JP2011018050A - External strobe for digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external strobe for a digital camera which is easy to operate and takes a high quality photograph with appropriate exposure.SOLUTION: The external strobe for the digital camera includes a manual light quantity switching device that can be used in three modes, which are an automatic mode, a manual mode, and a TTL mode, and has a first operation knob 92 used for switching at least two of the three modes and actuated in the manual mode. When the TTL mode is set, the strobe detects a signal from the strobe, built in the digital camera, by use of a signal detecting means. and performs a light emitting operation in response to the signal. The strobe further includes an exposure correcting device for correcting exposure when the TTL mode is set. A knob for operating the manual light quantity switching device and a knob for operating the exposure correcting device are provided for use as an identical second operation knob 96.

Description

  The present invention relates to an improvement of a strobe externally attached to a digital camera with a built-in strobe.

In the present invention, both underwater use and land use are conceivable. The case of underwater use where the effect of the present invention is great will be mainly described, but use on land is also possible.
When using a digital camera (hereinafter sometimes referred to simply as a camera) for underwater photography, the digital camera is generally used by placing it in a colorless and transparent waterproof housing of a genuine commercial product. The reason for being colorless and transparent is that when using a strobe built into the digital camera (hereinafter referred to as a built-in strobe), the strobe light passes through the waterproof housing as it is to illuminate the subject.
Underwater, it is often darker than on land, so strobe light is required rather than on land. In that case, if you use the built-in strobe light, the strobe light may hit the dust, microorganisms, fine objects, etc. in the seawater near the lens and reflect it in white, and you may not be able to take a beautiful picture. This is also called a marine snow phenomenon.
Also, if you use the built-in flash, the center of the screen will become brighter and the photo will look flat. In addition, there is a problem that the amount of light of the built-in strobe is insufficient underwater, resulting in insufficient exposure.
Even in the case of product photography on land, the spotted light from the built-in flash may be reflected from the subject and cannot be photographed beautifully. This is a problem that occurs because the flash unit on the camera side is close to the lens.

In order to solve such a problem, an external strobe that detects light from the built-in strobe and emits light based on the signal is used. This is because the light emitting part of the external strobe can be separated from the lens of the camera, so the problems with the use of the built-in strobe are reduced, and a beautiful picture can be taken accordingly.
As an external strobe function, an auto strobe that keeps the amount of light constant even when the shooting distance changes is often used. This is because the operation is simpler than a manual strobe that requires light intensity adjustment when the subject distance changes.
In order to achieve proper exposure using an auto strobe, the aperture value of the camera and the aperture value of the strobe (the aperture value of the strobe is the value of the intensity of the light that will actually give the correct light intensity. In order to make it easier, it is necessary to replace the aperture value on the normal camera side and set the same on the auto light quantity switching knob.
In other words, there is a problem that the flash aperture value must be changed every time the camera aperture is changed, and when you want to correct the exposure, set the flash aperture value further from the flash aperture value set to the same as the camera aperture value. There is a problem that the operation becomes complicated because the direction must be changed in the plus or minus direction.
Also, in order to operate correctly, the auto strobe sensor needs to be correctly directed toward the subject.
If you want to make fine adjustments to the exposure, you can also adjust the light amount of the external flash manually. This is effective when the distance from the camera to the subject does not change much, and it is only necessary to adjust the light quantity of the external strobe once to achieve the desired exposure.
If both an auto flash function and a manual function are included in a single external flash, it will be even easier to use.
Next, in the case of an external strobe for underwater use, it is necessary to reduce the shaft of the external control knob, so it is necessary to reduce it, and the installation space is also small, so two is the limit as shown in FIG. . In this case, it is necessary to give each operation knob various functions as much as possible.
In the following explanation, it is assumed that the strobe is normally used for short-distance shooting, and the shooting distance is assumed to be about 0.5 m to 1.5 m.

Next, it demonstrates using a figure. FIG. 2 shows a conventional method and apparatus in which a digital camera 1 including a lens 5, a CCD 4, a control circuit 3, a strobe light emitting unit 6 and the like is put in a waterproof housing 2 in water. The waterproof housing 2 is unnecessary on land.
A conventional external strobe 11b is attached to the waterproof housing. Although the external strobe needs to emit light in synchronization with the X contact of the camera, most of the genuine housings do not have a sync cord terminal for connection to the external strobe.
This is because the connection part must be waterproofed, and there are some cameras that do not have an X contact terminal attached. In this case, it is impossible to attach the connection part.
As a simple method without using a sync cord, infrared light (through a filter 7 that blocks the visible light of the built-in strobe light as shown in FIG. 2 and transmits infrared light (including near infrared light) (see FIG. 2). A method and an apparatus are used in which a near-infrared light (including near-infrared light) is guided by an optical fiber 8 as a light guiding means, a signal is detected by a light detection circuit 9, and an external strobe 11b is caused to emit light by the signal. When the distance between the built-in strobe and the external strobe is close to the light guide means, the optical fiber 8 may be unnecessary.
In that case, the infrared light (including near-infrared light) of the built-in strobe reaches the light detection circuit 9 (sensor) directly through air or water (seawater).

In operation, when the shutter lever is first pressed, the built-in flash 6 first emits light. At the same time, the light of the built-in strobe is guided to the light detection circuit 9 by the optical fiber 8 and converted into an electric signal, and reaches the control circuit 10b of the external strobe 11b.
This pre-emission is not necessary for the external flash 11b, and there are cases where the pre-emission is ignored and no emission is made, or a minute emission that is not related to the main emission is made.
The next main light emission is performed at the same time as the shutter is released after about 100 mS, but the built-in strobe light is blocked by the filter 7 and therefore does not hit the subject.
The light is guided in the same manner as the pre-emission, and the control circuit 10b determines that the main emission is made, and the external strobe 11b operates. The irradiation light 13 from the reflecting mirror 12 strikes the subject.
The reflected light 16 from the subject returns to the sensor 17, and the sensor 17 converts the light into an electrical signal. This electric signal is integrated by an integrating circuit in the control circuit 10b, and when it reaches a predetermined value (appropriate exposure), a signal is output from the control circuit to stop light emission. This makes it possible to take a photo with proper exposure using an external strobe.
In the case of manual control, a resistor is used instead of the sensor 17 by a known method, and the resistance value is varied to adjust the amount of light by changing the light emission stop timing of the external strobe so that an appropriate exposure is obtained. .

In the case of such an auto strobe device, as described above, in order to obtain an appropriate exposure, the aperture value of the camera and the aperture value of the strobe need to be set to be the same. .
2. To correct the exposure, it is necessary to change the aperture value of the strobe to the plus or minus direction when the camera aperture value and the strobe aperture value are matched.
3. If the strobe 11b does not face the center of the subject, the sensor 17 will not receive the reflected light from the subject correctly, so the exposure may not be accurate, and it is troublesome to set the orientation.
4. When the filter or converter lens is attached to the front of the camera lens, the exposure changes, but this cannot be corrected automatically.
5. A normal camera has a zoom lens, and the actual angle of view is different between the tele and wide sides. The sensor 17 of the external flash 11b has a fixed light reception angle and does not synchronize with the angle of view, so a photometric error may occur.
6. When the camera side is set to the program mode, the aperture and the shutter speed change depending on the brightness of the surroundings, but it is not easy to adjust the external strobe to the value, and it is difficult to achieve an appropriate exposure. Because of these problems, it was difficult to use them easily.
As for the problem of the operation knob, there is a problem that when the automatic light quantity switching knob and the manual light quantity switching knob are separated, two spaces are required and the arrangement cannot be performed.

JP 2002-31478 A Japanese Patent Laid-Open No. 9-211566

  The present invention has been made in view of such a conventional technique, and an object of the present invention is to detect a signal of a built-in strobe of a digital camera by a signal detecting means, and in an external strobe that emits light by the signal, the camera side Control the external flash with pre-flash and main flash to trigger the proper exposure and eliminate the need to set the aperture value on the flash, making it easy to operate and high-quality photos with proper exposure Outside the digital camera, which is characterized by being able to take pictures, easily adjusting the exposure with the control knob of the external flash, and increasing the functions of auto, manual, etc. by using two external flash control knobs. It is to provide an attached strobe.

  The invention of claim 1 made to solve the above-mentioned problem can be used in three modes of an auto mode, a manual mode, and a TTL mode, and switches at least two of the three modes. A manual light amount switching device having a first operation knob and operating in the manual mode is provided, and the signal of the built-in strobe of the digital camera is detected by the signal detection means in the TTL mode, and the signal When the built-in flash is pre-flashed, pre-flash start means for starting the external flash using the flash signal as a trigger and pre-flash of the external flash using the pre-flash stop of the built-in flash as a trigger When the pre-flash stop means for stopping the flash and the built-in flash fires, A digital camera provided with a main light emission starting means for starting the light emission of the external strobe with the light emission signal of the main flash as a trigger and a main light emission stopping means for stopping the main light emission of the external strobe with the stop of the main light emission of the built-in strobe light as a trigger The external strobe includes an exposure correction device that performs exposure correction in the TTL mode, and includes an operation knob for operating the manual light amount switching device and an operation knob for operating the exposure correction device. , Provided as the same second operation knob.

  The invention of claim 2 is characterized in that, in addition to the structure of the invention of claim 1, it can be used underwater with a strobe device externally attached to a digital camera contained in a waterproof housing.

As described above, according to the present invention, the light emitting portion of the built-in strobe of the camera is shielded by the light shielding means, so that the marine snow phenomenon caused by the light emission of the built-in strobe does not occur (the light shielding means In addition, since the reflected light from the subject of the external strobe is measured through the lens of the camera, the above 1-6, which are the disadvantages of the auto strobe, can be solved.
The operation of the external flash can be simplified, and there is an effect that a high-quality photograph can be easily taken with a proper exposure with less photometric error.
When exposure compensation is required, there is an effect that can be easily compensated with the control knob of the external strobe.
The number of external flash control knobs is reduced to increase the function. Among the functions of auto light quantity switching, manual light quantity switching, and exposure compensation, there is an effect that two or three kinds of combinations can be made with one knob.

For underwater use, the digital camera is used in a waterproof housing 2 as shown in FIG. The underwater waterproof housing integrated camera is a unit in which the waterproof housing and the internal parts of the camera are integrated, but can be used in the method and apparatus of the present invention. Further, when used on land, the waterproof housing 2 is unnecessary.
The signal detection means of the present invention is a method and apparatus for converting an optical signal into an electric signal in the external strobe light detection circuit 9 for detecting the light of the built-in strobe light.
Therefore, as shown in FIG. 1, the signal detection means includes a light guide means and a light shielding means. However, since it is sufficient if a signal is detected, a configuration excluding these light guide means and the light shielding means is also established for the following reason. To do.
When the distance between the built-in strobe and the external strobe is short, the optical fiber 8 does not have to be used for the light guiding means. In that case, the light from the built-in strobe light (including infrared light and near infrared light) reaches the light detection circuit 9 or the light detection circuit 18 directly through air or water (seawater).

The shading means will be described in detail later, but even in the case of a device without the shading means, a picture can be taken.For example, it is better to take pictures underwater, but the appearance of the picture is individual subjectivity. The reference point is not clear.
Even if there is no light-shielding means, the marine snow phenomenon will be reduced compared to the conventional case, and a certain effect will be obtained if the subject is illuminated with both the built-in strobe and the external strobe rather than illuminating the subject with only the built-in strobe. Further, in the present invention, since the exposure can be adjusted by the exposure correction means, there is an effect that it can be adjusted to a desired exposure.
For this reason, in the present invention, it is possible to take a better picture if the light shielding means is included in the configuration of the signal detection means, but it is possible to remove the photograph and includes the excluded configuration.
In the present invention, it is preferable that the visible light of the built-in strobe does not strike the subject for the above reason. This method and apparatus are publicly known, and a filter that transmits infrared light (including near-infrared light) and blocks visible light, such as the filter 7 in FIGS. 1 and 2, is disposed on the front surface of the built-in flash. Methods and apparatus for doing so have become commonplace.

There are many examples of implementation of this method and apparatus, and it may not be necessary to completely block visible light. In the present invention, details of the light shielding means will be described later.
The external strobe 11a is arranged at a distance from the camera, and uses an optical fiber 8 as a well-known light guide means so as to receive a signal from the light shielding means. Since other circuits have a complicated configuration, details will be described later.

First, the prerequisite technology of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the signal flow of the present invention.
As a light shielding means subordinate to the signal detecting means, an infrared transmission visible light blocking filter 7 is pasted on the light emitting portion 6 of the camera in advance before being inserted into the waterproof housing 2. The same applies to land use.
In this way, when the built-in strobe emits light, visible light is blocked and does not leak from the surroundings, and the marine snow phenomenon caused by this does not occur.
Next, as the light guide means subordinate to the signal detection means, the infrared light emitted from the built-in strobe reaches the light detection circuit 9 via the optical fiber 8 and is converted into an electrical signal. The electric signal is applied to the control circuit 10a, and the external strobe 11a is controlled to emit light.
If the sensor 18 which is a part of the light detection circuit is attached to the tip of the cord 19, the optical fiber 8 is not necessary. Therefore, if it is not desired to use the optical fiber, such a configuration can be adopted.

In the light shielding means, the position where the filter for blocking infrared transmission and visible light is applied may be another place where the effect is equally effective, and may be inside the waterproof housing 2 or outside the waterproof housing 2.
A representative example is shown on the right side of FIG. 1 and FIG. 2, 7 a being affixed to the inside of the waterproof housing 2, and 7 e being affixed to the outside of the waterproof housing 2.
Further, when the waterproof housing 2 is opaque, it is not necessary to attach an infrared transmission visible light blocking filter, and an example is shown in 7b. In this case, it is only necessary to open 7c or 7d as a small hole for taking light. There is no problem if the light arrives even if the position is not in front of the reflector as in 7d or 7h. Reference numeral 7f denotes a transparent window, which is arranged in a transparent or opaque housing.
In this case, an infrared transmitting visible light blocking filter may be attached to the front or rear surface of this window part, or a hole may be made in a fiber, a plate or the like that blocks light, such as 7g, and the position of lighting is 7d or 7h. Thus, it is not necessary to be in front of the light emitting part. Further, 7g may be moved to the inside of 7f to shield it.
In the case of an underwater (amphibious) digital camera, the filter is attached to the front surface of the light emitting part of the built-in strobe as in 7e, or as in 7g or 7c. That is, the waterproof housing 2 of FIG. 1 has the appearance of an amphibious camera, and it is sufficient to consider that the camera parts are contained therein, and the effect is the same as described above.

Up to this point, the use of an infrared transmitting visible light blocking filter has been mainly described as a light blocking means, but there is no problem even if light leaks as long as it does not affect the appearance of a photograph. Even if the light blocking member blocks light or has some light leakage, the light blocking member may be disposed in front of the built-in flash. Therefore, many light shielding means can be considered.
For example, a filter that transmits near infrared rays close to visible light, a red filter, or a filter that attenuates the amount of light may be used. In this case, for example, it is effective to attenuate the light quantity of the built-in strobe to about 1/4 or less.
Also, a plastic resin molded product having the same characteristics as those described above can be used. In this case, the resin can be freely formed, and the resin of the waterproof housing 2 can have this characteristic.
Further, any light blocking material may be used instead of a filter, and a light blocking member such as a fiber or plate may be disposed in front of the built-in flash. The location of the arrangement in this case is not limited as long as it is a location where light is blocked. Since it is necessary to take light, a small hole may be made in the light shielding member and taken from there, or it may be taken from another place where light leaks.
This case will be described with reference to the figure. 7e may be changed to a light shielding member, and a hole for daylighting may be formed in a part thereof to obtain 7g.
Further, it is possible to shift the daylighting location without opening a hole in the light shielding member, such as 7h, or to place the light shielding member slightly away from the housing and install an optical fiber therebetween. (Not shown)

When a wide conversion lens or a close-up lens is attached to the front of the camera lens, the edge of the lens is usually large and the built-in strobe light is blocked. This is shown in 7k. In this case, there may be no other light shielding member, and the same effect can be obtained in this case.
Next, there are things such as single-lens reflex cameras that pop up the light emitting part of the built-in flash. In this case, there is a thing that pops up completely and faces down like 7i before the light emitting part faces the front, and even in this case there is something that emits light. The light emitted from the light emitting part is blocked by the head of the camera and hardly hits the subject. That is, the head of the camera serves as a light shielding means and can be illuminated like 7j, and the filter or the light shielding member may or may not be provided.
The housing 2 in this case may be transparent or opaque. Further, as in the previous example, a member such as the filter may be disposed in front of the light emitting unit.

Next, details of the operation will be described mainly with reference to FIGS. 1, 5, and 6.
At present, a method and apparatus for controlling exposure by performing pre-light emission and main light emission are common in strobes of digital cameras, and the present invention will be described based on this method and apparatus. FIG. 5 is a block diagram and wiring diagram showing an embodiment of the strobe device of the present invention. Known operations will be described in a simplified manner.
When the switch 22 is turned on, power is supplied from the battery 21 and the high voltage boosted by the booster circuit 24 is charged in the main capacitor 25.
When the voltage of the main capacitor 25 exceeds a predetermined value, the ready circuit 26 indicates that light emission is ready.
Thereafter, when the shutter button of the camera is pressed, the built-in flash 6 shown in FIG. The state of this light emission is shown in FIG. 6 and the rising edge of the pre-flash of the built-in strobe is 71 and the falling edge is 72.
The pre-emission light of the built-in strobe 6 is guided to the light detection circuit 9 using an optical fiber 8 as one of light guide means.

An example of the pre-emission start means will be described until the external strobe starts to emit light using this pre-emission as a trigger.
The light detection circuit 9 includes a phototransistor 32 and a load resistor 33, and the light is converted into an electric signal.
This signal is applied to the light emission start signal detection circuit 45. The light emission start signal detection circuit 45 detects the rise of the signal. The rise of the signal detected by the capacitor 40 is AC amplified by the transistor 41 and detected by the transistor 43 via the capacitor 42.
Further, when the transistor 44 is used as a buffer and a light emission start signal is applied as an ON signal to the trigger circuit 27, the trigger circuit operates and the discharge tube 28 starts to emit light. (When the change-over switch 113 is TTL, the pre-flash cancel circuit 102 becomes inoperative and the signal passes as it is)
The pre-flash time of the built-in flash is very short as indicated by 71 and 72 in FIG. This light emission stop is a falling signal such as 72, and light is guided to the photodetection circuit 9 using the optical fiber 8 in the same manner as described above, and further converted into an electrical signal by the same phototransistor 32 as described above.
In this example, the light emission start and the light emission stop are detected by the same phototransistor, but a total of two can be used separately.

An example of the pre-flash stop means will be described until the external strobe stops flashing with the pre-flash emission stop as a trigger.
In this case, the light emission stop signal detection circuit 39 detects the falling edge when the light emission is stopped. The differential capacitor 34 detects the falling edge (edge), and the signal is exchanged by the transistor 36 via the capacitor 35. Amplified. Next, the signal is detected by the transistor 38 via the capacitor 37 and becomes an ON signal.
Next, the operation when the changeover switch 113 is TTL will be described. TTL is a common name, in this case, a connection that operates in response to pre-flash and main flash signals from the camera.
In this case, the pre-emission stop signal is applied from the emission stop signal detection circuit 39 to the pre-emission control circuit 108, the transistor 109 is turned on, and the voltage from the gate voltage generation circuit 23 is integrated through the resistor 111 and the backflow prevention diode 110 to the integrating circuit 120. To be applied. The capacitor 112 acts to extend the ON time of the transistor 109.

The integrating circuit 120 includes a known speed-up resistor 121, an integrating capacitor 122, and a discharging resistor 123, and is integrated by the resistor 111 and the integrating capacitor 122. When the voltage of the integrating capacitor 122 reaches a predetermined voltage, a light emission stop signal is output from the light emission stop signal generation circuit 124 and applied to the light emission stop signal input circuit 30, and the signal is applied to the light emission control circuit 29. The light emission stops immediately after the operation.
Next, the light emission stop signal generating circuit 124 that also functions as an exposure correction means is composed of a comparator 126, a resistor 125 for generating a comparison voltage, a resistor group 127, and a changeover switch 128. The resistor group 127 can be adjusted by changing to the variable resistor 129.
For example, if the operating voltage of the comparator is changed from 0.1V (selection switch 128 on the left side) to 3V (selection switch 128 on the right side), when the voltage is low (0.1V), immediately after the pre-emission control circuit 108 operates A signal is output from the comparator 126. That is, the integration circuit 120 becomes 0.1 V with almost no time.

The exposure correction means has a variable means, and this variable means operates so that the signal output time is gradually delayed as the changeover switch 128 is gradually turned to the right. (Because the operating point of the comparator 126 gradually increases)
When the external strobe is operated by this signal, the operation timing for stopping the light emission of the discharge tube is changed by the correction action of the exposure correction means as described above, and the light emission waveform of the discharge tube 28 is as shown by 131 to 135 in FIG. Change.
Finally, it is necessary to adjust the values of the resistor 111 and the integrating circuit 120 to determine the best value. (The waveform in FIG. 7 shows a change and is not an optimum value.)
Here, the resistance group 127 of the comparator 126 is adjusted to be variable, but as another method and apparatus, a large number of capacitors of the integrating circuit 120 can be prepared and switched. Also, a known circuit that uses the ON characteristics of a transistor instead of a comparator can be used.
Here, a discrete circuit is used for ease of explanation, but the present invention includes a case where a digital circuit or a microcomputer using the same operation is used.

The effect will be described when the emission waveform of the discharge tube 28 changes as indicated by 131 to 135 in FIG. In a digital camera, in the method of determining the exposure of the main light emission by the pre-light emission, the exposure of the main light emission is determined based on the amount of reflected light from the subject during the pre-light emission.
Therefore, if the amount of pre-emission light is reduced from the appropriate point, the reflected light from the subject is reduced, and the main light emission operates to emit light multiple times. That is, the exposure becomes positive.
Conversely, if the amount of pre-emission light is increased from the appropriate point, the reflected light from the subject increases, and the main light emission operates to emit less light. That is, the exposure is negative.
If this principle is used, exposure compensation can be easily performed with the operation knob of the external strobe.
The reason why the flash time is shortened as indicated by 131 in FIG. 7 is that the start of light emission is delayed for the reason described later, but the light emission stop is less delayed.
The gate voltage generating circuit 23 operates to supply necessary power to the light emission stop signal input circuit 30 while the strobe is emitting light.

The circuit for detecting the start of light emission and the stop of light emission is an example, and other devices may be used as long as they have the same effect. For example, a circuit that digitizes and detects rise and fall. It works with IC circuits that use operational amplifiers and comparators.
The standard light emission operation of this external strobe is shown in FIG. 6 b, where the light emission start timing is 75 and the light emission stop timing is 76.
In order to achieve standard exposure, the external flash has a larger light intensity overall, so it is common to use more pre-flashes than the built-in flash. It is good to decide to become.
With an external flash, there will be a slight delay in starting the flash. This is because the gas in the discharge tube does not activate immediately and is due to physical properties.
When there is almost no delay in other electric circuit portions, a delay of about 20 μS (microseconds) appears as shown in FIG. However, this delay looks large when written in the figure, but it is actually very small. Moreover, as described above, the light from the built-in strobe does not hit the subject, and the light from the external strobe hits the subject instead. Therefore, there is no problem because the light from both the built-in strobe and the external strobe is not doubled.
In the electric circuit portion, in order to reduce the delay in operation as much as possible, the circuit is simplified and delay components (bypass capacitors or the like) are not used or made very small. Note that no bypass capacitor is used in the light emission start signal detection circuit 45 and the light emission stop signal detection circuit 39 of FIG.

Next, when the light emission is stopped, there is no delay as much as the start of light emission. The element that stops the light emission of the discharge tube is a semiconductor, so the operation speed is fast and there is almost no operation delay.
Currently, IGBT is used for this element. When this IGBT is turned off, the current flowing in the discharge tube is immediately cut off, but the gas inside the discharge tube is shining and there is some afterglow. However, there is almost no operation delay due to afterglow.
By adjusting the characteristics of this discharge tube and the operation time of the electric circuit as described above, the light emission stop timing can be made faster or slower, and if the appropriate value is brought near the center of the changeover switch, the built-in strobe is built into the camera circuit. Even if it operates with the same numerical data as when light is emitted, there is no problem.
Next, the pre-emission light 13 strikes the subject 14, and the reflected light 15 passes through the lens of the camera and is converted into an electrical signal by the CCD (CMOS) 4, and the amount of the main emission is calculated by the control circuit 3 based on the level of the value. . After about 100mS (milliseconds), the built-in flash starts to fire like 73.
The main emission light of the built-in strobe 6 is guided to the light detection circuit 9 using the optical fiber 8 in the same manner as the pre-emission.

The main light emission starting means is the time until the external flash starts the main light emission using the main light emission as a trigger. This operation is the same as that in the case of starting the pre-light emission described above, and light emission is started as indicated by 77.
Thereafter, when the predetermined value (appropriate exposure) is reached, the main flash of the built-in flash stops as in 74.
This light signal is also guided to the light detection circuit 9 using the optical fiber 8 in the same manner as the pre-light emission, and the main light emission stop means until the main light emission stops with the stop of the main light emission as a trigger.
In this case, the stop of the main light emission does not need to vary the timing time of the stop as in the pre-light emission stop means. The timer 101 and the delay ON circuit 103 are devices that are not changed when the main light emission stop signal is received. In operation, a positive signal is output from the timer 101 for about 0.2 seconds when the first pre-light emission start signal is output.

At the time when the built-in strobe is pre-flashed, the delay ON circuit 103 is not yet operated because the base voltage is not applied to the transistor 107 and the transistor 104 by the integrating circuit of the resistor 105 and the capacitor 106. Thereafter, a voltage is applied to the capacitor 106 until the main light emission, so that the transistors 107 and 104 are turned on and the resistor 111 is short-circuited.
For this reason, during the main light emission, a voltage is immediately generated in the integrating circuit 120 and there is no time delay. The timer 101 and the delay ON circuit 103 have been described for an ideal circuit configuration, and these circuits are not necessarily required. This is because the influence is reduced when the variable time of the variable means for the pre-light emission is reduced.
The other operations are the same as in the pre-flash, and finally the main flash is stopped as in 78, and the series of operations ends.
As described above, the light emission waveform of the external strobe corrects and optimizes the light emission waveform of the built-in strobe, so that even if the light of the built-in strobe does not hit the subject, the exposure is appropriate.

Next, an embodiment will be described with reference to FIG. 3 and FIG.
In the case of an underwater strobe, the operation knobs need to be waterproof, and there is little space to arrange them, so it is better to use as few as possible. Specifically, it is necessary to make it within two. (It is better to have less land use than more)
The operation part of the underwater strobe is shown in FIG. 3, and an operation knob 92 and an operation knob 96 battery cover 97 are provided on the back surface 99 of the strobe.
Since the arrangement place is limited in this way, if a single knob can have many functions, it becomes an unprecedented multifunctional external flash.
This circuit will be explained with reference to FIG. 5. As described above, when the change-over switch 113 is in the TTL position, the change-over switch 128 functions as exposure compensation. Further necessary functions are the auto function and the manual function as described above.
This function will be described. In the present invention, these functions can be added by sharing the light emission stop signal generation circuit 124 and the integration circuit 120.
When the changeover switch 113 is set to the AUTO side, the TTL connection is cut off and the pre-emission control circuit 108 becomes inoperative. Instead, it is connected to the phototransistor 114.

This circuit has a general auto circuit configuration, and its operation is known and is the same as the conventional one.
First, the light emitted from the external strobe strikes the subject, the reflected light from the subject is received by the phototransistor 114, and the light is converted into an electrical signal. When this electric signal is integrated by the integration circuit 120 and reaches a predetermined value (appropriate exposure), a signal is output from the light emission stop signal generation circuit 124, and the discharge tube 28 stops light emission in the same flow as described above.
If the value of the resistor group 127 is set to an appropriate value and the selector switch 128 is switched, a large number of exposures can be handled. In the present invention, since a maximum of three types of modes are also used, the range of switching in the auto mode is preferably 0.5 to 1 aperture. (In FIG. 3 and FIG. 4, the width is one stop)
Next, when the changeover switch 113 is set to the MANUAL side, other connections are cut off and manual control is performed.
In the case of this manual control, a resistor 117 is used instead of the phototransistor 114 by a known method, the resistance value is adjusted to an optimum value, and the resistor group 127 of the light emission stop signal generation circuit 124 is further switched to thereby connect an external strobe. The light emission stop timing is changed to gradually increase from a small amount of light so that it can be changed to a light amount suitable for photographing.
However, since the width of the variable change cannot be optimized only by the resistor 117, the manual control circuit 116 corrects the rising portion of the light emission waveform and its vicinity by the resistor 115 and the capacitor 119. This value should be determined experimentally.
The switching width should be 0.5 aperture to 1 aperture. Other operations are the same as the auto circuit because the phototransistor 114 is changed to a resistor.

In the case of auto and manual, it is not necessary to emit light when the built-in strobe pre-emits, so the pre-emission cancel circuit 102 is operated.
Using this method and device, up to three modes can be operated with a single knob. FIGS. 3 and 4 show an example in which this combination is arranged on the back surface 99 of the strobe. The changeover switch 128 is linked to the operation knob 96, and the changeover switch 113 is linked to the operation knob 92.
The operation knob 96 is used as an exposure correction 93, a manual light amount switch 94, and an automatic light amount switch 95.
In FIG. 4, a, b, c, and d are combinations of these, and (d is no combination), and can be freely combined, so that a large number of requests can be met.

It is an implementation figure for demonstrating operation | movement of the apparatus of this application. It is an implementation figure for demonstrating operation | movement of the apparatus of a prior art example. It is drawing of the operation part of the attached strobe of this application. It is drawing of the operation part of the external strobe of this application. It is an implementation figure for demonstrating the circuit operation | movement of the apparatus of this application. It is a wave form diagram for demonstrating light emission operation | movement of the apparatus of this application. It is a wave form diagram for demonstrating light emission operation | movement of the apparatus of this application.

1 Digital Camera 2 Waterproof Housing 5 Lens 6 Built-in Strobe 7 Filter 8 Optical Fiber 9 Optical Detection Circuit
11a External strobe (invention)
14 Subject
28 discharge tube
29 Light emission control circuit
30 Light emission stop signal input circuit
32 phototransistor
39 Light emission stop signal detection circuit
45 Light emission start signal detection circuit
99 Back of strobe
101 timer
102 Pre-flash cancellation circuit
103 Delay ON circuit
108 Pre-flash control circuit
116 Manual control circuit
120 integration circuit
124 Light emission stop signal generation circuit

Claims (2)

It can be used in three modes, an auto mode, a manual mode, and a TTL mode, and has a first operation knob for switching at least two of the three modes, and operates in the manual mode. In addition to having a manual light amount switching device, the signal of the built-in strobe of the digital camera is detected by the signal detection means in the TTL mode, and the light emission is performed by the signal. The pre-flash start means for starting the external flash using the trigger as a trigger, the pre-flash stop means for stopping the pre-flash of the external flash using the pre-flash stop as a trigger, and the built-in strobe When the external flash is fired using the flash signal as a trigger In external flash digital camera that includes a main flash stopping means for stopping the light emission of the external flash to stop the light emission of the built-in flash and the emission start means for starting as a trigger,
An exposure correction device that performs exposure correction in the TTL mode is provided, and an operation knob for operating the manual light quantity switching device and an operation knob for operating the exposure correction device are the same second External strobe for digital cameras, which is provided as an operation knob.   The external strobe for a digital camera according to claim 1, wherein the strobe device can be used underwater with a strobe device externally attached to the digital camera contained in a waterproof housing.