JP2001311988A - Strobe light control system and camera equipped with strobe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a comparatively simply constituted strobe light control system which is excellent in linearity and whose accuracy is high, and to provide a camera with the strobe light control system. SOLUTION: The number of pulses per unit time almost proportional to the intensity of incident light is generated by an optical sensor, an integration unit, a comparison unit and a pulse converter. The system is provided with a counter for counting the number of pulses, a light emission starting means for starting a strobe light emitting operation, simultaneously, generating the new pulse in the integration unit, and a light emission stopping means for automatically stopping the light emission when the quantity of the incident light reaches a desirable value, A counting target value is obtained based on pulse intervals in accordance with the desirable value. A light emission stopping pulse is outputted when the counted value reaches the counting target value, then, the light emission is stopped. Besides, it is allowed to use a software timer instead of the counter. In addition to the normal light emission, examples of red-eye light emission and light emission by fixed light quantity are shown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera equipped with a strobe, and more particularly, to a strobe automatic dimming system and method.

[0002]

2. Description of the Related Art In a camera having a wide range of lens F-numbers, such as a zoom model and a model having F-number (brightness) switching,
Strobe light control is performed by changing the integration constant of the integrator in multiple stages according to the lens F value or by providing a function of switching the reference voltage of the comparator in multiple stages.
However, these methods lose linearity by switching,
Dimming with high accuracy could not be performed. In addition, since many control ports for switching are required, the interface with the control unit tends to be complicated. Further, there have been problems such as a complicated circuit, an increase in a mounting area on a printed circuit board, and an increase in cost.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flash dimming method which has a relatively simple structure and has excellent linearity and high accuracy, a flash device which performs dimming based on the method, and a flash dimming method based on the method. An object of the present invention is to provide a device such as a camera having a strobe system. The camera may be a film camera or a digital camera.

[0004]

According to the present invention, there is provided a strobe dimming system, comprising: pulse generating means for generating a number of pulses per unit time substantially proportional to the luminous intensity of incident light; and a count value counting the pulses. Counter means for giving a strobe light, light emission start means for generating a new pulse in the pulse generation means at the same time as starting the light emission of the strobe, and automatically emitting the light emission when the amount of the incident light reaches a desired value. And a light emission stopping means for stopping the light emission.
The pulse generating means includes, for example, the optical sensor 62, the amplifier 64, the integrator 66, the reference voltage generator 68,
It includes a comparator 70. The light emission starting means is CP
U52 fulfills its function and performs the light emitting operation described in step 102 in FIG. The light emission stopping means is the counter circuit 74 and a two-input OR gate, or the CPU 52. When the CPU functions as the light emission stop means, the control contents of steps 138 and 140 in FIG. 2 correspond to the control operation as the light emission stop means. According to a second aspect of the present invention, in the flash dimming system according to the first aspect, the pulse generation unit has an optical sensor, an integration unit that integrates a signal from the optical sensor, and an integration output of the integration unit reaches a reference voltage. It is characterized by including a comparing means for sometimes generating the pulse. According to a third aspect of the present invention, in the flash dimming system according to the first or second aspect, the light emission stopping unit sets the count target value obtained based on the pulse interval in accordance with the desired value in the counter unit. And a stop pulse means for stopping light emission by a light emission stop pulse, wherein the counter means includes a light emission stop pulse output means for outputting the light emission stop pulse when the count value reaches the count target value. It is characterized by. The means for setting the count target value in the counter means is, for example, the CPU 52. When the CPU 52 functions as the means, the control content shown in step 136 in FIG. 2 corresponds to the control operation as the means. . The stop pulse means is, for example, a strobe drive circuit. The light emission stop pulse means is, for example, a counter circuit 74.

According to a fourth aspect of the present invention, there is provided a flash dimming system.
3. The timer according to claim 1, wherein the light emission stop unit starts counting time from the start of light emission, and a timer target value calculation unit that obtains a timer target value based on the pulse interval according to the desired value. And stop pulse means for stopping light emission by a light emission stop pulse when the timer value reaches the timer target value. The timer means is the CPU 52,
When U52 functions as timer means, the control content of step 104 in FIG. 2 corresponds thereto. The timer target value calculating means is the CPU 52, and corresponds to step 136 in FIG.
The control contents shown in (1) correspond to the control operation as the means. The stop pulse means is, for example, a CPU.
In the case where 52 functions as the means, the control contents of steps 138 and 140 in FIG. 2 correspond to this. Claim 5
The strobe light control system according to any one of claims 1 to 4, wherein the exposure amount is reduced when the number of the pulses in the first predetermined period during light emission exceeds a first predetermined upper limit. It is characterized in that it further includes downward correction means. The lower exposure amount correcting unit is, for example, the CPU 52. When the CPU 52 functions as the unit, the control contents of steps 106, 108, and 110 in FIG. 2 correspond thereto. According to a sixth aspect of the present invention, in the strobe dimming system according to the fifth aspect, the exposure amount lowering correction unit performs an operation of reducing the aperture, increasing the shutter speed, reducing the sensitivity of the CCD, or any combination thereof. It is characterized by comprising means. According to a seventh aspect of the present invention, in the strobe light control system according to the fifth or sixth aspect, when the number of the pulses in the second predetermined period during the light emission exceeds a second predetermined upper limit value, the light emission is stopped and the photographing is performed. And further includes a light amount excess processing unit for notifying the user of the light amount excess. The light amount excess processing means is, for example, the CPU 52, and when the CPU 52 functions as the means, the CPU 52 performs steps 120, 12 in FIG.
The processing contents by 2, 124 correspond to the means. An electronic flash dimming system according to claim 8, further comprising: means for increasing the reference voltage when the interval or cycle of the pulse is smaller than a first predetermined value. Features. The means for increasing the reference voltage is, for example, the CPU 52. When the CPU 52 functions as the means, the processing contents of steps 112 and 114 in FIG. 2 correspond to the means. The strobe dimming system according to claim 9, further comprising: means for lowering the reference voltage when the interval or cycle of the pulse is smaller than a second predetermined value. Features. The means for lowering the reference voltage is, for example, a CPU 5
2, and when the CPU 52 functions as the means, the processing contents of steps 116 and 118 in FIG. 2 correspond to the means.

According to a tenth aspect of the present invention, in the strobe dimming system according to any one of the first to ninth aspects, the number of the pulses in the third predetermined period during the emission is less than the first predetermined lower limit. And an exposure amount upward correction means for increasing the exposure amount. The exposure upper correction means is, for example, the CPU 52. When the CPU 52 functions as the means, the processing contents of steps 126 and 128 in FIG. 2 correspond to the means. According to a tenth aspect of the present invention, in the strobe dimming system according to the tenth aspect, the exposure upper correction means performs an operation of opening the aperture, reducing the shutter speed, increasing the sensitivity of the CCD, or any combination thereof. It is characterized by comprising means. The means for performing the operation is, for example, the CPU 52, and the CPU 5
Step 2 of FIG. 2 if 2 functions as the means.
The processing contents of 26 and 128 correspond to the means. Claim 1
2. The strobe light control system according to claim 2, wherein the light emission is stopped when the number of the pulses in the fourth predetermined period during the light emission is less than a second predetermined lower limit value according to any one of claims 5 to 11. In addition, the apparatus further includes a light quantity shortage processing unit that stops photographing and notifies the user of the light quantity shortage. The light quantity shortage processing means is, for example, the CPU 52,
When the CPU 52 functions as the means, the processing contents of steps 130, 132, and 134 in FIG. 2 correspond to the means. According to a thirteenth aspect of the present invention, there is provided a strobe light control system according to any one of the first to twelfth aspects, further comprising a red-eye emission unit that emits red-eye in a predetermined emission sequence. The red-eye emitting means is, for example, a CPU.
52, and when the CPU 52 functions as the means, the processing contents of steps 152 to 168 in FIG. 4 correspond to the means. According to a fourteenth aspect of the present invention, there is provided a strobe light control system according to any one of the first to thirteenth aspects, further comprising a constant light quantity light emitting means for performing a constant light quantity light emission in a predetermined light emission sequence. The constant light quantity light emitting means
For example, when the CPU 52 functions as the unit, the processing in steps 152 to 162 in FIG. 4 corresponds to the unit. The strobe light control system according to claim 15, further comprising a distance calculation unit for counting the pulses within a predetermined time and calculating a distance to a subject based on the number of pulse signals according to any one of claims 1 to 14. It is characterized by.

[0007] A camera with a strobe according to claim 16 is
Pulse generating means for generating a number of pulses per unit time substantially proportional to the luminous intensity of the incident light, counter means for counting the pulses and providing a count value, and simultaneously starting the emission of a strobe light, the pulse generating means A light emission start means for generating a new pulse and a light emission stop means for automatically stopping the light emission when the amount of the incident light reaches a desired value are provided. According to a seventeenth aspect of the present invention, in the camera with the strobe according to the sixteenth aspect, the pulse generating means includes an optical sensor, an integrating means for integrating a signal from the optical sensor, and an integrated output of the integrating means reaching a reference voltage. And a comparing means for generating the pulse. According to a eighteenth aspect of the present invention, in the camera with a strobe according to the sixteenth or seventeenth aspect, the light emission stopping means sets the count target value obtained based on the pulse interval according to the desired value in the counter means. Means, and stop pulse means for stopping light emission by a light emission stop pulse, wherein the counter means includes light emission stop pulse output means for outputting the light emission stop pulse when the count value reaches the count target value. Features. 20. The camera with a strobe according to claim 19, wherein the light emission stop means starts counting time from the start of light emission, and a timer based on an interval of the pulse according to the desired value. It is characterized by including timer target value calculating means for obtaining a target value and stop pulse means for stopping light emission by a light emission stop pulse when the timer value reaches the timer target value.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and the accompanying drawings. When the same element is shown in a plurality of drawings, the same reference numeral is given. (Embodiment 1) FIG. 1 is a block diagram schematically showing an embodiment of a camera provided with a flash control system according to the present invention. In FIG. 1, a camera 1 includes a mechanical optical system 2 including an optical system and a mechanical system for operating the optical system, a display unit 3 that indicates the state of the camera, an operation unit 4 that allows a user to operate the camera, and a camera 1. Controller 5 for overall control
It has. The controller 5 includes a CPU (central processing unit) 52 and a ROM (read-only storage) for storing various programs and data for controlling the operation of the CPU 52.
And a RAM (read / write memory) 56 for storing data necessary for the operation of the CPU 52. Camera 1
Further includes a strobe light 84 and a strobe drive circuit 8
2 and a strobe control unit 6. Operation unit 4
Includes at least a shutter button 42, a strobe operation mode selection switch 44, and a strobe light amount adjustment switch 46. The strobe operation mode that can be selected by the user is one of a normal light emission mode, a red-eye light emission mode, and a constant light amount mode. If the luminous intensity is insufficient during the AF (automatic focus control) operation, AF auxiliary light emission is automatically performed. The strobe control unit 6 turns on an optical sensor 62 for detecting light arriving at the camera 1 and an output of the optical sensor 62.
Open / close switch 63, amplifier 64 for amplifying the output of switch 63, integrator (integrating means) 66 for integrating output voltage Va of amplifier 64, reference voltage generator (reference voltage generating means) 68 for generating reference voltage Vref , Integrator 66
(Comparing means) 70 for comparing the output voltage Vi with the reference voltage Vref, a pulse converter (pulse converting means) 72 for converting the output pulse signal Sc of the comparator 70 into a pulse having a constant pulse width, and pulse conversion. Output pulse P of the heater 72
A counter circuit (counter means) 74 for counting the number of i, an AND gate 76 for giving the logical product of the output signal Sc of the comparator 70 and the output signal Pi of the pulse converter 72, the output signal of the AND gate 76 and the output from the controller 5. A 3-input OR gate 78 for applying a logical sum of a strobe light emission start signal Ss and an integrator reset signal Sr to a reset terminal of an integrator 66, a strobe light emission stop signal Se output from a counter circuit 74, and light emission from the controller 5. The logical sum of the stop signal St is calculated by the light emission stop terminal 82 of the strobe drive circuit.
It comprises an OR gate 80 for giving B. In the following description, the term “pulse” simply indicates the output pulse Pi of the pulse converter 72. The opening and closing of the switch 63 is performed by a control signal Sd from the controller 5. The signal Sd is controlled so that the switch 63 is normally turned on and the elements 64 to 74 are inhibited, and only when it is desired to control the stop of the strobe light 84 by software, the signal 63 is turned off. It is preferable that the reference voltage Vref of the reference voltage generator 68 be configured to be set by the controller 5. The counter circuit 74 is preferably configured such that a count target value can be set from the controller 5 and the count value can be read out at any time during counting. Counter circuit 74
Is to output one pulse of a predetermined pulse width when counting up to the set target value.

FIG. 2 shows signal waveforms of a strobe light emission start signal Ss, an amplifier 64 output Va, an integrator 66 output Vs, a comparator 70 output Sc, a pulse converter 72 output pulse Pi, and a counter circuit 74 output Se. FIG. 1 and 2, the output of the optical sensor 62 is
Is supplied to the amplifier 64 via the. Amplifier 6
4 is at a low level before the strobe light is emitted, but the controller 5 outputs the strobe emission start pulse S
s is output, and when the strobe starts to emit light, it goes to a high level. The output Va of the amplifier 64 is integrated by the integrator 66 to become a signal Vs. The integration signal Vs increases with a slope proportional to the input voltage Va, but is returned to the zero level each time a reset pulse is output from the three-input OR gate. This zero clear occurs as follows. The comparator 70 calculates the integrated voltage V
s is the reference voltage Vre given from the reference voltage generator 68.
When the integrated voltage Vs reaches the reference voltage Vref, the comparison output Sc is changed from, for example, logic 0 to logic 1 (arrow Ta). At this time, the pulse converter 72 detects the rising edge of the comparison output Sc, and outputs a pulse Pi having a predetermined pulse width T (arrow Tb). This pulse Pi is given to one input of the AND gate 76, and the other input of the AND gate 76 is connected to the output Sc of the comparator 70 which is currently in the state of logic 1;
It is applied to the reset terminal of integrator 66 via R gate 78. Since the integrator 66 is configured so that the input of the reset terminal detects a change from logic 0 to logic 1 and is cleared to zero, the integrator 66 is cleared to 0 at the rising edge of the pulse Pi (arrow Tc). The output Sc of the comparator 70 also returns to zero according to the change of the integration signal Vs at this time. In this way, the pulse converter 72 outputs a number of pulses Pi approximately proportional to the light flux detected by the optical sensor 62. Therefore, it can be considered that the number of pulses Pi output after the start of the flash emission is substantially proportional to the exposure amount after the start of the flash emission. Therefore, the counter circuit 74
When the number of pulses Pi input to the counter circuit 74 reaches the target value N by setting an appropriate count target value N by the controller 5, the counter circuit 74 outputs a strobe light emission stop pulse Se ( Arrow Te). The emission stop pulse Se is applied to the terminal 82B of the strobe drive circuit 82 via the OR gate 80, whereby the emission of the strobe light ends (Tf). Thus, the strobe control unit 6 is configured to automatically stop the strobe light emission when the predetermined start pulse number N is reached when the controller 5 outputs the light emission start signal Ss.

Next, the strobe system 3 to 84 of the present invention.
Before describing the dimming operation of the camera using the camera, the basic specifications of the flash system will be described. (1) Depending on the setting of the user, a) normal light emission, b) red-eye light emission (light emission for a very short time before light emission at the moment of release (tentatively referred to as main light emission) (tentatively referred to as preliminary light emission)
Light emission method), and c) light emission with a constant light intensity (a light emission method for maintaining a constant light emission intensity during the effective period by repeating short light emission until a predetermined light intensity is reached). (2) If the number of pulses N1 within a predetermined time T1 after the light emission exceeds a predetermined value, the exposure amount is reduced. As a method of lowering the exposure amount, for example, a) reducing the aperture (not shown)
There are methods such as b) increasing the speed of a shutter (not shown), c) decreasing the sensitivity of a CCD (Charge Coupled Device) not shown, or d) arbitrarily combining these. (3) When the pulse Pi interval is shorter than a predetermined length (for example, the duration of the pulse), the reference voltage Vref is increased to increase the pulse generation cycle.
By reducing the reference voltage Vref, the pulse generation cycle is shortened. (4) When the number of pulses N2 within a predetermined time T2 (T1 <T2) exceeds a predetermined value after the light emission, the light emission is stopped and the photographing is interrupted so that an image with an excessive light amount is not photographed. A warning of an excessive light amount is issued to the user by an LED, LCD display, sound, or the like. (5) If the pulse P1 (initial pulse) is not detected within the predetermined time T3 (T2 ≦ T3) after the light emission or is equal to or less than the predetermined pulse number N3, the exposure amount is increased, and an image with insufficient light quantity is captured. Not to be. Methods of increasing the exposure amount include, for example, a) opening an aperture (not shown), b) reducing the speed of a shutter (not shown), c) increasing the sensitivity of a CCD (Charge Coupled Device) not shown, or d) There is a method of arbitrarily combining these. (6) If the pulse P1 (first pulse) is not detected within a predetermined time T4 (T3 <T4) after the light emission or is equal to or less than a predetermined number N4 (N3 <N4), the light emission is stopped and the photographing is performed. Is interrupted so that an image with insufficient light quantity is not captured, and the user is notified of the insufficient light quantity by an LED, LCD display, sound, or the like. (7) After the strobe light is emitted, for a predetermined period T5 (for example, T
Based on the pulse interval in 2 <T5), a target value of the exposure amount is set, and when the target value is reached, the strobe light emission is stopped. As the target value at this time, a) the light emission time and b) the number of output pulses of the pulse converter 72 can be considered. (8) Vref can be adjusted by operating the strobe exposure adjustment switch 46 of the operation unit 4. (9) The distance to the subject is determined based on the number of pulses within a predetermined time during flash emission. The operation of the strobe system (3-84) having the above features will be described.

(Normal Light Emission) FIG. 2 shows the operation under the control of a program stored in the ROM 54 when the shutter button 42 is pressed in a state where the flash mode switch 44 is set to the normal light emission (NORMAL) in the operation unit. 9 is a flowchart illustrating an example of a process executed by a CPU 52. Normally, the switch 63 is assumed to be closed. When a strobe light emission instruction is received,
As shown in (5), the CPU 52 first outputs a strobe light emission start signal Ss to cause the strobe to emit light, and at the same time, sets a predetermined value in the counter circuit 74 (step 102), and receives a timer interrupt pulse from a clock circuit (not shown). The software timer to be started is started or cleared to zero (104). Here, the current value of the timer is represented by t. In step 106, after the start of light emission, a first predetermined time T1 elapses (ie, t = T
Wait until 1). When t = T1, the current count value (number of pulses) n of the counter circuit 74 is read, and it is determined whether or not n exceeds a predetermined upper limit value N1 (that is, n> N1) (step 108). If it exceeds, the exposure amount is reduced according to the basic specification (2) described above (step 110).
Proceed to step 112. In the case of NO at step 108, the process directly proceeds to step 112. In step 112, the interval of the pulse Pi is determined (T1 / N1), which is smaller than the first predetermined pulse interval D1 (ie, T1 / N1).
It is determined whether 1 ≦ D1). If it is smaller, the reference voltage Vref is increased so that the pulse cycle does not become too short, and the cycle is lengthened (step 114). If not, it is determined whether the pulse interval is larger than the second predetermined interval D2 (that is, T1 / N1 ≧ D1) (step 116). If it is larger, the reference voltage Vref is lowered so that the pulse cycle does not become too long, and the cycle is shortened (step 118).

In step 120, after the strobe light is emitted, the process waits until a second predetermined time T2 elapses, and proceeds to step 122. The current count value n of the counter circuit 74
Is a second predetermined upper limit N2 which is larger than the above upper limit N1.
Is exceeded (that is, n> N2) (step 122), and if so, the strobe light emission stop pulse St
Is output to stop light emission, stop shooting to prevent an image with an excessive amount of light from being shot, and display an LCD, LED,
The user is notified that the light amount is excessive by voice or a combination thereof (step 124), and the dimming process ends. In step 122, the determination result is NO
In step 126, it is determined in step 126 whether the count value n is less than a predetermined lower limit value N3 (ie, N3 <N4). If not, in step 128, the exposure amount is increased and the light amount becomes insufficient. Prevent images from being captured,
Proceed to step 130. If the result of the determination at step 126 is NO, the process immediately proceeds to step 130. In step 130, after the light emission starts, the process waits for a fourth predetermined time, and in step 132, the current counter value n is less than the fourth predetermined value N4 (that is, n <N4).
(N3 <N4)) is determined. If not, in step 134, a light emission stop pulse St is output to stop light emission, stop photographing so that an image with insufficient light quantity is not captured, and use the LCD, LED, sound or a combination thereof to perform light emission insufficient. The user is notified that there is (step 134), and the dimming process ends. If the determination result in the determination step 132 is NO, the process proceeds to a step 136 to calculate an exposure amount according to the pulse interval.
A software timer (not shown) or a counter circuit 74 is set to a value corresponding to the calculated exposure amount. FIG. 3 shows an example in which the target value of the timer is set. When a timer is used, the counter circuit 74 is not used. In order to prevent the light emission from being interrupted by the output Se of the counter circuit 74, the switch 63 is opened by the control signal Sd in step 136. In step 138, the process waits until the value t of the timer reaches the target value.
At 0, a light emission stop pulse St is output to stop light emission,
The light control processing ends. In step 136,
When the target value is set in the counter circuit 74, the light emission stop pulse Se is automatically output when the counter circuit 74 counts up to the target value to stop the light emission, so that steps 138 and 140 are unnecessary.

(Red Eye Emission) FIG. 4 is a flowchart showing an example of a dimming operation performed by the CPU 52 when a flash instruction is received when the flash mode selection switch 44 of the operation unit 4 is set to the red eye emission mode. It is. In FIG. 4, first, 1 is set as an initial value in a light emission number counter C (step 152). The number of pulses corresponding to the light emission period of the preliminary light emission is set in the counter circuit 74 (step 154). The light emission start pulse Ss is output to start light emission (step 156), and the software timer is reset to start measuring the light emission cycle (step 157). It is determined whether the value C of the light emission number counter has reached a predetermined value (step 158). If not reached, the counter value C is incremented (step 160), and after waiting for the timer to reach a predetermined light emitting cycle, step 1 is executed.
Returning to step 56, the next preliminary light emission is performed. Decision step 158
In the case where the number-of-light-emissions counter C reaches a predetermined value, the process waits for a predetermined light-emission cycle (step 164).
In step 166, the number of pulses corresponding to the predetermined duration of the main light emission is set in the counter circuit 74, the light emission start pulse Ss is output to start the main light emission (168), and the dimming process in the red-eye light emission mode is performed. finish. (Constant light quantity light emission) The constant light quantity light emission can be realized by changing the light emission duration, the light emission cycle, and the number of light emission in FIG. 4 so that the light quantity is constant light emission, and omitting the steps from step 164 onward. . In the above description, the pulse converter 72 outputs one pulse Pi in accordance with the rise of the output Sc of the comparator 70, but the pulse converter 72 outputs one pulse Pi in response to one rise of the output Sc of the comparator 70. , A plurality of pulses Pi may be output. When the exposure adjustment switch 46 of the operation unit 4 is operated, the CPU 52
Adjusts the reference voltage Vref. Further, the number of pulse signals is counted within a predetermined time, and the distance to the subject is calculated based on the number of pulse signals. For example, if the number of pulse signals is small, it is determined that the subject distance is long, and if it is large, it is determined that the subject distance is short. Alternatively, the time from the start of light emission to the output of the pulse signal is measured, and the distance to the subject is calculated based on the time. For example, if the time is long, it is determined that the subject distance is long, and if the time is short, it is determined that the subject distance is short.

(Embodiment 2) FIG. 5 is a block diagram schematically showing a second embodiment of a camera provided with a flash control system according to the present invention. In the second embodiment, the elements 68 to 80 of the first embodiment are integrated together with the CPU 52 into an IC. In the embodiment of FIG.
Although all the elements up to 0 have been integrated into an IC, it is of course possible to integrate only some of them into an IC. The above is merely an example of the embodiment for the description of the present invention. Therefore, it is easy for those skilled in the art to make various changes, modifications, or additions to the above-described embodiment in accordance with the technical idea or principle of the present invention. Therefore, the present invention should not be construed as being limited to the above-described embodiments, but should be construed in accordance with the appended claims. In each of the claims, the pulse generating means includes, for example, the optical sensor 62, the amplifier 64, the integrator 66, the reference voltage generator 68, and the comparator 70 in the embodiment.
Is included. The light emission starting means is, for example, a CPU 5
A control unit such as 2 performs its function, and corresponds to step 1 in FIG.
02 is performed. The light emission stopping means includes a counter circuit 74 and a two-input OR gate, or a CPU.
52. When the CPU functions as the light emission stop means, the control contents of steps 138 and 140 in FIG. 2 correspond to the control operation as the light emission stop means. The means for setting the count target value in the counter means is, for example, a CPU
52, and when the CPU 52 functions as the means, the control content shown in step 136 in FIG. 2 corresponds to the control operation as the means. The stop pulse means is, for example, a strobe drive circuit. The light emission stop pulse means is, for example, a counter circuit 74. The timer means is, for example, the CPU 52, and when the CPU 52 functions as the timer means, the control content of step 104 in FIG. 2 corresponds thereto. The timer target value calculation means is a CPU
The control content shown in step 136 in FIG. 2 corresponds to the control operation as the means. The stop pulse means is, for example, a CPU. When the CPU 52 functions as the means, the control contents of steps 138 and 140 in FIG. 2 correspond thereto. The lower exposure amount correcting unit is, for example, the CPU 52. When the CPU 52 functions as the unit, the control contents of steps 106, 108, and 110 in FIG. 2 correspond thereto. The light amount excess processing means is, for example, the CPU 52, and when the CPU 52 functions as the means, steps 120, 122, and 124 in FIG.
Corresponds to the means. The means for raising the reference voltage is, for example, the CPU 52. When the CPU 52 functions as the means, the CPU 52 performs steps 112 and 11 in FIG.
The processing content of No. 4 corresponds to the means. The means for lowering the reference voltage is, for example, the CPU 52. When the CPU 52 functions as the means, steps 116 and 118 in FIG.
Corresponds to the means. The exposure upper correction means is, for example, the CPU 52. When the CPU 52 functions as the means, the processing contents of steps 126 and 128 in FIG. 2 correspond to the means. Exposure upper correction means,
The means for opening the aperture, reducing the shutter speed, increasing the sensitivity of the CCD, or performing any combination of these operations is the CPU 52, for example. , 1
The processing contents of 28 correspond to the means. The light quantity shortage processing unit is, for example, the CPU 52. When the CPU 52 functions as the unit, the CPU 130 performs steps 130 and 132 in FIG.
The processing contents of 134 correspond to the means. The red-eye emitting unit is, for example, the CPU 52. When the CPU 52 functions as the unit, the processing contents of steps 152 to 168 in FIG. 4 correspond to the unit. The constant light quantity light emitting means is, for example, the CPU 52. When the CPU 52 functions as the means, the processing contents of steps 152 to 162 in FIG. 4 correspond to the means.

[0015]

As described above, according to Claims 1 to 4 and Claims 16 to 19, there is no need to switch the integration constant in multiple steps depending on the lens F value.
Dimming with high accuracy is possible, and the circuit can be simplified, reduced in space, and reduced in cost. Furthermore, since it is not related to the lens F value, there is no need to change the design for each camera.
Excellent in commonality. According to the third and eighteenth aspects, the operation of the dimming circuit can be automatically stopped by calculating the light emission stop time from the pulse signal and setting the same in the counter, so that it is possible to quickly shift to the next operation. As much as possible, the current consumption of the dimming circuit can be reduced. According to the fifth to seventh aspects, it is possible to prevent an image of the exposure overlay from being shot by short-range shooting or high-brightness shooting. Claim 8
According to 9 and 9, by varying the reference signal (Vref), the dimming sensitivity of each camera can be corrected for adjustment at the factory and according to the user's application. . According to the tenth to twelfth aspects, it is possible to detect an insufficient amount of light of the strobe, an insufficient amount of light, and the like, and increase an exposure amount of the camera so that an underexposed image is not captured. According to the thirteenth aspect, red-eye reduction emission can be performed with an appropriate amount of light. According to the fourteenth aspect, light emission with a constant light amount is possible. According to the fifteenth aspect, it is possible to calculate the distance to the subject using the strobe light.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a first embodiment of a camera including a strobe control system according to the present invention.

FIG. 2 is a strobe emission start signal Ss and an amplifier output V;
FIG. 3A is a diagram showing signal waveforms of an integrator output Vs, a comparator output Sc, a pulse converter output pulse Pi, and a counter circuit output Se.

FIG. 3 is a flowchart illustrating an operation example of a CPU 52 when light is emitted in a normal light emission mode.

FIG. 4 is a flowchart illustrating an operation example of a CPU 52 when emitting light in a red-eye emission mode.

FIG. 5 is a block diagram schematically showing a second embodiment of a camera including a strobe control system according to the present invention.

[Explanation of symbols]

1 camera, 2 optomechanical system, 3 display unit, 4 operation unit, 5 controller, 42 shutter button, 44
Strobe mode selection switch, 46 exposure adjustment switch, 52 CPU, 54 ROM, 46 RAM, 6
2 optical sensor, 64 amplifier, 66 integrator, 68 reference voltage generator, 70 comparator, 72 pulse converter, 74
Counter circuit, 76 AND gate, 78 3-input O
R gate, 80-input OR gate, 82 strobe drive circuit, 84 strobe light.

Claims (19)

[Claims] 1. A pulse generating means for generating a number of pulses per unit time substantially proportional to the luminous intensity of incident light, a counter means for counting the pulses and providing a count value, A light emission start unit that generates a new pulse in the pulse generation unit; and a light emission stop unit that automatically stops the light emission when the amount of the incident light reaches a desired value. Flash dimming system. 2. The pulse generating means includes an optical sensor, an integrating means for integrating a signal from the optical sensor, and a comparing means for generating the pulse when an integrated output of the integrating means reaches a reference voltage. The flash dimming system according to claim 1, wherein 3. A light emitting stop means for setting a count target value obtained based on an interval between the pulses in the counter means in accordance with the desired value, and a stop for stopping light emission by a light emission stop pulse. 3. A pulse output means for outputting a light emission stop pulse when the count value reaches the count target value, wherein the counter means includes a light emission stop pulse output means.
Strobe dimming system as described. 4. The timer according to claim 1, wherein the light emission stop means starts counting time from the start of light emission, a timer target value calculation means for obtaining a timer target value based on the pulse interval according to the desired value, The strobe light control system according to claim 1 or 2, further comprising: stop pulse means for stopping light emission by a light emission stop pulse when a timer value reaches the timer target value. 5. The apparatus according to claim 1, further comprising an exposure amount lowering correction unit that reduces an exposure amount when the number of pulses in the first predetermined period during light emission exceeds a first predetermined upper limit. The strobe light control system according to any one of claims 1 to 4. 6. The exposure amount lowering correction means comprises means for reducing the aperture, increasing the shutter speed, reducing the sensitivity of the CCD, or performing any combination of these operations. Strobe dimming system as described. 7. When the number of pulses during a second predetermined period during light emission exceeds a second predetermined upper limit, light emission is stopped, photographing is stopped, and a light amount notifying a user of an excessive light amount is provided. 7. The strobe light control system according to claim 5, further comprising an over-processing means. 8. The strobe light control according to claim 2, further comprising: means for increasing the reference voltage when the interval or cycle of the pulse is smaller than a first predetermined value. Light system. 9. The strobe flash control according to claim 2, further comprising: a unit for lowering the reference voltage when an interval or a period of the pulse is smaller than a second predetermined value. Light system. 10. The apparatus according to claim 1, further comprising an exposure amount upper correction unit that increases an exposure amount when the number of pulses during a third predetermined period during light emission is less than a first predetermined lower limit. Item 10. A strobe light control system according to any one of Items 1 to 9. 11. The apparatus according to claim 10, wherein said upper exposure amount correcting means comprises means for opening an aperture, lowering a shutter speed, increasing a sensitivity of a CCD, or performing an operation of any combination thereof. Strobe dimming system as described. 12. When the number of pulses during a fourth predetermined period during light emission is less than a second predetermined lower limit, light emission is stopped, photographing is stopped, and a user is notified of insufficient light quantity. 12. The strobe light control system according to claim 5, further comprising a light quantity shortage processing unit. 13. The strobe light control system according to claim 1, further comprising a red-eye light emitting unit that emits red-eye light in a predetermined light emission sequence. 14. The strobe light control system according to claim 1, further comprising a constant light emission means for emitting a constant light according to a predetermined light emission sequence. 15. The apparatus according to claim 1, further comprising a distance calculating means for counting the number of pulses within a predetermined time and calculating a distance to a subject based on the number of pulse signals.
The flash dimming system according to any one of the above. 16. A pulse generating means for generating a number of pulses per unit time substantially proportional to the luminous intensity of incident light, a counter means for counting the pulses and providing a count value, A flash unit comprising: a light emission start unit for generating a new pulse in the pulse generation unit; and a light emission stop unit for automatically stopping the light emission when the amount of the incident light reaches a desired value. With camera. 17. The pulse generating means, comprising: an optical sensor;
17. The strobe light control system according to claim 16, further comprising integrating means for integrating a signal from an optical sensor, and comparing means for generating the pulse when an integrated output of the integrating means reaches a reference voltage. 18. A light emitting stop means for setting a count target value obtained based on an interval between the pulses in the counter means in accordance with the desired value, and a stop for stopping light emission by a light emission stop pulse. Pulse means;
18. The flash dimming system according to claim 16, wherein the counter unit includes a light emission stop pulse output unit that outputs the light emission stop pulse when the count value reaches the count target value. 19. The timer according to claim 19, wherein the light emission stop means starts counting time from the start of light emission, a timer target value calculation means for obtaining a timer target value based on the pulse interval according to the desired value, 18. The strobe light control system according to claim 16, further comprising stop pulse means for stopping light emission by a light emission stop pulse when a timer value reaches the timer target value.