JP3139067B2 - Auto focus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus camera having an auxiliary light device for autofocus (AF) which emits light when the luminance of a subject is low or when the contrast is low.

[0002]

2. Description of the Related Art Conventionally, in this type of autofocus camera, the contrast of a subject is low (hereinafter, referred to as "autofocus").
When the subject brightness is low (hereinafter, referred to as low light), an auxiliary light source such as an LED built in the camera body or provided in an external flash is projected onto the subject, Focus adjustment is performed by detecting the subject distance and detecting the focus by receiving the reflected light, and photographing is performed. And this detection
When a charge storage type light receiving element (for example, CCD) is used for
In this case, the charge is stored normally and the storage ends normally.
Is to receive the light for a certain amount of time
is necessary. However, flash is generally very short
Light emission with a high chevron curve occurs only once in between, so charge accumulation
It is not suitable as a light source for light receiving elements of the type. Therefore, in such an autofocus camera , the flash
The use of a flash as an auxiliary light source has not been realized , and in cameras with a built-in flash, an auxiliary light source is provided separately from the flash. A flash light source and an auxiliary light source are provided separately.

[0003]

To mow and [0008], is obtained by separately provided auxiliary light source for auto focusing during low light camera using flash the number of components is increased, there is a drawback in terms of cost reduction . SUMMARY OF THE INVENTION The present invention solves the above-described problems, and it is possible to intermittently emit a flash light.
So that intermittent light emission continues during charge accumulation.
To obtain a substantially uniform continuous light.
And possible way, intended to be made available flash as auxiliary light for auto-focus, also serves as a flash device of the auxiliary light source and a flash photography to provide an autofocus camera which attained cost reduction And

[0004]

Means for Solving the Problems The present invention to achieve the above object, a light emitting means for irradiating light to shoot a subject and detects information relating to the distance to the Utsushitai
A detecting means including a charge storage type light receiving element of the eye, and determining means for determining whether or not can be detected by pre-Symbol detection unit, when it is determined that the undetectable by the determination means, the detection of said detecting means In front of the light emitting means as an auxiliary light source in
Control means for continuously and intermittently emitting light during the charge accumulation of the light receiving element . According to a second aspect of the present invention, in the camera according to the first aspect,
The determining means determines whether or not detection is possible based on the brightness or contrast of the subject. Also, billing
The invention according to claim 3 provides the camera according to claim 1.
And further includes photometric means for measuring the brightness of the subject.
The determining means performs the detection based on a photometric result of the photometric means.
It is determined whether or not detection by means is possible. Ma
The invention according to claim 4 is the camera according to claim 1.
In the above, the determination means is based on an output of the detection means.
To determine whether or not detection by the detection means is possible
It is.

[0005]

According to the above arrangement, a charge storage type light receiving element can be used.
Of information related to subject distance by detecting means including
The determination means determines whether or not detection is possible, and detection is not possible.
When it is determined that, the control means for the detection of the detection means
Light emitting means is used as an auxiliary light source while the charge of the light receiving element is stored
To emit light intermittently. In this way, the subject
Light emitting means for shooting is used to detect subject distance information
Can be used as auxiliary light.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An autofocus camera (hereinafter, referred to as a camera) according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a functional block configuration of the camera. In FIG. 1, a camera control unit 1 is configured by a microcomputer or the like, and is connected to various external circuits and the like described below, and controls the entire camera including these components. The camera has a built-in flash 2 as a flash device, and an external flash 4 can be attached. The built-in flash 2 has a pop-up /
It is driven to a position where flash emission is possible or impossible by the down unit 3. The built-in flash 2 has an IGBT (Insulated Gate) in its control circuit.
Bipolar Transistor), and can perform continuous tuning light emission in a short cycle. The camera control unit 1 outputs the following control signal to the built-in flash 2 and receives the control signal from the built-in flash 2. The FCHG signal is a charge start signal, the TRIG (trigger) signal is a signal for starting light emission, the FSTOP signal is a light emission stop signal, and the FULL signal is a signal indicating that charging is completed. The built-in flash 2 or the external flash 4 is also used as a light source that emits auxiliary light for AF distance measurement when focus detection is impossible due to low brightness or contrast of a subject.

[0007] The focus detecting section 5 measures the subject distance (AF) in accordance with a command from the camera control section 1 and outputs the result to the camera control section 1. The lens data storage unit 6 stores lens data of a photographic lens (not shown) and outputs the data to the camera control unit 1. The lens drive unit 7 drives the focus lens with a motor in accordance with a drive signal from the camera control unit 1. The photometric unit 8 measures the luminance of the subject and outputs the result to the camera control unit 1. Note that the camera control section 1 constitutes the determination means and the control means described in the claims. The switch S0 is an eyepiece detection switch, which is turned on when the photographer looks into the viewfinder, and the camera becomes operable. The switch S1 is a photometry / distance measurement switch that is turned on by half-pressing a release button (not shown).
In response to the switch ON signal, the camera control unit 1 causes the photometry unit 8
And the subject brightness and subject distance information from the focus detection unit 5. A switch S2 is a release switch that is turned on by pressing a release button, and starts exposure. The switch S3 is an auxiliary light emission prohibition switch. When the switch is turned on, a mode for prohibiting light emission of the autofocus auxiliary light is set, and when turned off, a mode for automatically emitting auxiliary light is set.

Next, a control circuit of the built-in flash 2 will be described with reference to FIG. Built-in flash 2
Are a charge control unit 10, a charge voltage monitor unit 11, a trigger circuit 12, a light emission control unit 13, a main capacitor 20, an IG
It is composed of a BT 21 and a xenon tube 22.
The charge control unit 10 receives a charge start signal FCH from the camera control unit 1.
When G is input, charging of the main capacitor 20 is started. When the TRIG signal is input from the camera control unit 1, the light emission control unit 13 turns on the IGBT 21,
When a signal is input, I
Turn off the GBT. The charging voltage monitoring unit 11
FULL when charging of the main capacitor 20 is completed
A signal is output to the camera control unit 1. The trigger circuit 12
This is a circuit that turns on / off the xenon tube 22 by turning on / off the GBT 21.

Next, the operation of the camera having the above configuration will be described with reference to the flow charts of FIGS. 3, 4, 5 and 6. Here, the operation after the switch S0 is turned on is shown. When the switch S0 is turned on by the eyepiece detection, continuous eyepiece distance measurement (AF) is performed (# 1).
Next, it is checked whether the switch S1 is turned on (# 3). If not, the state of the switch S0 is checked (# 5).
If not turned on, it is determined that the photographing operation has been interrupted, and a standby state is set. If the switch S1 is turned on in the determination of # 3, the object distance is measured by passive distance measurement (# 7), and photometry of the object luminance is performed (# 9). As a result of the photometry, it is checked whether or not the light is low (# 11).
In the case of low light, it is checked whether or not the external flash 4 is mounted (# 13). If the external flash is not mounted, the built-in flash 2 is popped up (# 15).
Proceed to 7. If it is not low light in # 11, and if the external flash 4 is attached in # 13 even if it is low light, the process immediately proceeds to # 17.

In step # 17, it is checked from the distance measurement result in step # 7 whether the subject is a low contrast. If it is lowcon,
Next, it is checked whether or not the auxiliary light emission (AL) is prohibited due to the limitation of the number of times of light emission (# 19). If the mode for prohibiting the auxiliary light emission is not specified, then the focus of the used lens is determined. It is checked whether the distance f is equal to or smaller than a predetermined value (for example, 300 mm) (# 21). If the distance f is equal to or smaller than the predetermined value, it is next checked whether the aperture of the lens is equal to or larger than a predetermined value (# 2).
3) If the lens aperture is not equal to or larger than the predetermined value, it is next checked whether or not macro photography of the same size or larger is performed (# 2).
5) When it is determined that the macro shooting is not the same magnification or higher, the subject brightness value Bv (hereinafter, simply referred to as Bv)
It is checked whether or not is less than -1 (# 27). If Bv is -1 or less, it is checked whether or not the external flash 4 is attached (# 29).

On the other hand, if it is determined in step # 17 that the low contrast is not established, and if the auxiliary light emission is prohibited in step # 19, there is no need to emit the auxiliary light. When the focal length f is larger than the predetermined value in # 21, the subject distance is often long, so that it does not reach even if the auxiliary light is emitted. If the lens aperture is equal to or larger than the predetermined value in # 23, the auxiliary light is vignetted by the lens. If the macro photography is equal to or greater than 1 in # 25, it is too close to irradiate. If it is determined in # 27 that Bv is not less than −1, it is determined that the light is not a low light and the effect of emitting the auxiliary light has no effect. Therefore, a mode in which the auxiliary light emission is prohibited is set (# 41). ). When the external flash 4 is not attached in # 29, it is determined whether the subject brightness value Bv is equal to or less than -3 (# 3).
1) If Bv is -3 or less, it is checked whether the built-in flash 2 has popped up (# 33). When the pop-up is displayed, it is checked whether or not a mode for prohibiting the auxiliary light emission by the built-in flash 2 is designated (# 35). If the prohibition mode is not specified, the auxiliary light emission mode by the built-in flash 2 is set (# 37).

On the other hand, when the external flash 4 is mounted in # 29, the auxiliary light emission mode by the external flash 4 is set (# 39). In addition, the above # 29
No external flash 4 is attached, and B in # 31
When v is not less than −3, that is, Bv is −3 <Bv
When <−1, when the built-in flash is not popped up in # 33, and when the mode for prohibiting the auxiliary light emission by the built-in flash 2 is specified in # 35 (switch S3 is ON), # 41 is set. Then, the mode in which the auxiliary light emission is prohibited is set. In the above processes # 27 to # 31, if Bv is -1 or less and the external flash 4 is attached, the external flash mode is immediately set in # 39. This is because it is possible to project a pattern on a subject and to provide contrast between light and dark by using the auxiliary light emission by the external flash 4. When the external flash 4 is not mounted, even when Bv is -1 or less, and when Bv is not -3 or less, the distance measurement information is considered to be reliable, and the built-in flash 2 is automatically focused. It does not need to emit light as auxiliary light for use.

After each of the mode sets # 41, # 37, and # 39, the process proceeds to step # 43 to perform distance measurement. In the distance measurement subroutine, AF auxiliary light emission is performed as described later, and the distance measurement is performed. After this distance measurement, it is checked whether or not it is a low contrast (# 45). When it is determined that the distance is not low contrast, the distance measurement value is regarded as having high reliability, and the lens is driven based on the distance measurement value (# 47), and the remaining lens drive amount a (a Is a predetermined value, for example, it is checked whether it is less than 100 μm (# 4).
9). If the lens drive amount is smaller than a, the lens drive is performed until the focal point is determined to be almost in focus (# 67), and the in-focus display is performed (# 69). If the lens drive amount is not smaller than a, the setting status of the auxiliary light emission mode by the built-in flash 2 is checked (# 51). If the mode is set, the built-in flash 2 is charged (# 53). ) The second distance measurement subroutine is executed (# 55). If the mode is not set, the process proceeds to step # 55 without performing step # 53.

After executing the distance measurement subroutine of # 55,
It is checked again whether or not it is a low contrast (# 57). If it is not a low contrast, the lens is driven based on the distance measurement value (# 57).
59). Next, the lens driving direction in # 59 is # 47
Check whether the direction is the same as the lens driving direction at (#
61). If the driving direction is the same as the previous driving direction, the accuracy of the lens driving is high, so the lens driving amount b (b is a predetermined value larger than a, and
(# 1000 μm).
5). If it is less than b, it is determined that the lens is almost in focus, and the remaining lenses are driven up to the focal point (# 67), and focus display is performed (# 69). If the driving direction is not the same as the previous driving direction in # 61, it is checked whether the lens driving amount is smaller than a (# 63). Then, the process proceeds to step # 75 and thereafter to perform further distance measurement. When the drive amount is not smaller than b in # 65, the process also proceeds to # 75. Also, in the case of low contrast in # 57, the process proceeds to # 75 and thereafter to perform further distance measurement.

In step # 75, the setting status of the auxiliary light emission mode by the built-in flash 2 is checked. If the mode is set, the built-in flash 2 is already emitted twice as auxiliary light in steps # 43 and # 55 to measure the distance. So it goes into a standby state,
Wait for the switch S1 to be turned on again. If the mode is not set in # 75, a third distance measurement subroutine is executed (# 77).

If it is determined in step # 45 that the camera is still low contrast, since the reliability of the distance measurement value is low, low contrast scan for driving the lens while performing passive distance measurement is performed (# 99). . Here, first, the focus lens is driven to the near end side. Next, it is checked whether or not the auxiliary light emission mode by the built-in flash 2 is set (# 101). If not, the subroutine of distance measurement using the external flash 4 is executed (# 103).
Thereafter, it is checked whether or not it is a low contrast (# 10)
5). If it is not the low contrast, the lens is driven based on the distance measurement value (# 107). Then, similarly to the above, it is checked whether the lens driving amount is smaller than a (# 109).
If the number is small, proceed to # 67 to drive the lens (# 6
7) In-focus display is performed (# 69). If the lens drive amount is not smaller than a, the process returns to step # 51 for further distance measurement.

In step # 101, the built-in flash 2
When the auxiliary light mode is set, and when low contrast is determined in # 105, low contrast scanning is further performed (# 111). Here, the focus lens is driven to the ∞ end side. Next, a subroutine for distance measurement is executed (# 113). Thereafter, it is checked whether or not it is a low contrast (# 115), and if it is still a low contrast, the lens is set at a specific position (# 117), and a standby state is set. If it is determined in # 115 that it is not a low contrast, # 10
Proceed to 7 to drive the lens.

After executing the distance measurement subroutine in # 77, it is checked again whether the camera is a low contrast or not (# 79). If it is no longer low contrast, the lens is driven based on the distance measurement value (# 81). . Then, similarly to the above, it is checked whether the lens driving direction is the same as the previous lens driving direction (# 83), and if it is the same direction, it is further checked whether the lens driving amount is smaller than b (# 83). # 8
7). As a result, when it is smaller than b, proceed to # 67,
If not less than b, a distance measurement subroutine is further executed (# 89). If it is not the same as the previous driving direction in # 83, it is checked whether the lens driving amount is smaller than a (# 85).
Then, if it is not less than a, a subroutine for distance measurement is executed (# 89). If it is a low contrast in # 79, the process immediately proceeds to # 89 to execute a distance measurement subroutine.

After executing the distance measurement subroutine of # 89, it is checked again whether or not it is a low contrast (# 91), and if it is still a low contrast, it is put on standby without further distance measurement. If it is no longer low contrast, the lens driving direction is checked (# 93). Similarly to the above, if the driving is in the same direction as the previous time and the driving amount is smaller than b, the process proceeds to # 67 and is not small. When in the standby state. If it is not the same direction as the previous time in # 93, it is checked whether the driving amount is smaller than a (# 95), and if it is smaller, the process proceeds to # 67,
When the number is not small, the apparatus enters a standby state.

After the in-focus display is performed in step # 69, it is checked whether the switch S2 is ON (# 71).
If so, exposure (photographing) is performed, and if not, it is further checked whether or not the switch S1 is turned on (# 73). If the switch S1 is in the ON state, it is determined that the photographing operation has been continued, and the process proceeds to # 69 to perform AF lock, and the in-focus display is continued. Return to

Next, the above-described subroutine for distance measurement will be described with reference to FIG. FIG. 7 shows a timing chart at the time of this distance measurement. When the distance measuring operation starts, it is first checked whether or not the auxiliary light emission prohibition mode is set (# 2).
01), when set, integration of the accumulated charge of the CCD built in the focus detection unit 5 is performed based on the distance measurement value by passive distance measurement (# 219), and the data is dumped (# 219).
221), perform an operation (# 223), and return. If the auxiliary light emission prohibition mode is not set, the setting status of the auxiliary light emission mode by the built-in flash 2 is checked (# 203). Built-in flash 2 when set
Is charged (# 205), and emission of flash light is started (# 207). When the auxiliary light emission mode by the built-in flash 2 is not set, the auxiliary light emission mode by the external flash 4 is considered.
The process proceeds to step # 207 without performing step # 205, and emission of flash light by the external flash 4 is started.

Then, integration is performed based on the auxiliary light emission of any one of these flash lights (# 209), the auxiliary light emission is stopped (# 211), and it is determined whether or not the charge amount has exceeded a predetermined amount. Check (# 213). When the amount exceeds the predetermined amount, the data is dumped (# 215), an operation is performed (# 217), and the process returns. If the charge amount is not equal to or more than the predetermined amount in # 213, charging is performed to further emit auxiliary light (# 216), and then # 207
Thereafter, the same processing is repeated until the charge amount becomes equal to or more than the predetermined amount.

According to the above-described processing, it is determined once that the low contrast has been detected from the data of the first passive distance measurement (# 7) (# 17), and the auxiliary light emission mode by the built-in flash is set (# 37). In the distance measurement subroutine of # 43, the distance is measured by the auxiliary light emission by the built-in flash. If the contrast is still low, the distance measurement is performed by the second auxiliary light emission in the distance measurement subroutine of # 113. Even if the distance measurement is performed, if it is still low contrast, it is set to a standby state and waits until S1 is turned on again. When the auxiliary light emission mode by the external flash is set (# 39), the above-described # 4
3, # 55, # 113, # 103, # 77, # 8
Auxiliary light emission distance measurement is possible in the distance measurement subroutine of No. 9. Since the auxiliary light for AF is intermittently emitted, there is an effect that the subject is not dazzled as compared with the case where the light is temporarily emitted with a large amount of light. Further, the present invention is not limited to the configuration of the above embodiment, and various modifications are possible. For example, the light emission of the built-in flash is controlled by the IGBT, but the external flash may be controlled by the IGBT.

[0024]

As described above, according to the present invention, the automatic
Uses a charge-storage photodetector for focus detection
In the case of, as auxiliary light for the detection, so as to intermittently emit light emitting means for photographing an object
As a result, continuous light is given to the light-receiving element to store charges normally.
And detection becomes possible. As a result,
Auxiliary light source and the subject for exiting can also serves as a light emitting means for photographing, it is not necessary to provide them separately.
Therefore, the number of parts can be reduced, and the cost of the apparatus can be reduced. In addition, since the auxiliary light is emitted intermittently, there is an effect that the subject is not dazzled as compared with a case where light is temporarily emitted with a large amount of light.

[Brief description of the drawings]

FIG. 1 is a block diagram of an autofocus camera according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a built-in flash.

FIG. 3 is a flowchart showing the operation of the camera.

FIG. 4 is a flowchart of the above.

FIG. 5 is a flowchart of the above.

FIG. 6 is a flowchart showing a subroutine of a distance measuring operation.

FIG. 7 is a timing chart during a distance measuring operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera control part 2 Built-in flash 4 External flash 5 Focus detection part 7 Lens drive part 8 Photometry part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-136721 (JP, A) JP-A-60-32015 (JP, A) JP-A-60-46517 (JP, A) JP-A-63 44639 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 7/28 G03B 15/05

Claims (4)

(57) [Claims] 1. A light emitting means for irradiating light to photograph a subject, for detecting information relating to the distance to the Utsushitai, electrostatic
A detection means including a light receiving element of the luggage storage type, a determination unit configured to determine whether possible detection by pre-Symbol detection unit, when it is determined that the undetectable by the determining means, aid in the detection of said detecting means The light emitting means as a light source
Control means for continuously and intermittently emitting light during the charge accumulation of the light receiving element . 2. The camera according to claim 1, wherein the determination unit determines whether or not detection is possible based on brightness or contrast of a subject. 3. A photometric device for measuring the brightness of a subject is further provided.
Wherein the determining means is based on a photometric result of the photometric means.
To determine whether or not detection by the detection means is possible
The camera according to claim 1, wherein: 4. The determination means according to claim 1, wherein
Determine whether or not detection by the detection means is possible based on the
The camera according to claim 1, wherein: