A method and device for generating an exposure trigger signal in an external trigger mode

Abstract

The present invention discloses a method and device for generating an exposure trigger signal in an external trigger mode. The method for generating an exposure trigger signal specifically includes: monitoring an external trigger signal to be processed, and providing an initial trigger cycle and a corresponding initial pulse valid signal; pre-dividing the external trigger signal according to the pre-adjustment of the initial trigger cycle, and obtaining a first trigger cycle and a corresponding first trigger signal; based on the adjustment of the first trigger cycle, dividing and doubling the first trigger signal, and obtaining a second trigger cycle and a corresponding second trigger signal; combining comparative analysis of the initial pulse valid signal and the second trigger signal, synchronously processing the second trigger signal, and providing an exposure trigger signal. The exposure trigger signal generation scheme provided by the present invention can improve the stability and accuracy of the trigger, and also ensure the synchronization of the exposure trigger signal and the external trigger signal, and adapt to the exposure trigger requirements in different application scenarios.

Description

Technical Field

[0001] The present invention belongs to the technical field of camera exposure trigger control, and in particular relates to a method and device for generating an exposure trigger signal in an external trigger mode. Background Art

[0002] The common trigger modes of industrial cameras are generally divided into two modes: internal trigger and external trigger. Internal trigger is the trigger signal given by the device to control the camera to acquire images, while external trigger is the signal given by the external device connected to the camera to acquire images.

[0003] The external trigger mode can control multiple cameras for signal acquisition simultaneously through one trigger source, which can ensure the synchronization of signal acquisition of multiple cameras and has strong flexibility. It is widely used in actual production.

[0004] For example, patent CN114630044A provides a method for synchronous external triggering of multiple cameras in multi-channel dynamic interferometry. The USB to TTL serial port module is connected to the computer and the industrial camera. The serial port module uses the USB serial interface to communicate with the computer. The trigger signal sent by the serial port module is transmitted to the splitter through the SMA radio frequency line. After being split by the splitter, it is transmitted to the industrial camera through the No. 2 pin of the GPIO line. Then, LabVIEW is used to control the serial port module on the host computer to send a trigger signal. The trigger signal sent by the serial port module reaches each camera at the same time through the branch for synchronous triggering. The internal triggering is avoided because the inherent mechanical properties of the timing chip are inconsistent, so the internal trigger signals generated by the two industrial cameras have a time difference. Compared with other external triggering methods, it has the characteristics of small size, low cost, simple structure and easy control.

[0005] In addition, there are many studies on key issues such as the synchronization of signal acquisition of multiple cameras. For example, patent CN115277982A provides a synchronous exposure processing method, device and storage medium, which can solve the problem of frame loss when a multi-camera system is collecting images and achieve synchronous exposure. The method includes: determining the first duration of the target image sensor; the first duration is the time required for the target image sensor to generate and transmit a frame of image; the first duration is less than a signal cycle of the exposure trigger signal received by the target image sensor; at least based on the first duration, determining the minimum pixel clock frequency of the target image sensor; based on the minimum pixel clock frequency, determining the target pixel clock frequency of the target image sensor; the target pixel clock frequency is greater than or equal to the minimum pixel clock frequency; based on the target pixel clock frequency, controlling the target image sensor to perform an exposure operation, so that multiple image sensors of the multi-camera system are exposed synchronously.

[0006] Although the external trigger technology has made significant progress, there are still some problems and challenges in practical application. The main points are as follows: 1. The problem of adaptability of external trigger signals of different frequencies. The frequency of the external input trigger signal varies widely, from 1 Hz to several MHz. It is a challenge for the camera's detection system to achieve adaptability while ensuring the monitoring accuracy of the trigger signal in a large frequency variation range; 2. The synchronization problem between the camera exposure trigger signal and the external trigger signal. Current synchronization research has hardly considered the fluctuation of the external trigger signal. In particular, when the frequency of the external trigger signal drops sharply, the actual exposure trigger signal frequency cannot keep up with the change in time, which will affect the camera's image acquisition; 3. The accuracy and flexibility of the exposure trigger signal. Different application scenarios have different trigger frequency requirements, which have high requirements on the flexibility and accuracy of the trigger signal.

[0007] Therefore, how to process the external trigger signal to generate an exposure trigger signal to overcome the problems and challenges in current applications and adapt to the exposure trigger requirements in different application scenarios is an issue that needs to be urgently resolved by those skilled in the art. Summary of the invention

[0008] In view of the defects existing in the above-mentioned prior art, the present invention provides a method and device for generating an exposure trigger signal in an external trigger mode, and the exposure trigger signal generation method specifically includes: monitoring the external trigger signal to be processed, and providing an initial trigger period and a corresponding initial pulse valid signal; pre-dividing the external trigger signal according to the pre-adjustment of the initial trigger period, and obtaining a first trigger period and a corresponding first trigger signal; based on the adjustment of the first trigger period, dividing and doubling the first trigger signal, and obtaining a second trigger period and a corresponding second trigger signal; combining the comparative analysis of the initial pulse valid signal and the second trigger signal, synchronously processing the second trigger signal, and providing an exposure trigger signal. The exposure trigger signal generation scheme provided by the present invention can improve the stability and accuracy of the trigger, and also ensure the synchronization of the exposure trigger signal and the external trigger signal, and adapt to the exposure trigger requirements in different application scenarios.

[0009] In a first aspect, the present invention provides a method for generating an exposure trigger signal in an external trigger mode, which specifically comprises the following steps:

[0010] Monitor the external trigger signal to be processed, and provide the initial trigger cycle and the corresponding initial pulse valid signal;

[0011] According to the pre-adjustment of the initial trigger period, the external trigger signal is pre-divided to obtain a first trigger period and a corresponding first trigger signal;

[0012] Based on the adjustment of the first trigger period, the first trigger signal is processed by frequency division and frequency multiplication to obtain a second trigger period and a corresponding second trigger signal;

[0013] Combined with the comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to provide an exposure trigger signal.

[0014] Further, the external trigger signal to be processed is monitored, and an initial trigger period and a corresponding initial pulse valid signal are given, specifically including:

[0015] Monitor the current external trigger signal, count the period of the current external trigger signal in real time, and obtain the period count value of the current external trigger signal at a preset time node as the initial trigger period of the current external trigger signal, and based on the initial trigger period, give a corresponding initial pulse valid signal;

[0016] If the frequency of the current external trigger signal drops suddenly, the drop node is used as the preset time node;

[0017] If the real-time count of the current external trigger signal cycle reaches the threshold, the node reaching the threshold is used as the preset time node;

[0018] If the current external trigger signal does not drop suddenly, and the next external trigger signal is detected and the real-time count of the current external trigger signal period does not reach the threshold, the node when the next external trigger signal is detected is used as the preset time node.

[0019] Furthermore, based on the initial trigger period, a corresponding initial pulse valid signal is given, specifically including:

[0020] All rising edges of the initial trigger cycle are acquired, and delay processing corresponding to the cycle of the external trigger signal is performed on the rising edges to form a corresponding initial pulse valid signal.

[0021] Further, according to the pre-adjustment of the initial trigger period, the external trigger signal is pre-divided to obtain the first trigger period and the corresponding first trigger signal, which specifically includes:

[0022] Determine a pre-frequency division coefficient, pre-adjust the initial trigger period, and form a first trigger period;

[0023] Performing pre-frequency division processing on the external trigger signal with a first trigger period to obtain a first trigger signal;

[0024] The initial trigger period is pre-adjusted, specifically including:

[0025] Analyze the frequency of the current external trigger signal. If the initial trigger period of the current external trigger signal is not higher than the threshold value, the initial trigger periods of the N consecutive external trigger signals before the current external trigger signal are accumulated according to the pre-division coefficient N. If the initial trigger period of the current external trigger signal is higher than the threshold value, the initial trigger period of the current external trigger signal is multiplied by the pre-division coefficient N according to the pre-division coefficient N.

[0026] Further, based on the adjustment of the first trigger period, the first trigger signal is frequency-divided and frequency-multiplied to obtain the second trigger period and the corresponding second trigger signal, which specifically includes the following steps:

[0027] Determine the frequency division and frequency multiplication ratio coefficients, and provide the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period;

[0028] The first trigger cycle is processed by frequency division and frequency multiplication in sequence to obtain the second trigger cycle, which is specifically expressed as:

[0029]

[0030] Wherein, T2 is the second trigger period, T1 is the first trigger period, D is the frequency division coefficient, and M is the frequency multiplication coefficient;

[0031] Based on the second trigger cycle, the first trigger signal is processed by frequency division and frequency multiplication to form a second trigger signal.

[0032] Further, determining the frequency division and frequency multiplication ratio coefficients, and providing the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period, specifically includes:

[0033] Obtain any frequency multiplication coefficient, combine it with the determined frequency division and frequency multiplication ratio coefficient, and give the initial frequency division coefficient;

[0034] Iterate the frequency multiplication coefficient by comparing the initial frequency division coefficient with the preset limit value;

[0035] Iterating the initial frequency division coefficient synchronously with the iterative frequency multiplication coefficient until the frequency division coefficient is not less than a preset limit value;

[0036] The frequency division coefficient is given by the frequency multiplication coefficient and the frequency division ratio coefficient, which is specifically expressed as:

[0037]

[0038] Among them, D is the frequency division coefficient, K s is the frequency division and multiplication ratio coefficient, and M is the multiplication coefficient.

[0039] Furthermore, combined with comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to provide an exposure trigger signal, which specifically includes the following steps:

[0040] Based on the analysis of the pre-adjustment process of the initial trigger cycle and the adjustment process of the first trigger cycle, determining the input-output frequency ratio of the conversion from the external trigger signal to the exposure trigger signal;

[0041] Based on the input-output frequency ratio, analyzing the relationship between the second trigger signal and the initial pulse valid signal within the initial trigger period;

[0042] The second trigger signal is synchronously processed to provide an exposure trigger signal.

[0043] Furthermore, the input-output frequency ratio of the external trigger signal to the exposure trigger signal is determined, which is specifically expressed as:

[0044]

[0045] Among them, R is the input-output frequency ratio, N is the pre-division coefficient, and Ks is the frequency division and multiplication ratio coefficient.

[0046] Further, based on the input-output frequency ratio, the relationship between the second trigger signal and the initial pulse valid signal in the initial trigger period is analyzed, specifically including:

[0047] Combined with the input-output frequency ratio and the initial pulse valid signal in the initial trigger period, the maximum number threshold of the pulse valid signal in the second trigger signal in the second trigger period is analyzed;

[0048] The number of pulse valid signals generated in the second trigger signal in the second trigger cycle is analyzed based on the maximum number threshold.

[0049] In a second aspect, the present invention further provides an exposure trigger signal generating device in an external trigger mode, which adopts the exposure trigger signal generating method in the external trigger mode as described above, and specifically comprises:

[0050] A monitoring module is used to monitor the external trigger signal to be processed and provide an initial trigger period and a corresponding initial pulse valid signal;

[0051] A pre-scaling module, used to perform pre-scaling processing on the external trigger signal according to the pre-adjustment of the initial trigger period, and obtain a first trigger period and a corresponding first trigger signal;

[0052] A frequency division and multiplication module, configured to perform frequency division and multiplication processing on the first trigger signal based on the adjustment of the first trigger period, and obtain a second trigger period and a corresponding second trigger signal;

[0053] The exposure trigger signal generating module is used to combine the comparative analysis of the initial pulse effective signal and the second trigger signal, perform synchronous processing on the second trigger signal, and provide an exposure trigger signal.

[0054] The present invention provides a method and device for generating an exposure trigger signal in an external trigger mode, which at least have the following beneficial effects:

[0055] (1) The exposure trigger signal generation scheme provided by the present invention can improve the stability and accuracy of the trigger, and also ensure the synchronization between the exposure trigger signal and the external trigger signal, so as to adapt to the exposure trigger requirements in different application scenarios.

[0056] (2) By pre-adjusting the initial trigger period, the instability of external trigger signals, especially high-frequency external trigger signals, can be solved, thus improving the stability and accuracy of the trigger.

[0057] (3) By setting the frequency division and frequency multiplication ratio coefficient, the frequency division and frequency multiplication of the first trigger signal can be realized, which is more convenient and simple to use, improves the frequency division and frequency multiplication accuracy of the first trigger signal, increases the flexibility during processing, and is suitable for exposure triggering requirements in different application scenarios.

[0058] (4) The input-output frequency ratio is the ratio of the exposure trigger signal frequency to the external trigger signal frequency, which is determined by the external trigger signal frequency, the pre-scaling factor, and the frequency division and multiplication ratio. By setting the input-output frequency ratio, the number of pulse valid signals in the exposure trigger signal can be strictly generated in accordance with the input-output frequency ratio, ensuring that when the external trigger signal stops inputting, the exposure trigger signal also stops being generated synchronously, thereby enhancing the accuracy of the camera exposure trigger signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic flow chart of a method for generating an exposure trigger signal in an external trigger mode provided by the present invention;

[0060] Figure 2 A schematic diagram of a flow chart of obtaining a second trigger period and a corresponding second trigger signal according to an embodiment of the present invention;

[0061] Figure 3 In one embodiment of the present invention, by combining comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to provide a flow chart of the exposure trigger signal;

[0062] Figure 4 An example diagram of an external trigger signal and an exposure trigger signal provided by a certain embodiment of the present invention;

[0063] Figure 5 A schematic diagram of the architecture of an exposure trigger signal generating device in an external trigger mode provided by the present invention. DETAILED DESCRIPTION

[0064] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0066] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0067] In order to improve the problems existing in the prior art and better adapt to different application scenarios, we start from the stability and accuracy of the trigger, and consider the synchronization between the exposure trigger signal and the external trigger signal in different application scenarios. For the input external trigger signal, we perform frequency division and frequency multiplication processing according to the exposure trigger requirements, and then generate the actual exposure trigger signal.

[0068] In addition, there will be a certain response delay in the frequency division and frequency multiplication processing. That is, when the frequency of the external trigger signal is greatly reduced or the external trigger signal stops triggering, the actual exposure trigger signal cannot respond immediately and stop triggering in time, which leads to the risk of false triggering and it is difficult to ensure the accuracy of the actual exposure trigger signal.

[0069] Therefore, if Figure 1 As shown, the present invention provides a method for generating an exposure trigger signal in an external trigger mode, which specifically includes the following steps:

[0070] Monitor the external trigger signal to be processed, and provide the initial trigger cycle and the corresponding initial pulse valid signal;

[0071] According to the pre-adjustment of the initial trigger period, the external trigger signal is pre-divided to obtain a first trigger period and a corresponding first trigger signal;

[0072] Based on the adjustment of the first trigger period, the first trigger signal is processed by frequency division and frequency multiplication to obtain a second trigger period and a corresponding second trigger signal;

[0073] Combined with the comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to provide an exposure trigger signal.

[0074] The exposure trigger signal generation process can be carried out around the FPGA end. The exposure trigger signal generation scheme provided by the present invention solves the problem of instability of the external trigger signal (especially the high-frequency external trigger signal) by pre-adjusting the initial trigger period, and can improve the stability and accuracy of the trigger. By comparing and analyzing the initial pulse effective signal and the second trigger signal, the synchronization of the exposure trigger signal and the external trigger signal is guaranteed. Through frequency division and frequency multiplication processing, the flexibility of external trigger signal processing is increased to adapt to the exposure trigger requirements in different application scenarios.

[0075] Among them, monitoring the external trigger signal to be processed, giving the initial trigger period and the corresponding initial pulse valid signal, specifically includes:

[0076] Monitor the current external trigger signal, count the period of the current external trigger signal in real time, and obtain the period count value of the current external trigger signal at a preset time node as the initial trigger period of the current external trigger signal, and based on the initial trigger period, give a corresponding initial pulse valid signal.

[0077] The external trigger signal can be input to the FPGA through the IO port, and then the initial trigger cycle of the external trigger signal will be counted and confirmed. The detection of the current external trigger signal is regarded as the starting point of the initial trigger cycle, and the preset time node is regarded as the end point of the initial trigger cycle.

[0078] In actual applications, when the external trigger signal changes significantly, for example, when the external trigger signal stops inputting, the external trigger signal will not immediately become 0, but will show a significant decreasing process. If the external trigger signal is not analyzed, the trigger cycle cannot be obtained in time, making it impossible for the exposure trigger signal in this time period to keep pace with the external trigger signal.

[0079] Taking into account the diversity and complexity of external trigger signals, the initial trigger period of the current external trigger signal at different times is determined by setting preset time nodes under different situations, so that the subsequent exposure trigger signal can follow the external trigger signal synchronously.

[0080] First, considering the change trend of the external trigger signal, if the frequency of the current external trigger signal drops suddenly, the sudden drop node is used as the preset time node. That is, when the frequency of the current external trigger signal drops suddenly, the time period between monitoring the current external trigger signal and the sudden drop of the frequency of the current trigger signal is used as the initial trigger period.

[0081] Secondly, from the perspective of the presence or absence of an external trigger signal, if the real-time count of the current external trigger signal cycle reaches a threshold, the node that reaches the threshold is the preset time node. That is, if the real-time count of the current external trigger signal cycle has reached the preset threshold, and the next external trigger signal has not yet been detected, it is deemed that there is no next external trigger signal. At this time, the real-time count of the cycle of the current external trigger signal stops, and the threshold is used as the initial trigger cycle. The setting of the threshold is related to the specific scenario and is not further limited here. For example, in a certain scenario, the threshold can be set to twice the cycle count of the previous external trigger signal. The real-time calculation of the current external trigger signal cycle reaches twice the cycle count of the previous external trigger signal, and the next external trigger signal has not yet arrived, it is deemed that there is no next external trigger signal. At this time, the real-time count of the cycle of the current external trigger signal stops, and twice the cycle count of the previous external trigger signal is used as the initial trigger cycle of the current external trigger signal.

[0082] Third, considering the continuous triggering angle of the external trigger signal, if the current external trigger signal does not drop suddenly, and the next external trigger signal is detected and the real-time count of the current external trigger signal period does not reach the threshold, the node when the next external trigger signal is detected is the preset time node.

[0083] It should be noted that the current external trigger signal is not an external trigger signal under a fixed time frame. The current external trigger signal, the previous external trigger signal, and the next external trigger signal only indicate continuous external trigger signals within a real-time period. In addition, the initial trigger period of each external trigger signal needs to be updated, that is, the initial trigger period of the external trigger signal corresponding to each time frame needs to be updated when the external trigger signal is monitored.

[0084] Based on the initial trigger cycle, the corresponding initial pulse valid signal is given, specifically including:

[0085] All rising edges of the initial trigger cycle are acquired, and delay processing corresponding to the cycle of the external trigger signal is performed on the rising edges to form a corresponding initial pulse valid signal.

[0086] In order to ensure the synchronization between the exposure trigger signal and the external trigger signal, when monitoring the external trigger signal, it is necessary to delay the initial pulse valid signal of the external trigger signal, that is, by delaying the initial pulse valid signal, the initial pulse valid signal is made to correspond to the subsequent pre-adjusted first trigger period.

[0087] For the acquired external trigger signal, the pre-scaling mode will be selected according to its frequency. Specifically, according to the pre-adjustment of the initial trigger period, the external trigger signal is pre-scaled to obtain the first trigger period and the corresponding first trigger signal, which specifically includes:

[0088] Determine a pre-frequency division coefficient, pre-adjust the initial trigger period, and form a first trigger period;

[0089] The external trigger signal is pre-divided in a first trigger cycle to obtain a first trigger signal.

[0090] The initial trigger period is pre-adjusted, specifically including:

[0091] Analyze the frequency of the current external trigger signal. If the initial trigger period of the current external trigger signal is not higher than the threshold value, the initial trigger periods of the N consecutive external trigger signals before the current external trigger signal are accumulated according to the pre-division coefficient N. If the initial trigger period of the current external trigger signal is higher than the threshold value, the initial trigger period of the current external trigger signal is multiplied by the pre-division coefficient N according to the pre-division coefficient N.

[0092] The pre-scaling factor N can be preset, and the specific value is determined according to different application scenarios, and no further limitation is made here. In a specific scenario, the pre-scaling factor can be selected as an integer multiple of the initial trigger period of the current external trigger signal.

[0093] The current external trigger signal is judged to be high frequency or low frequency according to the initial trigger period of the acquired external trigger signal. The high-frequency external trigger signal is pre-divided, and a new trigger period, i.e., the first trigger period, is formed by accumulating N initial trigger periods, thereby reducing the instability of the high-frequency external trigger signal; the low-frequency external trigger signal is pre-divided by directly multiplying the initial trigger period of the current external trigger signal by the pre-dividing coefficient N to obtain a new trigger period, i.e., the first trigger period.

[0094] The threshold value for judging the frequency of the external trigger signal can be preset, and the specific value of the threshold value is also determined according to different application scenarios, and no further limitation is made here. In a specific scenario, the threshold value is set to 10μs, that is, when the initial trigger period of the external trigger signal is less than or equal to 10μs, it is a high-frequency signal; when the initial trigger period of the external trigger signal is greater than 10μs, it is a low-frequency signal.

[0095] The first trigger period T1 is multiplied and divided to obtain a new trigger period, that is, the second trigger period T2, so as to achieve the purpose of dividing and doubling the frequency of the first trigger signal. Figure 2 As shown, based on the adjustment of the first trigger period, the first trigger signal is frequency-divided and frequency-multiplied to obtain the second trigger period and the corresponding second trigger signal, which specifically includes the following steps:

[0096] Determine the frequency division and frequency multiplication ratio coefficients, and provide the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period;

[0097] The first trigger cycle is processed by frequency division and frequency multiplication in sequence to obtain the second trigger cycle, which is specifically expressed as:

[0098]

[0099] Wherein, T2 is the second trigger period, T1 is the first trigger period, D is the frequency division coefficient, and M is the frequency multiplication coefficient;

[0100] Wherein, T2 is the second trigger period, T1 is the first trigger period, D is the frequency division coefficient, and M is the frequency multiplication coefficient;

[0101] Based on the second trigger cycle, the first trigger signal is processed by frequency division and frequency multiplication to form a second trigger signal.

[0102] The frequency division coefficient D and the frequency multiplication coefficient M can be generated by the frequency division and frequency multiplication ratio coefficient Ks. The frequency division and frequency multiplication ratio coefficient Ks can be set in advance. In a specific application scenario, after the user sets the frequency division and frequency multiplication ratio coefficient Ks, the host computer generates the frequency division coefficient D and the frequency multiplication coefficient M by calculation and sends them to the FPGA end, which simplifies the user setting and improves the accuracy of the signal. The specific value of the frequency division and frequency multiplication ratio coefficient Ks is determined according to different application scenarios, and no further limitation is made here. The accuracy of the frequency division and frequency multiplication ratio coefficient Ks can be up to 0.001.

[0103] Determine the frequency division and frequency multiplication ratio coefficients, and provide the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period, specifically including:

[0104] Obtain any frequency multiplication coefficient, combine it with the determined frequency division and frequency multiplication ratio coefficient, and give the initial frequency division coefficient;

[0105] Iterate the frequency multiplication coefficient by comparing the initial frequency division coefficient with the preset limit value;

[0106] Iterating the initial frequency division coefficient synchronously with the iterative frequency multiplication coefficient until the frequency division coefficient is not less than a preset limit value;

[0107] The frequency division coefficient is given by the frequency multiplication coefficient and the frequency division ratio coefficient, which is specifically expressed as:

[0108]

[0109] Where D is the frequency division coefficient, K s is the frequency division and multiplication ratio coefficient, and M is the multiplication coefficient.

[0110] The frequency division coefficient D is the actual frequency division value. In order to facilitate FPGA calculation, 2 MAs the actual multiplication value. In order to ensure the resolution, the frequency division coefficient D and the multiplication coefficient M are distributed only after the frequency division coefficient D is greater than or equal to the preset limit value P. Of course, the specific value of the limit value P is determined according to different application scenarios, and no further limitation is made here. In a specific application scenario, the limit value P is equal to 1000, that is, the resolution at this time is 1 / 1000.

[0111] By setting the frequency division and frequency multiplication ratio coefficient, the frequency division and frequency multiplication of the first trigger signal can be achieved, which is more convenient and simple to use, improves the frequency division and frequency multiplication accuracy of the first trigger signal, increases the flexibility in processing, and is suitable for exposure triggering requirements in different application scenarios.

[0112] like Figure 3 As shown, combined with the comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to give an exposure trigger signal, which specifically includes the following steps:

[0113] Based on the analysis of the pre-adjustment process of the initial trigger cycle and the adjustment process of the first trigger cycle, determining the input-output frequency ratio of the conversion from the external trigger signal to the exposure trigger signal;

[0114] Based on the input-output frequency ratio, analyzing the relationship between the second trigger signal and the initial pulse valid signal within the initial trigger period;

[0115] The second trigger signal is synchronously processed to provide an exposure trigger signal.

[0116] Determine the input and output frequency ratio of the external trigger signal to the exposure trigger signal, which is specifically expressed as:

[0117]

[0118] Among them, R is the input-output frequency ratio, N is the pre-division coefficient, and Ks is the frequency division and multiplication ratio coefficient.

[0119] Based on the input-output frequency ratio, the relationship between the second trigger signal and the initial pulse valid signal in the initial trigger period is analyzed, specifically including:

[0120] Combined with the input-output frequency ratio and the initial pulse valid signal in the initial trigger period, the maximum number threshold of the pulse valid signal in the second trigger signal in the second trigger period is analyzed;

[0121] The number of pulse valid signals generated in the second trigger signal in the second trigger cycle is analyzed based on the maximum number threshold.

[0122] For the generation of the exposure trigger signal, an addition count is used to count the number of pulse valid signals in the second trigger cycle, and the number of pulse valid signals in the second trigger cycle is limited by comparison with the maximum number threshold, so as to ensure the accuracy of the number of triggers in the exposure trigger signal. Specifically, if the number of pulse valid signals in the second trigger cycle is greater than the maximum number threshold, no redundant pulse valid signals are generated, thereby ensuring that when the external trigger signal stops inputting, the exposure trigger signal also stops being generated synchronously.

[0123] The input-output frequency ratio is the ratio of the exposure trigger signal frequency to the external trigger signal frequency, which is determined by the external trigger signal frequency, the pre-scaling coefficient, and the frequency division and multiplication ratio coefficient. By setting the input-output frequency ratio, the number of pulse valid signals in the exposure trigger signal can be strictly generated in accordance with the input-output frequency ratio, ensuring that when the external trigger signal stops inputting, the exposure trigger signal also stops being generated synchronously, thereby enhancing the accuracy of the camera exposure trigger signal.

[0124] In a certain application scenario, the frequency of the exposure trigger signal required by the camera needs to be twice the frequency of the monitored external trigger signal. First, the external trigger signal is pre-divided, then divided and multiplied, and synchronized to finally obtain the exposure trigger signal. The pre-dividing factor N is set to 1, and the dividing and multiplying ratio factor Ks is set to 0.5.

[0125] like Figure 4 As shown, the external trigger signal A is monitored to obtain the initial trigger period T0 and the corresponding initial pulse valid signal a; the initial trigger period is pre-adjusted, and the first trigger period T1 and the corresponding first trigger signal b are obtained through pre-division processing; the second trigger period T2 and the corresponding second trigger signal c are obtained through frequency division and multiplication processing; finally, the exposure trigger signal TEXP is generated according to the second trigger period T2 and the input-output frequency ratio R, and the period of the exposure trigger signal TEXP is T2, which is equal to 2*T0.

[0126] like Figure 5 As shown, the present invention also provides an exposure trigger signal generating device in an external trigger mode, which adopts the exposure trigger signal generating method in the external trigger mode as described above, and specifically includes:

[0127] A monitoring module is used to monitor the external trigger signal to be processed and provide an initial trigger period and a corresponding initial pulse valid signal;

[0128] A pre-scaling module, used to perform pre-scaling processing on the external trigger signal according to the pre-adjustment of the initial trigger period, and obtain a first trigger period and a corresponding first trigger signal;

[0129] A frequency division and multiplication module, configured to perform frequency division and multiplication processing on the first trigger signal based on the adjustment of the first trigger period, and obtain a second trigger period and a corresponding second trigger signal;

[0130] The exposure trigger signal generating module is used to combine the comparative analysis of the initial pulse effective signal and the second trigger signal, perform synchronous processing on the second trigger signal, and provide an exposure trigger signal.

[0131] The present invention provides a method and device for generating an exposure trigger signal in an external trigger mode, which at least have the following beneficial effects:

[0132] (1) The exposure trigger signal generation scheme provided by the present invention can improve the stability and accuracy of the trigger, and also ensure the synchronization between the exposure trigger signal and the external trigger signal, so as to adapt to the exposure trigger requirements in different application scenarios.

[0133] (2) By pre-adjusting the initial trigger period, the instability of external trigger signals, especially high-frequency external trigger signals, can be solved, thereby improving the stability and accuracy of the trigger.

[0134] (3) By setting the frequency division and frequency multiplication ratio coefficient, the frequency division and frequency multiplication of the first trigger signal can be realized, which is more convenient and simple to use, improves the frequency division and frequency multiplication accuracy of the first trigger signal, increases the flexibility during processing, and is suitable for exposure triggering requirements in different application scenarios.

[0135] (4) The input-output frequency ratio is the ratio of the exposure trigger signal frequency to the external trigger signal frequency, which is determined by the external trigger signal frequency, the pre-scaling factor, and the frequency division and multiplication ratio. By setting the input-output frequency ratio, the number of pulse valid signals in the exposure trigger signal can be strictly generated in accordance with the input-output frequency ratio, ensuring that when the external trigger signal stops inputting, the exposure trigger signal also stops being generated synchronously, thereby enhancing the accuracy of the camera exposure trigger signal.

[0136] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for generating an exposure trigger signal in an external trigger mode, characterized in that: The specific steps include: Monitor the external trigger signal to be processed, and provide the initial trigger cycle and the corresponding initial pulse valid signal; According to the pre-adjustment of the initial trigger period, the external trigger signal is pre-divided to obtain the first trigger period and the corresponding first trigger signal, which specifically includes: determining the pre-dividing coefficient, pre-adjusting the initial trigger period to form the first trigger period; pre-dividing the external trigger signal with the first trigger period to obtain the first trigger signal; wherein the pre-adjustment of the initial trigger period specifically includes: analyzing the frequency of the current external trigger signal, if the initial trigger period of the current external trigger signal is not higher than the threshold value, according to the pre-dividing coefficient N, accumulating the initial trigger periods of N consecutive external trigger signals before the current external trigger signal; if the initial trigger period of the current external trigger signal is higher than the threshold value, according to the pre-dividing coefficient N, multiplying the initial trigger period of the current external trigger signal by the pre-dividing coefficient N; Based on the adjustment of the first trigger period, the first trigger signal is processed by frequency division and frequency multiplication to obtain a second trigger period and a corresponding second trigger signal; Combined with the comparative analysis of the initial pulse effective signal and the second trigger signal, the second trigger signal is synchronously processed to give an exposure trigger signal, which specifically includes the following steps: based on the analysis of the pre-adjustment process of the initial trigger period and the adjustment process of the first trigger period, the input-output frequency ratio of the conversion from the external trigger signal to the exposure trigger signal is determined; based on the input-output frequency ratio, the relationship between the second trigger signal and the initial pulse effective signal in the initial trigger period is analyzed; the second trigger signal is synchronously processed to give an exposure trigger signal.

2. The method for generating an exposure trigger signal in an external trigger mode according to claim 1, wherein: Monitor the external trigger signal to be processed, and give the initial trigger period and the corresponding initial pulse valid signal, including: Monitor the current external trigger signal, count the period of the current external trigger signal in real time, and obtain the period count value of the current external trigger signal at a preset time node as the initial trigger period of the current external trigger signal, and based on the initial trigger period, give a corresponding initial pulse valid signal; If the frequency of the current external trigger signal drops suddenly, the drop node is used as the preset time node; If the real-time count of the current external trigger signal cycle reaches the threshold, the node reaching the threshold is used as the preset time node; If the current external trigger signal does not drop suddenly, and the next external trigger signal is detected and the real-time count of the current external trigger signal period does not reach the threshold, the node when the next external trigger signal is detected is the preset time node.

3. The method for generating an exposure trigger signal in an external trigger mode as claimed in claim 2, characterized in that: Based on the initial trigger cycle, the corresponding initial pulse valid signal is given, specifically including: All rising edges of the initial trigger cycle are acquired, and delay processing corresponding to the cycle of the external trigger signal is performed on the rising edges to form a corresponding initial pulse valid signal.

4. The method for generating an exposure trigger signal in an external trigger mode according to claim 1, wherein: Based on the adjustment of the first trigger period, the first trigger signal is frequency-divided and frequency-multiplied to obtain the second trigger period and the corresponding second trigger signal, which specifically includes the following steps: Determine the frequency division and frequency multiplication ratio coefficients, and provide the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period; The first trigger cycle is processed by frequency division and frequency multiplication in sequence to obtain the second trigger cycle, which is specifically expressed as: ； Wherein, T2 is the second trigger period, T1 is the first trigger period, D is the frequency division coefficient, and M is the frequency multiplication coefficient; Based on the second trigger cycle, the first trigger signal is processed by frequency division and frequency multiplication to form a second trigger signal.

5. The method for generating an exposure trigger signal in an external trigger mode as claimed in claim 4, characterized in that: Determine the frequency division and frequency multiplication ratio coefficients, and provide the frequency division coefficient and frequency multiplication coefficient for adjusting the first trigger period, specifically including: Obtain any frequency multiplication coefficient, combine it with the determined frequency division and frequency multiplication ratio coefficient, and give the initial frequency division coefficient; Iterate the frequency multiplication coefficient by comparing the initial frequency division coefficient with the preset limit value; Iterating the initial frequency division coefficient synchronously with the iterative frequency multiplication coefficient until the frequency division coefficient is not less than a preset limit value; The frequency division coefficient is given by the frequency multiplication coefficient and the frequency division ratio coefficient, which is specifically expressed as: ； Where D is the frequency division coefficient, K s is the frequency division and multiplication ratio coefficient, and M is the multiplication coefficient.

6. The method for generating an exposure trigger signal in an external trigger mode according to claim 1, wherein: Determine the input and output frequency ratio of the external trigger signal to the exposure trigger signal, which is specifically expressed as: ； Among them, R is the input-output frequency ratio, N is the pre-division coefficient, and Ks is the frequency division and multiplication ratio coefficient.

7. The method for generating an exposure trigger signal in an external trigger mode according to claim 1, wherein: Based on the input-output frequency ratio, the relationship between the second trigger signal and the initial pulse valid signal in the initial trigger period is analyzed, specifically including: Combined with the input-output frequency ratio and the initial pulse valid signal in the initial trigger period, the maximum number threshold of the pulse valid signal in the second trigger signal in the second trigger period is analyzed; The number of pulse valid signals generated in the second trigger signal in the second trigger cycle is analyzed based on the maximum number threshold.

8. An exposure trigger signal generating device in an external trigger mode, characterized in that: The method for generating an exposure trigger signal in the external trigger mode according to any one of claims 1 to 7 specifically comprises: A monitoring module is used to monitor the external trigger signal to be processed and provide an initial trigger period and a corresponding initial pulse valid signal; A pre-scaling module, used to perform pre-scaling processing on the external trigger signal according to the pre-adjustment of the initial trigger period, and obtain a first trigger period and a corresponding first trigger signal; A frequency division and multiplication module, configured to perform frequency division and multiplication processing on the first trigger signal based on the adjustment of the first trigger period, and obtain a second trigger period and a corresponding second trigger signal; The exposure trigger signal generating module is used to combine the comparative analysis of the initial pulse effective signal and the second trigger signal, perform synchronous processing on the second trigger signal, and provide an exposure trigger signal.

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