JP5467797B2 - Camera and LED lighting control method - Google Patents

Description

  The present invention relates to a camera and an LED lighting control method.

  In recent years, an optical image is converted into an electric signal using an image pickup device (image sensor) such as a charge coupled device (CCD) sensor or a complementary metal-oxide semiconductor (CMOS) sensor, and the obtained electric signal is digitized and recorded. Digital cameras are popular.

  In particular, in mobile terminal devices such as camera-equipped mobile phones that have become widespread in recent years, MOS-based image sensors represented by CMOS (Complementary Metal-oxide Semiconductor) sensors are likely to be mounted for reasons such as low power consumption. It has become. Here, an imaging device such as a CMOS sensor performs pixel readout (line exposure) for each line on an imaging surface having a plurality of lines. Therefore, in a CMOS sensor that performs line exposure, the exposure start timing differs between the first line and the last line on the imaging surface.

  Also, in mobile terminal devices such as camera-equipped mobile phones, in order to reduce the size, an LED (Light Emitting Diode) that is smaller than a xenon flash mounted on a general digital camera or the like is used for camera shooting. It is installed as a flash. For example, as a light emitting method of a flash LED (LED flash), there is a conventional technique in which an LED emits light in synchronization with an exposure time (shutter speed) (see, for example, Patent Document 1). That is, the mobile terminal device synchronizes the lighting start timing of the LED with the exposure start timing of the CMOS sensor.

JP 2003-241266 A

  Compared with xenon flash, the LED flash has a small amount of light because of its small size. For this reason, the LED flash secures a photographing light amount in a low illuminance environment by irradiating light for a certain period of time. Therefore, the lighting time (on the order of several tens of milliseconds) of the LED flash is much longer than, for example, the lighting time of the xenon flash (less than 1 msec), and is comparable to the exposure time (shutter speed) in a low illumination environment.

  Here, when performing line exposure, the exposure start timing between the first line and the last line on the imaging surface is different from each other. For this reason, when performing line exposure, if an LED flash that requires a lighting time comparable to the exposure time (shutter speed) is emitted in synchronization with the exposure time (shutter speed) of the CMOS sensor as in the prior art, There may be a difference in the lighting time of the LED flash during exposure between the vicinity of the first line and the vicinity of the last line on the imaging surface. In this case, display unevenness may occur in the captured image.

  For example, as shown in FIG. 1, the case where the exposure time (shutter speed) is 200 msec and the LED lighting time is 200 msec will be described. In addition, the entire line readout time from the first line to the last line on the imaging surface, that is, the vertical synchronization time of the CMOS sensor is 50 msec. Further, as shown in FIG. 1, the camera synchronizes the lighting start timing of the LED flash with the exposure start timing of the CMOS sensor (that is, the exposure start timing of the first line).

  At this time, when the first line and the last line shown in FIG. 1 are compared, the LED flash is lit for 200 msec from the exposure start timing to the exposure end timing in the first line, whereas in the last line, the LED flash starts from the exposure start timing. It is lit for 150msec only halfway. That is, on the last line, the exposure is performed even during the time zone when the LED flash is not lit (50 msec in FIG. 1). In other words, in the captured image, the lighting time of the LED flash is different between the vicinity of the first line and the vicinity of the final line, so the image near the final line of the captured image becomes partly dark, and the vicinity of the first line and the vicinity of the final line Display unevenness between the two.

  Here, in order to eliminate display unevenness between the vicinity of the first line and the vicinity of the last line on the imaging surface, it is considered that when the exposure time (shutter speed) increases, the lighting time of the LED flash is also increased in synchronization. It is done. However, there is a problem that the LED generates heat when used for a long time. For this reason, when the exposure time (shutter speed) becomes long, the LED flash cannot be lit continuously for the exposure time of all lines in synchronization with the exposure time (shutter speed).

  In this way, when using an LED flash that requires a lighting time comparable to the exposure time (shutter speed) in a low-light environment, if the exposure time (shutter speed) increases, display irregularity occurs in the captured image. End up. That is, when the LED flash is used, the exposure time (shutter speed) for capturing an appropriate image is limited.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a camera and an LED lighting control method capable of capturing an appropriate image without restricting the exposure time even when an LED flash is used. And

The camera according to one aspect of the present invention includes an image sensor that performs line exposure for reading out pixels for each line on an imaging surface having a plurality of lines, a flash LED, and an exposure time at the time of the line exposure. And a control means for switching the lighting start timing of the LED with respect to the exposure start timing of line exposure.

In the LED lighting control method according to one aspect of the present invention, the exposure of the line exposure is performed according to an exposure time at the time of the line exposure by an image sensor that performs line exposure for reading out pixels for each line on an imaging surface having a plurality of lines. The lighting start timing of the flash LED with respect to the start timing is switched.

  According to the present invention, even when an LED flash is used, an appropriate image can be acquired without limiting the exposure time.

The figure which shows the subject of this invention 1 is a block diagram showing a configuration of a camera according to Embodiment 1 of the present invention. The figure which shows the flow of the LED lighting control processing which concerns on Embodiment 1 of this invention. The figure which shows an example of the LED lighting control processing which concerns on Embodiment 1 of this invention The figure which shows an example of the LED lighting control processing which concerns on Embodiment 1 of this invention The block diagram which shows the structure of the camera which concerns on Embodiment 2 of this invention. The figure which shows the flow of the LED lighting control processing which concerns on Embodiment 2 of this invention. The figure which shows an example of the LED lighting control processing which concerns on Embodiment 2 of this invention. The figure which shows an example of the other LED lighting control processing which concerns on Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 2 shows the configuration of the camera according to this embodiment. In the camera 100 illustrated in FIG. 2, the operation unit 101 receives an operation on the camera 100 from a photographer. Then, the operation unit 101 outputs information indicating the operation content for the camera 100 to the control unit 102.

  Based on the operation content indicated in the information input from the operation unit 101 or the image information input from the image signal processing unit 111, the control unit 102 performs an AE (Auto Exposure) function, AF (Auto Focus). Focus) function or lighting of the LED 106 is controlled. As shown in FIG. 2, the control unit 102 has a configuration including an AE control unit 103, an AF control unit 104, and an LED control unit 105. Hereinafter, an internal configuration of the control unit 102 will be described.

  The AE control unit 103 of the control unit 102 controls the exposure time (shutter speed) of the image sensor 109 and the gain of the image signal processing unit 111 based on the image information input from the image signal processing unit 111. For example, the AE control unit 103 determines the exposure time (shutter speed) of the image sensor 109 based on image information including subject luminance information obtained at the time of shooting. Then, the AE control unit 103 outputs information indicating the exposure time (shutter speed) to the LED control unit 105 and the image sensor 109, and outputs information indicating the gain to the image signal processing unit 111.

  The AF control unit 104 of the control unit 102 controls the AF driver 107 based on the image information input from the image signal processing unit 111. For example, the AF control unit 104 calculates an AF evaluation value as an evaluation value for AF operation using the image information, and controls the AF driver 107 so as to detect a maximum value of the calculated AF evaluation value.

  The LED control unit 105 of the control unit 102 controls the lighting time of the LED 106 according to the exposure time (shutter speed) indicated in the information input from the AE control unit 103. Specifically, the LED control unit 105 switches the lighting start timing of the LED 106 with respect to the exposure start timing of line exposure by the image sensor 109 according to the exposure time (shutter speed). Similarly, the LED control unit 105 switches the lighting end timing of the LED 106 with respect to the exposure end timing of line exposure by the image sensor 109 according to the exposure time (shutter speed). Then, the LED control unit 105 outputs information including the lighting start timing and the lighting end timing to the LED 106.

  The LED 106 for flashing emits light according to the lighting start timing and lighting end timing included in the information input from the LED control unit 105 of the control unit 102.

  The AF driver 107 drives the lens 108 based on an instruction from the AF control unit 104 of the control unit 102.

  The lens 108 performs focusing by moving in the optical axis direction according to the operation of the AF driver 107.

  The image sensor 109 converts the optical image formed by the lens 108 into an electrical signal (analog signal) based on an exposure time (shutter speed) indicated by information input from the AE control unit 103 of the control unit 102. Here, the image sensor 109 is, for example, a CMOS sensor. That is, the image sensor 109 performs line exposure for reading out pixels for each line on an imaging surface having a plurality of lines. Then, the image sensor 109 outputs the obtained analog signal to an ADC (Analog to Digital Converter) 110.

  The ADC 110 converts the analog signal input from the image sensor 109 into a digital signal and outputs the digital signal to the image signal processing unit 111.

  The image signal processing unit 111 performs image signal processing on the digital signal input from the ADC 110. For example, gain adjustment is performed on the digital signal according to the gain indicated in the information input from the AE control unit 103. Then, the image signal processing unit 111 outputs the signal after the image signal processing to the buffer memory 112.

  The buffer memory 112 accumulates signals input from the image signal processing unit 111 and temporarily stores them as digital information.

  The display unit 113 is, for example, a monitor, acquires the digital information stored in the buffer memory 112 via the image signal processing unit 111 and the control unit 102, and displays it as a visible image.

  Next, details of the operation of the camera 100 (FIG. 2) according to the present embodiment will be described. In the following description, the lighting time of the LED 106 is set in advance.

  First, the flow of the lighting control process of the LED 106 in the camera 100 according to the present embodiment will be described in detail. FIG. 3 shows the flow of the lighting control process of the LED 106 in the camera 100.

  In step (hereinafter referred to as ST) 101, the control unit 102 of the camera 100 starts shooting according to the operation of the operation unit 101, for example.

  When the exposure time (shutter speed) determined by the AE control unit 103 of the control unit 102 is equal to or less than the difference between the preset lighting time of the LED 106 and the total line readout time (ST102: YES), in ST103, LED control is performed. The unit 105 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the first line on the imaging surface, and sets the lighting end timing of the LED 106 to the same timing as the exposure end timing of the last line on the imaging surface. That is, the LED control unit 105 turns on the LED 106 in synchronization with the exposure start timing of the first line, and turns off the LED 106 in synchronization with the exposure end timing of the last line (LED lighting pattern A).

  On the other hand, when the exposure time (shutter speed) determined by the AE control unit 103 of the control unit 102 is longer than the difference between the preset lighting time of the LED 106 and the total line readout time (ST102: NO), ST104 The LED control unit 105 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the last line, and sets the lighting end timing of the LED 106 to the same timing as the exposure end timing of the first line. That is, the LED control unit 105 turns on the LED 106 in synchronization with the exposure start timing of the last line, and turns off the LED 106 in synchronization with the exposure end timing of the first line (LED lighting pattern B).

  That is, the LED control unit 105 of the control unit 102 determines the lighting start timing of the LED 106 according to the exposure time (shutter speed), the exposure start timing (LED lighting pattern A) of the first line and the exposure start timing (LED of the last line). Switching between lighting pattern B). Further, the LED control unit 105 determines the lighting end timing of the LED 106 according to the exposure time (shutter speed), the exposure end timing of the last line (LED lighting pattern A), and the exposure end timing of the first line (LED lighting pattern B). Switch between.

  Next, details of the lighting control process of the LED 106 in the LED control unit 105 will be described. In the following description, it is assumed that the preset lighting time of the LED 106 is 200 msec, and the total line readout time (CMOS sensor vertical synchronization time) is 50 msec.

  First, as shown in FIG. 4A, a case where the exposure time (shutter speed) determined by the AE control unit 103 is 150 msec will be described.

  In this case, the exposure time (shutter speed) 150 msec is less than 50 msec (= 200 msec−50 msec) between the preset lighting time 200 msec of the LED 106 and the total line readout time 50 msec (that is, ST102: YES). Therefore, as shown in FIG. 4A, the LED control unit 105 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the first line, and sets the lighting end timing of the LED 106 to the same timing as the exposure end timing of the last line. To do. That is, the LED control unit 105 controls lighting of the LED 106 according to the LED lighting pattern A in ST103 of FIG.

  That is, when the exposure time (shutter speed) is equal to or less than the difference between the preset lighting time of the LED 106 and the total line readout time, the LED control unit 105 performs the line exposure time (image sensor 109 (CMOS sensor)). That is, it is determined that the time from the exposure start timing of the first line to the exposure end timing of the last line (shown in FIG. 4A) falls within the preset lighting time of the LED 106. As a result, the LED 106 continues to be lit from the start of exposure to the end of exposure in all lines on the imaging surface. That is, as shown in FIG. 4A, in all the lines, the LEDs 106 are lit in all time zones of an exposure time (shutter speed) of 150 msec. In other words, the lighting times of the LEDs 106 in all lines on the imaging surface are the same.

  Next, as shown in FIG. 4B, a case where the exposure time (shutter speed) determined by the AE control unit 103 is 250 msec will be described.

  In this case, the exposure time (shutter speed) 250 msec is longer than the difference 50 msec between the preset lighting time 200 msec of the LED 106 and the total line readout time 50 msec (that is, ST102: NO). Therefore, as shown in FIG. 4B, the LED control unit 105 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the last line, and sets the lighting end timing of the LED 106 to the same timing as the exposure end timing of the first line. To do. That is, the LED control unit 105 controls the lighting of the LED 106 according to the LED lighting pattern B in ST104 of FIG.

  Accordingly, for example, in the first line shown in FIG. 4B, the LED 106 is turned off for the first 50 msec out of the exposure time (shutter speed) 250 msec, and is turned on for the remaining 200 msec. On the other hand, in the final line shown in FIG. 4B, the LED 106 is turned off for the first 200 msec out of the exposure time (shutter speed) 250 msec, and turned off for the remaining 50 msec. That is, as shown in FIG. 4B, the LED 106 is lit for the same time (200 msec) in both the first line and the last line. The same applies to lines other than the first line and the last line.

  In this way, the LED control unit 105 controls the lighting time of the LED 106 so that the lighting time of the LED 106 is uniform in all lines regardless of the exposure time (shutter speed). Specifically, the LED control unit 105 determines the lighting start timing of the LED 106 depending on whether or not the exposure time (shutter speed) is equal to or less than the difference between the preset lighting time of the LED 106 and the total line readout time. And the lighting end timing, that is, the lighting pattern (lighting pattern A (FIG. 4A) or lighting pattern B (FIG. 4B)) is switched. Thereby, in any case of the exposure time (shutter speed), in the camera 100, the lighting time of the LED 106 can be made the same in all the lines on the imaging surface. That is, the amount of light emitted from the LEDs 106 to all lines on the imaging surface is uniform.

  Thus, according to the present embodiment, the camera switches the LED lighting pattern in accordance with the exposure time (shutter speed). As a result, the camera can uniformly irradiate the LED flash light to all the lines on the imaging surface regardless of the exposure time (shutter speed), resulting in display unevenness in the image captured by the line exposure. Can be prevented. Therefore, according to the present embodiment, an appropriate image can be acquired without restricting the exposure time even when an LED flash is used.

(Embodiment 2)
As described above, the LED may be damaged by heat generation when used for a long time. Therefore, it is necessary to limit the time (maximum lighting time) during which the LED can be lit continuously.

  Therefore, in the present embodiment, the camera further measures the elapsed time from the lighting start timing of the LED, and turns off the LED when the elapsed time exceeds the maximum lighting time of the LED.

  FIG. 5 is a block diagram showing a configuration of camera 200 according to the present embodiment. Note that the camera 200 has the same basic configuration as that of the camera 100 (see FIG. 2) described in Embodiment 1, and the same components are denoted by the same reference numerals and description thereof is omitted. .

  In the camera 200 shown in FIG. 5, the timer 201 of the control unit 102 measures the elapsed time (that is, the lighting time of the LED 106) from the lighting start timing of the LED 106 determined by the LED control unit 202. In addition, when the elapsed time being counted is equal to or longer than the preset maximum lighting time of the LED 106, the timer 201 indicates that the elapsed time from the lighting start timing of the LED 106 is equal to or longer than the maximum lighting time of the LED 106. The indicated information is output to the LED control unit 202.

  Similar to the LED control unit 105 of the first embodiment, the LED control unit 202 switches the lighting pattern of the LED 106 according to the exposure time (shutter speed). Further, the LED control unit 202 turns off the LED 106 when information indicating that the elapsed time from the lighting start timing of the LED 106 (lighting time of the LED 106) is equal to or longer than the maximum lighting time of the LED 106 is input from the timer 201. Let

  Next, details of the operation of the camera 200 (FIG. 5) according to the present embodiment will be described. In the following description, as in the first embodiment, the lighting time of the LED 106 is set in advance.

  First, the flow of the lighting control process of the LED 106 in the camera 200 according to the present embodiment will be described in detail. FIG. 6 shows the flow of the LED 106 lighting control process in the camera 200.

  In ST201, as in ST101 (FIG. 3) of the first embodiment, the LED control unit 202 of the camera 200 starts shooting according to an instruction from the operation unit 101, for example.

  When the exposure time (shutter speed) determined by the AE control unit 103 of the control unit 102 is equal to or less than the difference between the preset lighting time of the LED 106 and the total line readout time (ST202: YES), in ST203, the imaging device 109 starts line exposure. In ST204, the LED control unit 202 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the first line on the imaging surface. That is, LED control section 202 turns on LED 106 in synchronization with the exposure start timing of the first line (LED lighting pattern A), as in ST103 of the first embodiment.

  In ST205, for example, the LED control unit 202 determines whether or not the exposure of the last line on the imaging surface has been completed based on the control result of the exposure time (shutter speed) by the AE control unit 103. When the exposure of the last line is not completed (ST205: NO), the LED control unit 202 does nothing and returns to ST205. On the other hand, when the exposure of the last line is completed (ST205: YES), in ST206, the LED control unit 202 turns off the LED 106. That is, the LED control unit 202 turns off the LED 106 in synchronization with the exposure end timing of the final line (LED lighting pattern A), as in ST103 of the first embodiment.

  On the other hand, when the exposure time (shutter speed) determined by the AE control unit 103 of the control unit 102 is longer than the difference between the lighting time of the LED 106 and the entire line readout time (ST202: NO), in ST207, the image sensor 109 Starts line exposure. In ST208, the LED control unit 202 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the last line on the imaging surface. That is, LED control section 202 lights LED 106 in synchronization with the exposure start timing of the final line (LED lighting pattern B), as in ST104 of the first embodiment. In ST209, the timer 201 starts measuring the elapsed time from the lighting start timing of the LED 106 in ST208 (timer start).

  When the elapsed time measured by the timer 201 is equal to or longer than the maximum lighting time of the LED 106 (ST210: YES), that is, information indicating that the elapsed time from the lighting start timing of the LED 106 is equal to or longer than the maximum lighting time. When input from the timer 201 to the LED control unit 202 is performed, in ST211, the LED control unit 202 turns off the LED 106 (LED lighting pattern B ′). On the other hand, when the elapsed time being measured by the timer 201 is less than the maximum lighting time of the LED 106 (ST210: NO), the process proceeds to ST212.

  In ST212, the LED control unit 202 determines whether or not the exposure of the first line on the imaging surface has been completed, as in ST205. If the exposure of the first line is not completed (ST212: NO), the LED control unit 202 does nothing and returns to ST210. On the other hand, when the exposure of the first line is completed (ST212: YES), in ST213, the LED control unit 202 turns off the LED 106. That is, the LED control unit 202 turns off the LED 106 in synchronization with the exposure end timing of the first line (LED lighting pattern B), as in ST104 of the first embodiment.

  That is, when the exposure time (shutter speed) is longer than the difference between the lighting time of the LED 106 and the total line readout time (ST202: NO), the LED control unit 202 performs the first line in the same manner as in the first embodiment. The LED 106 is turned off in synchronization with the exposure end timing (LED lighting pattern B), and the LED 106 is turned off based on the time counted by the timer 201 (LED 106 lighting time) (LED lighting pattern B ′). is there.

  Next, details of the lighting control processing of the LED 106 in the LED control unit 202 will be described. In the following description, as in the first embodiment (FIGS. 4A and 4B), the preset lighting time of the LED 106 is 200 msec, and the total line readout time (CMOS sensor vertical synchronization time) is 50 msec. The maximum lighting time of the LED 106 is 250 msec. That is, the LED 106 can be lit longer than the preset lighting time 200 msec by 50 msec.

  Here, the series of processing of ST203 to ST206 shown in FIG. 6 is the same as the processing of ST103 shown in FIG. 3 of the first embodiment, and the LED control unit 202 turns on the LED as shown in FIG. 4A, for example. The lighting of the LED 106 is controlled according to the pattern A.

  Similarly, a series of processes of ST207, 208, 212, and 213 shown in FIG. 6, that is, the exposure of the first line is completed within the time counted by the timer 201 is less than the maximum lighting time of the LED 106 (ST210: NO). In this case (ST212: YES), the process is the same as the process of ST104 shown in FIG. 3 of the first embodiment. In this case, the LED control unit 202 controls the lighting of the LED 106 according to the lighting pattern B as shown in FIG. 4B, for example.

  Therefore, here, as shown in FIG. 7, a case where the exposure time (shutter speed) determined by the AE control unit 103 is 350 msec, which is longer than those in FIG. 4A (150 msec) and FIG. 4B (250 msec) will be described. .

  In this case, the exposure time (shutter speed) 350 msec is longer than the difference 50 msec between the preset lighting time 200 msec of the LED 106 and the total line readout time 50 msec (that is, ST202: NO). Therefore, as shown in FIG. 7, the LED control unit 202 sets the lighting start timing of the LED 106 to the same timing as the exposure start timing of the final line. Then, the LED control unit 202 turns on the LED 106 in synchronization with the exposure start timing of the final line in the image sensor 109 (ST208).

  At the same time, as shown in FIG. 7, the timer 201 starts measuring the elapsed time from the lighting start timing of the LED 106 (ST209: timer start). Then, when the elapsed time being counted becomes the maximum lighting time of the LED 106 of 250 msec or more (ST210: YES), the timer 201 confirms that the elapsed time from the lighting start timing of the LED 106 is equal to or longer than the maximum lighting time. The indicated information is output to the LED control unit 202. Then, the LED control unit 202 turns off the LED 106 (ST211).

  That is, in FIG. 7, the LED control unit 202 determines the elapsed time from the lighting start timing of the LED 106 (lighting of the LED 106) before the exposure end timing of the first line (that is, the lighting end timing of the LED 106 in the LED lighting pattern B). When the (time) exceeds the maximum lighting time of the LED 106, the LED 106 is forcibly turned off (LED lighting pattern B ′).

  Even in the case of this LED lighting pattern B ', the time during which the LEDs 106 are lit in all the lines on the imaging surface is the same. For example, as shown in FIG. 7, the LED 106 is lit for 250 msec (the maximum lighting time of the LED 106) out of the exposure time (shutter speed) 350 msec in all lines. In other words, the LED control unit 202 controls the lighting of the LEDs 106 so that the lighting times of the LEDs 106 are uniform in all the lines on the imaging surface and the lighting time of the LEDs 106 does not exceed the maximum lighting time.

  As described above, the LED control unit 202 determines whether the exposure time (shutter speed) is equal to or less than the difference between the lighting time of the LED 106 and the total line readout time, as in the first embodiment. Switch the lighting pattern of. Further, the LED control unit 202 determines that the lighting time of the LED 106 is equal to or greater than the maximum lighting time even when the exposure time (shutter speed) is longer than the difference between the lighting time of the LED 106 and the entire line reading time (ST202: NO). In this case, the LED 106 is forcibly turned off. Thereby, in the camera 200, it becomes possible to make uniform the light quantity of LED106 irradiated to all the lines of an imaging surface, without damaging LED106.

  Thus, according to the present embodiment, the camera switches the LED lighting pattern according to the exposure time (shutter speed), and when the LED lighting time is longer than the maximum LED lighting time. The LED is forcibly turned off. Thereby, the camera can irradiate LED flash light uniformly with respect to all the lines of an imaging surface, without damaging LED flash. That is, according to the present embodiment, it is possible to acquire an appropriate image without restricting the exposure time, as in the first embodiment, while preventing the LED flash from being damaged.

  In the present embodiment, a preset LED used by the camera for determination of switching between LED lighting pattern A and LED lighting pattern B (or LED lighting pattern B ′) (determination in ST202 shown in FIG. 6). The case where the lighting time (200 msec in FIG. 7) is different from the maximum LED lighting time (250 msec in FIG. 7) has been described. However, in the present invention, the preset LED lighting time and the maximum LED lighting time that the camera uses to determine switching between the LED lighting pattern A and the LED lighting pattern B (or LED lighting pattern B ′) are the same. But you can. For example, as shown in FIG. 8, a case where the preset LED lighting time and the maximum LED lighting time are the same 200 msec will be described. Even in this case, as shown in FIG. 8, the camera can make the lighting times of the LEDs uniform in all the lines on the imaging surface.

  The embodiments of the present invention have been described above.

  The line exposure is sometimes referred to as a rolling shutter.

  In addition, the camera according to the above embodiment can be mounted on a mobile terminal device such as a mobile phone, for example.

  The present invention is suitable for a digital still camera, a digital video camera, a mobile phone equipped with a camera unit, a PDA, or the like where an image with good image quality is required.

DESCRIPTION OF SYMBOLS 100,200 Camera 101 Operation part 102 Control part 103 AE control part 104 AF control part 105,202 LED control part 106 LED
107 AF driver 108 Lens 109 Image sensor 110 ADC
111 Image Signal Processing Unit 112 Buffer Memory 113 Display Unit 201 Timer

Claims (6)

An image sensor that performs line exposure to read out pixels for each line on an imaging surface having a plurality of lines;
LED for flash,
Control means for controlling the line exposure and the LED;
A camera comprising:
The control means includes
When the exposure time at the time of the line exposure is equal to or less than the difference between the lighting time of the LED and the reading time of all lines on the imaging surface, the lighting start timing of the LED is set to the exposure starting timing of the first line on the imaging surface And
If the LED lighting time is longer than the difference between the all line readout time, the lighting start timing is set to the exposure start timing of the last line of the imaging surface,
camera. The control means includes
When the exposure time at the time of the line exposure is equal to or less than the difference between the lighting time of the LED and the reading time of all lines on the imaging surface, the lighting end timing of the LED is set to the exposure end timing of the last line on the imaging surface And
If the LED lighting time is longer than the difference between the all line readout time, the lighting end timing is set to the exposure end timing of the first line of the imaging surface,
The camera according to claim 1. Further comprising means for measuring the elapsed time from the lighting start timing,
The control means includes
When the elapsed time is longer than the maximum lighting time of the LED, the LED is turned off.
The camera according to claim 1. An image sensor that performs line exposure to read out pixels for each line on an imaging surface having a plurality of lines;
LED for flash,
An LED lighting control method for controlling the LED in a camera comprising :
Comparing the exposure time during the line exposure and the difference between the lighting time of the LED and the total line readout time of the imaging surface;
When the exposure time at the time of the line exposure is equal to or less than the difference between the lighting time of the LED and the reading time of all lines on the imaging surface, the lighting start timing of the LED is set to the exposure starting timing of the first line on the imaging surface And
If the LED lighting time is longer than the difference between the all line readout time, the lighting start timing is set to the exposure start timing of the last line of the imaging surface,
LED lighting control method. When the exposure time at the time of the line exposure is equal to or less than the difference between the lighting time of the LED and the reading time of all lines on the imaging surface, the lighting end timing of the LED is set to the exposure end timing of the last line on the imaging surface And
If the LED lighting time is longer than the difference between the all line readout time, the lighting end timing is set to the exposure end timing of the first line of the imaging surface,
The LED lighting control method according to claim 4. The camera further includes means for measuring an elapsed time from the lighting start timing,
Comparing the elapsed time and the maximum lighting time of the LED;
Turning off the LED when the elapsed time is equal to or longer than the maximum lighting time of the LED,
The LED lighting control method according to claim 4.

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