A high-precision trigger delay camera external trigger system and method

Abstract

The application provides a high-precision camera external trigger system and method, which is used to solve the technical problem that the trigger delay stability is poor and it is difficult to realize stable delay synchronization demand in the existing camera external trigger shooting technology because the trigger delay stability is related to the camera frame frequency. The high-precision camera external trigger system provided by the application comprises a rising edge detection module, a timing reset module and a stable shooting module. When the camera is externally triggered to shoot, the shooting frame frequency timing of the camera is dynamically adjusted through the rising edge detection module, the timing reset module and the stable shooting module. The trigger delay can be reduced from the ms level to the ns level. The trigger delay stability of the application is not related to the camera shooting frame frequency, and stable trigger delay shooting can be realized.

Description

Technical Field

[0001] This invention relates to camera external triggering technology, and more particularly to a camera external triggering system and method with high-precision trigger delay. Background Technology

[0002] External camera triggering is mainly used in scenarios where cameras are simultaneously shooting, such as binocular imaging, 3D imaging, and panoramic imaging. The stability of the trigger delay directly affects the synchronization accuracy. The existing external camera triggering shooting technology mainly uses the direct synchronization method, which starts shooting on the rising edge of the next shooting clock after receiving an external trigger signal.

[0003] The existing timing sequence for externally triggered camera shooting technology mainly consists of the external trigger timing sequence (TRI), the camera clock (CLK), the shooting clock (FRAM_CLK), and the effective frame rate (FRAM). For example... Figure 1 The diagram shows the camera external trigger timing. After the camera starts, the camera clock CLK is automatically generated internally. Based on the camera clock CLK, the shooting clock FRAM_CLK is generated. When the external trigger timing TRI is received, shooting begins at the next shooting clock FRAM_CLK.

[0004] After the camera is powered on, the shooting clock FRAM_CLK runs continuously based on the camera clock CLK, but the triggering time of the external trigger timing TRI is uncertain. For example... Figure 2 As shown, the trigger delay is at its maximum when the rising edge of the external trigger timing TRI arrives after the rising edge of the shooting clock FRAM_CLK, i.e., the maximum trigger delay T. max It is 1 / f1, where f1 is the camera frame rate. For example... Figure 3 As shown, the trigger delay is minimized when the rising edge of the external trigger timing TRI arrives simultaneously with the rising edge of FRAM_CLK, i.e., the minimum trigger delay T. min The value is 0. Therefore, the trigger delay stability T is 0. jetter for:

[0005] T jetter =|T max -T min |=|1 / f1 -0|=1 / f1

[0006] It can be seen that in the existing 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 the synchronization requirement of stable delay. For example, when the camera frame rate is 30fps, the trigger delay stability is 33ms. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problem in 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. The invention provides a camera external triggering system and method with high-precision trigger delay.

[0008] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0009] A high-precision trigger delay camera external trigger system is characterized by including a rising edge detection module, a timing reset module, and a steady-state shooting module.

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

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

[0012] The first and second input terminals 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. The third input terminal synchronously receives the camera clock CLK and is used to detect the reset timing RES in real time. After detecting the rising edge of the reset timing RES, it outputs the effective frame frequency FRAM with the same waveform as the shooting clock FRAM_CLK. The rising edge of the effective frame frequency FRAM is used as the camera trigger moment to trigger the camera to shoot.

[0013] 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, 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 camera image chip reset time.

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

[0016] In addition, the present invention also provides a camera external triggering method based on the above-mentioned high-precision trigger delay camera external triggering system, which is characterized by including the following steps:

[0017] Step 1: Start the camera. The camera automatically generates a camera clock CLK with a frequency of f0.

[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 output is low. After a reset delay t, the reset timing RES output is high, thus resetting the working timing.

[0019] Step 3: The timing reset module operates according to the level state of the input reset timing RES. When the reset timing RES is low, the timing reset module stops outputting. When the reset timing RES is high, it generates a continuous square wave with a frequency of f, and uses the square wave with a frequency of f as the shooting clock FRAM_CLK.

[0020] Step 4: The steady-state shooting module detects the reset timing RES in real time. After detecting the rising edge of the reset timing RES, it outputs the effective frame frequency FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the effective frame frequency FRAM as the camera trigger time to trigger the camera to shoot.

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

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

[0023] The advantages of this invention compared to the prior art are as follows:

[0024] This invention provides a high-precision external triggering system and method for camera triggering with delay. When shooting with external triggering, the system dynamically adjusts the shooting frame rate timing of the camera through a rising edge detection module, a timing reset module, and a steady-state shooting module. This can reduce the trigger delay from 1 / frame rate (ms level) to 1 / camera high-speed clock (ns level). Furthermore, the trigger delay stability of this invention is independent of the camera shooting frame rate, enabling stable trigger-delay shooting. Attached Figure Description

[0025] Figure 1 This is a timing diagram of the external triggering of existing camera-external triggering shooting technology.

[0026] Figure 2 This is a timing diagram illustrating the maximum trigger delay in existing external camera-triggered shooting technologies.

[0027] Figure 3 This is a timing diagram illustrating the minimum trigger delay in existing external camera-triggered shooting technologies.

[0028] Figure 4This is a schematic block diagram illustrating the principle of an embodiment of a high-precision trigger delay camera external triggering system according to 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 illustrating the maximum trigger delay in an embodiment of the present invention;

[0031] Figure 7 This is a timing diagram illustrating the minimum trigger delay in an embodiment of the present invention. Detailed Implementation

[0032] To make the advantages and features of the present invention clearer, the present invention will be 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, timing reset module, and steady-state shooting module all use the camera clock CLK as their timing reference.

[0034] The rising edge detection module has two inputs: the external trigger timing sequence TRI and the camera clock CLK. It detects the rising edge of the external trigger timing sequence TRI using the camera clock CLK and outputs a reset timing sequence RES based on the detection result. Specifically, when a rising edge of the external trigger timing sequence TRI is detected, the rising edge detection module outputs a low-level signal. After a reset delay t, the rising edge detection module outputs a high-level signal. All the low-level and high-level signals form the reset timing sequence RES, used to reset the operating timing. The reset delay t is the reset time before the camera resumes shooting, and is generally not less than the camera image chip reset time.

[0035] The first input of the timing reset module is connected to the output of the rising edge detection module, and the second input synchronously receives the camera clock CLK. When the reset timing RES is high, it generates a continuous square wave with a frequency of f and outputs it as the shooting clock FRAM_CLK. When the reset timing RES is low, the output stops.

[0036] The first and second input terminals of the steady-state shooting module are connected to the output terminals of the rising edge detection module and the timing reset module, respectively. The third input terminal synchronously receives the camera clock CLK and 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 frequency FRAM with the same waveform as the shooting clock FRAM_CLK is output. The rising edge of the effective frame frequency FRAM is used as the camera trigger moment to trigger the camera to perform effective shooting.

[0037] The camera's operating timing in this invention mainly consists 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), as detailed below:

[0038] (1) External Trigger Timing (TRI): A square wave sent to the camera by an external device, which generally uses the rising edge or high level as the trigger start point.

[0039] (2) Camera Clock CLK: The high-frequency clock with an internal frequency of f0 in the camera serves as the reference for the timing of the various modules within the camera. The rising edges of the output waveforms from the rising edge detection module, timing reset module, and steady-state shooting module are in phase with the camera clock CLK. The reset delay t is an integer multiple of the camera clock CLK, and the periods of the output waveforms from the timing reset module and steady-state shooting module are also integer multiples of the camera clock CLK. In this embodiment, f0 is 200MHz.

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

[0041] (4) Shooting clock FRAM_CLK: Generated by the timing reset module inside the camera. When the reset timing RES is high, it starts to emit a square wave with a frequency of f. Each frame must be captured starting from 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 25Hz.

[0042] (5) Effective frame rate FRAM: generated by the steady-state shooting module based on the shooting clock FRAM_CLK, and the camera is triggered to perform effective shooting by using the rising edge of the effective frame rate FRAM as the camera trigger time.

[0043] Based on the aforementioned high-precision trigger delay camera external triggering system, this invention also provides a high-precision trigger delay camera external triggering method, specifically including the following steps:

[0044] Step 1: Start the camera. The camera automatically generates a 200MHz camera clock CLK, which is used as the reference for the entire camera's operating 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 output is low. After a delay of 1us, the reset timing RES output is high to reset the working timing.

[0046] Step 3: The timing reset module operates according to the level state of the input reset timing RES. When the reset timing RES is low, the timing reset module stops outputting. When the reset timing RES is high, it generates a continuous square wave with a frequency of f and uses it as the shooting clock FRAM_CLK.

[0047] Step 4: The steady-state shooting module detects the reset timing RES in real time. After detecting the rising edge of the reset timing RES, it outputs the effective frame frequency FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the effective frame frequency FRAM as the camera trigger time to trigger the camera to shoot.

[0048] This invention relates to a camera external trigger timing based on external trigger timing (TRI), camera clock (CLK), reset timing (RES), shooting clock (FRAM_CLK), and effective frame rate (FRAM) as follows: Figure 5 As shown. After the camera is powered on, it runs continuously 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, the trigger delay is at its maximum when the rising edge of the external trigger timing TRI arrives after the rising edge of the camera clock CLK, i.e., the maximum trigger delay T. max It is t+1 / f0. For example... Figure 7 As shown, the trigger delay is minimized when the rising edge of the external trigger timing TRI and the rising edge of the camera clock CLK arrive simultaneously, i.e., the minimum trigger delay T. min Let t be the trigger delay stability. jetter for:

[0050] T jetter =|T max -T min |=|t+1 / f0-t|=1 / f0

[0051] It can be seen that the trigger delay stability T between receiving the external trigger timing TRI and outputting the effective frame frequency FRAM in this invention is [not specified]. jetter It is only related to the high-frequency clock with frequency f0 inside the camera. At any frame rate, the trigger delay stability is 1 / f0, that is, the trigger delay stability of this invention is independent of the camera frame rate. At the same time, since f0 is generally relatively large, the trigger delay stability 1 / f0 is very small. In this embodiment, the trigger delay stability is 5ns, realizing ultra-high precision external trigger delay.

[0052] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

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

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

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

4. A high-precision trigger delay camera external triggering method, employing the high-precision trigger delay camera external triggering system as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Start the camera. 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 output is low. After a reset delay t, the reset timing RES output is high, thus resetting the working timing. Step 3: The timing reset module operates according to the level state of the input reset timing RES. When the reset timing RES is low, the timing reset module stops outputting. When the reset timing RES is high, it generates a continuous square wave with a frequency of f, and uses the square wave with a frequency of f as the shooting clock FRAM_CLK. Step 4: The steady-state shooting module detects the reset timing RES in real time. After detecting the rising edge of the reset timing RES, it outputs the effective frame frequency FRAM with the same waveform as the shooting clock FRAM_CLK, and uses the rising edge of the effective frame frequency FRAM as the camera trigger time to trigger the camera to shoot.

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

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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