JPH01147529A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To perform a highly efficient automatic focusing action by automatically shifting to a flashing state photographing action when an object has low luminance or when it is in a counter light state so that focusing is performed and executing a focusing action based on corresponding distance information when range measurement information exceeds an auxiliary attainable distance. CONSTITUTION:A luminance decision part 8 compares photometric data AE from a photometry part 6 with 1st and 2nd reference values, for example, EV9 and EV3. When the photometric data AE is under the reference values, a start signal and a range signal are respectively outputted. A range decision part 9 which simultaneously receives both of the signals compares the range measured data AF from a range measuring part 7 with the attainable distance of auxiliary light. Only when the data AF exceeds the attainable distance, it is substituted with limit data LIM corresponding to the attainable distance and outputted to a lens control part 10. Thus, countermeasure is adopted for three kinds of values, for example, EV9 or more, exceeding EV3 and under EV9, EV3 or less, according to the luminance of the object. Moreover, even if the value is EV3 or less, the different countermeasure can be adopted according to whether or not the data AF is the attainable distance and beyond.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to an autofocus camera, and more particularly to an autofocus camera that can be attached to or has a built-in flash device that projects auxiliary light onto a subject. be.

(b) Prior Art In a conventional autofocus camera, when the brightness of the subject is extremely low, the entire viewfinder screen of the camera becomes dark, and a target mark (ranging area The display frame becomes very difficult to see, and even if the operator has aligned the target mark with the subject he or she really wants to photograph, the target mark may actually shift left or right, making it difficult to accurately capture the subject's position, and as a result, the target mark may not be accurately captured as intended. Often, backgrounds that were not visible became objects of distance measurement.

Therefore, it can be said that there is little point in performing distance measurement in such extremely low brightness conditions.

On the other hand, in addition to the autofocus mechanism, the autofocus camera generally has an autoexposure mechanism and a strobe (flash device) linked to the autofocus mechanism. If the reachable distance of the auxiliary light is 5 m and the distance to the subject is 8 m, the autofocus mechanism outputs distance measurement data corresponding to the 8 m and adjusts the photographic lens to the corresponding focus. It tries to drive to the focus position, but the predetermined reference value (5
m) and the above distance measurement data, if the subject is in a position that the fill light cannot reach, there is little point in measuring the distance as described above, so the above 5 m is forced to be in focus. It was configured to limit the amount of movement (driving amount) of the photographing lens so that the position of the photographic lens is adjusted.

By the way, even in the same low-brightness situation, for example, in a so-called backlit situation where the subject has the sun behind him, only the subject is in low brightness, so by projecting filler light, the subject will also be brighter, and the entire image can be photographed with the correct exposure. (This kind of shooting method is called daytime synchronization.) However, as mentioned above, when the subject is of low brightness, conventional cameras that uniformly limit the amount of movement described above cannot use daytime synchronization. Even when an attempt is made to take a photograph, the camera is forced to focus on a position at a distance of 5 m, so there is a problem in that an object located at a position of 8 m ends up being photographed completely out of focus.

(c) Purpose The present invention was made in view of the above-mentioned circumstances, and its purpose is to reduce the brightness of the subject when it is low enough to require auxiliary light, or when the subject is backlit to the extent that synchronized photography is required. When the camera is in this state, it can automatically shift to flash photography operation and perform focusing operation based on distance measurement information.
On the other hand, when the subject has very low brightness, the camera automatically switches to flash photography, and when the distance measurement information exceeds the auxiliary light range, the camera automatically switches to flash photography based on the information corresponding to the auxiliary light range. An object of the present invention is to provide an autofocus camera that can perform a focusing operation and can increase the probability of focusing, especially at extremely low brightness.

(d) Structure In order to achieve the above-mentioned object, the present invention measures the brightness of the subject in an autofocus camera that can be attached to or has a built-in flash device that projects auxiliary light onto the subject. a photometric means for outputting corresponding photometric data;
A distance measuring means that measures the distance to the subject and outputs distance measurement data corresponding to the distance, a first reference value corresponding to low luminance that requires auxiliary light for the subject, and a distance measuring means that measures the distance to the subject and outputs distance measurement data corresponding to this; an operation instruction signal for receiving the photometric data and activating the flash device when the photometric data falls below the first reference value; and a brightness determination means that outputs a distance determination instruction signal when the photometric data is less than the second reference value, and a brightness determining means that simultaneously receives the activation signal and the distance determination instruction signal, and furthermore, the distance measurement data is If the reachable distance of the auxiliary light is exceeded, a photographing distance determining means outputs limit data corresponding to the reachable distance in millimeters, and a photographing lens receives the distance measurement data or the limit data and moves the photographing lens to the distance measurement data. and a lens drive control means for controlling drive to a focus position corresponding to the above-mentioned limit data or a predetermined limit position corresponding to the limit data, and when the distance to the subject exceeds the above-mentioned reachable distance when photographing using the above-mentioned flash device. In this case, the driving amount of the photographing lens is limited only when the brightness of the subject is extremely low, which is significantly lower than the second reference value.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of an autofocus camera according to the present invention, and FIGS. 2 and 3 are flowcharts showing the operational sequence of the embodiment shown in FIG. 1.

In FIG. 1, reference numeral 1 denotes a strobe system la, l as a flash device that projects auxiliary light onto a subject (not shown).
b, lc both constitute the above-mentioned strobe system 1, and 1a has a dimming signal (STOP) and a status signal (STOP) at the input terminal.
TU), SI:, A circuit section that receives the to signal (SYC) and outputs a charge completion signal (COK) from the output terminal, lb forms a part of this circuit section 1a, and is used to generate high voltage. The main capacitor 1c is a light emitting unit that is driven by the circuit unit 1a and projects auxiliary light, and the strobe system 1 is housed in the camera body (not shown) when not in use and has a protruding habit, and is locked. It is configured to be locked by a member (not shown) to maintain the stored state, and to protrude to the outside of the camera body by releasing the lock.

2 is a magnet for releasing the locking member; 2a;
is a magnet drive circuit that drives the magnet 2 by receiving a start signal (STR) at its input terminal. 3 is linked with the strobe system 1, the common contact 3a is grounded, the down contact 3b is open (no connection), and the up contact 3
When the common contact 3a is connected to the pop-up switch 3c, the pop-up switch outputs the status signal (TUS) at L level indicating that the strobe system 1 is protruding (POP UP) from the up contact 3c.

4 is an open contact 4a which works in conjunction with a lens barrier (none of which is shown) that freely opens and closes the front surface of the photographic lens of the camera body.
is grounded, the closing contact 4b is connected to the power supply +■, and the lens barrier opening/closing switch has a common contact 4c. R.L.
I and RL2 are release switches each having one end connected to the common contact 4c of the barrier opening/closing switch 4,
Linked to the release button (not shown) on the camera body, the release switch RLI is turned ON when the release button is pressed halfway (first stroke), and RL2 is turned ON following RLI when the release button is pressed fully (second stroke). configured to be in the state.

5 is the release switch RLI, the other end of which is connected to the input end of RL2, and the corresponding release signal (RLI
) and (RL2), and a control signal (C
This is a switch input section that sends and receives TL.

6 receives the above-mentioned release signal (RLI) at the input terminal, measures the brightness of the subject, and outputs photometric data (AE) corresponding to this.
This is a photometering unit that outputs a photometer. Reference numeral 7 designates a distance measuring unit as a distance measuring means that receives a photometry end signal (FIN) at an input end, measures the distance to the subject, and outputs distance measurement data (AF) corresponding thereto.

8 and 9 constitute the main parts of the embodiment, and of these, 8 receives the photometric data (AE), the charge completion signal (COK), and the status signal (TUS) at its input terminal, and internally An RO in which data of EV9, for example, as a first reference value, and EV3, for example, as a second reference value, is stored in advance.
M and a memory IJ M R1 such as a RAM for temporarily storing the above "l!I optical data (AE), etc., and when the 31g optical data (AE) falls below the first and second reference values, respectively, This is a brightness determination section as a brightness determination means that outputs a start signal (STR) as an operation instruction signal and a range signal as a distance determination instruction signal from an output terminal, and sends and receives the control signal (CTL) to an input/output terminal. Note that the photometry end signal (FIN) is also output from the output end, and the timing of this output will be described later.

9 receives the distance measurement data (AF), the range signal (RNG), the start signal (STR), and the synchronization signal (SYC) at its input end, and receives the light emitted from the light emitting unit IC of the strobe system 1 inside. The memory MR2 includes a ROM that stores data on the reachable distance (for example, 5 m) of the auxiliary light, and a RAM that temporarily stores the distance measurement data (AF), etc., and the range signal (RNG) and the start signal. When receiving signals (STR) at the same time, if the distance measurement data (AF) exceeds the above reachable distance, the distance measurement data (AF) will not be output from the output end and the distance measurement will be performed within the reachable distance. The corresponding limit data (L I M) is output, and if the above range is not exceeded, this limit data (L I M) is not output and the received ranging data (AF) is sent.
is output as is, and the above control signal (CTL) is output to the input/output terminal.
This is a range determining section that serves as a shooting distance determining means for transmitting and receiving information. Note that a winding signal (WD) is also output from the output end, which will be described in detail later.

Reference numeral 10 denotes a lens control section as a lens drive control means that receives distance measurement data (AF) or limit data (LIM) at an input end and controls a stepping motor 10a that drives a photographic lens (not shown). .

A film feeding section 11 receives the winding signal (WD) and controls a winding motor lla that winds a film (not shown). A shutter control unit 12 receives the release signal (RL2) and controls the opening and closing of the shutter member 12a, and outputs a synchronization signal (syc) that becomes an H level when the shutter member is open and an L level when the shutter member is closed, for example.

Reference numeral 13 indicates a brightness determination section 8, a range determination section 9, and a switch input section 5 by transmitting and receiving the control signal (CTL) described above.
This is a comprehensive control unit that controls the

The range determining section 9 outputs a winding signal (WD) according to the falling edge of the synchronizing signal (SYC), and the circuit section 1a of the strobe system 1 outputs a winding signal (WD) based on the falling edge of the synchronizing signal (SYC).
The light emitting section 1c is configured to start emitting light at the rising edge of the light emitting section 1c.

In addition, the state signal (
The input terminal receiving TUS) and the input terminal connected to the other terminals of the release switches RLI and RL2 of the switch input section 5 are configured to be pulled up internally, and therefore, these input terminals The signal level of is normally held at H level, and becomes effective as a signal input when inverted to L level.

The operation of this embodiment configured as described above will be explained with reference to the flowcharts of FIGS. 2 and 3.

First, when the operator opens the lens barrier of the camera body, the lens barrier opening/closing switch 4 is brought into the state shown in FIG. 1, that is, the common contact 4c is connected to the open contact 4a. Then, when the operator presses the release button (not shown) to the first stroke and presses it halfway, the release switch RLI is closed. At this point the second
The flowchart shown starts from rRLl-ONJ. That is, a release signal (RLI) corresponding to the release switch RLI is output from the switch input section 5. In the first "photometry operation", the photometry section 6 that receives the release signal (RLI) starts photometry and outputs photometry data (AE) corresponding to the brightness of the subject. And photometric data (A
E) is assumed to be EV2.

In the next conditional branch “Is the photometric data less than EV9?”
The brightness determination unit 8 receives photometric data (AE) called EV2,
This is stored in the memory MRI and compared with a first reference value of EV9. In this case, since the photometric data (AE) is lower, a start signal (STR) is output, and the flowchart branches to YES.

In the next strobe POP UPJ, the magnet drive circuit 2a that receives the start signal (STR) drives the magnet 2 and releases the locking of the locking member. At the primary "charging start" when the common contact 3a of the pop-up switch 3 is switched from the down contact 3b to the up contact 3c as shown in FIG. 1, the pop-up main≠3 is output. The circuit section 1a of the strobe system 1 that receives the L-level status signal (TUS) starts charging the main capacitor 1b. Then, at the next conditional branch "Charging completed?", the circuit section 1a continues to branch to NO until the charging capacitor 1b reaches a predetermined voltage (for example, 400V). When the predetermined voltage is reached, a charge completion signal (COK) is output, and the flowchart is YE.
Branch to S. Note that the operation from the above-mentioned "strobe POP UPJ" to the above-mentioned "Charging complete?" branching to YES will be hereinafter referred to as "light emission preparation operation".

In the next "distance measurement operation", the charge completion signal (COK
), the brightness determination unit 8 receives a photometry end signal (FIN).
Upon receiving this, the distance measuring section 7 starts distance measurement and outputs distance measurement data (AF) corresponding to the distance to the subject. Now, suppose that the distance to the subject is 8 meters, and the range determination unit 9 receives this ranging data (AF) and stores it in the memory M.
At the 0th order conditional branch "Is the photometry data less than EV3?" stored in R2, the comprehensive control unit 13 sends a control signal (CTL) indicating that the range determination unit 9 has received the distance measurement data (AF).
and instructs the brightness determining section 8 to perform the comparison again through a control signal (CTL). Upon receiving this, the brightness determination unit 8 compares the photometric data (AE) of EV2 stored in the memory MHI with the second reference value of EV3,
In this case, the photometric data (AE) is below EV3, so the range signal (RNG) is output, and the flowchart is YE.
Branch to S.

In the next conditional branch "Is the distance measurement data beyond 5 m?", the range determination unit 9 determines that the range signal (RNG) and start signal (STR) are both input.
Compare the distance measurement data (AF) of 8m stored in Step 2 with the reachable distance of 5m. In this case, since it is beyond 5m, the branch is YES, and in the next "distance measurement data replacement", the range determination unit 9 outputs the limit data (LIM) of 5m without outputting the distance measurement data (AF). .

The lens control unit 10 receives this limit data (LIM).
In the next "lens drive", the stepping motor 10a is controlled to drive the photographing lens to the focusing position corresponding to the above 5 m. Then, the flowchart in FIG. 2 reaches point (3) and moves to FIG. 3.

In addition, the above “Distance data is beyond 5m?” which branches to YES.
Hereinafter, the above-mentioned "distance data replacement" operation will be referred to as "range limiting operation." Furthermore, the operation of the camera body shown in FIG. 2 will be referred to as a "photography preparation operation."

Now, moving to ■ in Figure 3, the first conditional branch
' [Continue RL1 operation? ” and the next conditional branch rRL2
Is there any operation? ”, the comprehensive control unit 13 outputs a control signal (CT
The release switch RL is connected to the switch input section 5 via the
Check the status of I and RL2.

In other words, if the operator holds the release button in a half-pressed state as described above, is rRL2 operated? ” to N
Branch to o and continue rRL1 operation again? '' and repeat this operation, and if you release the above half-press state, continue rRL1 operation? ” is branched to No, and the general control unit 13 instructs the range determination unit 9 to that effect at the first “lens initial position”, and the range determination unit 9 outputs the initial position data as ranging data (AF). Then, upon receiving this, the lens control section 10 drives the photographing lens to an initial position (for example, a position on the infinity distance side). Then, in the next "photometry/distance measurement data clear", the brightness determination section 8 and the range determination section 9 clear the contents of the memories MRI and MR2, respectively, according to an instruction from the general control section 13. All operations end with the next rENDJ.

Now, when the release button is further pressed to the second stroke from the half-pressed state, the release switch RLI and RL2 are closed, and the switch input section 5 outputs a release signal (RLI) corresponding to this.

(RL2) respectively, and the flowchart is the above r
Is there RL2 operation? ” branches to YES.

Shutter control section 1 receiving this release signal (RL2)
2 opens the shutter member 12a in the next "shutter opening operation" and raises the synchronization signal (SYC). Range determination unit 9 receives the rising edge of this synchro signal (SYC)
stores this fact in the memory MR2, and on the other hand, the circuit section 1a of the strobe system 1, which similarly receives the rise of the synchronization signal (SYC), executes a first-order conditional branch rPOP UP?
At J, the signal level of the status signal (TUS) is checked, and in this case it is L level, so the flowchart branches to YES, and in the next "strobe light emission", the circuit section 1a emits light due to the high voltage of the main capacitor 1b. The section 1c starts emitting light. Therefore, as a matter of course, when the status signal (TUS) is at H level, that is, when the strobe system 1 is housed in the camera body, the circuit section 1a stops the light emitting section 1c from emitting light even if it receives the synchronization signal (syc). Don't let it start.

In other words, this operation is shown in the flowchart as rpop
UP? This corresponds to the case where J is branched to NO.

The brightness of the subject increases in response to the auxiliary light projected from the light emitting unit 1c, and the photometry unit 6 measures the changes (increases) in this brightness moment by moment and outputs photometry data (AE) corresponding to this. The brightness determining unit 8 receiving this outputs a dimming signal (STOP) when the brightness reaches a predetermined brightness (appropriate exposure). In response to this, the circuit section 1a performs a zero-order "shutter shutter closing operation" that stops the light emission of the light emitting section 1c, causing the shutter control section 1
2 closes the shutter member 12a and lowers the synchronization signal (syc) after the proper exposure time has elapsed.

Next, the above-mentioned "initial lens position" is executed, and in the next "film feed", the range determination section 9 refers to the memory MR2 and stores that there is a rising edge of the synchronization signal (SYC) as described above. In other words, it remembers that the photo was taken.

A winding signal (WD) is output at the time when the fall of the synchronization signal (syc) is detected. Upon receiving this, the film feeding section 11 drives the winding motor lla to wind up the film for one frame after shooting. And the next rEND
All operations end with J.

In the above explanation, the photometric data (AE) is the second reference value EV.
3 or less, but if the photometric data (AE) is equal to or higher than the first reference value EV9, the above-mentioned "flash preparation operation" and the above-mentioned "range "limiting operation" and "stroboscopic light emission" in FIG. 3 are omitted (not executed).

Further, when the photometric data (AE) is below EV9 and exceeds EV3, the lens limiting operation is omitted from the light emission preparation operation.

Further, if the photometric data (AE) is EV3 or lower and the distance measurement data (AF) is within 5 m, only the "distance measurement data replacement" in FIG. 2 is omitted.

In this way, in this embodiment, the brightness determination section 8
The photometric data (AE) from is compared with a first reference value of EV9 and a second reference value of EV3, and when the photometric data (AE) falls below these reference values, the start signal (STR) and the range are set respectively. The range determination unit 9 outputs a signal (RNG) and receives both signals simultaneously, and compares the distance measurement data (A F) from the distance measurement unit 7 with the reachable distance of the auxiliary light (5 m). The distance measurement data (AF) is configured to be replaced with limit data (LIM) corresponding to the reachable distance and output to the lens control unit 10 only when the distance data (AF) exceeds the reachable distance. Therefore, depending on the brightness of the subject, EV9 or more, over Ev3 and less than EV9, E
Three types of support are possible: V3 or lower, and furthermore, EV3
Even in the case of ultra-low brightness, it is now possible to respond differently depending on whether the distance measurement data (AF) is more than 5 meters away, and it is possible to respond extremely flexibly depending on the brightness of the subject and the distance to the subject. This has the advantage of eliminating mistakes (out-of-focus photos) when shooting with medium sync.

In addition, even if the strobe system 1 is in the POP UPL state and the operator accidentally measures the background at a distance of 15 m even though the subject to be photographed is at a distance of 10 m, the brightness of the background If the range exceeds Ev3, the range determining unit 9 is configured not to output the limit data (LIM) corresponding to the reachable distance of 5 m, so even if it is not appropriate, it is possible to prevent a completely erroneous shooting. The advantage is that it does not.

It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented in various modifications without departing from the spirit thereof.

For example, the first reference value is not limited to EV9, but is a subject brightness of EV9 to Ev at which there is a risk of camera shake.
It may have a width of about 11.

In addition, the reachable distance of the auxiliary light is not limited to 5m,
F number of photographic lens, G number of strobe system 1,
It may be changed as appropriate depending on the ISO sensitivity of the film.

Further, the strobe system 1 is not limited to a built-in type that can be stored and protruded, but may be an external type that can be attached. Furthermore, when the subject has low brightness, the strobe system 1 may be configured to automatically emit light on its own, or may have a light emitting switch that can be operated externally to forcefully emit light.

Also, instead of performing distance measurement at the time of "distance measurement operation" shown in Figure 2, it is performed between rRLl-ONJ and "Is the photometry data less than EV9?" The order of "distance measurement operation" and "photometry operation" may be reversed.

Also, are the operations from "distance measurement operation" shown in FIG. 2 to just before "lens drive" performed with or without rRL2 operation in FIG. 3? "and[
It may also be inserted between the shirt opening operation and the shirt opening operation.

Further, if the configuration is such that distance measurement is not performed again after the release switch RL2 is closed, RL2 may be omitted and only RLI may be used. However, in this case, is there rRL2 operation in Figure 3? ' shall be deleted.

Furthermore, the first and second reference values are not limited to Ev9 and EV3, respectively, and may be changed as appropriate depending on the F[ of the photographing lens, the G number of the strobe system 1, and the ISO sensitivity of the film. For example, the brightness determination unit 8
The CAS switch 14 may be connected to the input end of the camera, so that various information about the film, including the above-mentioned ISO sensitivity, can be read from the film cartridge.

(e) Effects As detailed above, according to the present invention, when the brightness of the subject is low enough to require an auxiliary light or when the subject is backlit to the extent that synchronized photography is required during the day, the It is possible to shift to flash shooting operation and perform focusing operation based on distance measurement information obtained by the distance measuring means.On the other hand, when the subject has extremely low brightness, it automatically shifts to flash shooting operation as well. At the same time, when the distance measurement information does not exceed the auxiliary light reach distance, the focusing operation can be performed based on the distance measurement information, and when it exceeds the auxiliary light reach distance, the focusing operation can be performed based on the information corresponding to the auxiliary light reach distance. Therefore, it is possible to provide an autofocus camera that can significantly increase the probability of focusing during flash photography compared to conventional cameras.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the overall configuration of an autofocus camera according to the present invention, and FIGS. 2 and 3 are flowcharts showing the operational sequence of the embodiment shown in FIG. 1. 1...Strobe system, 1a...Circuit section. 1b... Main capacitor. 1c... Light emitting part, 2... Magnet, 2a... Magnet drive circuit, 3...
...Pop-up switch, 4... Lens barrier opening/closing switch. RLI, RL2...Release switch, 5...
...Switch input section, 6...Photometering section, 7...Distance measurement section. 8...Brightness determination unit, 9...Range determination unit, 10...Lens control unit, 11...Film feeding unit, 12... ...Shutter control section, 13... General control section. 14...CAS switch, (AE)...Photometry data, (AF)...Distance measurement data, (TUS)...Status signal, (RNG )......Range signal. (STR)...Start signal, (LIM)
...Limit data, (syc), old synchro signal, (CTL), control signal. Patent applicant Rico Co., Ltd. −

Claims (1)

[Claims] (1) In an autofocus camera that can be equipped with or has a built-in flash device that projects auxiliary light onto the subject, a photometric means that measures the brightness of the subject and outputs corresponding photometric data; a first reference value corresponding to low luminance that requires auxiliary light for the subject; It has a memory storing a second reference value corresponding to ultra-low brightness, and receives the photometric data and outputs an operation instruction signal for operating the flash device when the photometric data falls below the first reference value. ,
a brightness determination means that outputs a distance determination instruction signal when the photometric data is less than the second reference value; and a brightness determination means that simultaneously receives the activation signal and the distance determination instruction signal, and further includes a brightness determination means that outputs a distance determination instruction signal when the photometric data is less than the second reference value; If the reachable distance is exceeded, a photographing distance determining means outputs limit data corresponding to the reachable distance, and a photographing distance determining means that receives the distance measurement data or the limit data and focuses the photographing lens in accordance with the distance measurement data. or a lens drive control means for controlling the drive to a predetermined limit position corresponding to the limit data, and when the distance to the subject exceeds the reachable distance when shooting using the flash device, An autofocus camera characterized in that the amount of drive of the photographing lens is limited only when the luminance of the lens is extremely low, which is significantly lower than the second reference value.