Imaging apparatus, method for controlling the same, program, and storage medium

Abstract

To provide an imaging apparatus capable of reducing the irregularity of a shutter time lag when performing photographing, while performing LV display.SOLUTION: The imaging apparatus for imaging an image for recording, while displaying a live view image includes a first timing generation part for generating the reading timing of an imaging element, a second timing generation part for generating the system timing of the imaging apparatus, a third timing generation part having a synchronous relationship with the second timing generation part and generating the update timing of the display of an image, a difference detection part for detecting a difference between the reading timing and the system timing at a predetermined timing, and a control part for delaying the update timing from the system timing, according to the difference and synchronizing the reading timing and the update timing.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an imaging device and a control method thereof.

Background Art

[0002] In recent years, in addition to compact digital cameras, mirrorless cameras have become increasingly popular, and as a display member for confirming a subject, those equipped with a display panel or an electronic viewfinder (hereinafter referred to as EVF) mounted on the back of the camera are increasing. The function of confirming a subject, which has been performed by a conventional optical viewfinder (OVF), has been assigned to a live view (hereinafter referred to as LV) image displayed on a display panel on the back or an EVF.

[0003] The LV image is realized by displaying image data obtained from an image sensor provided in the imaging device on a display panel on the back or an EVF. Here, when the imaging device has one image sensor, the image sensor needs to output both image data for still image recording and image data for LV display. In that case, the LV display reading has to be performed while the still image is being read out, and the control is not easy. Therefore, conventionally, while the image sensor is reading out image data for still image recording, processing such as blacking out the display has been performed.

[0004] In Patent Document 1, the exposure time of imaging one still image is divided to obtain a plurality of still images that are synthesized into one still image, and at the same time, one or more of the plurality of still images are sequentially used as LV images to perform LV display during a period when the LV image cannot be captured.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, with the conventional technology described above, image data for LV display is continuously displayed at regular intervals regardless of whether shooting is taking place or not. Therefore, during shooting, it was necessary to synchronize the image sensor readout timing with the LV display timing. As a result, the time from the start of shooting to the image sensor readout varied from one shoot to the next, leading to problems such as the inability to guarantee shutter time lag.

[0007] This invention has been made in view of the above-mentioned problems, and its purpose is to provide an imaging device that can reduce variations in shutter time lag when taking pictures while displaying LV. [Means for solving the problem]

[0008] The imaging device according to the present invention is an imaging device that captures a recording image while displaying a live view image, and is characterized by comprising: a first timing generation means for generating a readout timing of an image sensor; a second timing generation means for generating a system timing of the imaging device; a third timing generation means which is synchronous with the second timing generation means and generates an update timing for the display of the image; a difference detection means for detecting the difference between the readout timing and the system timing at a predetermined timing; and a control means for delaying the update timing from the system timing according to the difference and synchronizing the readout timing and the update timing. [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce variations in shutter time lag when shooting while displaying LV (Live View). [Brief explanation of the drawing]

[0010] [Figure 1] A block diagram showing the configuration of an imaging device according to a first embodiment of the present invention. [Figure 2]A timing chart showing the shooting process. [Figure 3] A timing chart showing the synchronization process in the first embodiment. [Figure 4] A timing chart showing the continuous shooting process. [Figure 5] A flowchart illustrating the operation of the imaging device in the second embodiment. [Figure 6] A flowchart illustrating the operation of the imaging device in the third embodiment. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0012] (First embodiment) Figure 1 is a block diagram showing the configuration of an imaging device according to a first embodiment of the present invention.

[0013] In Figure 1, the imaging device 100 includes an imaging unit 101, an image processing unit 102, a display unit 103, a display device 104, a control unit 105, a memory unit 107, an operation unit 108, a first timing generation unit 110, a second timing generation unit 111, and a synchronization signal generation unit 112. The control unit 105 is connected to a ROM 121 that stores a control program executed by the control unit 105 to control the entire imaging device 100, and a RAM 122 that the control unit 105 uses as a work area for executing the program.

[0014] The imaging device 100 also includes a compression / decompression unit for compressing image data or decompressing compressed data, and an external recording unit (neither of which are shown) for recording compressed data onto an external medium. The imaging device 100 has a function to capture a live view image and display a live view. Hereinafter, live view may be referred to as LV. The first timing control unit 110 generates a timing signal for reading signals from the image sensor 101a, and the second timing control unit 111 generates a timing signal for live view display.

[0015] The imaging unit 101 has an image sensor 101a, such as a CCD or CMOS sensor, which converts the received image of a subject into an electrical signal to create image data. The imaging unit 101 also has an AD converter that converts the analog image signal obtained by the image sensor 101a into a digital signal and outputs it as image data. The image data output from the imaging unit 101 is written to the memory unit 107 via the image processing unit 102.

[0016] The image processing unit 102 performs multiple processes such as shading correction, scratch correction, white balance adjustment, and gamma correction. By using one or more of these processes, the image processing unit 102 applies appropriate image processing to the image data. The image processing unit 102 also writes the processing results of the image processing to the memory unit 107.

[0017] The display unit 103 controls the display of the display device 104. The display unit 103 acquires image data processed by the image processing unit 102 from the memory unit 107 via the image processing unit 102. Then, it generates a display image after performing the necessary processing on the image data, superimposes it on the synchronization signal received from the synchronization signal generation unit 112 (described later), and transfers it to the display device 104.

[0018] The display unit 103 performs tasks such as brightness and color adjustment, scaling to fit the display image to the size of the display device 104, overlaying OSD (On-Screen Display) images, and format conversion to match the display device 104.

[0019] The display device 104 is composed of, for example, a liquid crystal display (LCD), an organic EL display (OLED), etc., and displays the image sent from the display unit 103. The display device 104 constitutes, for example, the display panel on the back of a digital camera and an electronic viewfinder (EVF). LV display is performed on the display panel and the electronic viewfinder.

[0020] The control unit 105 includes one or more processors that control the operation of the imaging device 100, and executes various controls and processes based on user operations via the operation unit 108 described later. For example, the control unit 105 controls the imaging unit 101, the image processing unit 102, the display unit 103, the first timing generation unit 110, the second timing generation unit 111, and the synchronization signal generation unit 112. In addition, it has a difference detection function for detecting the time difference between the timing output signals of the first timing generation unit 110 and the second timing generation unit 111.

[0021] The memory unit 107 has a storage capacity sufficient to store data such as a predetermined number of still images, a moving image for a predetermined time, and audio, and is composed of, for example, DRAM, etc. Note that the memory unit 107 may include a plurality of memories.

[0022] The operation unit 108 is used for the user to input to the control unit 105 a shutter operation and operations of various parameters of the imaging device 100. The parameters of the imaging device 100 are, for example, the ISO sensitivity setting value, the shutter speed setting value, etc.

[0023] The first timing generation unit 110 generates the timing for starting the readout of the image signal from the image sensor 101a. It operates according to instructions from the control unit 105, and for example, when taking still images, it outputs a single timing signal in conjunction with pressing the shutter button. When taking continuous images, it continues to output timing signals at regular intervals according to the specifications of the imaging device 100 while the shutter button is pressed. When displaying LV, it continues to output timing signals at regular intervals specified by standards such as SMPTE (Society of Motion Picture and Television Engineers).

[0024] The second timing generation unit 111 generates the image update timing for the display device 104 and outputs it to the synchronization signal generation unit 112. This timing conforms to standards such as SMPTE. It also outputs a timing signal to the control unit 105 for use in reflecting parameter settings of the imaging device 100. This signal is usually the same timing signal as the signal output to the synchronization signal generation unit 112.

[0025] The synchronization signal generation unit 112 generates synchronization signals for the display device 104 and transmits them to the display unit 103. Synchronization signals include, for example, vertical synchronization signals (vblank, vsync) and horizontal synchronization signals (hblank, hsync). The synchronization signal generation unit 112 is in a synchronous relationship with the second timing generation unit 111 because it needs to operate at the same timing as the second timing generation unit 111, which generates timing compliant with standard specifications. However, it needs to output signals that depend on the display format and display device, and therefore operates on a different clock than the second timing generation unit 111. For this reason, the second timing generation unit 111 and the synchronization signal generation unit 112 exist as separate blocks.

[0026] Figure 2 shows an example of a timing chart indicating the timing of readout from the image sensor 101a and LV display. The image sensor readout timing 201 is the output of the first timing generation unit 110 and indicates the timing of the start of readout of the image signal from the image sensor 101a belonging to the imaging unit 101. The image sensor readout time 202 indicates the time during which the image is read from the image sensor 101a.

[0027] The LV display timing 203 is a signal output from the second timing generation unit 111 to the synchronization signal generation unit 112, and indicates the update timing of the LV display. The vblank 204 is part of the signal output from the synchronization signal generation unit 112 to the display unit 103, and indicates the vblank signal. The LV display time 204 indicates the time the LV is displayed on the display device 104.

[0028] When the shutter button is pressed at time 206, the readout of image 1 from the image sensor begins at time 207. Triggered by the completion of image 1 readout at time 208, the readout of image 2 for the LV image begins at the next image sensor readout time 209. Furthermore, at the LV display update time 210, synchronized with the image sensor readout time 209 (this synchronization will be described later), the display of image 2' on the display device 104 begins. Note that the readout time of the image sensor 101a, i.e., the time between time 207 and time 208, is a value determined by shooting conditions such as exposure time, and the completion time of image 1 readout at time 208 can be determined at the start time of image 1 readout 207.

[0029] Here, we will explain how to synchronize the LV display timing with the image sensor readout timing using Figure 3.

[0030] As already explained, the image sensor readout timing 201 is the output of the first timing generation unit 110. The counter 302 shows the transition of the count value of the counter circuit for generating the system timing 303 and the LV display timing 203. The system timing 303 is a signal output from the second timing generation unit 111 to the control unit 105.

[0031] The LV display timing 203 is a signal output from the second timing generation unit 111 to the synchronization signal generation unit 112. The counter 305 shows the transition of the count value of the counter circuit for generating the synchronization signal generation timing 306 and vblank 204.

[0032] The synchronization signal generation timing 306 is a signal output from the synchronization signal generation unit 112 to the control unit 105. Also, vblank204 is a signal output from the synchronization signal generation unit 112 to the display unit 103.

[0033] Counters 302 and 305 both operate in down-count mode. The initial values ​​a and b of the counters correspond to the interval at which timings are generated, i.e., the total number of pixels in one image. When the count value is "0", the initial values ​​of the counters are loaded, and various timings are output simultaneously.

[0034] vblank204 is part of the synchronization signal to the display device 104 and is generated by referencing the count value of counter 305. Specifically, the count values ​​n and m of counter 305, corresponding to the rising and falling edges of the vblank204 waveform, are set. Normally, the LV display timing 203 and the synchronization signal generation timing 306 are synchronized, but specifically, the timing is aligned by loading the initial value b of the counter 305's count value using the output of the timing signal of the LV display timing 203.

[0035] The time difference between the image sensor readout timing 201 and the LV display timing 203 detected by the control unit 105 is assumed to be d. The process up to the execution of the synchronization process at time 308 will be explained in reverse. Various settings are made at the synchronization signal generation timing 306 and are reflected in the circuit at the next synchronization signal generation timing.

[0036] At time 309, a setting equivalent to the delay amount d is made for the LV display timing 203. Specifically, the value set is obtained by subtracting the count value d' equivalent to the delay amount d from the initial value a of counter 302, "a-d'". As a result, at the time when the count value of counter 302 becomes a-d', i.e., timing 211, a timing signal is output to counter 305, and the initial value b of counter 305 is loaded at this timing.

[0037] The system timing 303 and LV display timing 203 output their timings by referring to the count value 302. However, without changing the timing of the system timing 303, only the LV display timing 203 is synchronized with the image sensor readout timing 201.

[0038] Furthermore, the synchronization signal generation timing 306 and vblank 204 are always synchronized with the LV display timing 203, and follow the LV display timing 211 without changing the initial value of the counter 305 or the rising and falling edge settings of vblank.

[0039] In other words, the timing of image sensor readout (time 312) and the timing of synchronization signal generation (time 310) coincide, and synchronization was performed for approximately 1V from the initial setting time (time 309) to the time 308 when synchronization was executed (synchronization processing time).

[0040] As explained above, the synchronization start time is determined at the readout start time of Image 1 (207), and the synchronization process is started at the time (211) when Image 1 is being read out from the image sensor. As a result, the time (210) on the LV display follows the image sensor readout time (209), and synchronization is performed.

[0041] In this way, instead of synchronizing the image sensor readout timing with the LV display timing during shooting, synchronizing the LV display timing with the readout timing makes it possible to reduce the shutter time lag for each shot.

[0042] (Second embodiment) In the first embodiment, the synchronization method shown in Figure 3 requires approximately 1V for the synchronization process.

[0043] Figure 4 shows an example of a timing chart when the readout time for still image capture is short, as shown in Image 5. The legend for the timing chart is the same as in Figure 2.

[0044] When the shutter button is pressed at time 401, the readout of image 5 from the image sensor begins at time 402. Triggered by the completion of the readout of image 5 at timing 403, the readout of image 6, which is an LV image, begins at the next still image readout timing 404. At the LV display timing 405, synchronized with the still image readout timing 404, the display of image 6' on the display device 104 begins.

[0045] Here, the readout time for still image capture is less than 1V, and if we go back approximately 1V from the LV display update time 405, which is the time required for synchronization processing, the timing of the start of synchronization processing will be before the start of image 5 readout timing 402, meaning that the synchronization processing will not be completed in time.

[0046] In the second embodiment, a method for suppressing shutter time lag will be described when the synchronization method shown in Figure 3 is applied to continuous shooting, taking into account the case where the readout time for still image shooting is short.

[0047] Figure 5 is a flowchart illustrating the operation of continuous shooting in this embodiment. The operation shown in the flowchart of Figure 5 is realized by the control unit 105 loading the control program stored in the ROM 121 into the RAM 122 and executing it. The configuration of the imaging device in this embodiment is the same as that of the first embodiment.

[0048] First, in step S501, this flow is initiated.

[0049] In step S502, the control unit 105 sets a threshold a to determine whether or not to perform the synchronization process. In practice, it sets a value corresponding to the time required for the synchronization to be performed, which in this embodiment corresponds to "1V".

[0050] In step S503, the control unit 105 starts continuous shooting in response to a user's instruction to start shooting, such as pressing the shutter button.

[0051] In step S504, the control unit 105 starts reading out the image signal from the image sensor 101a.

[0052] As mentioned above, the readout time of the image sensor 101a can be determined at the timing of the start of readout from the image sensor 101a. Therefore, in step S505, the control unit 105 determines the readout time t of the signal from the image sensor 101a.

[0053] In step S506, the control unit 105 compares the threshold a set in step S502 with the readout time t of the image sensor 101a determined in step S505. If "t > a", the control unit 105 proceeds to step S507 and starts the synchronization process at a time that is the time required for the synchronization to be performed, prior to the timing when the synchronization should be performed. If "t ≤ a", the control unit 105 does not perform the synchronization process and proceeds to step S508.

[0054] In step S508, the control unit 105 determines whether the user has instructed the end of continuous shooting, such as by ceasing to press the shutter button. If continuous shooting has not ended, the control unit 105 returns to step S504. If continuous shooting has ended, the operation of this flow ends in step S509.

[0055] As explained above, according to the second embodiment, by determining the time required for signal readout from the image sensor and deciding whether or not to perform synchronization processing depending on the length of the signal readout time from the image sensor, it is possible to reduce the shutter time lag for each shot.

[0056] (Third embodiment) While the continuous shooting speed of imaging devices is increasing year by year, there is also a demand for conventional, relatively slower continuous shooting. In response to this, recent imaging devices have made it possible for users to select the continuous shooting speed. Furthermore, in the synchronization method described in Figure 3 in the first embodiment, the visibility of the LV display is improved, but the shorter the shooting interval in continuous shooting, the less the shutter time lag is perceived due to the characteristics of human vision. Based on this fact, the third embodiment will describe a method of changing the synchronization method described in Figure 3 according to the continuous shooting speed.

[0057] Figure 6 is a flowchart showing the operation of continuous shooting in the third embodiment. The operation of the flowchart in Figure 6 is realized by the control unit 105 loading the control program stored in the ROM 121 into the RAM 122 and executing it. The configuration of the imaging device in this embodiment is the same as that of the first embodiment.

[0058] First, in step S601, this flow is initiated.

[0059] In step S602, the control unit 105 sets a threshold b to determine whether or not to perform the synchronization process. In practice, this is set to a value corresponding to the continuous shooting speed, for example, the number of frames shot per second.

[0060] In step S603, the control unit 105 selects the continuous shooting speed v based on the user's operation. In this embodiment, the continuous shooting speed is described as being either "faster" or "slower" than the threshold b set in step S602, but there may be more than two switching levels.

[0061] In step S604, the control unit 105 starts continuous shooting in response to a user's instruction to start shooting, such as pressing the shutter button.

[0062] In step S605, the control unit 105 compares the threshold b set in step S602 with the continuous shooting speed v. If v ≤ b, the control unit 105 proceeds to step S606; if v > b, it proceeds to step S609.

[0063] In step S606, the control unit 105 starts reading out the image signal from the image sensor 101a.

[0064] In step S607, the control unit 105 starts the synchronization process at a time that is set back from the timing at which the synchronization is to be performed by the time required for the synchronization to be performed.

[0065] In step S608, the control unit 105 determines whether the user has stopped pressing the shutter button or otherwise instructed the end of continuous shooting. If continuous shooting has not ended, the control unit 105 returns to step S606. If continuous shooting has ended, the operation of this flow ends in step S611.

[0066] Meanwhile, in step S609, the control unit 105 starts reading out the image signal from the image sensor 101a.

[0067] In step S610, the control unit 105 determines whether the user has stopped pressing the shutter button or otherwise instructed the end of continuous shooting. If continuous shooting has not ended, the control unit 105 returns to step S609. If continuous shooting has ended, the operation of this flow ends in step S611.

[0068] As described above, according to the third embodiment, the decision of whether or not to perform synchronization processing is made based on the continuous shooting speed. The determination of the continuous shooting speed may be made by referring to various statuses of the imaging device, such as the remaining buffer capacity during continuous shooting.

[0069] The disclosures herein include the following imaging devices, methods, and programs.

[0070] (Item 1) An imaging device that captures images for recording while displaying a live view image, A first timing generation means for generating the readout timing of the image sensor, A second timing generation means for generating the system timing of the imaging device, A third timing generation means, which is in a synchronous relationship with the second timing generation means, generates the update timing for the image display, A difference detection means for detecting the difference between the read timing and the system timing at a predetermined timing, Control means for delaying the update timing from the system timing according to the difference, and synchronizing the read timing and the update timing, An imaging device characterized by comprising:

[0071] (Item 2) The imaging apparatus according to item 1, characterized in that the second timing generation means is configured using a counter.

[0072] (Item 3) The imaging apparatus according to item 2, characterized in that the update timing is delayed based on the value of the counter of the second timing generation means.

[0073] (Item 4) The imaging apparatus according to any one of items 1 to 3, characterized in that the third timing generation means is configured using a counter.

[0074] (Item 5) The imaging apparatus according to any one of items 1 to 4, characterized in that the second timing generation means generates a signal with the same timing as the third timing generation means.

[0075] (Item 6) The imaging apparatus according to any one of items 1 to 5, characterized in that the third timing generation means outputs a vertical synchronization signal and a horizontal synchronization signal.

[0076] (Item 7) The imaging device according to any one of items 1 to 6, characterized in that the control means determines whether or not to synchronize the readout timing and the update timing based on the shooting conditions of the imaging device.

[0077] (Item 8) The imaging apparatus according to item 7, characterized in that the control means performs the synchronization when the readout time of the signal from the image sensor based on the shooting conditions of the imaging apparatus is longer than the processing time for the synchronization.

[0078] (Item 9) The imaging device according to any one of items 1 to 8, characterized in that the predetermined timing is the timing at which the capture of the image for recording is instructed.

[0079] (Item 10) The imaging device according to any one of items 1 to 9, characterized in that the control means performs the synchronization when the shooting interval of continuous shooting is longer than predetermined.

[0080] (Item 11) A method for controlling an imaging device that captures images for recording while displaying a live view image, A first timing generation step for generating the readout timing of the image sensor, A second timing generation step for generating the system timing of the imaging device, A third timing generation step, which is synchronous with the second timing generation step and generates the update timing for displaying the image, A difference detection step for detecting the difference between the read timing and the system timing at a predetermined timing, A control step that delays the update timing from the system timing according to the difference, and synchronizes the read timing and the update timing, A control method for an imaging device, characterized by having the following features.

[0081] (Item 12) A program that causes a computer to execute each step of the control method described in item 11.

[0082] (Item 13) A computer-readable storage medium containing a program that causes a computer to execute each step of the control method described in item 11.

[0083] (Other embodiments) Furthermore, the present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0084] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0085] 101: Imaging unit, 101a: Image sensor, 102: Image processing unit, 103: Display unit, 104: Display device, 105: Control unit, 107: Memory unit, 108: Operation unit, 110: First timing generation unit, 111: Second timing generation unit, 112: Synchronization signal generation unit

Claims

1. An imaging device that captures an image for recording while displaying a live view image, a first timing generating means for generating a read timing of the image sensor; a second timing generating means for generating a system timing of the imaging device and an update timing of an image display; a synchronization signal generating means for generating a synchronization signal for a display device based on the update timing; a difference detection means for detecting a difference between the read timing and the system timing at a predetermined timing; a control means for delaying the update timing from the system timing in accordance with the difference, and synchronizing the read timing and the update timing; An imaging device comprising:

2. The imaging device as described in Claim 1, characterized in that the second timing generation means and the synchronization signal generation means operate on different clocks.

3. 2. The image pickup apparatus according to claim 1, wherein the second timing generating means is configured using a counter.

4. 3. The image pickup apparatus according to claim 2, wherein the update timing is delayed based on a value of a counter of the second timing generating means.

5. 2. The image pickup apparatus according to claim 1, wherein the synchronization signal generating means is configured using a counter.

6. 2. The image pickup apparatus according to claim 1, wherein the second timing generating means generates a signal having the same timing as that of the synchronization signal generating means.

7. 2. The image pickup apparatus according to claim 1, wherein the synchronization signal generating means outputs a vertical synchronization signal and a horizontal synchronization signal.

8. 2. The image pickup apparatus according to claim 1, wherein the control means determines whether or not to synchronize the read timing and the update timing based on an image pickup condition of the image pickup apparatus.

9. 8. The imaging device according to claim 7, wherein the control means executes the synchronization when a readout time of a signal from the imaging element based on an imaging condition of the imaging device is longer than a processing time for the synchronization.

10. 2. The imaging apparatus according to claim 1, wherein the predetermined timing is a timing when an instruction to capture the image for recording is given.

11. 2. The imaging apparatus according to claim 1, wherein the control means executes the synchronization when an interval between successive photographing operations is longer than a predetermined interval.

12. 1. A method for controlling an imaging device that captures an image for recording while displaying a live view image, comprising: a first timing generation step of generating a readout timing of the image sensor; a second timing generation step of generating a system timing of the imaging device and an update timing of an image display; a synchronization signal generating step of generating a synchronization signal for a display device based on the update timing; a difference detection step of detecting a difference between the read timing and the system timing at a predetermined timing; a control step of delaying the update timing from the system timing according to the difference, thereby synchronizing the read timing and the update timing; 13. A method for controlling an imaging apparatus comprising:

13. A program for causing a computer to execute each step of the control method according to claim 12.

14. A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to claim 12.

Images