JP2008219712A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an imaging device from being burnt while a camera is used. <P>SOLUTION: The camera comprises: a mirror 101 for switching an optical path to a finder optical system and an optical path to an imaging device 107 which images an object; a display section 120 for displaying thereon an image generated on the basis of image signals outputted from the imaging device 107; a determination means 117 for determining whether or not a signal indicating a high-luminance object having an output equal to or larger than the fixed quantity of light is included in the image signals; and a warning means 117 which displays a caution on the display section 120 when it is determined by the determination means 117 that the signal indicating the high-luminance object is included. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a camera having an image sensor protection function.

Conventionally, when the power is turned off, a camera that drives the focus of the lens to the closest side so that an infinite subject does not form an image on the image sensor and prevents image sensor and filter burn-in due to the incidence of high-intensity light. Is known (for example, Patent Document 1).
JP 2000-209491 A

  However, the conventional camera is intended to prevent image pickup when the camera is not used, and cannot prevent image pickup when the camera is in use.

The camera according to the first aspect of the present invention displays a mirror that switches between the optical path to the finder optical system and the optical path to the image sensor that images the subject, and an image generated based on the image signal output from the image sensor. A display unit, a determination unit that determines whether or not the image signal includes a signal indicating a high-brightness subject having an output of a certain amount or more, and a high-brightness subject that has an output of a certain amount or more by the determination unit. A warning means for displaying a warning on the display unit when it is determined that the signal to be displayed is included.
According to a second aspect of the present invention, in the camera according to the first aspect, the determining means is a predetermined light amount or more based on an image signal obtained when the subject is imaged with an exposure value at which the exposure amount per unit time is minimized. It is characterized in that it is determined whether or not a signal indicating a high-intensity subject having an output of is included.
According to a third aspect of the present invention, in the camera according to the first or second aspect of the present invention, the camera further includes a blocking unit that blocks an optical path incident on the image sensor after the warning by the warning unit.
According to a fourth aspect of the present invention, in the camera according to the third aspect, the blocking means performs any one of blocking an optical path by a mirror and blocking an optical path by a shutter provided in an incident optical path to the image sensor. And
According to a fifth aspect of the present invention, in the camera according to any one of the first to fourth aspects, the time during which a signal indicating a high-luminance subject having an output of a certain amount of light or more is continuously included in the image signal. And a warning means for displaying a warning on the display unit when the measured time is equal to or longer than a predetermined time.
According to a sixth aspect of the present invention, in the camera according to the fifth aspect, after the warning, a time during which a signal indicating a high-luminance subject having an output greater than a certain amount of light is continuously included in the image signal is measured. A second time measuring unit is further provided, and the blocking unit blocks the optical path incident on the image sensor when the measured time is equal to or longer than a predetermined time.
According to a seventh aspect of the present invention, in the camera according to any one of the first to sixth aspects, the determination unit performs the determination based on an output value of a specific pixel in the image signal.

  According to the present invention, a warning can be displayed on a display unit when an image signal having an output of a predetermined light amount or more is detected continuously for a predetermined time or longer while an image is displayed on the display unit.

-First embodiment-
A first embodiment of a camera according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a main part of the electronic camera 100. FIG. 2 is a block diagram of a control system of the electronic camera 100. In the electronic camera 100 shown in FIG. 1, an interchangeable lens 200 including a photographing lens L1 and a diaphragm 201 is detachably mounted.
1 and 2, the electronic camera 100 includes a quick return mirror 101, a focusing screen 102, a pentaprism 103, a photometric sensor 104, an eyepiece lens 105, a shutter 106, an image sensor 107, a focus detection sensor 108, and an AFE. (Analog Front End) circuit 111, timing generator 113, image processing unit 114, compression circuit 115, RAM 116, CPU 117, ROM 118, LCD drive circuit 119, LCD 120, operation unit 121, card interface 122, and memory card 123.

  In the camera of the present embodiment, for example, a shooting mode and a live view mode are provided as operation modes of the electronic camera. As shooting modes, a still image mode, a moving image mode, and the like are provided. When the still image mode is selected, the quick return mirror 101 is driven up and down for each shooting frame, and a still image is shot and recorded as described below. In the moving image mode, shooting and recording are performed while displaying the moving image on the LCD 120 with the quick return mirror 101 held at the up position indicated by the solid line in FIG. The live view mode is a mode in which an image is displayed on the LCD 120 as a moving image before release when the still image mode is set.

First, a case where the still image mode is set and the live view mode is not set will be described.
The subject light that has passed through the interchangeable lens 200 and entered the electronic camera 100 is guided upward by the quick return mirror 101 positioned as shown by a solid line in FIG. The subject image formed on the focusing screen 102 is guided to the eyepiece 105 by the pentaprism 103 and also to the photometric sensor 104. The photometric sensor 104 includes a CCD image sensor provided with a plurality of photoelectric conversion elements. The photometric sensor 104 outputs a photoelectric conversion signal obtained by photoelectrically converting the incident light beam incident from the pentaprism 103 to the CPU 117 as a photometric signal.

  Part of the subject light passes through the semi-transmissive region of the quick return mirror 101, is reflected downward by the sub mirror 1101a, and enters the focus detection sensor 108. For example, the focus detection sensor 108 divides a focus detection light beam into a pair of focus detection light images and forms a focus detection optical system and a pair of split light images, and a focus detection signal corresponding thereto. A pair of CCD line sensors. A focus detection signal output from the CCD line sensor is input to the CPU 117.

  After the release, the quick return mirror 101 is rotated to a position indicated by a broken line in FIG. 1, and subject light is guided to the image sensor 107 through the shutter 106, and a subject image is formed on the imaging surface. The image sensor 107 is a photoelectric conversion element such as a CCD or a CMOS that converts received light of an object into an image signal corresponding to its intensity. Pixels are arranged in a matrix on the image sensor 107. One of R (red), G (green), and B (blue) filters is attached to the light receiving surface of each pixel of the light receiving element of the image sensor 107 in a Bayer array. Microlenses are provided on the front surface (subject side) of each filter in order to increase the light receiving sensitivity.

  The AFE circuit 111 is a circuit that performs analog processing on the image signal output from the image sensor 107 and then converts it to digital image data. Analog processing includes amplifier gain control and correlated double sampling. The gain of the amplifier is determined based on the ISO sensitivity set by the CPU 117. The timing generator 113 is a circuit that outputs a timing signal to the image sensor 107 and the AFE circuit 111 in accordance with an instruction from the CPU 117 and controls the drive timing of the image sensor 107 and the AFE circuit 111.

  The CPU 117 is an arithmetic circuit that controls each component of the electronic camera 100 and executes various data processing. In addition to controlling the timing generator 113, the CPU 117 controls an image processing unit 114, a compression circuit 115, a card interface 122, and an LCD drive circuit 119, which will be described later. The CPU 117 calculates the shutter speed and the aperture value of the interchangeable lens 200 based on the brightness of the subject and the imaging sensitivity (ISO sensitivity) calculated based on the photometric signal output from the photometric sensor 104 described above. Further, the CPU 117 calculates a focus adjustment state such as a defocus amount based on the focus detection signal output from the focus detection sensor 108 described above.

  The image processing unit 114 is configured by an ASIC or the like. The image processing unit 114 performs image processing such as white balance processing, gamma correction processing, color interpolation processing, contour enhancement, and vignette correction on the image data. The compression circuit 115 is a circuit that executes JPEG compression processing on the main image data that has been subjected to image processing by the image processing unit 114. The CPU 117 generates an image file from the main image data subjected to JPEG compression processing.

  The memory card interface 122 is an interface to which the memory card 123 can be attached and detached. The memory card interface 122 is an interface circuit that writes an image file to the memory card 123 or reads an image file recorded on the memory card 123 based on the control of the CPU 117. The memory card 123 is a semiconductor memory card such as a compact flash (registered trademark) or an SD card.

  The LCD drive circuit 119 is a circuit that drives the LCD 120 based on a command from the CPU 117. The LCD 120 is a liquid crystal display panel. The LCD 120 is used as a liquid crystal viewfinder and displays display data created by the CPU 117 based on the image file recorded on the memory card 123. The LCD 120 displays various information (shutter speed, aperture value, ISO sensitivity, file name, etc.) related to the image file. The LCD 120 displays various setting menu screens of the electronic camera 100 based on an operation of an operation unit 121 described later. The contents of the setting menu include a shooting mode setting.

  The RAM 116 is used to temporarily store data during or after image processing, image compression processing, and display data creation processing. It is also used to temporarily store image data of a plurality of frames taken continuously during continuous shooting and moving image shooting. The ROM 118 is a memory that stores program data executed by the CPU 117.

  The operation unit 121 is a switch that receives a user operation. The operation unit 121 includes a power switch, a release switch, a setting menu display changeover switch, a setting menu determination button, and the like. The above-described shooting mode and live view mode are also set by the operation unit 121.

Next, a case where the still image mode and the live view mode are set will be described.
The user can set the live view mode by operating the operation unit 121. When the live view mode is set, the CPU 117 rotates the quick return mirror 101 to the position indicated by the broken line in FIG. 1, opens the shutter 106, and the subject light that has passed through the photographing lens L <b> 1 is guided to the image sensor 107. Let them be. Then, the CPU 117 calculates the shutter speed of the electronic shutter so that an optimal exposure value is obtained based on the image signal from the image sensor 107. An image generated by performing the above-described processes on the image signal output from the image sensor 107 is displayed on the LCD 120 as a moving image at a predetermined cycle such as 1/30 seconds. Therefore, the user can determine the composition of shooting while looking at the image displayed on the LCD 120.

  After the release, the CPU 117 rotates the quick return mirror 101 to the position indicated by the solid line in FIG. 1, and the shutter 106 is closed. As a result, the incident light on the image sensor 107 that has passed through the photographing lens L1 is temporarily blocked. Then, the CPU 117 performs actual photographing in the same manner as after the release in the still image mode.

  A case where the moving image mode is set will be described. After the moving image mode is set and released, the CPU 117 rotates the quick return mirror 101 to the position indicated by the broken line in FIG. 1, opens the shutter 106, and the subject light that has passed through the photographing lens L1 is captured by the image sensor. It is guided to 107. An image generated by performing the above-described processing on the image signal output from the image sensor 107 is recorded as a moving image on the memory card 123 and displayed on the LCD 120. The CPU 117 continues the above process while being released. When the release is completed, the CPU 117 rotates the quick return mirror 101 to the position indicated by the solid line in FIG. 1, the shutter 106 is closed, and the moving image shooting is ended.

Next, the protection function of the image sensor 107 in the live view mode or the moving image mode will be described.
-Live view mode-
When the live view mode is set by operating the operation unit 121, the subject light is incident on the image sensor 107 as described above. The CPU 117 outputs a signal (hereinafter referred to as highlight) indicating a high-luminance subject having an output of a predetermined light amount or more based on each image signal output from each pixel constituting the image sensor 107 or an output of an image signal. The presence or absence of a pixel in which is saturated is detected. That is, the CPU 117 detects the presence or absence of a pixel whose incident light amount exceeds a predetermined threshold value. Note that the threshold value depends on the characteristics of the image sensor 107 and is determined in advance as a value that does not cause the image sensor 107 to be burned by incident light from a large amount of light such as the sun.

  When a highlight is detected, the CPU 117 sets the shutter speed by the electronic shutter to the highest speed and narrows the aperture 201 so that the aperture value is maximized, that is, the exposure amount per unit time of the image is minimized. An exposure value is set and an image for highlight detection is acquired. Then, the CPU 117 uses the acquired highlight detection image to detect the presence / absence of highlight again as described above. When highlight is detected again by highlight detection, the CPU 117 starts time measurement. During the time T1, the acquisition of the highlight detection image and the detection of the presence / absence of the highlight are repeated at a predetermined time, for example, every second. If the highlight is detected even after the time T1 has elapsed, the CPU 117 displays a warning such as “Please do not point the camera at the sun” on the LCD 120, for example. Note that the image acquired by the CPU 117 with an appropriate exposure value is displayed on the LCD 120 until the next highlight detection image is acquired after the highlight detection image is acquired. When the highlight detection image is acquired, the CPU 117 displays on the LCD 120 an image acquired one frame before the highlight detection image is acquired.

  After a predetermined time, for example, 1 second has elapsed since the warning was displayed, the CPU 117 acquires a highlight detection image and detects the presence or absence of the highlight. When a highlight is detected, the CPU 117 starts time measurement as before the warning display, and during the time T2, acquisition and highlighting of highlight detection images are performed for a predetermined time, for example, every second. Repeated detection of presence or absence. If the highlight is still detected after the time T2 has elapsed, the CPU 117 displays a warning such as “End the live view mode” on the LCD 120, for example. The CPU 117 closes the shutter 106 and rotates the quick return mirror 101 to the position indicated by the solid line in FIG. 1 to block the optical path to the image sensor 107. As described above, when the incident light amount equal to or larger than the predetermined light amount is continuously detected for the predetermined time T1 + T2, the CPU 117 forcibly ends the live view mode. The times T1 and T2 are times determined depending on the durability of the image sensor 107.

-Movie mode-
After the moving image mode is set by the operation of the operation unit 121 and released, the quick return mirror 101 is raised and the shutter 106 is opened as in the live view mode, and the subject light continues to the image sensor 107 as described above. Then enter. In the same manner as in the live view mode, the CPU 117 detects the presence / absence of highlight based on each of the image signals output from each pixel constituting the image sensor 107. When highlight is detected, the CPU 117 reduces the aperture 201 so that the shutter speed of the electronic shutter is maximized and the aperture value is maximized, so that the exposure amount of the image per unit time is minimized. To acquire the highlight detection image again. Although the highlight detection image is acquired every second, the cycle for acquiring the highlight detection image is not limited to one second. The period for acquiring the highlight detection image may be changed depending on the durability of the image sensor 107 and the shooting conditions. Moreover, you may acquire the image for highlight detection for every predetermined imaging frequency. In this case, for example, the highlight detection image may be captured once every 30 times.

  When a highlight is detected from the highlight detection image, the CPU 117 acquires a highlight detection image every second for a predetermined time T1, as in the live view mode, and whether or not there is a highlight. Is detected. If the highlight is detected even after the predetermined time T1 has elapsed, the CPU 117 displays a warning such as “Please do not point the camera at the sun” on the LCD 120, for example. Further, the CPU 117 acquires a highlight detection image every second for a predetermined time T2 after the warning is displayed, and detects the presence or absence of the highlight. If the highlight is still detected after the time T2 has elapsed, the CPU 117 displays a warning such as “Finish the moving image mode” on the LCD 120, for example. The CPU 117 closes the shutter 106 and rotates the quick return mirror 101 to block the optical path to the image sensor 107. As a result, the moving image mode is forcibly ended by the CPU 117. Note that the highlight detection image acquired in the moving image mode is not recorded on the memory card 123 and is further controlled by the CPU 117 so as not to be displayed on the LCD 120.

The protection operation of the image sensor 107 of the camera according to the first embodiment will be described using the flowcharts shown in FIGS. 3 to 5 are executed by the CPU 117 executing a program. 3 to 5 are stored in a memory (not shown), and are activated when a shooting mode selection operation signal is input from the operation unit 121.
In step S1, it is determined whether the live view mode or the moving image mode is set by the operation unit 121. In the live view mode, the process proceeds to step S2. In step S2, a subroutine is called to perform the protection operation of the image sensor 107 in the live view mode, and the series of processes is terminated. When the moving image mode is set, the process proceeds to step S3, a subroutine is called, the protection operation of the image sensor 107 in the moving image mode is performed, and the series of processes is terminated.

Each process in the subroutine in the live view mode executed in step S2 will be described with reference to the flowchart shown in FIG.
In step S201, the quick return mirror 101 is rotated to the position indicated by the broken line in FIG. 1, the shutter 106 is opened, and the process proceeds to step S202. In step S202, flags i and j indicating that the time measurement is being performed are set to 0 by a timer (not shown), and the process proceeds to step S203. In step S203, an image is acquired under the photographing conditions set with the optimum exposure value, and the process proceeds to step S204.

  In step S204, the presence / absence of highlight is determined based on the image signal output from each pixel constituting the image sensor 107 using the image acquired in step S203. If there is no highlight, a negative determination is made in step S204, the process proceeds to step S206, the image acquired in step S203 is displayed on the LCD 120, and the process returns to step S203. If there is a highlight, that is, if there is a pixel whose amount of incident light exceeds a predetermined threshold, an affirmative decision is made in step S204 and the operation proceeds to step S205.

  In step S205, the image acquired in step S203 is displayed on LCD 120, and the process proceeds to step S207. In step S207, the shutter speed by the electronic shutter is set to the highest speed, the aperture 201 is narrowed down so that the aperture value is maximized, the highlight detection image is acquired, and the process proceeds to step S208. In step S208, the presence / absence of highlight is determined in the same manner as in step S204, using the highlight detection image acquired in step S207. If it is determined that there is a highlight, an affirmative determination is made in step S208 and the process proceeds to step S209.

  In step S209, it is determined whether or not the flag i is 0. If the flag i is 0, step S209 is affirmed and the process proceeds to step S210. In step S210, a timer (not shown) is started to start time measurement, the flag i is set to 1, and the process proceeds to step S211. When the flag i is 1, a negative determination is made in step S209, and step S210 is skipped and the process proceeds to step S211.

  In step S211, it is determined whether the time measured by the timer activated in step S210 has exceeded a predetermined time T1. If the time T1 is exceeded, an affirmative determination is made in step S211 and the process proceeds to step S212. In step S212, a warning such as “Please do not point the camera at the sun” is displayed on the LCD 120, and the process proceeds to step S213.

  In step S213, the timer started in step S210 is stopped and the process proceeds to step S214. In step S214, as in step S203, an image is acquired under the shooting conditions set to the optimum exposure value, and the process proceeds to step S215. In step S215, the image acquired in step S214 is displayed on LCD 120, and the process proceeds to step S216. In step S216, it is determined whether one second has elapsed since the warning was displayed in step S212. If one second has not elapsed, a negative determination is made in step S216, and the process returns to step S214. If 1 second has elapsed, an affirmative decision is made in step S216 and the operation proceeds to step S217. Steps S217 (highlight detection image acquisition) and step S218 (highlight presence / absence determination) are the same as steps S207 (highlight detection image acquisition) and step S208 (highlight presence / absence determination). Execute the process.

  In step S219, it is determined whether or not the flag j is 0. If the flag j is 0, an affirmative determination is made in step S219 and the process proceeds to step S220. In step S220, a timer (not shown) is started to start time measurement, the flag j is set to 1, and the process proceeds to step S221. When the flag j is 1, a negative determination is made in step S219, and step S220 is skipped and the process proceeds to step S221.

  In step S221, it is determined whether the time measured by the timer activated in step S220 has exceeded a predetermined time T2. If the predetermined time T2 is not exceeded, a negative determination is made in step S221 and the process returns to step S214. If the predetermined time T2 is exceeded, an affirmative determination is made in step S221 and the process proceeds to step S222.

  In step S222, a warning such as “Exiting the live view mode” is displayed on LCD 120, and the process proceeds to step S223. In step S223, the quick return mirror 101 is rotated to the position indicated by the solid line in FIG. 1, the shutter 106 is closed, and the series of processes is completed.

  In step S224, in which the negative determination is made in step S208, it is determined whether or not the flag i is 1. When the flag i is 1, an affirmative determination is made in step S224 and the process proceeds to step S225. In step S225, the timer started in step S210 is stopped and the process returns to step S202. If the flag i is 0, a negative determination is made in step S224 and the process returns to step S202.

  Each process from step S226 (image acquisition) to step S228 (1 second elapsed determination) advanced after the negative determination in step S211 is the same as each process from step S214 (image acquisition) to step S216 (1 second elapsed determination). Similar processing is performed.

  In step S229, in which the negative determination is made in step S218, it is determined whether or not the flag j is 1. If the flag j is 1, an affirmative determination is made in step S229 and the process proceeds to step S230. In step S230, the timer started in step S220 is stopped and the process proceeds to step S231. If the flag j is 0, a negative determination is made in step S229 and the process proceeds to step S231. In step S231, the warning displayed on LCD 120 in step S212 is deleted, and the process returns to step S202.

Each process in the subroutine in the moving image mode executed in step S3 will be described with reference to the flowchart shown in FIG.
In step S301, it is determined whether the operation unit 121 has been released. If the release is not performed, a negative determination is made in step S301, and the determination in step S301 is repeated. If the shutter has been released, an affirmative decision is made in step S301 and the operation proceeds to step S302. Each process from step S302 (mirror up and shutter open) to step S332 (warning clear) is the same as each process from step S201 (mirror up and shutter open) to step S231 (warning clear) in the flowchart of FIG. Perform processing.

According to the camera in the first embodiment described above, the following operational effects can be obtained.
(1) When an image is displayed on the LCD 120 in the live view mode or the moving image mode, a signal indicating a high-intensity subject having an output of a predetermined light amount or more in the image signal from the image sensor 107 continues for a time T1. If it is determined that it is included, the CPU 117 displays a warning on the LCD 120. Accordingly, the user is warned that the image sensor 107 may be burned by incident light from a high-luminance subject such as the sun, and the user must take necessary measures to protect the image sensor 107. Can do.

(2) The CPU 117 sets the shutter speed by the electronic shutter to the highest speed, narrows down the aperture 201 so that the aperture value is maximized, sets the exposure value so that the exposure amount per unit time is minimized, and sets 1 Get the frame image. Then, the CPU 117 detects whether or not the image signal from the image sensor 107 includes a signal indicating a high-luminance subject having an output of a certain amount of light or more using the acquired one-frame image. . That is, the CPU 117 detects that the output of the image sensor 107 exceeds a predetermined threshold under predetermined shooting conditions when shooting a high-luminance subject, so that the image sensor 107 is likely to be burned, such as the sun. It is possible to reliably detect a high-luminance subject.

(3) After displaying a warning on the LCD 120, the quick return mirror 101 is rotated to the position indicated by the solid line in FIG. 1, and the shutter 106 is fully closed. Accordingly, the incidence of subject light on the image sensor 107 is blocked, so that the image sensor 107 can be reliably prevented from being burned.

(4) Even when a warning is displayed on the LCD 120, the image signal from the image sensor 107 includes a signal indicating a high-luminance subject having an output of a certain amount of light or more continuously for a predetermined time T2. The CPU 117 uses the quick return mirror 101 and the shutter 106 to block the optical path on which the subject light enters the image sensor 107. Therefore, since the live view mode or the moving image mode does not end immediately after the warning is displayed, the user can select a response such as turning the camera in a different direction or ending the shooting.

-Second Embodiment-
The camera according to the second embodiment has the same configuration as the camera according to the first embodiment shown in FIGS. Hereinafter, differences from the protection operation of the image sensor 107 in the first embodiment will be mainly described. The camera according to the first embodiment monitors the presence / absence of a pixel that outputs an image signal exceeding a threshold value for all pixels of the image sensor 107 during times T1 and T2, and displays a warning, a live view mode, and a moving image mode. Canceled processing was executed. In the camera according to the second embodiment, for a specific pixel of the image sensor 107, a pixel that outputs an image signal exceeding a threshold is monitored for a time T1, T2, and the warning, the live view mode, and the moving image mode are stopped. Execute the process.

-Live view mode-
When the live view mode is set, the CPU 117 detects the presence / absence of highlight based on the image signal from each pixel constituting the image sensor 107 as in the case of the first embodiment. . When highlight is detected, the CPU 117 records the coordinates of the pixel whose incident light amount exceeds a predetermined threshold in a predetermined recording area. Then, the CPU 117 acquires the highlight detection image again, as in the case of the live view mode in the first embodiment.

  The CPU 117 detects the presence or absence of highlights using the acquired highlight detection image. When the highlight is detected, the CPU 117 determines whether or not the coordinates of the pixel whose incident light amount exceeds a predetermined threshold match the coordinates of the previously recorded pixel. When the coordinates of the respective pixels match, the CPU 117 repeats the acquisition of the highlight detection image, the detection of the presence / absence of the highlight, and the determination as to whether or not the pixels are the same during time T1, for example, every second. If the amount of light incident on the same pixel exceeds a predetermined value after the time T1 has elapsed, the CPU 117 displays a warning such as “Please do not point the camera at the sun” on the LCD 120, for example. When the highlight detection image is acquired, the CPU 117 displays the image acquired one frame earlier on the LCD 120, as in the first embodiment.

  After displaying the warning, the CPU 117 repeats the acquisition of the highlight detection image, the detection of the presence / absence of the highlight, and the determination of whether or not the pixels are the same for each time period T2. If the amount of light incident on the same pixel exceeds a predetermined threshold even after the time T2 has elapsed, the CPU 117 displays a warning such as “End the live view mode” on the LCD 120, for example. The CPU 117 closes the shutter 106 and rotates the quick return mirror 101 to the position indicated by the solid line in FIG. 1 to block the optical path to the image sensor 107. As a result, when the incident light amount equal to or larger than the predetermined light amount is continuously detected for the same pixel for the predetermined time T1 + T2, the CPU 117 forcibly ends the live view mode.

-Movie mode-
After the moving image mode is set and released, the CPU 117 detects the presence / absence of highlight based on the image signal from each pixel constituting the image sensor 107 as in the case of the first embodiment. When the highlight is detected, as in the live view mode, the CPU 117 records the coordinates of the pixel whose incident light amount exceeds a predetermined threshold in a predetermined recording area. Then, in the same manner as in the moving image mode in the first embodiment, the CPU 117 acquires the highlight detection image again.

  Thereafter, as in the live view mode, the CPU 117 repeats the determination of the presence / absence of highlight and the determination of whether or not the pixels are the same using the highlight detection image acquired every second for a predetermined time T1. When the amount of incident light on the same pixel exceeds the threshold after the predetermined time T1 has elapsed, the CPU 117 displays a warning such as “Please do not point the camera at the sun” on the LCD 120. Further, after displaying the warning, the CPU 117 acquires a highlight detection image every second for a predetermined time T2, detects the presence / absence of the highlight, and determines whether or not the pixel is the same. When the amount of incident light on the same pixel exceeds a predetermined threshold after the time T2 has elapsed, the CPU 117 displays a warning such as “Finish the moving image mode” on the LCD 120, for example. Then, the CPU 117 closes the shutter 106 and rotates the quick return mirror 101 to block the optical path to the image sensor 107 and forcibly ends the moving image mode.

The protection operation of the image sensor 107 of the camera according to the second embodiment will be described using the flowcharts shown in FIGS. Each processing procedure in FIGS. 6 to 7 is performed by the CPU 117 executing a program. A program for performing each process of FIGS. 6 to 7 is stored in a memory (not shown). The program for performing the process of FIG. 6 is activated when the process proceeds to step S2 in FIG. 3, and the program for performing the process of FIG. 7 is activated when the process proceeds to step S3 of FIG.
Each process from step S401 (mirror up, shutter open) to step S404 (highlight presence determination) in FIG. 6 is performed from step S201 (mirror up, shutter open) to step S204 (highlight presence determination) in FIG. The same processing as that described above is performed. In step S405, the coordinates of the pixel whose incident light amount detected in step S404 exceeds a predetermined threshold value are recorded, and the process proceeds to step S406.

  Each process from step S406 (image display) to step S409 (highlight presence / absence determination) is the same as each process from step S205 (image display) to step S208 (highlight presence / absence determination). In step S410, it is determined whether or not the coordinates of the pixel in which the amount of incident light detected in step S409 exceeds a predetermined threshold match the coordinates of the pixel recorded in step S405. If the coordinates match, an affirmative determination is made in step S410 and the process proceeds to step S411. If the coordinates do not match, a negative determination is made in step S410 and the process proceeds to step S427.

  Each process from step S411 (determination of flag i = 0) to step S420 (determination of presence / absence of highlight) is performed from step S209 (determination of flag i = 0) to step S218 (determination of presence / absence of highlight). The same processing is performed. In step S421, as in step S410, it is determined whether or not the coordinates of the pixel whose incident light amount detected in step S420 exceeds a predetermined threshold match the coordinates of the pixel recorded in step S405. If the coordinates match, an affirmative determination is made in step S421 and the process proceeds to step S422. If the coordinates do not match, a negative determination is made in step S421 and the process proceeds to step S432. Each process from step S422 (determination of flag j = 0) to step S434 (deletion of warning) performs the same process as each process from step S219 (determination of flag j = 0) to step S231 (deletion of warning). .

Next, the protection operation of the image sensor 107 when the moving image mode is set will be described with reference to FIG.
Each process from step S501 (release press determination) to step S505 (highlight presence determination) is the same as each process from step S301 (release press determination) to step S305 (highlight presence determination) in FIG. Perform processing. In step S506, the coordinates of the pixel whose incident light amount detected in step S505 exceeds a predetermined threshold are recorded, and the process proceeds to step S507.

  Each process from step S507 (image display) to step S510 (highlight presence / absence determination) is the same as each process from step S306 (image display) to step S309 (highlight presence / absence determination). In step S511, it is determined whether or not the coordinates of the pixel in which the incident light amount detected in step S510 exceeds a predetermined threshold match the pixel coordinates recorded in step S506. If the coordinates match, an affirmative decision is made in step S511 and the operation proceeds to step S512. If the coordinates do not match, a negative determination is made in step S511, and the process proceeds to step S528.

  Each process from step S512 (determination of flag i = 0) to step S521 (determination of presence / absence of highlight) is performed from step S310 (determination of flag i = 0) to step S319 (determination of presence / absence of highlight). The same processing is performed. In step S522, as in step S511, it is determined whether or not the coordinates of the pixel in which the amount of incident light detected in step S521 exceeds a predetermined threshold match the coordinates of the pixel recorded in step S506. If the coordinates match, an affirmative determination is made in step S522 and the process proceeds to step S523. If the coordinates do not match, a negative determination is made in step S522 and the process proceeds to step S533. Each process from step S523 (determination of flag j = 0) to step S535 (deletion of warning) is the same as each process from step S320 (determination of flag j = 0) to step S332 (deletion of warning). .

According to the camera of the second embodiment described above, in addition to the functions and effects obtained by the camera of the first embodiment, the following functions and effects are obtained.
The CPU 117 is configured to block the warning display and the optical path of incident light to the image sensor 107 when the output from the specific pixel of the image sensor 107 exceeds a predetermined threshold value for a predetermined time T1 and T2. Accordingly, it is possible to prevent a situation in which incident light from a high-luminance subject such as the sun forms an image at a specific location of the image sensor 107 for a long time and burns the image sensor 107.

The protection operation of the image sensor 107 by the camera of the embodiment described above can be modified as follows.
(1) Instead of detecting highlights based on image signals output from the respective pixels constituting the image sensor 107, the scene analysis of the subject is performed to detect high-intensity light sources such as the sun and highlight Detection may be performed. The scene analysis is performed by calculating the color temperature of each pixel based on the color information of each RGB color output from the image sensor 107. In this case, the CPU 117 may execute the protection operation of the image sensor 107 described with reference to FIG. 4 or FIG. 5 for the region corresponding to the region where the high-intensity light source is detected in the highlight detection image.

(2) When acquiring an image for highlight detection, in addition to setting the shutter speed by the electronic shutter to the fastest and narrowing the aperture 201 so that the aperture value is maximized, the ISO sensitivity is set to the minimum. Also good.
(3) If the dynamic range of the image sensor 107 is wide, it is not necessary to set the shutter speed by the electronic shutter and the control value of the aperture 201 to the minimum exposure values when acquiring the highlight detection image. In this case, when the incident light amount calculated from the highlight detection image picked up with the predetermined exposure set by the shutter speed and the aperture value is equal to or larger than the predetermined incident light amount determined in consideration of the durability of the image sensor. In addition, it may be determined that a high brightness subject is being imaged.

  In addition, the present invention is not limited to the above-described embodiment as long as the characteristics of the present invention are not impaired, and other forms conceivable within the scope of the technical idea of the present invention are also within the scope of the present invention. included.

It is a figure explaining the principal part structure of the camera in embodiment of this invention. It is a block diagram explaining the circuit structure of the control system of the camera in an embodiment. 4 is a flowchart for describing an image sensor protection operation of the camera according to the first embodiment. It is a flowchart explaining the image pick-up element protection operation | movement in live view mode. 5 is a flowchart for describing an image sensor protection operation in a moving image mode. 10 is a flowchart illustrating an image sensor protection operation in a live view mode according to the second embodiment. It is a flowchart explaining the image pick-up element protection operation in the moving image mode in 2nd Embodiment.

Explanation of symbols

101 Quick Return Mirror 106 Shutter 107 Image Sensor 117 CPU
120 LCD

Claims (7)

A mirror that switches between the optical path to the viewfinder optical system and the optical path to the image sensor that images the subject;
A display unit for displaying an image generated based on an image signal output from the image sensor;
Determination means for determining whether or not the image signal includes a signal indicating a high-luminance subject having an output of a predetermined light amount or more;
A camera comprising: a warning unit that displays a warning on the display unit when the determination unit determines that a signal indicating the high-luminance subject having an output equal to or greater than a predetermined amount of light is included. The camera of claim 1,
The determination means includes
Based on the image signal obtained when the subject is imaged with an exposure value that minimizes the exposure amount per unit time, a signal indicating the high-luminance subject having an output of a predetermined light amount or more is included in the image signal. A camera characterized by determining whether or not it is included. The camera according to claim 1 or 2,
The camera further comprising: a blocking unit that blocks an optical path incident on the imaging device after the warning by the warning unit. The camera according to claim 3.
The camera is characterized in that the blocking means performs either blocking of an optical path by the mirror or blocking of an optical path by a shutter provided in an incident optical path to the image sensor. The camera according to any one of claims 1 to 4,
A first time measuring means for measuring a time during which the signal indicating the high-luminance subject having an output of a predetermined light amount or more is continuously included in the image signal;
The warning means displays a warning on the display unit when the measured time is equal to or longer than a predetermined time. The camera according to claim 5, wherein
After the warning, the image signal further comprises a second time measuring means for measuring a time during which the signal indicating the high-luminance subject having an output of a predetermined light amount or more is continuously included,
The camera, wherein the blocking means blocks an optical path incident on the image sensor when the measured time is a predetermined time or more. The camera according to any one of claims 1 to 6,
The camera according to claim 1, wherein the determination unit performs determination based on an output value of a specific pixel in the image signal.

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