JPH07104544B2 - camera - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement of a camera having a prefocus function.

(Background of the Invention) Conventionally, a photograph having a composition in which the distance measuring operation and the release operation can be separately operated and the main subject to be focused is not located in the center of the photographing screen (within the distance measuring mark) When shooting, first hold the camera so that the main subject is in the center of the screen and perform only the distance measurement operation, store the distance measurement result and then reposition the camera to the composition you want to shoot and perform the release operation Therefore, a camera provided with a prefocus function capable of capturing an image in focus on the stored distance measurement result is widely known.

The majority of cameras equipped with such functions belong to the category called compact cameras (lens shutter cameras),
Most of these compact cameras are automated so that they can be used by men and women of all ages and are convenient, but they have the following drawbacks. For example, although such a camera has a built-in strobe device, it is difficult to provide a strobe device having a large light emission amount from the viewpoint of portability and operability. Therefore, the subject is distant and relatively dark. In a scene or a backlit scene, the emitted light does not reach the subject, resulting in an underexposed photograph in many cases. With a strobe device of about GN ₀ 10 (when using ISO 100 film) that is built into such a camera as standard, if the brightness of the shooting lens is FN ₀ = 2.8,
The flash photography possible distance with the strobe device is within about 3.6 m.

As a method of solving the above-mentioned drawbacks, when the subject distance and subject brightness are detected and it is determined that the subject at that time is a relatively dark scene or a backlit scene, it is already widely known. In addition, the fact that the focal position (f) of the Fresnel lens 2 arranged in front of the reflection shade 1 (see FIG. 4) is considerably behind the light emitter 3 such as a xenon tube makes use of the position of the Fresnel lens 2. Can be moved to the position shown by the dotted line, and the luminous flux emitted from the light emitting body 3 can be condensed to prevent insufficient exposure. However, the light flux emitted from the light-emitting body 3 is effectively condensed only when the main subject is located at the center of the screen, that is, when the composition-change photographing (hereinafter referred to as prefocus photographing) is not performed. Therefore, if it is possible to automatically know whether the main subject is located in the center of the shooting screen, that is, whether it is prefocus shooting, before the shooting operation is started, the light distribution of the strobe device can be performed. The inventor believes that it is of great help in properly controlling changes.

This will be described in more detail with reference to FIG.
FIG. 5 is a schematic diagram of how the strobe device emits light, showing the density (brightness) of the luminous flux in the lengthwise direction and the polar coordinates with the emission angle (irradiation angle) in the angular direction. Reference character a denotes a light emission state when the Fresnel lens 2 in FIG. 4 is at the position indicated by the solid line, and reference character b denotes the light emission state when the Fresnel lens 2 is at the position indicated by the dotted line. As can be understood from this figure, if the distance between the Fresnel lens 2 and the light emitter 3 is increased to the position shown by the dotted line in FIG. 4, the degree of converging of the emitted light flux increases, and the brightness on the axis of the light emission direction, that is, at the center of the shooting screen is improves. Therefore, even if the main subject is in a distant place and is in a relatively dark scene or a backlit scene, if it is possible to know that the main subject is located in the center of the screen, it is possible to provide appropriate exposure by performing such switching. Becomes

(Object of the Invention) A first object of the present invention is to determine that the position of the prefocus target on the screen has not changed without any troublesome operation, and to change the position of the prefocus target on the screen. It is an object of the present invention to provide a camera having a prefocus function that enables more appropriate shooting by setting a shooting condition that gives priority to a prefocus target over other subjects as compared with a case where the change is not made.

A second object of the present invention is to change the light distribution state of the flash unit in accordance with whether or not there is a change in the distance to the prefocus target, thereby allowing the light distribution state of the flash unit to act more appropriately. To provide a camera having a prefocus function.

(Characteristics of the Invention) In order to achieve the first object, the invention described in claim 1 of the present application is a camera having a prefocus function, and a detection means for detecting a prefocus signal for a prefocus target. First activating means for operating the detecting means with respect to a prefocus target before the photographing operation is started in response to the operation of the release member for starting the photographing operation, and further operating the release member thereafter. In response to the operation, the second activating means for operating the detecting means again before the photographing operation is started, and the focus adjustment for adjusting the focus of the photographing optical system according to the detection result of the detecting means for the prefocus object. And a detection result of the detection means for the prefocus target and a subsequent detection result of the detection means. And a determination unit that determines that there is no change in the detection result of the detection unit and the subsequent detection result of the detection unit, as compared with the case where it is determined that there is a change. And a photographing condition determining means for determining a photographing condition prioritized over the subject.

In order to achieve the above-mentioned second object, the invention according to claim 2 of the present application provides a camera having a prefocus function, a detection means for detecting a prefocus signal for a prefocus target, and the detection means. Starting means for operating the prefocus target and again operating the detection unit in the process leading to photographing, detection results of the detection unit for the prefocus target, and detection of the detection unit in the process leading to subsequent photographing It is characterized by having a judging means for judging whether or not the distance to the detection target has changed based on the result, and a control means for changing the light distribution state of the flashing means in response to the judging means.

(Examples of the Invention) Hereinafter, the present invention will be described in detail based on illustrated examples.

FIG. 1 is a block diagram showing an embodiment of the present invention. SW
1 is a switch that is turned on by half-pressing a release button (not shown), SW 2 is a switch that is turned on by full-pressing, 4 is a logic control circuit for sequentially controlling distance measuring operation, photometric operation, film winding operation, and the like, 5 is distance measuring In the present embodiment, the circuit includes a light emitting diode that emits near-infrared light, a light-receiving element that receives the near-infrared reflected light from the subject, and the like, and starts a distance measurement operation by a start signal from the logic control circuit 4. However, it is assumed that it is configured to output the obtained distance measurement information. 6,7 are registers having a memory function and a memory value output function,
The register 6 stores the distance measurement signal required when the switch SW1 is on, and the register 7 stores the distance measurement signal required when the switch SW2 is on. Reference numeral 8 is a D / A conversion circuit that converts the distance measurement signal input from the register 6 as a digital signal into an analog signal and outputs it. Reference numeral 9 is a built-in strobe device GN ₀ (guide number), film sensitivity and shooting lens. The flashable distance is calculated from the FN ₀ value of, and a reference signal (voltage) corresponding to the stop designated distance (predetermined distance for zone focusing) of the taking lens closest to the distance is generated. It is a reference signal generation circuit.

Reference numeral 10 is a comparator that compares the output of the register 6 input through the D / A conversion circuit 8 with the output of the reference signal generation circuit 9 and outputs a high level signal when the output of the register 6 is larger. Reference numeral 11 compares two distance measurement results to determine whether or not prefocus shooting is performed, that is, when both values match, it is determined not to be prefocus shooting and a high-level signal is output to detect a match. The circuit, 12 compares the distance measurement signal from the register 6 with the lens position signal from the lens position signal generation circuit 13, and outputs a high level signal when they match, 14 is a pull-down resistor, 15 is the above-mentioned This is a transistor that turns on when a high-level signal is input from the comparator 12 and excites the magnet Mg1 for stopping the lens barrel. 16 indicates that the output of the comparator 10 is a high-level signal. A NAND gate that outputs a low level signal only when the output of the coincidence detection circuit 11 is a high level signal when the subject whose distance is measured is not within the flash photographing range, that is, when it is not prefocus shooting, 17 is a pull-up resistor , 18 is a switch for changing the shooting angle of view, which is turned on when the telephoto side (telephoto side) is selected by the photographer and turned off when the wide side (wide angle side) is selected. Reference numeral 19 is an AND gate, 20 is a pull-down resistor, and 21 is a transistor that is turned on when the output of the AND gate 19 becomes a high level signal to excite the magnet Mg2.

FIG. 2 is a built-in strobe device and a mechanical configuration diagram related thereto, and the same portions as those in FIG. 4 are represented by the same reference numerals. Reference numeral 22 is a protector of a stroboscopic device having a Fresnel lens, to which guide members 23 and 24 are integrally attached, and the guide members 23 and 24 are guided by an arrow A or a guide hole 25 fixed to a structural member (not shown). It is slidably supported in the B direction. Reference numeral 26 is a compression spring having a function of pushing the collar portion 23a integral with the guide member 23 to slide the protector 22 rearward, 27 is a transparent glass cover, 28
Is a locking claw rotatably supported by a structural member (not shown) fitted in the hole 28a. When the armature part 28b is not attracted by the magnet Mg2, the claw part 28c is the groove part 23c of the guide member 23. It rotates counterclockwise according to the bias of the spring 29 until it engages with. Reference numeral 30 denotes a charge cam in which a shaft 30a is rotatably fitted to a structural member (not shown), the cam portion 30b is configured to charge the spherical portion 23d of the guide member 23, and the gear portion 30c is provided in the lower stage. Have 31
Is a gear connected to a film winding mechanism (not shown), and when one film frame is wound, it makes one full rotation about the shaft 31a, and this rotational force is transmitted to the gear portion 30c of the charge cam 30.

Next, the operation of the camera configured as above will be described. The camera of this embodiment is assumed to be capable of switching between tele / wide, but a monofocal camera without tele / wide switching is easier to understand, so first of all, an explanation of operation as a monofocal camera will be given. This is performed according to the flowchart of FIG. The circuit configuration in this case is the first
From the circuit configuration in the figure, pull-up resistor 17 to AND gate
Think of it as omitting up to 19.

When the photographer half-presses the release button with the main subject positioned in the center of the screen (within the distance measuring mark), switch SW1 turns on and a start signal is generated in the logic control circuit 4 to measure the distance. The distance measurement operation is started by the circuit 5,
A distance measurement signal (distance measurement information) to the main subject is required. The distance measurement signal at this time is stored in the register 6 and displayed by a known display device. At this time, a known photometric operation is also started, and a circuit (not shown) determines whether the brightness level at that time is higher or lower than a prescribed level, that is, the brightness determination. As a result, if it is determined that it is dark,
When the flash device is instructed to start charging and the shooting mode is switched to the flash shooting mode, and conversely, when it is determined that the shooting mode is bright, a shooting display is displayed on a known display device.

Next, after confirming the photographable display or the strobe charging completion display, when the photographer fully presses the release button,
The switch SW2 turns on, and the shooting operation starts. As a result of the light / dark discrimination, when it is determined that the image is dark and the photographing mode is switched to the flash photographing mode, the logic control circuit 4 causes the film sensitivity, the FN _{0 of} the photographing lens and the G of the strobe device to change.
The flashable distance is calculated from N _0, a reference signal (voltage) corresponding to the flashable distance is generated in the reference signal generating circuit 9 in the next stage, and the signal is input to the inverting input terminal of the comparator 10. The distance measurement signal stored in the register 6 is sent to the D / A conversion circuit 8, converted into an analog signal and input to the non-inverting input terminal of the comparator 10. The output of the register 6 is also input to the coincidence detection circuit 11. The comparator 10 compares the above-described distance measurement signal with the reference signal. If the distance measurement signal is larger (longer distance), a high level signal is generated, and is input to one input terminal of the NAND gate 16. input.

When the switch SW2 is turned on as described above, the activation signal is generated again in the logic control circuit 4, and the distance measuring circuit 5 performs the distance measuring operation again before the exposure operation is started. The signal is sent to the register 7. The coincidence detection circuit 11 compares the first distance measurement signal input from the register 6 with the second distance measurement signal input from the register 7, and when they match, that is, the distance measurement zone in the screen. Assuming that the composition change operation was not performed when the subject distance of
A high level signal is output to the other input terminal of the. Therefore, when the outputs of the comparator 10 and the coincidence detection circuit 11 are both high level signals from the NAND gate 16, in other words, when the main subject is farther than the flash photographing possible distance, and at the center of the screen. A low level signal is output when the main subject exists. Thus, only when the main subject is farther than the flash-capable distance and when the main subject exists in the center of the screen, the transistor 21
Remains off, and in this case magnet Mg
No. 2 is not excited, and flash photography is performed with the Fresnel lens in the state shown in FIG.

For example, if you have built-in GN ₀ 10 strobe device, ISO100
If the FN _{0 of} the photographic lens is 2.8 using the film No. 2, the possible shooting distance at the time of flashing is about 3.6 m as described above, but with the Fresnel lens positioned as shown in FIG. 2 as described above. When the image is taken up to, the light emitted from the light emitter 3 is condensed as shown by the dotted line b in FIG. 5, and the light amount at the center of the screen is increased to about 2 times (1.4 times for GN ₀ ). In the central area, the flash range is extended to 5m. Therefore, it is possible to solve the problem that the emitted light does not reach the subject, resulting in an underexposed photograph.

In cases other than the above (here, when the main subject is located at a short distance), the output of the NAND gate 16 becomes a high-level signal, the transistor 21 is turned on, and the magnet Mg2 is excited. Therefore, the magnet portion 28b is applied to the magnet Mg2. Is sucked, the locking claw 28 rotates clockwise against the spring 29, and the claw 28c and the groove 23c of the guide member 23 are disengaged from each other, so that the protector 22 biases the compression spring 26. Accordingly, it moves in the direction of arrow A to a position where it comes into contact with a stopper (not shown). Therefore, in such a case, flash photography is performed in the light emitting state as indicated by the solid line a in FIG.

After that, the gear 31 makes one full rotation in the counterclockwise direction in conjunction with the well-known film winding operation.
30 rotates once in the clockwise direction, and at this time, the cam portion 30b moves the spherical portion 23d of the guide member 23 integral with the protector 22 in the direction of arrow B against the compression spring 26, that is, charges and has the Fresnel lens again. Return the protector 22 to the state shown in FIG.

In the initial stage of the above-mentioned photographing operation, the coincidence detection circuit 12 compares the distance measurement signal from the register 6 with the lens position signal from the lens position signal generation circuit 13 which is the positional information of the photographing lens, and at the time of coincidence. That is, a high-level signal is output to the transistor 15 when the photographing lens reaches the in-focus position. This turns on transistor 15,
The magnet Mg1 is excited and the retraction operation of the taking lens stops. Since such focus adjustment operation is already known, detailed description thereof will be omitted.

Next, the case of the tele / wide switchable camera of this embodiment will be described. When the telephoto side is selected by the photographer, the switch 18 is turned on, and a low level signal is always input to one input end of the AND gate 19. Therefore, regardless of the output state of the NAND gate 16, the output of the AND gate 19 becomes a low level signal, the transistor 21 is not turned on, and the magnet Mg2 is not excited. Therefore, when the tele side is selected in this way,
The protector 22 having the Fresnel lens is still in the state shown in FIG. 2, that is, flash photography is performed in the light emitting state shown by the dotted line b in FIG. In the telescopic state, the angle of view of the taking lens is narrowed, and therefore the periphery of the screen does not become extremely dark even with the light emission shown by the dotted line b in FIG.

When the wide side is selected by the photographer, switch 18
Is off, and a high level signal is input to one input terminal of the AND gate 19.
The output signal of the AND gate 19 changes according to the output state of the. That is, in this case, as in the case of the above-described single-focus camera, when the main subject is farther than the flash photographing possible distance, and when the main subject exists in the center of the screen (when not in prefocus photographing). Does not turn on the transistor 21, and flash photography is performed with the Fresnel lens in the state shown in FIG. 2, but at other times, the transistor 21 is turned on.
Since 21 is turned on, flash photography is performed in the light emitting state shown by the solid line a in FIG.

According to this embodiment, not only when the release button is pressed halfway,
Since the distance measurement signal is obtained even when the button is pressed all the way down and both distance measurement signals are compared, it is possible to know whether or not the prefocus shooting has been performed with the composition changing operation. In addition, the Fresnel information is obtained based on the information on whether or not the pre-focus photographing is performed and the distance information on the main subject at this time (information on whether or not the distance is longer than the flash photographing possible distance of the built-in flash device). Since it is decided whether or not to condense the light emitted from the light emitter 3 by moving the lens, a subject of 3.6 m to 5.0 m, for which proper exposure cannot be obtained, and a camera of this kind is used. Since it is possible to shoot a scene in which the main subject, which will occupy most of the shooting used, is in the center of the screen, the compact camera can be made easier to use.

(Correspondence between Invention and Embodiment) In this embodiment, the distance measuring circuit 5 serves as the detecting means of the present invention.
The switch SW1 and the logic control circuit 4 serve as the first starting means, the switch SW2 and the logic control circuit 4 serve as the second starting means, the switches SW1, SW2 and the logic control circuit 4 serve as the starting means, and the coincidence detecting means 12 is provided.
The lens position signal generating circuit 13, the pull-down resistor 14 and the transistor 15 correspond to the focus adjusting means, the coincidence detecting circuit 11 corresponds to the judging means, the transistor 21 and the magnet Mg2 correspond to the photographing condition determining means, and the transistor 21 corresponds to the controlling means. .

(Modification) In the present embodiment, the information on whether or not the prefocus photographing is performed is obtained by comparing the first and second distance measurement signals, and the light distribution of the strobe device is changed based on the information. However, the present invention is not limited to this, and in a camera having a large number of distance measuring zones (distance measuring points) in the screen, information indicating whether or not prefocus photographing is performed by comparing the first and second distance measuring signals. Alternatively, the direction of the strobe light may be changed by determining the moving direction of the main subject within the screen. In addition, when the main subject is not in the center of the screen, of course, most of the time, shooting is performed with the background other than the main subject in mind, so the shutter opening is regulated to increase the depth so that the background is well captured. It will be easy for those skilled in the art to configure the above.

(Effects of the Invention) As described above, according to the invention described in claim 1 of the present application, it is confirmed that the position of the prefocus target on the screen has not changed in the camera having the prefocus function. It is more appropriate by determining without complicated operations and by setting the shooting conditions that give priority to the prefocus target over other subjects compared to when the position of the prefocus target on the screen has not changed. Shooting becomes possible.

According to the invention described in claim 2 of the present application,
In a camera having a prefocus function, by changing the light distribution state of the flash unit depending on whether or not there is a change in the distance to the prefocus target, it is possible to more appropriately act the light distribution state of the flash unit. Become.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a strobe device which is also incorporated therein, and a mechanical configuration diagram related thereto, FIG. 3 is a flow chart, and FIG. 4 is a general Fresnel lens. And a diagram for explaining the relationship between the luminous body and
FIG. 5 is a diagram for explaining a light emitting state of emitted light according to the movement of the Fresnel lens in FIG. 4 ... Logic control circuit, 5 ... Distance measuring circuit, 6,
7 ... Register, 9 ... Reference signal generation circuit, 10 ... Comparator, 11,12 ... Match detection circuit, 16 ... Nand gate, SW1, SW2 ... Switch, Mg1, Mg2 ... Magnet.

Claims (2)

[Claims] 1. A camera having a prefocus function, wherein the detecting means detects a prefocus signal for a prefocus object, and the detecting operation is started before the shooting operation is started in response to an operation of a release member for starting the shooting operation. First activating means for activating the means with respect to the prefocus object, and second activating means for activating the detecting means again before the photographing operation is started in response to further operation of the release member. A focus adjustment means for adjusting the focus of the photographing optical system according to the detection result of the detection means for the prefocus target, and the detection result of the detection means for the prefocus target and the subsequent detection result of the detection means. Determination means for determining whether or not there is an error, and the determination means detects the detection result of the detection means and the subsequent detection of the detection means. When it is determined that there is no change in the results compared to when it is determined that there is a change, camera, comprising an imaging condition determining means for determining priority photographing conditions from a subject pre-focus target other. 2. In a camera having a prefocus function, a detecting means for detecting a prefocus signal for a prefocus target, and the detecting means in the process of operating the detecting means for the prefocus target and thereafter photographing. Starting means for operating again, and determination means for determining whether or not the distance to the detection target has changed based on the detection result of the detection means for the prefocused object and the detection result of the detection means in the process up to the subsequent photographing. And a control unit that changes the light distribution state of the flash unit in response to the determination unit.