JP2003015195A - Imaging unit, and method for controlling auxiliary light quantity therfor, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure uniform product characteristic by eliminating variation in brightness of picked up images among each product when using stroboscopic light. SOLUTION: In an electronic still camera, in the state in which a built-in stroboscope is assembled, brightness of a picked up image is detected by making a discharge tube 10 actually emit light against a wall having a constant reflection factor, and picking up an image by a CCD 2. When the detection result is not within the range of a predetermined reference, a comparator 13 compares the reference outputted from an MPU 9 with the voltage charged in a capacitor 15 by a photo sensor receiving the reflected light, and the reference voltage value outputted from the MPU 9 is made to change, to make the stroboscope re-emit light of a different quantity. This operation is repeated until the detection result falls within the range of the reference, and the voltage value when the detection result falls within the range of the reference is stored in an EEPROM 7. Thereafter, when the stroboscope is used, the stroboscopic light is controlled on the basis of the stored voltage value. Thus, variation in brightness of the picked up image including not only peripheral circuits of the stroboscope but also sensitivity of the CCD can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device having a built-in flash device, an auxiliary light amount control method therefor, and a recording medium used for realizing them.

[0002]

2. Description of the Related Art In recent years, digital cameras have been in widespread use in which a CCD or MOS type solid-state image sensor is used to image a subject and record it as image data in a recording medium such as a flash memory. Many of such digital cameras also have a built-in flash device (hereinafter, strobe) similar to that of a conventional silver halide camera, and during shooting, by emitting auxiliary light (strobe light) as needed, not only at night It is possible to shoot in various situations during the day.

A strobe built in a camera body generally boosts a voltage from a battery to charge a capacitor, supplies it to a discharge tube at a photographing timing, and causes the discharge tube to emit light. By receiving the reflected light (from the subject) of the light by the sensor and stopping the light emission when the received light amount reaches the specified amount,
It is configured to control appropriate shooting auxiliary light.

On the other hand, the individual electronic devices constituting the strobe have variations in characteristics, and even if the same circuit configuration is adopted, there is a limit in making the amount of strobe light obtained during operation constant. For this reason, when the strobe is incorporated into the camera body, the strobe is individually emitted in advance, the amount of light is measured using a measuring instrument, and adjustment is performed to bring the measurement result close to a constant value, so that the strobe is present in each strobe. The variation of light quantity was absorbed (corrected).

[0005]

However, although the amount of light emitted from each strobe can be adjusted by the above method,
In a digital camera that incorporates it, CCD
There are variations in sensitivity. Therefore, even if the light emission amount is corrected on the strobe side, there is a problem in that the brightness of the captured image at the time of capturing by the CCD or the like using the strobe cannot be accurately corrected. This is because at the time of capturing the captured image, the gain for amplifying the image pickup signal output from the CCD or the like must be set to the minimum.

The present invention has been made in view of the above conventional problems, and it is possible to eliminate variations in the brightness of a photographed image when using auxiliary light for each product and to secure uniform product characteristics. An object of the present invention is to provide an imaging device that can be used, an auxiliary light amount control method for the imaging device, and a recording medium used to realize them.

[0007]

In order to solve the above-mentioned problems, in the invention of claim 1, an image pickup device for picking up an image of a subject is provided, and the flashlight device is built in. In the assembled state, the setting when the brightness of the image picked up by the image pickup unit reaches a predetermined brightness while adjusting the light emission amount of the flash device by changing the set value that determines the light emission amount A storage means for storing a value; and a control means for controlling a light emission amount of the flash device based on a set value stored in the storage device in an imaging mode requiring auxiliary light from the flash device. I made it.

In such a configuration, the set value stored in the storage means is adjusted in a state where not only the characteristics of the electronic device forming the flash device but also the characteristics of the electronic device forming the image pickup means are reflected. It is a set value that can obtain auxiliary light. Therefore, the auxiliary light emitted by the flash device in the imaging mode requiring the auxiliary light can be the auxiliary light in which the variation in the light amount due to the characteristics of both the flash device and the imaging means is eliminated.

Further, in the invention of claim 2, the detecting means for detecting the brightness of the image picked up by the image pickup means and the set value for determining the light emission amount in the setting operation mode are changed. According to the above, the light control means for causing the flash device to emit light while adjusting the light emission amount so that the detection result of the detection means becomes a predetermined brightness, and the light control means for adjusting the light emission amount of the flash device A storage control unit that stores the set value in the storage unit when the detection result of the detection unit has a predetermined brightness is provided.

In such a configuration, by operating the image pickup device in the set operation mode, the set value used in the image pickup mode requiring auxiliary light can be stored in the storage means independently without using another device. You can

According to a third aspect of the present invention, in a light quantity control method for a flash device incorporated in an image pickup device having an image pickup means for picking up an image of a subject, the flash device is assembled in the image pickup device. , Storing the set value in advance when the brightness of the image captured by the imaging unit reaches a predetermined brightness while adjusting the light emission amount of the flash device by changing the set value determining the light emission amount. Incidentally, in the imaging mode that requires the auxiliary light from the flash device, the light emission amount of the flash device is controlled based on the stored set value.

In such a method, the set value stored in advance is adjusted in a state in which not only the characteristics of the electronic device forming the flash device but also the characteristics of the electronic device forming the image pickup means are reflected. Since light can be obtained, variations in the amount of light due to the characteristics of both the flash device and the image pickup means are eliminated from the auxiliary light emitted by the flash device in the imaging mode that requires the auxiliary light. be able to.

According to another aspect of the invention, an image pickup means for picking up an object is provided, and a computer included in the image pickup apparatus including a flash device is stored in a storage section of the image pickup apparatus. While the flash device is assembled, the brightness of the image captured by the imaging means becomes a predetermined brightness while adjusting the light emission amount of the flash device by changing the set value that determines the light emission amount. A computer-readable recording medium having a program recorded thereon for functioning as control means for controlling the light emission amount of the flash device in an imaging mode that requires auxiliary light from the flash device based on the set value .

Therefore, by incorporating such a recording medium into an image pickup device having a built-in flash device, the image pickup device of claim 1 can be easily realized.

Further, in the invention of a fifth aspect, the computer further comprises a detecting means for detecting the brightness of an image picked up by the image pickup means, and a setting operation mode.
By changing the set value that determines the light emission amount, the light adjustment unit that emits light from the flash device while adjusting the light emission amount so that the detection result of the detection unit has a predetermined brightness, and the light adjustment unit sets the setting value. To function as storage control means for storing the set value in the storage means when the detection result of the detection means has a predetermined brightness while adjusting the light emission amount of the flash device by changing the value. A computer-readable recording medium in which a program is recorded is used.

Therefore, by incorporating such a recording medium into an image pickup device having a built-in flash device, the image pickup device of claim 2 can be easily realized.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a main part of an electronic still camera with a built-in flash, which is an image pickup apparatus of the present invention.

The electronic still camera includes a CCD 2 which is an image pickup means and a CC which captures an object image formed by the optical lens 1.
A CCD drive circuit 3 including a TG (Timing Generator) for driving D2, a CDS that holds an image pickup signal output from the CCD 2, a gain adjustment amplifier (AGC) that amplifies the image pickup signal, and an image pickup signal after amplification. The image signal sampling circuit 4 including an A / D converter (AD) for converting the image signal into a digital signal is provided. The CCD drive circuit 3 and the image signal sampling circuit 4 are connected to the MPU 6 via the bus 5.
It is connected to the.

The MPU 6 is connected to C via the CCD drive circuit 3.
While controlling the charge accumulation time of CD2, various signal processing is performed on the digital image pickup signal output from the image signal sampling circuit 4 using a DRAM (not shown) to display the imaged image on an LCD monitor (not shown). Alternatively, the captured subject image is compressed and recorded as image data in a flash memory or the like (not shown). Further, the MPU 6 is connected via the bus 5 to the storage means in the present invention and the EEPROM 7 as a recording medium. In the EEPROM 7, as shown in FIG.
Various data such as a control program 7a necessary for controlling each part of the electronic still camera by U6, a set reference voltage 7b (set value in the present invention) used when a strobe light is emitted, which will be described later, are stored. In addition, the control program 7
In particular, a includes a program for causing the MPU 6 to function as the control unit, the detection unit, the dimming unit, and the storage control unit of the present invention when the strobe light amount setting mode described later is set.

The electronic flash built in the electronic still camera is composed of the MPU 6 and the EEPROM 7 and the following circuits. That is, the electronic still camera has a capacitor for boosting the voltage of VCC2, a capacitor for charging the boosted voltage, and a charged voltage of 330V.
The charge control circuit 8 boosts the voltage to a weak level, and at the shooting timing when the shutter is pressed, the drive element (IGBT) 9 is turned on based on the light emission control signal sent from the MPU 6 operating with the voltage of VCC1 and the xenon An IGBT control circuit 11 is provided which applies a light emission trigger to the tube 10 and causes the xenon tube 10 to emit light (discharge).

The MPU 6 is connected to one input terminal of the comparator 13 via the resistor 12, and the comparator 1
The other input terminal of 3 is connected to a photosensor 14 for dimming, which receives reflected light of the light of the xenon tube 10, and a first capacitor 15, and the output terminal of the comparator 13 is an IGBT control circuit. 11 is connected. In addition,
A second capacitor 16 that is grounded together with the first capacitor 15 is provided between the resistor 12 and the comparator 13.
Are connected.

When the xenon tube 10 emits light, M
A reference voltage (D / A or PW) stored as the set reference voltage 7b from the PU 6 to the comparator 13.
M) is output, a voltage corresponding to the amount of received light is accumulated in the first capacitor 15 by the photo sensor 14, and when it exceeds the reference voltage, the comparator 13 causes the IGBT
A dimming signal is output to the T control circuit 11. Further, in response to the input of the dimming signal, the IGBT control circuit 11 controls the drive element (IGBT) 9 to the off state, and the emission of the xenon tube 10 (strobe emission) is stopped.

On the other hand, in the present embodiment, the set reference voltage 7b described above is stored in the EEPROM 7 by the following procedure when the assembling of the strobe is completed.

That is, in an environment in which a constant brightness (darkness) without external light is maintained, a wall surface with a constant reflectance (for example, manufactured by Superior Co., whose vertical and horizontal dimensions are twice the angle of view) , Oxford Gray No.22 background wall), with the camera body placed at a distance (1 m, etc.) from the electronic still camera, a strobe light intensity setting mode (preset) In the present invention, the setting operation mode) is set. Then, the MPU 6 executes the following operation based on the program, and the set reference voltage 7b is stored in the EEPROM 7.

FIG. 3 is a flowchart showing the processing contents of the MPU 6 when the strobe light amount setting mode is set. When such a mode is set, the MPU 6 firstly outputs the reference voltage (D
/ A or PWM) to a preprogrammed initial value (step S1), and then the xenon tube 10 is caused to emit light by the method described above (step S2). Next CC
The image is captured (captured) by D2, and the average value (Y) of the brightness per pixel is calculated for the image based on the captured digital signal (step S3). At this time, the image actually captured may be recorded, or the image data may only be generated as in the monitor-through in the shooting standby state.

Subsequently, the average value (Y) of the calculated luminances
, Is determined to be within the allowable range of the target reference value (step S4). For example, in the case of a resolution of 8 bits, the calculated brightness exists in the range of “0 to 255”,
If the reference value is "75" and the allowable width is "± 5", the allowable range is "70-80". If the calculated brightness is not within the allowable range (NO in step S4), first, it is determined whether the brightness is higher than the target allowable range, that is, the brightness is higher than the target brightness (step S6). ), When it is bright (brightness “81” or more in the above example), the reference voltage set at that time is increased by a certain amount (step S
7) When it is dark (brightness "69" or less in the above example), the reference voltage set at that time is lowered by a certain amount (step S8). Further, the value of the reference voltage after the change is set in a predetermined allowable range (in the present embodiment, MPU6
It is determined whether or not the corrected reference range is exceeded (NO in step S9), and the process returns to step S2 described above to output the changed reference voltage value to the comparator 13 and Light emission control signal IG
After outputting to the BT control circuit 11 to cause the xenon tube 10 to emit light again, the above-described processing is repeated.

Then, while the above process is repeated, if the average value (Y) calculated in step S3 falls within the allowable range (YES in step S4), the time point is regarded as acceptable and the reference voltage value currently set. (D / A or PWM value) is stored (set) in the EEPROM 7 as the set reference voltage 7b,
Exit the flash intensity setting mode. That is, as the set reference voltage 7b, a reference voltage value that reflects the sensitivity of the CCD 2 not related to strobe light emission and the difference in characteristics of the image signal sampling circuit 4 is stored. When the process immediately starts in the flash light initial setting mode (YES in step S4), the process proceeds to step S1.
The initial value set in step 3 is set as it is as the set reference voltage 7b (step S5).

When the value of the changed reference voltage exceeds the permissible range while repeating the above processing (YES in step S9), the set is a defective product that exceeds the limit of the light amount correction. Judgment is made, and an error display to that effect is displayed on the LCD monitor (not shown) (step S1).
0), the strobe light intensity setting mode ends.

Here, in the above modes, the EE
The set reference voltage 7b stored in the PROM 7 is the CCD 2
And the characteristics of the image pickup system such as the image signal sampling circuit 4 are reflected. Therefore, in the electronic still camera, after the operation in the strobe light amount setting mode is performed, when photographing using strobe light, each device constituting the strobe,
For example, not only variations in the amount of light caused by strobe peripheral circuits such as the xenon tube 10 and the photo sensor 14 but also the CCD
Including the variations in sensitivity and the like in item 2, variations in brightness in the captured image are eliminated. Therefore, it is possible to secure uniform product characteristics without variations among products in the brightness of captured images when using a flash.

Moreover, in the present embodiment, if the strobe light amount setting mode is set in the electronic still camera at the time when the strobe (partial) assembling is completed as described above, there is no need to use any other device. The set reference voltage 7b can be automatically stored in the EEPROM 7 alone. Therefore, at the time of factory shipment, the work of storing the set reference voltage 7b in the storage means can be performed very easily and quickly. Although such an effect cannot be obtained, when the strobe installation is completed, another device is used to perform the same process as that shown in FIG. 3 to acquire the set reference voltage 7b, and obtain the set reference voltage 7b. Voltage 7b is E
It may be stored in the EPROM 7. Even in that case, it is possible to obtain the effect that it is possible to secure uniform product characteristics without variations in the brightness of the captured image when the strobe is used.

In the present embodiment, the image range evaluated by the MPU 6 in step S3 described above is the entire image, but the outer peripheral portion of the captured image corresponding to the portion where the light amount drop around the lens can be ignored. In this case, the image range to be evaluated may be, for example, only the central region of about 6/8. Even in that case, the same effect as that of the present embodiment can be obtained.

Although the detection of the brightness of the picked-up image is performed based on the digital image signal output from the image signal sampling circuit 4, the image signal sampling circuit 4 is constituted, for example. The brightness of the captured image may be detected based on the analog image signal input to the A / D converter (AD).

[0033]

As described above, according to the inventions of claims 1 and 3, both the flash device and the image pickup means are operated from the auxiliary light emitted by the flash device in the imaging mode requiring the auxiliary light. It was made possible to eliminate the variation in the amount of light due to the characteristics of. Therefore, it is possible to eliminate variations in the brightness of the captured image when the auxiliary light is used for each product, and to secure uniform product characteristics.

According to the second aspect of the invention, by operating the image pickup device in the setting operation mode, the set value used in the image pickup mode requiring auxiliary light can be set independently without using another device. So that it can be stored in the storage means. Therefore, at the time of factory shipment, it is possible to extremely easily and quickly perform the work of storing the setting value used in the imaging mode that requires the auxiliary light in the storage means.

Further, in the inventions of claims 4 and 5, the inventions of claims 1 and 2 are easily implemented by incorporating the recording medium into an image pickup device having a built-in flash device. It becomes possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main part of an electronic still camera according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a storage area of an EEPROM.

FIG. 3 is a flowchart showing an operation in a strobe light initial setting mode in the electronic still camera.

[Explanation of symbols]

2 CCD 4 Image signal sampling circuit 6 MPU 7 EEPROM 7b Setting reference voltage 9 Drive element 10 xenon tube 11 IGBT control circuit 12 resistance 13 Comparator 14 photo sensor 15 First capacitor 16 Second capacitor

Claims (5)

[Claims] 1. An image pickup device comprising an image pickup means for picking up an image of a subject and having a built-in flash device, wherein the set value for determining a light emission amount is changed in a state where the flash device is assembled. A storage unit that stores the set value when the brightness of the image captured by the imaging unit reaches a predetermined brightness while adjusting the light emission amount, and an imaging mode that requires auxiliary light from the flash device. so,
An image pickup apparatus, comprising: a control unit that controls a light emission amount of the flash device based on a set value stored in the storage unit. 2. The detection result of the detection means is set to a predetermined value by changing the set value that determines the light emission amount in the set operation mode and the detection means that detects the brightness of the image picked up by the image pickup means. Light control means for emitting light from the flash device while adjusting the light emission amount so that the brightness becomes The image pickup apparatus according to claim 1, further comprising a storage control unit configured to store the set value in the storage unit when the storage condition becomes low. 3. A light amount control method for a flash device incorporated in an image pickup device having an image pickup means for picking up an image of a subject, wherein a set value for determining a light emission amount is changed in a state where the flash device is assembled in the image pickup device. Thus, while adjusting the light emission amount of the flash device, the set value when the brightness of the image captured by the image capturing unit reaches a predetermined brightness is stored in advance, and the auxiliary light by the flash device is stored. In the required image pickup mode, the light emission amount of the flash device is controlled on the basis of the stored set value. 4. An image pickup device for picking up an image of a subject is provided, and a computer included in the image pickup device having a built-in flash device is stored in a storage unit included in the image pickup device.
While the flash device is assembled, the brightness of the image captured by the imaging means becomes a predetermined brightness while adjusting the light emission amount of the flash device by changing the set value that determines the light emission amount. Based on the set value when
A computer-readable recording medium having recorded therein a program for causing it to function as control means for controlling the light emission amount of the flash device in an imaging mode that requires auxiliary light from the flash device. 5. The detection means for detecting the brightness of an image picked up by the image pickup means, and the detection means for changing the set value for determining the light emission amount in the setting operation mode. While adjusting the light emission amount to adjust the light emission amount of the flash device while adjusting the light emission amount so as to obtain a predetermined brightness, the light adjustment device changes the set value. The computer-readable recording medium according to claim 4, wherein a program for causing the storage unit to store the set value when the detection result of the detection unit has a predetermined brightness is recorded.