completed, the switch 10 is turned on and the switch 11 is turned on.
is on, and the switch 12 is on the a side. At this time, since the voltage at the X point is zero, the outputs of the comparators 14 and 15 are at a low level, and the transistor 20 is conductive and the LED 17 is lit. If you release the shutter now, the switch lO will turn from on to off at the same time as the first curtain starts, and the amplifier 5
．． The integrating capacitor 9 starts charging with a current corresponding to the film surface illuminance generated by a photometry circuit having a known configuration consisting of a light receiving element 6, a compression transistor 7, and an expansion transistor 8. Next, when the rear curtain starts, the switch 11 is turned from on to off, and charging of the capacitor 9 is stopped.

At this time, the charging voltage of the capacitor 9 is such that a current corresponding to the film surface illuminance is charged for a period of -7 (shutter time) between the start interval of the leading curtain and the trailing curtain. That is, the amount of exposure to the film surface is expressed as the amount obtained by integrating the film surface illuminance over the shutter time. Note that the reflectance of the lens-side surface of the front curtain of the shutter is equivalent to that of the photosensitive surface of the film. Switch 12 is set to a in conjunction with the completion of rear curtain travel.
The charging voltage of the integrating capacitor 9 is applied to the X point of the comparator 14.15. If this voltage is within the voltage range between the sliders 13a and 13b, the output of the comparator 14.15 becomes high level, the transistor 19 becomes conductive, and the LED 16 lights up, indicating that the exposure amount is appropriate. is displayed, and if it is out of range, the output of comparator 14.15 is low level, so transistor 2
0 conducts and LED 17 continues to light, indicating that the exposure is incorrect.
That is, malfunctions of the camera, inappropriate settings of shutter speed, aperture value, etc. are displayed in the viewfinder.

In this embodiment, the display circuit uses LEDs that emit light of different colors.
is provided in the viewfinder to make it easy to confirm the warning, but it is also possible to use a display that changes shape, a display based on the location of sound generation, etc.

As explained above, according to the present invention, since the exposure amount information display device of the camera is displayed on the front side of the camera for each shot, it is possible to display whether or not an appropriate exposure amount corresponding to the film sensitivity has actually been obtained on the film surface. Since the quality of the shooting result can be displayed, the photographer can immediately know the shooting result without developing or printing, and if the shooting result is unsatisfactory, he can immediately take another picture and avoid failures. can be prevented from occurring. In addition to inappropriate exposure due to all kinds of camera malfunctions such as shutter and aperture malfunctions, exposure meter and automatic exposure control circuit malfunctions, there are also malfunctions in exposure due to errors in shutter speed and aperture settings for manual cameras. Since you can shoot while checking not only if it is appropriate, but also if it is appropriate, you can shoot with confidence without worrying about the result.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an exposure amount information display device for a camera according to the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the same device.
FIG. 3 is a schematic configuration diagram of the camera showing the position of the light receiving element of the device. 1... Film surface sensitivity information setting circuit. 2... Film surface exposure amount detection circuit, 3... Exposure amount determination circuit, 4... Display circuit. 5... operational amplifier, 6... light receiving element, 7, 8.1
9.20...transistor. 9... Integrating capacitor, 10, 11, 12... Switch, 13... Variable resistor, 13a, 13b... Slider, 14.15... Comparator, 16.17...
・LED, 18...power supply, 21, 22, 23...resistance. Procedural Amendment G (Hakko) October 8, 1980 Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 146831 of 1983 2. Name of the invention Exposure amount information display device for camera; 3. Relationship with the case of the person making the amendment Applicant (052) Asahi Optical Industry Co., Ltd. 1, Agent 107 Telephone: 583-6939 Address:
Akasaka f, Minato-ku, Tokyo; ] N16 No. 4 No. 5, Column 6 for brief explanation of drawings in the specification subject to amendment, Contents of amendment

Claims (5)

[Claims] (1) A film sensitivity information setting circuit that converts the exposure amount required according to the film sensitivity of the loaded film into a reference voltage, and a film surface exposure amount detection circuit that converts the exposure amount of the film surface into a detection voltage. and an exposure amount determination circuit that determines an appropriate exposure amount by comparing the detection voltage of the film surface exposure amount detection circuit and the reference voltage of the film sensitivity information setting circuit, and according to the determination result of the exposure amount determination circuit. A camera exposure amount information display device comprising a display circuit that displays whether the exposure amount is appropriate or inappropriate. (2) The exposure amount information display device for a camera according to claim 1, wherein the exposure amount on the film surface is determined by measuring the light reflected from the film surface. (3) The exposure amount information display device for a camera according to claim 1, wherein the film sensitivity information setting circuit is linked to a film sensitivity setting device of the camera. (4) A method of determining and displaying whether or not the detected voltage is within a reference voltage range with upper and lower limits corresponding to an allowable range of exposure amount required in accordance with film sensitivity. An exposure amount information display device for a camera according to scope 1. (5) The exposure amount information display device for a camera as set forth in claim 1, wherein the display circuit has a light emitting diode provided within the viewfinder.