JPH0516585Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a strobe control device installed in a TTL light control type camera, and is particularly concerned with a strobe control device that prevents strobe light emission from being stopped due to noise before the appropriate amount of light is obtained. This invention relates to a strobe control device that can prevent such problems.

(Prior Art) When photographing a subject with low brightness or when performing exposure compensation, a strobe is used to improve the brightness of the subject.
Strobes used include those that are built into the camera, and those that are prepared separately from the camera and are connected to the camera as needed. When used, both may be used together. and,
When using a strobe, whether built-in or external, it is necessary to control the strobe light emission conditions so that the amount of strobe light irradiated to the subject is a predetermined amount, and for this reason, cameras are equipped with a strobe control device. There is.

Hereinafter, a strobe control device will be explained using a TTL light control type camera with a built-in strobe as an example. Fourth
The figure shows an example of this type of camera, which uses automatic focusing (AF) proposed by the applicant in this application.
1 is a block diagram schematically showing a camera with functions and a built-in strobe; FIG.

First, the overall configuration of this camera will be briefly explained. In FIG. 4, numeral 31 indicates a camera body, and numeral 11 indicates a photographic lens attached to this camera body 31.

The photographing lens 11 includes a lens system 15 including a lens 13 that is movable along the optical axis and contributes to focusing;
A driving force transmission mechanism 17 that transmits driving force from a driving source on the camera body 31 side to the movable lens 13 is provided. Furthermore, this photographic lens 11 has a lens ROM that stores information such as aperture value information of the photographic lens, position information of the movable lens 13, information as to whether this photographic lens can be used with the built-in strobe of the camera body, etc. (Read Only Memory) 1
9, this photographic lens 11 and camera body 31
and a lens-side electrical contact group 21 that electrically connects between the lenses.

On the other hand, the camera body 31 has a main mirror 3
3. an optical system such as a sub-mirror 35, a focusing plate 37, and a pentagonal prism 39; an imaging unit 41 that contributes to automatic focusing; and a drive mechanism 43 for driving the movable lens 13 within the photographic lens 11;
A light receiving element 45 for AE (automatic exposure control) for TTL flash control, a light receiving element 47 for use with a strobe, a central display section 49 for displaying the camera status, and a viewfinder for indicating the AF or AE status. an inner indicator 51, a built-in flash 53, a sequence motor 55 for winding and rewinding the film, a body-side electrical contact group 57 corresponding to the lens-side electrical contact group 21, and a release switch 5.
9 and, for example, an X contact 61 as a synchronizing contact.

Furthermore, this camera body 31 is equipped with an IPU, which is a microcomputer that controls the central display section 49.
(Indication Processing Unit) 71, interface of the imaging section 41, and sequence motor 55
AF motor 43, aperture, shutter release magnet, etc., and E ² PROM 7.
PCU (Power Control Unit) 73 with 3a
and a DPU (Data Processing
Unit) 75 and the central control microcomputer CPU
(Central Processing Unit) 77.
This CPU77 includes IPU71, PCU73, DPU7
5 and the lens ROM 19 in the photographic lens 11, respectively.

Note that the above-mentioned built-in strobe 53 is attached to the camera body 3.
It is located near the upper center of the pentagonal prism 39 of 1, which is a suitable position where it is easy to irradiate the subject with strobe light.When not in use, a strobe light emitting unit is built in, and when in use, a push button (not shown) is provided. ) The strobe light emitting section is configured to protrude and appear from the camera body 31 by the operation. Furthermore, this camera is configured to allow connection of an external strobe (not shown).

Next, a strobe control device included in the above-mentioned camera will be explained. FIG. 5 shows the strobe 53 mentioned above.
FIG. 3 is a diagram showing details of the strobe control device and the strobe control device. In the figure, what is indicated by 81 is a strobe control device, and in this case, the strobe control device 81
is mainly composed of a CPU 77, a DPU 75, a PCU 73, a light receiving element 47, a release switch 59, and an X contact 61. The strobe 53 includes a booster circuit 53a, a main capacitor 53b, a light emitting circuit 53d having a light emitting tube 53c, and a light emission stop circuit 53e.
are connected to each other via a trigger signal terminal 53f and a quench signal terminal 53g. When connecting an external strobe to the strobe control device 81, it is done through external strobe connection contacts equivalent to both contacts 53f and 53g provided at predetermined positions on the camera body 31.

Next, the operation of the strobe control device 81 as described above will be explained with reference to FIG. 5 and diagrams corresponding to the time charts shown in FIGS. 6A to 6J.

If the release switch 59 is turned on while the camera is in flash mode,
After a series of processes, the CPU 77 starts checking the voltage change at the X contact. Then, the voltage change at the X contact that occurs when the shutter is fully opened (see Figure 6 A).
SWX), the CPU 77 issues a trigger signal (X _TRIG ) to the light emitting circuit 53d of the strobe 53 (FIG. 6B). Based on this trigger signal, the light emitting circuit 53d supplies an electrical signal S _X having a waveform as shown in FIG.
c will emit light in response to this signal (6th
Figure G).

On the other hand, an integration circuit 75a provided in the DPU 75 integrates the output signal of the light receiving element 47 in response to an integration start signal S _S (FIG. 6D) issued from the CPU 77 in response to a trigger signal. Its integrated voltage S _I
As shown in FIG. 6E, as time elapses, the amount of light increases slightly and then increases sharply due to the light emission from the arc tube. This integrated voltage S _I is supplied to one input terminal of the comparator 75b.

Further, the CPU 77 sends a digital signal S _D indicating the appropriate exposure amount determined according to the ISO information of the film loaded in the camera and specified exposure compensation information, if any, etc., to the D/DPU 75. A
It is output to the converter 75c in advance for each photographing. This digital signal S _D is D/A converted, and the converted value (hereinafter referred to as reference value S ₀ ) is supplied to the other input terminal of the comparator 75b. The output terminal of the comparator 75b is connected to one of the AND circuits of the quench signal output regulation circuit shown at 75d.

In the circuit configured as described above, when the integrated voltage S _I reaches the reference value S ₀ , the comparator 75b outputs a signal that becomes the source of the quench signal to the AND circuit of the quench signal output regulation circuit 75d. This regulation circuit 75d receives an enable signal S _E from the CPU 77.
is supplied to the other input terminal of the AND circuit, and when the integrated voltage S _I reaches the reference value, a quench signal Q _U (sixth
Figure F) is output. The light emission of the strobe 53 is immediately stopped in response to this quench signal _QU (FIG. 6G).

(Problem to be solved by the invention) However, in the above-mentioned strobe control device, the output timing of the enable signal S _E has an important meaning, and problems may occur depending on this timing. This was discovered through a detailed study by the inventor.

That is, the CPU 77 sends the enable signal S E to the quench signal output regulation circuit _75d , as shown in FIG. 6H, before the noise N _T caused by the trigger signal of the electric signal S _X shown in FIG. 6C occurs. If the circuit malfunctions due to this noise, an erroneous quench signal _QUF as shown in FIG. 6I will be generated, making it impossible to emit light (FIG. 6J). This noise is largely caused by the arc tubes, etc., and requires extra work such as sorting the arc tubes in order to obtain normal light emission.

This invention was developed in view of these points, and therefore, the purpose of this invention is to provide a strobe control device that prevents strobe light emission from being stopped due to noise before an appropriate amount of light is obtained. It's about doing.

(Means for Solving the Problem) In order to achieve this objective, this invention provides a trigger signal that instructs the strobe to start emitting light and instructs the integrating circuit to start integrating the amount of reflected light from the subject. A strobe control device for a TTL light control type camera, comprising means for outputting a quench signal to the strobe when an enable signal is supplied and an integral value of the amount of reflected light reaches a predetermined value, It is preferable to set the above-mentioned predetermined time to the time when a predetermined time has elapsed from the time when the above-mentioned trigger signal is generated, and information for determining such a predetermined time is stored in an ^E
It is preferable to store it in a programmable ROM.

(Function) According to such a configuration, measurement of the amount of reflected light from the subject is started at the same time as the strobe light emission trigger signal is output. Further, the enable signal is supplied to the quench signal output means after the noise caused by the trigger signal becomes small.

Also, the generation timing of the enable signal is E ²
If you decide based on the information stored in PROM,
Since this information can be easily changed, it is possible to easily respond to changes in noise generation timing that occur when the lot of arc tubes is changed, the model of the arc tube is changed, etc.

(Embodiment) Hereinafter, an embodiment of the strobe control device of this invention will be described using an example in which it is applied to the AF camera with a built-in strobe described using FIGS. 4 and 5. However, the strobe control device of this invention is not only applicable to the above-mentioned AF camera, but also when an external strobe is connected to this AF camera, as well as other types of TTL flash control. It is clear that the present invention can be applied to photographic cameras and even electronic still cameras.

Device Configuration First, the configuration of each means provided in the strobe control device of the embodiment will be explained with reference to FIGS. 5 and 1.

The means for outputting a trigger signal to the strobe 53 includes a release switch 59, an X contact 61,
It mainly consists of CPU77.

The CPU 77 includes means for outputting a quench signal to the strobe 53 when the enable signal is supplied and the light from the subject reaches a predetermined amount of light.
The light receiving element 47 and the integrating circuit 75a in the DPU 75,
It mainly consists of a comparator 75b, a D/A converter 75c, and a quench signal output regulation circuit 75d.

Means for supplying the enable signal at a predetermined time after the occurrence of noise caused by the trigger signal (hereinafter referred to as
(referred to as enable signal supply means) is
It mainly consists of 3 E ² PROM 73a and CPU 77. FIG. 1 is a functional block diagram showing a specific configuration of this enable signal supply means, and in the figure, what is indicated by 90 is the enable signal supply means.

The enable signal supply means 90 of this embodiment is as follows:
A clock means 77a and a time setting means 77b provided in the CPU 77 are used. And PCU7
3.E ² Data indicating a predetermined time stored in advance in the PROM 73a is set by the time setting means 77b.
It is input to the CPU 77 and set in the clock means 77a. The timer 77a starts counting a set time using a trigger signal X _TRIG , and outputs an enable signal S _E when the clocking of the set time ends.

Note that the information indicating the predetermined time to be stored in the E ² PROM 73a is determined in advance experimentally and empirically depending on the type of strobe and the type of arc tube used. In some cases, E ² PROM73
A may be configured such that various types of information are stored in the camera, and when a strobe is attached to the camera, the corresponding information can be read out.

Operation Description FIGS. 2A and 2B are flowcharts of the CPU 77 that controls the trigger signal supply means, quench signal supply means, and enable signal supply means. The operation of the strobe control device according to the embodiment will be explained with reference mainly to FIGS. 2 and 5.

First, the strobe control device is initialized (step 101 in FIG. 2).

This initialization is performed by prohibiting TTL integration, that is, by prohibiting the integration of the output of the light receiving element 47, and by prohibiting the output of the quench signal. in particular,
To inhibit the output integration of the light receiving element 47, set the port for the integration start signal S _S of the CPU 77 to "1" and use the transistor Tr of the integration circuit 75a to connect the capacitor.
This is done by shorting both terminals of _C1 . The output of the quench signal is prohibited by setting the enable signal S _E port of the CPU 77 to "0".

Next, the camera performs photometry calculation processing for AE according to the program (step 103).
Appropriate shutter speed (Tv) and aperture value (Av)
In addition, information indicating the ISO value of the film (Sv) and information indicating the exposure compensation value (Xv) specified by the photographer are also included.
It is taken into CPU77.

Next, the CPU 77 checks the voltage state of the port connected to the release switch 59, and if the voltage level of this port is High, repeats the processing from step 103 (step 105). When the release switch is pressed and the voltage at this port becomes Low, the CPU 77 exits the photometry calculation process and displays the main mirror 33 and sub mirror 35 (see Figure 4).
control, aperture, etc. (step 107).

Next, the CPU 77 receives information indicating the appropriate exposure amount for photographing this frame for the integrated voltage of the light receiving element 47, which is determined according to information such as Sv and Xv.
It is output to the D/A converter 75c of the DPU 75 (step 109). In this case, this information is output as an 8-bit signal. Also, data for counting a predetermined time is output from the E ² PROM 73a and set in the clock means 77a (step
110).

After controlling the mirror and aperture, etc., the next step is to stop energizing the magnet that holds the front curtain of the shutter and allow the front curtain to run (step 111). Then, an interrupt is permitted by turning on the X contact so that the signal of the X contact, which turns on when the front curtain is completed, can be detected with top priority (step
113). After allowing the interrupt, the CPU 77
Time measurement for controlling the exposure time begins (step 131). Note that the interrupt processing is performed during execution of this time measurement.

The operation of the strobe control device in interrupt processing when the X contact is turned on will be explained with reference to FIGS. 3A to 3H in addition to FIG. 2B. In addition, Fig. 3 A~
H is a diagram based on a time chart of the strobe control device of the embodiment.

If there is an interrupt due to a voltage change at the X contact (Fig. 3A) during the exposure time measurement process in step 131,
The CPU 77 issues a trigger signal (X _TRIG ) to the light emitting circuit 53d of the strobe 53 (step 121 in FIG. 2B, FIG. 3B). This trigger signal
Based on X _TRIG , the light emitting circuit 53d sends an electrical signal _S
c, and the arc tube 53c emits light accordingly (FIG. 3G).

On the other hand, the integrating circuit 75a provided in the DPU 75 integrates the output signal of the light receiving element 47 in response to the integration start signal S _S (FIG. 3D) issued from the CPU 77 in response to the trigger signal (step 122). As shown in FIG. 6E, the integrated voltage S _I increases rapidly over time due to slight increase in light emission. This integrated voltage S _I is supplied to one input terminal of the comparator 75b. When this integrated voltage exceeds a reference value _S0 indicating the appropriate amount of light for the current shooting, which is input to the other input terminal of the comparator 75b, the comparator 75b outputs a quench signal to one terminal of the AND circuit of the quench regulation circuit. Outputs the signal that is the source of the signal.
On the other hand, in response to the trigger signal X _TRIG , the time measuring means 77a of the enable signal generating means 90 (see FIG. 1) starts measuring time (step 123). After measuring the predetermined time (T ₀ ), the enable signal S _E is output to the other input terminal of the AND circuit of the quench signal regulation circuit (step 124, FIG. 3H).

When the enable signal S _E and the signal that is the source of the quench signal are supplied as described above, the quench signal output regulation circuit 75d outputs the quench signal Q _U to the strobe 53 (FIG. 3F). The quench signal Q _U quickly stops the strobe light emission (the solid line portion after time t ₄ in FIG. 3G).

Next, the CPU 77 prohibits interrupts due to SWX ON (step 125).

When the opening time of the shutter reaches a predetermined time, driving of the rear curtain is started (steps 131 and 133 in A of FIG. 2).
After that, the film is wound (step
135), the photo shoot for one frame is completed and the step starts again.
Processing from 101 is repeated.

Note that this invention is not limited to the embodiments described above.

The configurations of the trigger signal output means, quench signal output means, and enable signal supply means are not limited to those in the embodiments, but may be other suitable configurations.

(Effects of the invention) As is clear from the above explanation, the strobe control device of this invention can start integrating the amount of reflected light from the subject at the same time as outputting the strobe light trigger signal, so the exposure amount of the subject can be accurately determined. can be measured. Furthermore, since the enable signal can be supplied to the quench signal output means after the noise caused by the trigger signal has decreased, the strobe light emission is based on the amount of light measured by the light receiving element (the amount of light integrated by the integrating circuit). It will be stopped only when a predetermined amount is reached. Therefore, it is possible to take good photographs using a strobe.

Furthermore, by using E ² PROM, the supply timing of the enable signal can be easily changed. Therefore, even if the timing of noise generation changes, such as when the lot of arc tubes changes or the model of the arc tube changes, it can be easily dealt with.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the function of the enable signal supply means provided in the strobe control device of the embodiment, FIGS. 2A and B are flowcharts of the CPU that drives the strobe control device of the embodiment, and FIG. 3A
-H are diagrams for explaining the operation of the strobe control device of the embodiment, FIG. 4 is a diagram for explaining the camera to which the strobe control device of the embodiment is applied, and FIG.
6A to 6J are diagrams used to explain the strobe control device of the embodiment, and FIGS. 6A to 6J are diagrams used to explain the prior art. DESCRIPTION OF SYMBOLS 11...Photographing lens, 13...Movable lens, 15...Lens system, 17...Driving force transmission mechanism, 19...Lens ROM, 21...Lens side electrical contact group, 31...Camera body, 33... ... Main mirror, 35 ... Submirror, 37 ... Focusing plate, 39 ... Pentagonal prism, 41 ... Imaging section, 43 ... Drive mechanism, 45 ... Light receiving element for AE (automatic exposure control), 47 ... Light receiving element for use with strobe, 49 ... Centralized display section,
51... Indicator in the viewfinder, 53... Built-in strobe, 53a... Boost circuit, 53b... Main capacitor, 53c... Light emitting tube, 53d... Light emitting circuit,
53e...Light emission stop circuit, 55...Sequence motor, 57...Body side electrical contact group, 59...Release switch, 61...X contact, 71...IPU
(Indication Processing Unit), 73...PCU
(Power Control Unit), 73a...E ² PROM,
75...DPU (Data Processing Unit), 75a
...Integrator circuit, 75b...Comparator, 75c...
D/A converter, 75d...quench signal output regulation circuit, 77...CPU (Central Processing
Unit), 77... Time measurement means, 77b... Time setting means, 81... Strobe control circuit, 90... Enable signal supply means.

Claims (1)

[Claims for Utility Model Registration] (1) Means for outputting a trigger signal for instructing a strobe to start emitting light and instructing an integrating circuit to start integrating the amount of light reflected from a subject, and an enable signal are supplied. A strobe control device for a TTL flash control camera, comprising means for outputting a quench signal to the strobe when the integral value of the amount of reflected light reaches a predetermined value, What is claimed is: 1. A strobe control device characterized by comprising means for supplying at a predetermined time after the occurrence of the strobe. (2) The strobe control device according to claim 1, wherein the predetermined time is a time when a predetermined time has elapsed since the trigger signal was generated. (3) The strobe control device according to claim 2, wherein information for determining the predetermined time period is stored in an E ² PROM provided in the camera.