JPH0522899B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field of the Invention) The present invention relates to a notification device for an automatic flash device that can confirm whether or not the amount of light emitted is appropriate. (Background of the Invention) Conventionally, automatic flash devices receive reflected light returning from a subject with a light receiving element, and stop emitting light when the integrated value of the output reaches a predetermined value determined according to film sensitivity. The amount of light emitted was controlled appropriately. If the subject exceeds the effective distance range of the automatic flash device, the exposure will be under-exposed.
Conventional automatic flash devices detect this when the light emission ends before the integrated output of the light receiving element reaches a predetermined value, and displays a warning with sound or light. By the way, the width of the exposure range of current films differs depending on the type of film. For negative film, there are three types of exposure ranges: +3 to -1EV, +2 to -1EV, and +1 to -1EV for the appropriate light amount determined by the film sensitivity.
There is +0.5 to - for reversal film.
There is an exposure range of 0.5EV. As long as the amount of exposure falls within this exposure range, the resulting photograph will be almost the same as when the appropriate amount of light was given, that is, the difference in brightness of the subject will be almost faithfully reproduced as a difference in photographic density. Become. However, as mentioned above, in conventional automatic flash devices, the appropriateness of the amount of light emitted is determined only by whether the integrated output of the light receiving element reaches a predetermined value uniformly determined by the film sensitivity. In the case of negative film, an absurd situation occurred in which the resulting photograph was found to be suitable despite a warning that it was unsuitable. (Object of the Invention) An object of the present invention is to provide a notification device for an automatic flash device that can accurately indicate the suitability of the amount of light emitted by taking into account the exposure range of the film in accordance with the actual photographic results. (Example) Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows exposure area information detection means for reading information regarding the exposure area from an information code provided on the film cartridge. In the figure, the information code is composed of n patches 1-1 to 1-n provided on the surface of the film cartridge 1, and information on the exposure range, film sensitivity, and number of films is coded. has been done. For exposure range information, select 1-1, 1-2, 1-n of each patch.
is used. Coding is achieved by having each patch coated with insulating paint or by exposing the metal cartridge surface. The tips of probes 2-1 to 2-n protrude from the inner wall of the patrone chamber of the camera (not shown).
These come into contact with the corresponding patches 1-1 to 1-n when the cartridge is loaded. Probe 2-n is grounded, and the remaining probes 2-1 to 2-n
-1 is connected to a resistor connected to the power supply line Vcc and to the input terminal of the decoder 3, respectively.
Therefore, among the probes 2-1 to 2-n-1, the potential of the probe that comes into contact with the painted patch becomes the level of the power supply line Vcc (H level), and the probe comes into contact with the patch with the exposed metal surface. The potential of the probe dropped to ground (L level). The decoder 3 has a plurality of output terminals, of which four of the illustrated output terminals generate H or L level outputs D1 to D4. This output D1
~D4 is a probe 2 that detects four types of exposure ranges.
-1 and 2-2 are generated in the manner shown in the table below.

[Table] FIG. 2 shows the entire circuit of an embodiment in which the present invention is applied to a single-lens reflex camera. First, an outline of the circuit will be explained using each block surrounded by broken lines. is a light emission amount detection means for detecting the amount of light emitted by the flash device, which receives the flash light reflected from the film surface during photographing, performs photoelectric conversion, and integrates the output. is a film sensitivity setting means for introducing the sensitivity of the film to be used; for example, film sensitivity information is detected from the information code of the film cartridge and sent to the light emission amount detection means, and the film sensitivity is taken into account in the light emission amount detection. is a light emission amount control means for controlling the light emission amount of the flash device, which causes the flash device to emit light according to the operation of the shutter, and stops the light emission when the integral output of the light emission amount detection means reaches a predetermined value. is an exposure suitability detection means for detecting the suitability of exposure by flash light, which receives the integral output of the light emission amount detection means via the light emission amount control means, and also receives exposure area information from the decoder 3, and determines whether the exposure by flash light is suitable for the film being used. It is detected whether the exposure is within the exposure range, that is, whether the difference in brightness of the subject is reproduced as a difference in density on the finished photograph. is an exposure adequacy notification means for visually informing the photographer of the adequacy of the exposure amount caused by the flash, and operates according to the detection output from the exposure adequacy detection means. is the shutter control means. Next, the present embodiment will be explained by going into the contents of each block in FIG. The light emission amount detection means includes a photodiode PD that photoelectrically converts reflected light from the film surface, an operational amplifier OP1 that outputs the photometric current of the photodiode PD as a logarithmically compressed voltage using a diode D1 in a feedback circuit, and the operational amplifier OP1. NPN transistor Q1 whose base is connected to the output terminal of OP1,
Integrating capacitor C with one end connected to the collector of transistor Q1 and the other end connected to the power supply line Vcc, PNP transistors Q2 and Q3 whose emitters and collectors are connected in parallel to capacitor C, turned off when the quick return mirror rises. The switch S1 is configured to cut off the base current and turn off the transistor Q2 by cutting off the base current, and the switch S2 switches from the terminal a side to the terminal b side during exposure in conjunction with the shutter, cutting off the base current and turning off the transistor Q3. . The film sensitivity setting means includes a current source CC0, a variable resistor VR having one end connected to the current source CC0 and the other end grounded, and a voltage follower OP2 having an input terminal connected to a connection point between the two. variable resistance VR
is set to a resistance value corresponding to the sensitivity of the loaded film, so the output of the voltage follower OP2 corresponds to the film sensitivity. This output is sent to the emitter of transistor Q1. Therefore, the collector current of transistor Q1 is equal to the photometric output of operational amplifier OP1 and the voltage follower.
This corresponds to the film sensitivity information output of OP2. Integrating capacitor C is connected to transistor Q1
The collector current of is integrated during exposure. The light emission amount control means includes a comparator CP1 and a transistor Q4. Comparator CP1
A reference voltage source E1 is connected to the inverting input terminal of the integrating capacitor C, and when the voltage value of the integrated output of the integrating capacitor C falls below the voltage of the reference voltage source E1, the comparator CP1 outputs an H level output to the base of the transistor Q4. send it and turn it on. The collector of the transistor Q4 is connected to the light emission stop terminal T2. This terminal is connected to a light emission stop circuit of a flash device (not shown), and this circuit is connected to a transistor Q.
4 is turned on, the light emission is stopped. Switch S2
The light emission starting terminal T1 connected to the terminal b of is connected to a light emission starting circuit of a flash device (not shown), and this circuit starts light emission when exposure is started and the switch S2 is switched to the terminal b. The exposure suitability detection means includes current sources CC1 to CC6,
The output D of the decoder 3 is connected in series with the current source CC2.
P-channel MOSFET whose opening/closing is controlled by 1
Q5, N-channel MOSFETs Q6 to Q8, which are connected in series to the current sources CC4 to CC6 and whose opening and closing are controlled by the outputs D2 to D4 of the decoder 3, respectively;
It has comparators CP2 and CP3, resistors R1 and R2 connected in series with each other, and a power source E2 whose negative electrode is connected to the connection point of both resistors. Comparator CP2 is
The amount of exposure from the flash is compared with the lower limit of the exposure range of the loaded film. For this purpose, the output of the integrating capacitor C is inputted as flash exposure amount information to the inverting input terminal, and a circuit for outputting the lower limit value information of the exposure range is connected to the non-inverting input terminal. The output voltage of this circuit is equal to the voltage generated by the current I1 flowing from the current source CC1 and the resistor R1, or the sum of the currents flowing from the current sources CC1 and CC2 (I1+I
2) and the voltage generated by resistor R1 from the voltage of voltage source E2. This voltage source E2
The voltage is equal to the voltage value of the integrating capacitor C when the proper exposure amount is reached by light emission from the flash device. Comparator CP3 compares the amount of exposure from the flash with the upper limit of the exposure range of the loaded film.
For this purpose, the output of the integrating capacitor C is inputted as flash exposure amount information to the non-inverting input terminal, and a circuit for outputting upper limit value information of the exposure range is connected to the inverting input terminal. The output voltage of this circuit is equal to the voltage generated by the current I3 flowing from the current source CC3 and the resistor R2, or by the voltage generated by the current source CC4 to CC4.
6 flows through any of the currents I4 to I6 and the current source CC
The voltage of the voltage source E2 is shifted by the voltage generated by the sum of the current I3 flowing through the voltage source E3 and the resistor R1. Here, the comparator CP representing the lower limit of the exposure range
A description will be given of how the voltage at the non-inverting input terminal of No. 2 and the voltage at the inverting input terminal of the comparator CP3 representing the upper limit of the exposure range are set. When a film with an exposure range of +3 to -1EV is loaded, as shown in the table above, both probes 2-1 and 2-2 go to L level, so the output D1 of decoder 3
~D3 is at L level, and D4 is at H level. When the output D1 is L level, the transistor Q5 is turned on, and when the outputs D2 and D3 are at the L level, the transistors Q6 and Q7 are turned off, and the output D4 is turned on.
When is at H level, transistor Q8 is turned on. Therefore, the voltage generated across resistor R1 is R1・(I
1+I2), and the voltage generated across resistor R2 is R
2.(I3+I6). Voltage R1 of resistor R1 at this time (I1+I2)
is set to a value equal to the charging voltage of the integrating capacitor C when the exposure is one step below the proper exposure (-1 EV). Also, the voltage R of resistor R2
2.(I3+I6) is set to be equal to the charging voltage of the integrating capacitor C when the exposure is three steps over (+3EV) than the proper exposure. When the exposure range is +2 to -1 EV, the value of the current flowing through the resistor R2 is different from the previous example. In other words, since only the output D3 of the decoder 3 is at H level, the transistor Q7
is turned on, and a current of (I3+I5) flows through the resistor R2. The voltage of resistor R2 is R2・(I3
+I5), but this value is set to be equal to the charging voltage of the integrating capacitor C when the exposure is two steps over (+2EV) than the proper exposure. When the exposure range is +1 to -1 EV, the current value flowing through the resistor R2 is different from the previous example. In other words, since only the output D2 of the decoder 3 is at H level, the transistor Q6
is turned on, and a current of (I3+I4) flows through the resistor R2. The voltage of resistor R2 is R2・(I3
+I4), and this value is set to be equal to the charging voltage of the integrating capacitor C when the exposure is one step over (+1EV) than the proper exposure. When the exposure range is +0.5~-0.5EV, resistor R1,
Both values of the current flowing through R2 are different from the previous example. In other words, since only the output D1 of the decoder 3 is at H level, all of the transistors Q5 to Q8 are turned off.
A current of I1 flows through the resistor R1, and a current of I3 flows through the resistor R2. The voltages R1 and I1 of the resistor R1 are set to be equal to the charging voltage of the integrating capacitor C when the exposure is 0.5 steps over (+0.5EV) than the proper exposure, and the voltages R2 and I3 of the resistor R2 are set to It is set to be equal to the charging voltage of the integrating capacitor C when the exposure is 0.5 steps below (-0.5EV). The exposure suitability notification block V is an AND gate.
AND, a display drive circuit 5 operated by its output;
It consists of a light emitting element LED that emits light by the output of the circuit. The four input terminals of the AND gate AND include a shutter control circuit 4, which will be described later, and a comparator CP.
2, each output terminal of CP3 and the power supply side terminal of switch S1 are connected respectively. The shutter control block consists of a shutter control circuit 4 and a shutter closing magnet Mg. Incidentally, E is a power supply, and the opening/closing of the power supply path thereof is controlled by a power switch S3. The operation of this embodiment will be explained below. An example will be explained in which a film with an exposure range of +1 to -1 EV is loaded into the camera. When the release is performed, switch S1 is turned off as the quick return mirror rises, and transistor Q2 is turned off. When the shutter is fully opened and the switch S2 is switched from terminal a to terminal b, the transistor Q3 is turned off, the flash device starts emitting light, and the integrating capacitor C begins to be charged. The next steps will be divided into the following three types. When the exposure is overexposed because the subject is too close, etc.When the exposure is underexposed because the subject is too far away.When the exposure is within the exposure range.Each case will be explained below in sequence. When overexposure occurs due to the subject being too close, etc. In this case, the charging voltage of the integrating capacitor C becomes the voltage value for proper exposure (voltage value of E1) immediately after the flash device fires, and a flash stop signal is issued from the comparator CP1. However, when the light emission actually stops due to a time delay in the circuit or the like, overexposure occurs and the charging voltage of the integrating capacitor C becomes higher than that during proper exposure. At this time, the voltage at the inverting input terminal of comparator CP3 is set to the value when the exposure amount is one step over, so when the charging voltage of the integrating capacitor C is lower than this value, that is, the amount of exposure is one step over. When the comparator is greater than
The output of CP3 becomes L level. Therefore, since the output of the AND gate AND remains at the L level, the user can know that the exposure was inappropriate since the light emitting element LED does not emit light. When underexposure occurs due to reasons such as the subject being too far away, etc. In this case, the flash occurs without the charging voltage of the integrating capacitor C reaching the appropriate exposure voltage value, that is, without the flash stop signal being issued from the comparator CP1. Since the device stops emitting light, it becomes underexposed and the integrating capacitor C
The charging voltage is lower than that at proper exposure. At this time, the voltage at the non-inverting input terminal of comparator CP2 is set to the value when the exposure amount is one step under, so when the charging voltage of the integrating capacitor C is higher than this value, that is, the amount of underexposure is one step. When it is larger than the stage, the output of comparator CP2 is
It becomes L level. Therefore, since the output of the AND gate AND remains at the L level, the user can know that the exposure was inappropriate since the light emitting element LED does not emit light. When the exposure is within the exposure range In this case, the charging voltage of the integrating capacitor C is
The voltage at the non-inverting input terminal of comparator CP2,
Since the voltage is between the voltage of the inverting input terminal of comparator CP3, that is, the exposure amount is between one step over and one step under, comparator CP2,
Both outputs of CP3 become H level. When the magnet Mg is de-energized to close the shutter, the output of the shutter control circuit 4 becomes H level, and all the input terminals of the AND gate AND become H level. Therefore, the display drive circuit 5 operates to cause the light emitting element LED to emit light, thereby informing the user that the amount of light emitted is appropriate. (Effects of the Invention) As described above, according to the present invention, it is displayed whether or not the exposure due to the flash falls within the exposure range of the film. There is no need to make corrections, or conversely, there is no need to miss a valuable photographic opportunity by mistaking a photograph that is not within the exposure range as a successful photograph.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a part (exposure area information detection means) of an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the entire embodiment. Explanation of symbols of main parts, 3...Exposure area information detection means,...Emission amount detection means,...Emission amount control means,...Exposure suitability detection means,...Exposure suitability notification means.

Claims (1)

[Scope of Claims] 1. A light emission amount detection means for photoelectrically converting the flash light reflected back from the subject and integrating the output to detect the light emission amount of the flash device; and an integration of the light emission amount detection means. a light emission amount control means for stopping the light emission when the output reaches a predetermined value; an exposure area information detection means for detecting information representing the exposure area of the film from the film used; an integrated output of the light emission amount detection means; Exposure suitability detection means receives the exposure range information of the exposure range information detection means and detects whether the exposure by the flash falls within the exposure range of the film; and operates according to the detection output from the exposure suitability detection means. 1. A notification device for an automatic flash device, characterized in that it has an exposure appropriateness notification means for notifying a photographer of the appropriateness of the exposure amount of flash light.