JP2006251731A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which can conduct an optimum stroboscopic light emission control without being adversely affected by the position of a main body to be photographed within a viewing angle and reflectivity. <P>SOLUTION: When it is turned on to a second SW in a SW judging process 21 and it is judged that a stroboscopic operation is required ("yes" in S10) in the stroboscopic judging process of the step S10, a multi-point range finding process 24 is again conducted and a distance comparing process 25 conducts comparison to judge whether a range finding area, that matches with first distance information stored in a memory 9 at the time of a first SW is turned on, exists or not. When the area having approximately same range finding data exists as a result of the comparison, the area is assumed to be the area where the main body to be photographed is located and the area of a stroboscopic light receiving section, which receives stroboscopic light emission, is set so that the range finding area becomes the center. Then, pre-light emission is actually conducted by a pre-light emission/light measuring process and reflected light beams are measured by the stroboscopic light receiving section. When the amount of the reflected light beams is greater than a reference reflection amount, the actual stroboscopic light emission amount is reduced. When the measured reflected light beam amount is less than the reference reflection amount, the actual stroboscopic light emission amount is increased (S10 to S17). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus capable of controlling strobe light emission of a strobe device during photographing.

A typical digital camera's strobe system is equipped with an optical system and a light-receiving element that match the angle of view at the center of the screen, and integrates the amount of reflected light from the strobe during shooting to stop the strobe when it reaches a predetermined value. I have to.
However, when shooting with the subject positioned around the screen using the focus lock function, there was a problem that the strobe light receiving element was not aligned with the subject and the flash output could not be set appropriately. .
On the other hand, when the camera has a distance measuring device, the subject is focused on the first release, and the flash emission amount is determined according to the distance information. Thereafter, even if the shooting angle of view is changed, it is possible to emit light appropriately to the subject. However, since the amount of light emission is determined uniformly from the distance, overexposure may occur depending on the reflectance of the subject.
Therefore, pre-light emission is a means for solving such a problem. Pre-light emission is performed before photographing, and the appropriate reflectance is obtained by obtaining the reflectance of the subject from the reflected light amount of the pre-light emission.
Patent Document 1 discloses a technique for obtaining an appropriate amount of strobe light even when photographing is performed by changing the angle of view after focusing by performing pre-light emission by the first release.
Japanese Patent Laid-Open No. 2004-228688 compares the divided photometry data when there is no flash emission and the divided photometry data at the time of pre-emission to determine the light control target area, and even if the main subject is not at the center of the screen, A technique for obtaining an appropriate strobe light emission amount is disclosed.
Japanese Patent Laid-Open No. 11-275439 JP 2000-155358 A

However, in Patent Document 1, pre-flash is performed by the first release. However, in the case of performing pre-flash for each first release, a misunderstanding that the shooting is finished is given to the photographer, and in terms of power consumption. However, there was a drawback that there was a lot of waste.
Further, in Patent Document 2, the light control target area is determined by comparing the divided photometry data at the time of pre-flash, but it is difficult to obtain accurate split photometry data from the main subject at an arbitrary distance by pre-flash. there were.
Accordingly, the present invention has been made in view of the above points, and provides an imaging apparatus capable of performing optimal strobe light emission control regardless of the position within the angle of view of the main subject and the reflectance. Objective.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a first switch for moving a lens to an in-focus position and the first switch in an imaging apparatus capable of controlling strobe emission of the strobe apparatus during photographing by an image imaging means. Switch means having a second switch operated after turning on, multi-point distance measuring means for measuring a subject when the first switch or the second switch is turned on, and the first switch being turned on Storage means for storing distance information measured by the multi-point distance measuring means as first distance information, and distance information measured by the multi-point distance measuring means when the second switch is turned on. A distance comparison means for comparing with the first distance information stored in the storage means, and pre-flashing the strobe of the strobe device when the second switch is turned on Comparison result of the distance comparing means when receiving the reflected light of the pre-light emitting means, the strobe light receiving means for receiving the reflected light obtained by the pre-light emission of the pre-light emitting means, and the strobe light receiving means. A light receiving area setting means for setting a light receiving area of the strobe light receiving means, and a book for calculating a light emission amount during main light emission for photographing a subject from a light reception amount received by the strobe light receiving means during the pre-light emission. And a light emission amount calculating means.
In the invention according to claim 2, the distance comparison means discriminates a main subject from the first distance measurement information and the second distance information measured by the multipoint distance measurement means, and the light receiving area setting means determines the main subject. The light receiving area of the strobe light receiving means is aligned with the area corresponding to the angle of view of the position of the main subject.
According to a third aspect of the present invention, the main light emission amount calculating means calculates the light emission amount during main light emission from the amount of light received by the strobe light receiving means from a subject approximately the same distance as the main subject during the pre-light emission. It is characterized by doing.
The invention described in claim 4 is characterized in that the strobe light receiving means is the image pickup means.
The invention according to claim 5 is characterized in that the strobe light receiving means is a divided light receiving element provided separately from the image pickup means.
The invention described in claim 6 is characterized in that the light emission amount of the pre-light emitting means or the electric gain of the strobe light receiving means is obtained from distance measurement information from the multipoint distance measuring means.

According to the first or second aspect of the present invention, even when the photographer changes the angle of view or the main subject moves after the focus lock, the main subject is located within the shooting angle of view. Since the pre-flash from the area can be received by the strobe light receiving means, the strobe main light emission of the strobe device suitable for the subject becomes possible.
According to the third aspect of the present invention, it is possible to control the flash light emission moderately even when the subject is mixed at the same distance as the main subject.
According to the fourth aspect of the present invention, since the photometry function of the image pickup means of the image pickup apparatus is diverted, there is no need to separately provide a strobe light receiving means, and the cost can be reduced accordingly.
According to the fifth aspect of the present invention, even when the image capturing unit of the image capturing apparatus does not have a photometric function for each area, it can be realized by using an inexpensive divided photometric element.
According to the sixth aspect of the present invention, the light emission amount of the pre-light emitting means or the electric gain of the strobe light receiving means is obtained from the distance measurement information from the multipoint distance measuring means. Can be performed optimally, without wasting power wastefully and obtaining a sufficient amount of received light.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a configuration diagram of an embodiment of a digital camera according to the present invention.
The digital camera shown in FIG. 1 includes a lens 1, a mechanical shutter 2, a CCD 3, and a CDS / AD (Correlated Double Sampling signal Analog) that performs A / D conversion on a signal obtained by canceling image noise by correlated double sampling of a CCD signal. -Digital converter) section 4.
A digital signal processor (DSP) that converts a digital signal A / D converted by the CDS / AD unit 4 into a luminance Y, color difference U, and V (vertical) signal, and performs digital signal processing for JPEG compression of the YUV data. Unit 5, driver unit 6 that drives a mechanical unit that performs focus driving for driving lens 1 and shutter opening / closing operation of mechanical shutter 2, CCD drive circuit unit 7, CPU 8 that controls the entire camera, and captured image data A memory (storage means) 9 used as a work memory for the DSP unit 5 and the CPU unit 8 to hold read data from the file for a period of time.
Furthermore, a communication driver unit 10 that communicates with the outside of the camera, a memory card 11 that can be attached to and detached from the camera, a display controller that converts a video output signal from the DSP unit 5 into a signal that can be displayed on an LCD (Liquid Crystal Display), and A display unit 12 having an LCD for actually displaying the image, a switch (SW) unit (switch means) 13 including various switches operated by the camera user, and a first computer such as a personal computer connected to the camera. The external device 14, the second external device 15 such as a telephone or a personal computer peripheral device connected to the first external device 14, and the signal from the input analog unit 17 are digitally converted to a DSP unit Audio COD that is transmitted to 5 or received from the DSP unit 5 is converted to analog and output to the output analog unit 18 An EC (Code and Decode device) 16 and a strobe device 19 that emits strobe light are provided.
If a display device (such as a monitor) is connected as the first external device 14, it is possible to display an image captured on the display unit 12 of the camera body as a larger image or to eliminate the display unit 12. Further, the first external device 14 may incorporate a charging circuit for charging the battery in the camera body.

FIG. 2 is a program configuration diagram in the digital camera of the present embodiment. As shown in FIG. 2, the program used in the digital camera of the present embodiment includes a main processing block 20 and a parallel processing block 40.
The main processing block 20 includes a SW determination process 21, an operation mode determination process, an AE process 23, a multipoint distance measurement process (multipoint distance measurement means) 24, a distance comparison process (distance comparison means) 25, and a pre-emission amount determination process. 26, main light emission amount calculation processing (main light emission amount calculation means) 27, light reception area setting processing (light reception area setting means) 28, pre-light emission / photometry processing (pre-light emission means) 29, main light emission amount shift processing 30, still image recording A program for performing processing 31 and card recording processing 32 is provided.
The parallel processing block 40 includes a program for performing a periodic timer interrupt process 41 and a monitoring process 42. Details of processing by each program will be described later.

FIG. 3 is a flowchart showing the main processing during recording.
In the present embodiment, a case where a still image is recorded will be described as an example.
Prior to the main processing at the time of recording, when a camera power source (not shown) is turned on in the recording mode, recording preparation processing such as initialization of hardware inside the camera and creation of file information in the card in the memory 9 is performed. . Thereafter, the main recording process is started.
In the main process, first, the monitoring state is checked (S1). If the recording is not being recorded in the monitoring stopped state (not recording in S2), the monitoring start process is performed (S3). If recording is in progress (recording in S2), the process proceeds to step S4.
Here, the monitoring process 42 of the concurrent processing program 30 executes a tracking process of AE (automatic exposure) and AWB (auto white balance) when displaying a through image of the camera. As a result, the image displayed on the display unit 12 can always be maintained at appropriate brightness and natural color.
Specifically, image data of the imaging unit such as the lens 1 and the CCD 3 is subjected to image processing by the DSP unit 5 so that the CPU 8 acquires evaluation values for each AE and AWB so that the evaluation values become predetermined values. Then, feedback control is performed to set the exposure time of the CCD drive circuit unit 7 and to adjust color parameters in the image processing of the DSP unit 5.
The SW determination process 21 in step S4 determines the SW information by the interrupt process input every 20 ms by the periodic timer interrupt process 41 of the concurrent process program 30, and passes the SW information to the operation mode determination process 22 (S5). .
The operation mode determination process 22 in step S5 functions to distribute the work to each process block according to the shooting mode. In the present embodiment, only a still image will be described, and description of other modes will be omitted.
If it is determined in the operation mode determination process 22 that the still image mode is selected, monitoring is stopped (S6). During still image shooting, when a first switch (hereinafter abbreviated as first SW) of a shutter button (not shown) provided in the switch unit 13 is turned on, the DSP unit 5 evaluates image data as an AE process 23. The exposure time value of the CCD set in the CCD drive circuit unit 7 is determined (S7).
Next, multipoint ranging processing 24 is performed in step S8.

Here, the multipoint distance measuring process 24 will be described. The principle is based on the triangulation, and the multipoint distance measuring process 24 is performed on each of the left and right sides of the AF (autofocus) unit as shown in FIG. The luminance signals detected by the line sensors 51L and 51R provided in the optical system are compared, and signals having strong correlations, for example, the central subject 53 as shown in FIGS. 4A and 4B, or FIG. a) The distance is obtained by calculation from the phase difference L of the right subject 54 as shown in (c). Thereby, the distance of the several area of a line sensor direction can be measured.
Generally, out of the multi-point distance measurement data, the focus lens is extended according to the distance measurement data with the closest area as the main subject.
On the other hand, in the present embodiment, the distance measurement data obtained by the multipoint distance measurement process 24 is stored in the memory 9 as the first distance information, and then the driver unit 6 performs the distance measurement data of the multipoint distance measurement process. A focus driving process for moving the lens 1 to adjust the focus is performed (S9). After the focus driving process is completed, the loop for returning to the monitoring state in step S1 is repeated.
On the other hand, in the SW determination process 21 in step S4, when a second switch (hereinafter referred to as the second SW) of a shutter button (not shown) is turned on, a strobe determination process in step S10 is performed. In “NO” in S10), the process proceeds to step S11.
In step S 11, as the still image recording process 31, the image data of the CCD 3 is subjected to image processing and compression processing in the DSP unit 5 and written in the memory 9.
Next, when the compressed image data is stored in the memory 9, the CPU 8 performs a card recording process 32 for recording it on the memory card 11 (S12).
As described above, in the digital camera according to the present embodiment, when the SW determination process 21 in step S4 determines that the image is a still image, the second SW is turned on when the first SW is on and the second SW is turned on. The still image recording process 31 is executed as the ON process, and the still image is written to the memory card 11.

Next, an operation at the time of flash emission, which is a characteristic operation of the digital camera of the present embodiment, will be described.
In the SW determination process 21 in step S4, when the second SW is turned on, and it is determined in the strobe determination process in step S10 that there is a strobe (“Yes” in S10), the process proceeds to step S13, and the multipoint distance measurement is performed again. Process 24 is performed. Then, in step S14, the distance comparison processing 25 compares whether or not there is a distance measurement area that matches the first distance information when the first SW is previously stored in the memory 9. As a result of the comparison, if there is an area with almost the same distance measurement data, the area is regarded as an area where the main subject is located, and in step S15, a flash light receiving unit (flash light) that receives the flash emission so that the distance measurement area is at the center. A light receiving area setting process for setting the area of the light receiving means) is performed. That is, the light receiving area of the strobe light receiving unit is aligned with the area corresponding to the angle of view of the position of the main subject by the light receiving area setting process.
In this case, the strobe light receiving unit may be the CCD 3 of the camera itself or a photosensor placed in an optical system different from the lens 2.
Next, pre-emission is actually performed by pre-emission / photometry processing (S16), and the reflected light is measured by the strobe light receiving unit. If the reflected light is larger than a reference reflection amount to be described later, it is determined that the reflectance of the subject is larger than expected, and the main flash emission amount is reduced in the main emission amount shift processing 30 in step S17. Conversely, if it is smaller than the reference reflection amount in step S16, it is assumed that the reflectance of the subject is smaller than expected, and in step S17, the main flash emission amount is increased.

Here, a method of calculating the reference reflection amount will be described with reference to FIG. FIG. 5 shows an example in which a CCD is also used as a strobe light receiving unit.
For example, in the light receiving area setting process 28, if an area corresponding to a part regarded as the area 52 with the main subject from the multipoint ranging area 51 is a light receiving area 53 at the time of pre-emission, the pre-emission amount is the pre-emission amount. The amount of light emission is determined from the data measured by the determination process 26, the lens F value of the strobe light receiving unit, and the pre-emission constant. The pre-emission constant is a constant for obtaining a level at which the output of the strobe light receiving unit by pre-emission can calculate the reflectance when the subject has a certain reflectance. This reflectance is set as a reference reflectance. For example, a human skin color equivalent is used as the reference reflectance. The main light emission amount is also calculated from the data measured based on the reference reflectance in the main light emission amount calculation processing 27 and the lens F value of the strobe light receiving unit.
Further, the image data of the CCD 3 is read into the memory 9 and, for example, the luminance data is integrated for each square of horizontal and vertical pixel units each of which divides the horizontal / vertical into 15 parts, so that the photometric data for each small divided area 3a is obtained. You may make it get.

FIG. 6 is a timing chart of each process from the release operation to the card recording process in the still image recording of the digital camera of the present embodiment described so far, and the horizontal axis indicates time. Therefore, according to the digital camera of this embodiment, even when the photographer changes the angle of view after the first SW is turned on or the main subject moves, the main subject within the shooting angle of view is located. Pre-flash emission from a location can be received, and flash light emission suitable for the subject can be performed.
In the present embodiment described so far, the strobe light receiving unit is also used as an image sensor, but it may be a divided photometric element that can obtain a photosensor output for each divided area arranged in another optical system.
In addition, when subjects are mixed at the same distance as the main subject, it is difficult to specify the position of the main subject. In such a case, the light emission amount of the main light emission may be obtained from the data from the strobe light receiving unit in the area of substantially the same distance by the main light emission amount calculation processing 27. Thus, even when it is difficult to specify the position of the main subject, it can be stably operated.
In addition, since the digital camera of the present embodiment includes a distance measuring unit, it is possible to calculate an optimal reflected light signal even during pre-emission, and it is possible to accurately measure reflectivity by pre-emission. Based on the distance measurement data, the actual emission amount is calculated based on the assumption of the reference reflectance, and the photographing lens F value and the amplifier gain at the time of photographing are calculated. The pre-emission amount A1 is also calculated from the distance measurement data, the lens F value of the strobe light receiving unit, and the amplifier gain to the light reception signal.
If the CPU 8 determines that the main light emission amount A2 is possible after the pre-light emission with the light emission amount A1, the pre-light emission is performed with the light emission amount A1. The light emission amount A1 is an optimum light emission amount for obtaining a necessary light reception level for a subject at a short distance, and power consumption is not wasted. The main light emission amount is smaller than the main light emission amount A2. When the CPU 8 determines that there is not enough, the shortage of the light emission amount A1 can be compensated by the amplifier gain to the light reception signal.

The block diagram of one Embodiment of the digital camera by this invention. The program block diagram in the digital camera of this embodiment. The flowchart which showed the main process at the time of recording. Explanatory drawing for demonstrating multipoint ranging processing. The figure which showed the example in the case of using CCD as a strobe light-receiving part. The figure which showed the timing chart of each process from the release operation in the still image recording of the digital camera of this embodiment to a card | curd recording process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lens, 2 ... Mechanical shutter, 3 ... CCD, 4 ... AD part, 5 ... DSP part, 6 ... Driver part, 7 ... CCD drive circuit part, 8 ... CPU, 9 ... Memory, 10 ... Communication driver, 11 ... Memory card, 12 ... Display unit, 13 ... SW unit, 14 ... First external device, 15 ... Second external device, 16 ... Audio CODEC, 17 ... Input analog unit, 18 ... Output analog unit, 19 ... Strobe device 20 ... main processing block, 30 ... parallel processing block

Claims (6)

  In an imaging apparatus capable of controlling the strobe light emission of the strobe device during shooting by the image imaging means, a switch means having a first switch for moving the lens to a focusing position and a second switch operated after the first switch is turned on Multi-point distance measuring means for measuring the distance of the subject when the first switch or the second switch is turned on, and distance information measured by the multi-point distance measuring means when the first switch is turned on. The storage means for storing the distance information and the distance information measured by the multipoint distance measuring means when the second switch is turned on are compared as the second distance information with the first distance information stored in the storage means. A distance comparison unit, a pre-flash unit that pre-flashes the strobe of the flash device when the second switch is turned on, and a pre-flash of the pre-flash unit When the reflected light from the strobe light receiving means is received by the strobe light receiving means, the setting relating to the light receiving area of the strobe light receiving means is made based on the comparison result of the distance comparing means. A light receiving area setting means for performing imaging, and a main light emission amount calculating means for calculating a light emission amount during main light emission for photographing a subject from a light reception amount received by the strobe light receiving means during the pre-light emission. apparatus.   The distance comparison unit determines a main subject from the first distance measurement information and the second distance information measured by the multipoint distance measurement unit, and corresponds to an angle of view of the position of the main subject by the light receiving area setting unit. 2. The image pickup apparatus according to claim 1, wherein the light receiving area of the strobe light receiving means is aligned with the area to be operated.   3. The main light emission amount calculating unit calculates a light emission amount during main light emission from a light reception amount received by the strobe light receiving unit from a subject approximately the same distance as the main subject during the pre-light emission. The imaging device described in 1.   The imaging apparatus according to claim 1, wherein the strobe light receiving unit is the image imaging unit.   The imaging apparatus according to any one of claims 1 to 3, wherein the strobe light receiving unit is a divided light receiving element provided separately from the image imaging unit.   6. The light emission amount of the pre-light emitting means or the electric gain of the strobe light receiving means is obtained from distance measurement information from the multipoint distance measuring means. The imaging device according to item.

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