Camera external triggering system and method with high-precision triggering delay

Abstract

The invention provides a camera external triggering system and a camera external triggering method with high-precision triggering delay, which are used for solving the technical problems that in the existing camera external triggering shooting technology, as the triggering delay stability is related to the frame frequency of a camera, the triggering delay stability is poor, and the requirement of stable delay synchronization is difficult to realize. The camera external triggering system with high-precision triggering delay comprises the rising edge detection module, the time sequence reset module and the steady-state shooting module, and when the camera is externally triggered to shoot, the shooting frame frequency time sequence in the camera is dynamically adjusted through the rising edge detection module, the time sequence reset module and the steady-state shooting module, so that the shooting frame frequency time sequence in the camera is adjusted; the trigger delay can be reduced from the ms level to the ns level, and the stability of the trigger delay is irrelevant to the shooting frame frequency of the camera, so that stable trigger delay shooting can be realized.

Description

Technical Field

[0001] The present invention relates to camera external trigger technology, and in particular to a camera external trigger system and method with high-precision trigger delay. Background Art

[0002] Camera external triggering is mainly used in scenes where cameras are synchronized for shooting, such as binocular imaging, 3D imaging, and panoramic imaging. The stability of the trigger delay directly affects the synchronization accuracy. The synchronization principle of existing camera external trigger shooting technology is mainly the direct synchronization method. When an external trigger signal is received, shooting starts at the rising edge of the next shooting clock.

[0003] The working sequence of the existing camera external trigger shooting technology is mainly composed of the external trigger timing TRI, the camera clock CLK, the shooting clock FRAM_CLK, and the effective frame rate FRAM. Figure 1 As shown in the figure, it is a timing diagram of camera external trigger. After the camera is started, the camera clock CLK is automatically generated internally. Based on the camera clock CLK, the shooting clock FRAM_CLK is generated. When the trigger of the external trigger timing TRI is received, shooting starts at the next shooting clock FRAM_CLK.

[0004] After the camera is powered on, the shooting clock FRAM_CLK continues to run based on the camera clock CLK, but the triggering time of the external trigger timing TRI is uncertain. Figure 2 As shown in FIG. 1 , when the rising edge of the external trigger timing TRI arrives after the rising edge of the shooting clock FRAM_CLK, the trigger delay is the largest, that is, the maximum trigger delay T max 1 / f 1 , f 1 is the camera frame rate. Figure 3 As shown in Figure 1, when the rising edge of the external trigger timing TRI arrives at the same time as the rising edge of FRAM_CLK, the trigger delay is the smallest, that is, the minimum trigger delay T min is 0. Therefore, the trigger delay stability T jetter for:

[0005] T jetter =|T max -T min |=|1 / f 1 -0|=1 / f 1

[0006] It can be seen that in the existing camera external trigger shooting technology, the trigger delay stability is related to the camera frame rate, resulting in poor trigger delay stability and difficulty in achieving stable delay synchronization requirements. For example, when the camera frame rate is 30fps, the trigger delay stability is 33ms. Summary of the invention

[0007] The purpose of the present invention is to solve the technical problem in the existing camera external trigger shooting technology that the trigger delay stability is related to the camera frame rate, resulting in poor trigger delay stability and difficulty in achieving stable delay synchronization requirements, and to provide a camera external trigger system and method with high-precision trigger delay.

[0008] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0009] A camera external trigger system with high-precision trigger delay, which is special in that it includes a rising edge detection module, a timing reset module and a steady-state shooting module;

[0010] The two input ends of the rising edge detection module are respectively used to receive the external trigger timing TRI and the camera clock CLK, and detect the rising edge of the external trigger timing TRI through the camera clock CLK. When the rising edge of the external trigger timing TRI is detected, the reset timing RES is used as the output of the rising edge detection module, and the output is a low level. After the reset delay t, the reset timing RES is used as the output of the rising edge detection module, and the output is a high level.

[0011] The first input end of the timing reset module is connected to the output end of the rising edge detection module, and the second input end synchronously receives the camera clock CLK, and is used to generate a continuous square wave with a frequency of f when the reset timing RES is at a high level, and output it as the shooting clock FRAM_CLK, and stop outputting when the reset timing RES is at a low level;

[0012] The first input end and the second input end of the steady-state shooting module are connected to the output end of the rising edge detection module and the output end of the timing reset module respectively, and the third input end synchronously receives the camera clock CLK, which is used to detect the reset timing RES in real time, and outputs the effective frame rate FRAM with the same waveform as the shooting clock FRAM_CLK after detecting the rising edge of the reset timing RES; the rising edge of the effective frame rate FRAM is used as the camera triggering moment to trigger the camera to shoot;

[0013] The rising edge of the waveform output by the rising edge detection module, the timing reset module and the steady-state shooting module has the same phase as the camera clock CLK, and the period is an integer multiple of the camera clock CLK.

[0014] Furthermore, the reset delay t is greater than or equal to the reset time of the camera image chip.

[0015] Furthermore, the reset delay t is 1 us.

[0016] In addition, the present invention also provides a camera external triggering method based on the above-mentioned camera external triggering system with high-precision triggering delay, which is special in that it includes the following steps:

[0017] Step 1: Start the camera, and the camera will automatically generate a frequency f 0 The camera clock CLK;

[0018] Step 2, the rising edge detection module detects the external trigger timing TRI in real time. When the rising edge of the external trigger timing TRI is detected, the reset timing RES outputs a low level. After the reset delay t, the reset timing RES outputs a high level to reset the working timing;

[0019] Step 3, the timing reset module works according to the level state of the input reset timing RES. When the reset timing RES is at a low level, the timing reset module stops outputting. When the reset timing RES is at a high level, a continuous square wave with a frequency of f is generated inside the module, and the square wave with a frequency of f is used as the shooting clock FRAM_CLK.

[0020] Step 4, the steady-state shooting module detects the reset timing RES in real time, and after detecting the rising edge of the reset timing RES, outputs a valid frame rate FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the valid frame rate FRAM as the camera triggering moment to trigger the camera to shoot.

[0021] Furthermore, in step 2, the reset delay t is greater than or equal to the reset time of the camera image chip.

[0022] Furthermore, in step 2, the reset delay t is 1 us.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a camera external triggering system and method with high-precision trigger delay. When the camera is externally triggered for shooting, the shooting frame rate timing inside the camera is dynamically adjusted through a rising edge detection module, a timing reset module and a steady-state shooting module. The trigger delay can be reduced from 1 / frame rate (ms level) to 1 / camera high-speed clock (ns level). In addition, the trigger delay stability of the present invention is independent of the camera shooting frame rate, and stable trigger delay shooting can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A camera external trigger timing diagram of the existing camera external trigger shooting technology;

[0026] Figure 2 It is a timing diagram of the maximum trigger delay in the existing camera external trigger shooting technology;

[0027] Figure 3 It is a timing diagram of the minimum trigger delay in the existing camera external trigger shooting technology;

[0028] Figure 4It is a schematic block diagram of the principle of an embodiment of a camera external trigger system with high-precision trigger delay of the present invention;

[0029] Figure 5 This is a timing diagram of camera external triggering according to an embodiment of the present invention;

[0030] Figure 6 This is a timing diagram of the maximum trigger delay in an embodiment of the present invention;

[0031] Figure 7 Schematic diagram of the timing of the minimum trigger delay in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 4 As shown, a high-precision trigger delay camera external trigger system includes a rising edge detection module, a timing reset module and a steady-state shooting module. The rising edge detection module, the timing reset module and the steady-state shooting module all use the camera clock CLK as the reference for the working timing.

[0034] The two input ends of the rising edge detection module are used to receive the external trigger timing TRI and the camera clock CLK respectively, and detect the rising edge of the external trigger timing TRI through the camera clock CLK, and output the reset timing RES according to the detection result. Specifically, when the rising edge of the external trigger timing TRI is detected, the rising edge detection module outputs a low-level signal. After the reset delay t, the rising edge detection module outputs a high-level signal. All low-level signals and high-level signals form the reset timing RES, which is used to reset the working timing. Among them, the reset delay t is the reset time before the camera restarts shooting, which is generally not less than the reset time of the camera image chip.

[0035] The first input end of the timing reset module is connected to the output end of the rising edge detection module, and the second input end synchronously receives the camera clock CLK, which is used to generate a continuous square wave with a frequency of f when the reset timing RES is at a high level, and output it as the shooting clock FRAM_CLK, and stop outputting when the reset timing RES is at a low level.

[0036] The first input terminal and the second input terminal of the steady-state shooting module are respectively connected to the output terminal of the rising edge detection module and the output terminal of the timing reset module, and the third input terminal synchronously receives the camera clock CLK, which is used to detect the reset timing RES in real time. When the rising edge of the reset timing RES is detected, the effective frame rate FRAM with the same waveform as the shooting clock FRAM_CLK is output; the rising edge of the effective frame rate FRAM is used as the camera triggering moment to trigger the camera to perform effective shooting.

[0037] The working timing of the camera in the present invention is mainly composed of the external trigger timing TRI, the camera clock CLK, the reset timing RES, the shooting clock FRAM_CLK, and the effective frame rate FRAM, which are as follows:

[0038] (1) External trigger timing TRI: A square wave sent to the camera by an external device, usually using a rising edge or high level as the trigger starting point.

[0039] (2) Camera clock CLK: The camera internal frequency is f 0 The high-frequency clock is the reference for the working timing of each module in the camera. The rising edge of the output waveform of the rising edge detection module, the timing reset module and the steady-state shooting module is in phase with the camera clock CLK, the reset delay t is an integer multiple of the camera clock CLK, and the period of the output waveform of the timing reset module and the steady-state shooting module is also an integer multiple of the camera clock CLK. In this embodiment, f 0 It is 200MHz.

[0040] (3) Reset timing RES: generated by the rising edge detection module inside the camera, after detecting the rising edge of the external trigger, RES becomes a low level, and after a reset delay t, it sends a high level to reset the shooting clock. In this embodiment, the reset delay t is 1 μs.

[0041] (4) Shooting clock FRAM_CLK: It is generated by the timing reset module inside the camera. When the reset timing RES is at a high level, it starts to emit a square wave with a frequency of f. Each frame must be shot at the rising edge of the shooting clock FRAM_CLK. The value of f is related to the camera clock CLK. In this embodiment, f is 25 Hz.

[0042] (5) Effective frame rate FRAM: It is generated by the steady-state shooting module based on the shooting clock FRAM_CLK. The rising edge of the effective frame rate FRAM is used as the camera triggering moment to trigger the camera to take effective pictures.

[0043] Based on the above-mentioned high-precision trigger delay camera external trigger system, the present invention also provides a high-precision trigger delay camera external trigger method, which specifically includes the following steps:

[0044] Step 1, start the camera, the camera will automatically generate a camera clock CLK with a frequency of 200MH, and use it as the basis for the entire camera working timing.

[0045] Step 2, the rising edge detection module detects the external trigger timing TRI in real time. When the rising edge of the external trigger timing TRI is detected, the reset timing RES outputs a low level. After a delay of 1us, the reset timing RES outputs a high level to reset the working timing.

[0046] Step 3, the timing reset module works according to the level state of the input reset timing RES. When the reset timing RES is at a low level, the timing reset module stops outputting. When the reset timing RES is at a high level, a continuous square wave with a frequency of f is generated internally and used as the shooting clock FRAM_CLK.

[0047] Step 4, the steady-state shooting module detects the reset timing RES in real time, and after detecting the rising edge of the reset timing RES, outputs a valid frame rate FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the valid frame rate FRAM as the camera triggering moment to trigger the camera to shoot.

[0048] The present invention is based on the camera external trigger timing TRI, camera clock CLK, reset timing RES, shooting clock FRAM_CLK, and effective frame rate FRAM. Figure 5 After the camera is powered on, it continues to run with the camera clock CLK as the working timing reference, but the triggering time of the external trigger timing TRI is uncertain.

[0049] like Figure 6 As shown in the figure, when the rising edge of the external trigger timing TRI arrives after the rising edge of the camera clock CLK, the trigger delay is the largest, that is, the maximum trigger delay T max =t+1 / f 0 .like Figure 7 As shown in Figure 1, when the rising edge of the external trigger timing TRI and the rising edge of the camera clock CLK arrive at the same time, the trigger delay is the minimum, that is, the minimum trigger delay T min Therefore, the trigger delay stability T jetter for:

[0050] T jetter =|T max -T min |=|t+1 / f 0 -t|=1 / f 0

[0051] It can be seen that the trigger delay stability T from receiving the external trigger timing TRI to outputting the effective frame rate FRAM of the present invention is jetter Only with the camera internal frequency f 0 The trigger delay stability is 1 / f at any frame rate. 0 , that is, the trigger delay stability of the present invention has nothing to do with the camera frame rate. 0 Generally large, so the trigger delay stability is 1 / f 0 Very small, the trigger delay stability in this embodiment is 5ns, achieving ultra-high precision external trigger delay.

[0052] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A camera external trigger system with high-precision trigger delay, characterized in that: It includes a rising edge detection module, a timing reset module and a steady-state shooting module; The two input ends of the rising edge detection module are respectively used to receive the external trigger timing TRI and the camera clock CLK, and detect the rising edge of the external trigger timing TRI through the camera clock CLK. When the rising edge of the external trigger timing TRI is detected, the reset timing RES is used as the output of the rising edge detection module, and the output is a low level. After the reset delay t, the reset timing RES is used as the output of the rising edge detection module, and the output is a high level. The first input end of the timing reset module is connected to the output end of the rising edge detection module, and the second input end synchronously receives the camera clock CLK, and is used to generate a continuous square wave with a frequency of f when the reset timing RES is at a high level, and output it as the shooting clock FRAM_CLK, and stop outputting when the reset timing RES is at a low level; The first input end and the second input end of the steady-state shooting module are connected to the output end of the rising edge detection module and the output end of the timing reset module respectively, and the third input end synchronously receives the camera clock CLK, which is used to detect the reset timing RES in real time, and outputs the effective frame rate FRAM with the same waveform as the shooting clock FRAM_CLK after detecting the rising edge of the reset timing RES; the rising edge of the effective frame rate FRAM is used as the camera triggering moment to trigger the camera to shoot; The rising edge of the waveform output by the rising edge detection module, the timing reset module and the steady-state shooting module has the same phase as the camera clock CLK.

2. According to claim 1, a camera external trigger system with high-precision trigger delay, characterized in that: The reset delay t is greater than or equal to the camera image chip reset time.

3. The camera external trigger system with high-precision trigger delay according to claim 2, characterized in that: The reset delay t is 1 μs.

4. A camera external trigger method with high-precision trigger delay, using the camera external trigger system with high-precision trigger delay as described in any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1, start the camera, and the camera automatically generates a camera clock CLK with a frequency of f0; Step 2, the rising edge detection module detects the external trigger timing TRI in real time. When the rising edge of the external trigger timing TRI is detected, the reset timing RES outputs a low level. After the reset delay t, the reset timing RES outputs a high level to reset the working timing; Step 3, the timing reset module works according to the level state of the input reset timing RES. When the reset timing RES is at a low level, the timing reset module stops outputting. When the reset timing RES is at a high level, a continuous square wave with a frequency of f is generated inside the module, and the square wave with a frequency of f is used as the shooting clock FRAM_CLK. Step 4, the steady-state shooting module detects the reset timing RES in real time, and after detecting the rising edge of the reset timing RES, outputs a valid frame rate FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the valid frame rate FRAM as the camera triggering moment to trigger the camera to shoot.

5. The camera external triggering method with high-precision trigger delay according to claim 4 is characterized in that: In step 2, the reset delay t is greater than or equal to the reset time of the camera image chip.

6. The camera external triggering method with high-precision trigger delay according to claim 5, characterized in that: In step 2, the reset delay t is 1 μs.

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