JP4540374B2 - Camera device provided with strobe lamp and imaging method of the camera device - Google Patents

Description

  The present invention relates to a camera device and an imaging method including a strobe lamp that emits light toward a subject, and more specifically to a digital camera.

FIG. 9 is a perspective view of a conventional digital camera. On the cabinet (2), there are a shutter button (20), an imaging lens (21), a strobe lamp (3), a liquid crystal display (22), and a slot (23) into which a memory card (4) is inserted. It is deployed as is well known. When a subject is imaged in a dark place, the strobe lamp (3) emits light (hereinafter referred to as “strobe imaging”), but suddenly strong light is not emitted, but an operation called pre-emission is performed.
This is an operation of causing the strobe lamp (3) to emit light weakly when the shutter button (20) is half-pressed to form an image of the subject and obtaining the distance from the subject (for example, see Patent Document 1). After obtaining the distance from the subject by pre-emission, the main emission is performed to strongly illuminate the strobe lamp (3).

FIG. 10 is an internal block diagram of a conventional digital camera. The imaging lens (21) can be moved along the optical axis by a drive mechanism (not shown), and an image of the subject is connected to the CCD (5) through the diaphragm (54) by the imaging lens (21). . The CCD (5) converts the received optical signal into an image signal, which is an electrical signal, and outputs the image signal. After the noise is reduced by the CDS (correlated double sampling) circuit (50), the AGC (automatic gain) The level is adjusted by the (control) circuit (51). The image signal is converted into a digital signal by the A / D converter (55), and after the black level and white balance are adjusted by the signal processing unit (52), the image signal is input to the CPU (1) as the control means. The signal of the shutter button (20) is input to the CPU (1), and the image signal is compressed by the compression / decompression circuit (53) and stored in the memory card (4).
The strobe circuit (30) is connected to the CPU (1), and the strobe circuit (30) charges the light emitting circuit (31) connected to the strobe lamp (3), the capacitor (6), and the capacitor (6). A charging circuit (32) is provided. The charging circuit (32) is a circuit for charging the capacitor (6) with the electric charge necessary for causing the strobe lamp (3) to emit light, and the charge level of the capacitor (6) is monitored by the CPU (1). When the capacitor (6) is fully charged (hereinafter referred to as “full charge”), the charging is stopped.
When the shutter button (20) is pressed after charging, a signal to that effect is sent from the CPU (1) to the light emitting circuit (31). First, a part of the charge charged in the capacitor (6) flows into the strobe lamp (3) to pre-emit light. Based on the principle described later, after obtaining the brightness of the subject connected to the CCD (5) and the distance to the subject, the remaining charge flows to the strobe lamp (3), and the strobe lamp (3) emits light.

FIG. 11 is a diagram for explaining the principle for obtaining the point at which the subject forms an image from the luminance, and FIG. 12 is a diagram for explaining the principle for obtaining the distance from the imaging lens (21) to the subject.
As described above, the image of the subject is imaged on the CCD (5) by the imaging lens (21). As shown in FIG. 11, if the imaging lens (21) is moved along the optical axis and the imaging lens (21) is stopped at the point P where the luminance detected by the CCD (5) is maximized, the subject ( The image of 9) is correctly formed on the CCD (5).
Further, as shown in FIG. 12, the distance from the imaging lens (21) to the subject (9) is a, the distance from the imaging lens (21) to the CCD (5) is b, and the focal length of the imaging lens (21) is. If f,
1 / a + 1 / b = 1 / f
Since f and b are known, a can be obtained.

Since the image of the subject (9) is formed on the CCD (5), the subject (9) is accurately captured. Also, since the illuminance of light is inversely proportional to the square of the distance from the strobe lamp (3), knowing the distance to the subject (9) knows the optimum amount of light emitted from the strobe lamp (3) and the condenser (6 It is possible to know whether or not the electric charge in () is sufficient for strobe imaging. The light emission amount of the strobe lamp (3) is a light emission amount corresponding to the difference between the luminance of the subject when the strobe lamp (3) is not emitted and the luminance required at the time of photographing. Further, by knowing the brightness of the subject and the distance to the subject (9), the optimum exposure amount can also be known.
After imaging, the charging circuit (32) charges the capacitor (6) again in preparation for the next imaging. If the charging is insufficient, the amount of emitted light is insufficient, and images are not captured correctly. Some camera devices have a function to ignore the operation of the shutter button (20) until the capacitor (6) is fully charged. .

JP 2001-358888 A

In a conventional camera device, when a subject is shot with a stroboscope and then the same subject is shot with a stroboscope, the capacitor (6) is fully charged before the stroboscope is allowed to be captured. Therefore, when the same subject is continuously photographed with a stroboscope, it is necessary to wait until the capacitor (6) is fully charged, and a photo opportunity may be missed. In particular, when the capacity of a battery (not shown) of the camera device is decreasing, it takes time until the battery is fully charged.
In addition, since pre-flash is performed every time the flash image is taken, the battery is wasted. Further, when the subject is a human, an image with the subject closed eyes may be captured by pre-flash, and an image unintentional for the photographer may be captured.
An object of the present invention is to reduce waiting time and reduce pre-emission when continuously shooting a subject with flash photography.

The camera device is provided with power storage means for accumulating charges to be supplied to the strobe lamp (3), and control means for controlling charge / discharge of the power storage means and measuring the brightness of the subject and the distance to the subject. Yes.
The control means is connected to memory means for storing the measured brightness of the subject and the distance to the subject,
The control means is such that the brightness of the subject measured at the time of imaging is equal to or higher than the brightness of the subject at the time of previous imaging stored in the memory means, and the distance to the subject measured at the time of imaging is the time of previous imaging stored in the memory means. When the first condition equal to the distance to the subject and the second condition in which the charging voltage of the power storage means is equal to or higher than the voltage before the previous strobe lamp (3) emits light, the strobe lamp (3 ) Is allowed to emit light.
Further, the control means has a function of switching between pre-flash that makes the strobe lamp (3) shine weakly and main flash that makes the strobe lamp (3) shine strongly,
When both the first condition and the second condition are satisfied, a determination function is provided that performs main light emission with the same light emission amount as that at the time of the previous imaging without performing pre-light emission.

The control means first obtains the brightness of the subject and the distance to the subject in the first imaging. In the second imaging, the first condition is that the measured luminance of the subject is equal to or higher than the luminance of the subject obtained in the first imaging, and the distance to the subject is equal to the distance to the subject obtained in the first imaging. Ask if it meets.
Next, the control means determines whether or not the charging voltage of the power storage means, specifically, the capacitor (6) satisfies the second condition that is equal to or higher than the voltage before the strobe lamp (3) emits light at the first imaging. Ask. When both the first condition and the second condition are satisfied, the flash lamp (3) is allowed to emit light.
That is, at the time of the second imaging, without waiting for the capacitor (6) to be fully charged, if the charging voltage of the capacitor (6) becomes equal to or higher than the charging voltage before the first light emission, the imaging standby state is entered.
This shortens the waiting time and reduces the chance of missing a photo opportunity. In particular, in a state where the battery has been reduced, it takes time until the capacitor (6) is fully charged, so the effect of shortening the waiting time is great.
In the second imaging, if the luminance at the time of imaging is equal to or higher than the luminance at the first imaging, and the distance to the subject is not different from that at the first imaging, imaging is performed without pre-flash. To do. Thereby, pre-light emission is not performed every time imaging is performed, and battery waste can be prevented. Further, by reducing the number of pre-flashes, when the subject is a human, it is possible to reduce the possibility of capturing an image with the subject closed.

Hereinafter, an example of the present invention will be described with reference to the drawings. The appearance of the digital camera is the same as the conventional one shown in FIG.
FIG. 1 is an internal block diagram of a digital camera according to this example. The configuration from the strobe circuit (30) and the imaging lens (21) to the CPU (1) is the same as the conventional one shown in FIG. The CPU (1) is connected to the memory (7), and the memory (7) operates with a RAM in which the brightness of the subject measured by the CPU (1), the distance to the subject, and the storage level of the capacitor (6) are stored. It also has a ROM that stores programs. The CPU (1) is also connected to a built-in memory (70) capable of storing several frames of image data. The luminance of the subject and the distance to the subject may be stored in a cache memory (not shown) built in the CPU (1).
The memory (7) stores a threshold value Yth, which is a luminance level that requires the strobe lamp (3) to emit light. That is, if the measured luminance of the subject is less than the threshold Yth, the strobe lamp (3) needs to be emitted. If the measured luminance of the subject is equal to or higher than the threshold Yth, the strobe lamp (3) needs to be emitted. Absent.
At the time of imaging, exposure is performed in accordance with strobe light emission. However, since the diaphragm (54) is a fixed diaphragm in the digital camera, the exposure control is performed by the speed of the electronic shutter of the CCD (5) and the AGC circuit (51). ) Gain adjustment is performed in combination. When determining the distance to the subject, exposure control called pre-exposure is performed according to the luminance of the subject. When storing image data in the memory card (4), a book with a higher gain level than pre-exposure is used. Exposure is performed.

(Imaging operation)
An overall outline of the imaging operation is shown in the flowchart of FIG. 2, and the step numbers given to the flowchart of FIG. 2 correspond to the step numbers of the flowcharts of FIGS. In the following description, an operation of imaging twice is shown. First, the luminance Y1 of the subject and the distance L1 to the subject are obtained by the first imaging (S1, S3). In the second imaging, if the obtained luminance Y2 of the subject is equal to or higher than Y1 and the distance L2 to the subject is the same as L1 (S19), the imaging is permitted (S27). If imaging is not permitted, the capacitor (6) is charged (S29), and if the charging voltage Vx is equal to or higher than the charging voltage Vb of the capacitor (6) before pre-emission (S30), the subject brightness Y4 and subject again Distance L4 is obtained. If the obtained luminance Y4 of the subject is equal to or higher than Y1 and the distance L4 to the subject is the same as L1 (S33), imaging is permitted. If it cannot be permitted again, the capacitor (6) is fully charged, and if it is fully charged, imaging is permitted (S46). If the battery is not fully charged, it is displayed that the image cannot be captured because the battery capacity is insufficient (S50).

Following the first imaging, the operation during imaging will be described in detail with reference to the flowcharts of FIGS. This example is characterized in that the time until the second imaging is shortened based on the luminance of the subject and the distance to the subject obtained at the first imaging, and the pre-light emission is not necessarily performed at the second imaging. . Initially, the capacitor (6) is sufficiently charged to pre-emit light.
When the shutter button (20) is first pressed (S1), pre-exposure is performed without pre-emission (S2). The imaging lens (21) moves along the optical axis so that the subject image is formed on the CCD (5) and image data is taken into the CPU (1). The CPU (1) obtains the subject brightness Y1 and the subject distance L1 (S3), and compares the brightness Y1 with the threshold value Yth (S4). The luminance Y1 and the distance L1 are stored in the memory (7).
If the luminance Y1 is equal to or higher than the threshold Yth, the luminance of the subject is sufficiently high, and the process proceeds to step S13. Without firing the flash lamp (3) (S14), the image data is captured, compressed and stored in the memory card (4) (S15), and the shutter button (20) returns to the operation standby state (S16).
If the luminance Y1 is less than the threshold value Yth, the strobe lamp (3) needs to emit light.
First, the CPU (1) measures the current charging voltage Vb of the capacitor (6) before pre-emission (S5) and stores it in the memory (7). Next, pre-emission and pre-exposure are performed (S6), and the charging voltage Vc of the capacitor (6) after pre-emission is measured (S7). The relationship between the charging voltages Vb and Vc and the voltage Va when fully charged is shown in FIG. 8. When the main light emission is performed after the pre-light emission, the charging voltage of the capacitor (6) decreases to Vd.
Based on the image data taken into the CPU (1) by the pre-flash, the optimum light emission amount F1 and the optimum exposure amount A1 of the strobe lamp (3) are known from the distance to the subject and the luminance of the subject (S8). The strobe lamp (3) emits light and is exposed (S9), image data is taken in, compressed, and stored in the memory card (4) (S10). The capacitor (6) is charged in preparation for the next imaging (S11). This completes the first imaging.

Preparation for second imaging After the first imaging, the following operation is performed in preparation for the next imaging. The CPU (1) measures the charging voltage Vx of the capacitor (6). When the charging voltage Vx becomes equal to or higher than the charging voltage Vc after the previous pre-emission (S12), pre-exposure is performed (S17). From the captured image data, the luminance Y2 of the subject and the distance L2 from the subject are obtained (S18). If the subject does not move and the ambient brightness of the camera device is the same as in the previous imaging, the luminance of the subject and the distance from the subject should not change. The CPU (1) reads the luminance Y1 and the distance L1 at the previous imaging from the memory (7), and compares the luminance Y2 with the luminance Y1, and the distance L2 with the distance L1 (S19). If Y2 ≧ Y1 and L2 = L1, a notification is made that strobe imaging or imaging is possible without causing the strobe lamp (3) to emit light. This notification is performed, for example, by turning on an LED (not shown) on the cabinet (2) in yellow (S20). If “NO” in the step S19, the process proceeds to a step S29 to continuously charge the capacitor (6).

When informing that strobe imaging is possible, the user can press the shutter button (20). The CPU (1) determines whether or not the shutter button (20) has been pressed within a predetermined time (S21). If not, the process proceeds to step S29, and the capacitor (6) is subsequently charged.
When the shutter button (20) is pressed within a predetermined time, pre-exposure is performed (S22), and the luminance Y3 of the subject and the distance L3 from the subject are obtained from the captured image data (S23).
The reason for obtaining the brightness Y3 and the distance L3 after obtaining the brightness Y2 and the distance L2 is to check whether the brightness of the subject and the distance to the subject have changed before the shutter button (20) is pressed. The step of obtaining the luminance Y3 and the distance L3 may be omitted.

The brightness Y3 is compared with the threshold value Yth (S24). If the brightness Y3 is equal to or greater than the threshold value Yth, the process proceeds to step S13, and the image data is captured and compressed without firing the flash lamp (3) (S14). Process and store in memory card (4).
If the luminance Y3 is less than the threshold value Yth, the luminance Y3 and the luminance Y1, and the distance L3 and the distance L1 are compared (S25). If Y3 ≧ Y1 and L3 = L1, the strobe lamp (3) is caused to emit light and exposed, and the image data is compressed and stored in the memory card (4) (S27). If Y3 = Y1, the light emission amount and exposure amount of the strobe lamp (3) become the same light emission amount F1 and exposure amount A1 as in the first imaging (S26). That is, the second imaging is finished without pre-flash.

In this example, during the second imaging, without waiting for the capacitor (6) to be fully charged, if the charging voltage Vx of the capacitor (6) becomes equal to or higher than the charging voltage Vc after the previous pre-light emission, The imaging standby state is entered. This shortens the waiting time and reduces the chance of missing a photo opportunity. In particular, in a state where the battery has been reduced, it takes time until the capacitor (6) is fully charged, so the effect of shortening the waiting time is great.
In the second imaging, if the luminance at the time of imaging is equal to or higher than the luminance at the first imaging, and the distance to the subject is not different from that at the first imaging, imaging is performed without pre-flash. To do. Thereby, pre-light emission is not performed every time imaging is performed, and battery waste can be prevented. Further, by reducing the number of pre-flashes, when the subject is a human, it is possible to reduce the possibility of capturing an image with the subject closed.

If NO in the second imaging failure step S25, the process proceeds to step S28 to notify that imaging is impossible. This notification is performed by, for example, issuing a warning sound. The capacitor (6) is continuously charged, and the CPU (1) ignores that the shutter button (20) is pushed in for the second time.
The CPU (1) subsequently charges the capacitor (6) (S29), and if the charging voltage Vx is equal to or higher than the charging voltage Vb of the capacitor (6) before pre-emission (S30), pre-exposure is performed (S31). ) The luminance Y4 of the subject and the distance L4 from the subject are obtained from the captured image data (S32). Next, luminance Y4 and luminance Y1, and distance L4 and distance L1 are compared (S33). If Y4 ≧ Y1 and L4 = L1, the subject does not move and the subject brightness is higher than that at the time of the first imaging, so the CPU (1) does not emit the strobe image or the strobe lamp (3). Notify that it is possible. This notification is performed, for example, by turning on an LED (not shown) on the cabinet (2) in blue (S34).
The CPU (1) determines whether or not the shutter button (20) has been pressed again within a predetermined time (S35). If not, the process proceeds to step S45, and the capacitor (6) is continuously charged.

When the shutter button (20) is pressed again within a predetermined time, pre-exposure is performed (S36), and the subject brightness Y5 and the subject distance L5 are obtained from the captured image data (S37).
The reason for obtaining the brightness Y5 and the distance L5 after obtaining the brightness Y4 and the distance L4 is to check whether the brightness of the subject and the distance to the subject have changed before the shutter button (20) is pressed. The step of obtaining the luminance Y5 and the distance L5 may be omitted.
The brightness Y5 is compared with the threshold value Yth (S38). If the brightness Y5 is equal to or greater than the threshold value Yth, the process proceeds to step S13, and the image data is captured and compressed without firing the flash lamp (3) (S14). Process and store in memory card (4).
If the luminance Y5 is less than the threshold Yth, the luminance Y5 and the luminance Y1, and the distance L5 and the distance L1 are compared (S39). If Y5 ≧ Y1 and L5 = L1, the subject does not move and the subject brightness is higher than that in the first imaging, so pre-flash and pre-exposure are performed (S40), and the optimum strobe lamp (3 ) And the optimum exposure amount A2 (S41). Since L5 = L1, the light emission amount F2 of the strobe lamp (3) seems to be the same as the first light emission amount F1, but if the subject luminance Y5> Y1, strictly speaking, F2 <F1.
The strobe lamp (3) emits light and is exposed (S42), the image data is taken in, compressed, and stored in the memory card (4) (S43). Charging of the capacitor (6) is started in preparation for the next imaging.
In this example, even if the second imaging fails, the imaging standby state is entered when the charging voltage Vx of the capacitor (6) becomes equal to or higher than the charging voltage Vb before the pre-emission of the first imaging. That is, imaging can be performed without waiting for the capacitor (6) to be fully charged.
This shortens the waiting time and reduces the chance of missing a photo opportunity. In particular, in a state where the battery has been reduced, it takes time until the capacitor (6) is fully charged, so the effect of shortening the waiting time is great.

If “NO” in the step S39, the process proceeds to a step S44 to turn on an LED (not shown) on the cabinet (2) or emit a warning sound to notify that imaging is impossible (S44). . The capacitor (6) is subsequently charged (S45).
When the charging voltage Vx becomes equal to the fully charged voltage Va (S46), the charging of the capacitor (6) is stopped (S47). The CPU (1) informs that strobe imaging or imaging is possible without causing the strobe lamp (3) to emit light. This notification is performed, for example, by turning on an LED (not shown) on the cabinet (2) in green (S48). The camera device waits for the shutter button (20) to be pressed (S49).
If the charging voltage Vx does not reach the fully charged voltage Va due to insufficient battery capacity or the like, the fact that full charging is not possible is displayed on the display 22 (S50), and the operation ends.
In the above description, the case where the image is picked up twice is illustrated, but the above operation is repeated when the image is picked up three times or more.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

It is an internal block diagram of a digital camera. It is a flowchart which shows the whole outline of imaging operation. It is a flowchart which shows the operation | movement at the time of imaging. It is a flowchart which shows the operation | movement at the time of imaging. It is a flowchart which shows the operation | movement at the time of imaging. It is a flowchart which shows the operation | movement at the time of imaging. It is a flowchart which shows the operation | movement at the time of imaging. It is a figure which shows the relationship between charging voltage Vb and Vc, and the voltage Va at the time of a full charge. It is a perspective view of the conventional digital camera. It is an internal block diagram of the conventional digital camera. It is a figure explaining the principle which calculates | requires the point which a to-be-photographed object forms from luminance. It is a figure explaining the principle which calculates | requires the distance from an imaging lens to a to-be-photographed object.

Explanation of symbols

(1) CPU
(2) Cabinet
(3) Strobe lamp
(4) Memory card
(5) CCD
(6) Capacitor
(7) Memory

Claims (5)

In a camera device provided with power storage means for accumulating charges to be supplied to the strobe lamp (3), and control means for controlling charge / discharge of the power storage means and measuring the brightness of the subject and the distance to the subject. And
The control means is connected to memory means for storing the measured brightness of the subject and the distance to the subject,
The control means is such that the brightness of the subject measured at the time of imaging is equal to or higher than the brightness of the subject at the time of previous imaging stored in the memory means, and the distance to the subject measured at the time of imaging is the time of previous imaging stored in the memory means. When both the first condition equal to the distance to the subject and the second condition in which the charging voltage of the power storage means is equal to or higher than the voltage before the previous strobe lamp (3) are emitted, the strobe lamp ( 3. A camera device having a discrimination function for permitting light emission according to 3). The control means has a function of switching between pre-flash that shines the strobe lamp (3) weakly and main flash that shines the strobe lamp (3) strongly,
2. The camera device according to claim 1, wherein when the first condition and the second condition are satisfied, the camera device has a determination function of performing main light emission with the same light emission amount as that at the time of immediately preceding imaging without performing pre-light emission. The control means has a determination function for permitting the flash lamp (3) to emit light when the charging condition of the power storage means is fully charged when the first condition is not satisfied during imaging. Camera equipment. The memory means stores a threshold value Yth, which is the luminance of a subject that can be imaged without causing the strobe lamp (3) to emit light,
When the distance to the subject measured at the time of imaging is different from the distance to the subject at the time of previous imaging stored in the memory means and the luminance of the subject is less than the threshold value, the control means The camera device according to claim 1, wherein the camera device has a discrimination function for permitting the flash lamp (3) to emit light when the battery is fully charged. Imaging of a camera device provided with power storage means for accumulating charges to be supplied to the strobe lamp (3), and control means for controlling charge / discharge of the power storage means and measuring the brightness of the subject and the distance to the subject A method,
Storing the measured brightness of the subject and the distance to the subject in a memory means;
The brightness of the subject measured at the time of imaging is greater than or equal to the brightness of the subject at the time of previous imaging stored in the memory means, and the distance to the subject measured at the time of imaging is the distance to the subject at the time of previous imaging stored in the memory means. Obtaining a first condition equal to the distance;
Obtaining a second condition in which the charging voltage of the power storage means is equal to or higher than the voltage immediately before the strobe lamp (3) emits light;
An imaging method for a camera device having a discrimination function including a step of permitting light emission of the strobe lamp (3) when the first condition and the second condition are satisfied.

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