CN115361506B - Control method of active pixel sensor, active pixel sensor and electronic equipment - Google Patents
Control method of active pixel sensor, active pixel sensor and electronic equipment Download PDFInfo
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Abstract
The invention relates to a control method of an active pixel sensor, the active pixel sensor and an electronic device, wherein the control method comprises the steps of applying a high-voltage pulse signal with a preset period to a photocathode of the active pixel sensor in a subsequent frame period according to the current illumination intensity, and controlling the low-level duration of the high-voltage pulse signal, wherein the preset period is equal to the frame period of the active pixel sensor. The invention has the technical effects that for the shooting process of the global shutter, the low-level duration of the photocathode in the subsequent frame period can be controlled through the actual illumination intensity delay, and the shooting performance of the active pixel sensor in different illumination environments is improved by utilizing the detection capability of the photocathode to weak light.
Description
Technical Field
The present invention relates to the field of active pixel sensors, and more particularly, to a control method of an active pixel sensor, and an electronic device.
Background
In existing electronic devices such as cameras, electron-bombarded active pixel sensors are used to adapt to different illumination environments. In a lower illumination environment, the photocathode in the electron bombardment type active pixel sensor can be excited to emit electrons under the irradiation of light, and meanwhile, the electrons are accelerated by a high-voltage electric field so as to bombard the electrons towards the pixel device layer.
However, in the current research of electron bombardment type active pixel sensors, how to control the photocathode of the active pixel sensor is not yet involved, so that the active pixel sensor can be well adapted to various illumination environments.
Disclosure of Invention
An object of the present invention is to provide a control method of an active pixel sensor, an active pixel sensor and a new technical scheme of an electronic device.
According to a first aspect of the present invention, there is provided a control method for an active pixel sensor of a global shutter, the control method comprising:
Step S101, repeatedly detecting the current illumination intensity according to the detection period;
step S102, comparing the current illumination intensity with a preset illumination intensity;
Step S201, if the current illumination intensity is smaller than the preset illumination intensity, the active pixel sensor is adjusted to enter a first working mode;
Step S202, applying a high voltage pulse signal of a predetermined period to the photocathode of the active pixel sensor in a subsequent frame period according to the current illumination intensity, and controlling a low level duration of the high voltage pulse signal, the predetermined period being equal to the frame period of the active pixel sensor.
Optionally, the step S202 includes:
According to the current illumination intensity and the light intensity standard, the duty ratio of the low-level duration corresponding to the high-voltage pulse signal in the subsequent frame period is obtained;
And adjusting the low-level duration in the subsequent frame period according to the duty ratio.
Optionally, the light intensity standard is embodied in gray scale values;
the step S202 includes calculating an average gray value of the pixels of the active pixel sensor in the current frame period.
Optionally, the average gray value is converted to the duty cycle by a preset function such that the duty cycle is inversely proportional to the average gray value.
Optionally, the duty cycle remains unchanged during one of the frame periods.
Optionally, the detection period is N times a frame period, and N is an integer of any one of 1 to 5.
Optionally, the step S202 includes: a high voltage pulse signal is applied to the photocathode and a low level duration is controlled from the following mth frame period, M being an integer of any one of 1 to 5.
Optionally, each frame period includes an exposure interval, and each predetermined period includes a pulse interval to which a high voltage pulse signal is applied;
and configuring the pulse interval in the exposure interval, wherein the duration of the pulse interval is smaller than or equal to the exposure interval.
Optionally, each frame period further comprises a read interval;
The pulse interval is completely staggered from the read interval.
Optionally, the control method further includes:
Step S301, if the current illumination intensity is larger than the preset illumination intensity, the active pixel sensor is adjusted to enter a second working mode;
Step S302, the application of the high voltage pulse signal to the photocathode of the active pixel sensor is canceled.
Optionally, adjusting the active pixel sensor into the first mode of operation includes: adjusting the lens assembly to focus the image on the photocathode;
Adjusting the active pixel sensor into the second mode of operation includes: the lens assembly is adjusted to focus the image on the pixel device layer of the active pixel sensor.
According to a second aspect of the present invention, there is provided an active pixel sensor for a global shutter for performing the control method of any one of the above, the active pixel sensor comprising:
the detection module is used for repeatedly detecting the current illumination intensity according to the detection period;
the comparison module is used for comparing the current illumination intensity with the preset illumination intensity;
The adjusting module is used for adjusting the active pixel sensor to enter a first working mode when the current illumination intensity is smaller than the preset illumination intensity;
The control module is used for applying a high-voltage pulse signal with a preset period to the photocathode of the active pixel sensor in a subsequent frame period according to the current illumination intensity and controlling the low-level duration of the high-voltage pulse signal, wherein the preset period is equal to the frame period of the active pixel sensor.
Optionally, the adjusting module is further configured to adjust the active pixel sensor into a second operation mode when the current illumination intensity is greater than a predetermined illumination intensity;
the control module is also used for canceling the application of a high-voltage pulse signal to the photocathode of the active pixel sensor.
According to a third aspect of the present invention there is provided an electronic device comprising an active pixel sensor as described above.
The invention has the technical effects that for the shooting process of the global shutter, the low-level duration of the photocathode in the subsequent frame period can be controlled through the actual illumination intensity delay, and the shooting performance of the active pixel sensor in different illumination environments is improved by utilizing the detection capability of the photocathode to weak light.
Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 is one of control methods of an active pixel sensor of a global shutter in an embodiment of the present disclosure.
Fig. 2 is a second control method of an active pixel sensor of a global shutter in an embodiment of the present disclosure.
Fig. 3 is a partial periodic schematic diagram of an active pixel sensor of a global shutter in an embodiment of the present disclosure.
Fig. 4 is a control delay schematic of an active pixel sensor of a global shutter in an embodiment of the present disclosure.
Fig. 5 is one of the duty cycle and illumination level schematic diagrams of the active pixel sensor of the global shutter in an embodiment of the present disclosure.
FIG. 6 is a second schematic diagram of duty cycle and illumination level of an active pixel sensor of a global shutter in an embodiment of the disclosure.
Fig. 7 is a schematic diagram of an active pixel sensor of a global shutter in an embodiment of the present disclosure.
Reference numerals illustrate:
1. A detection module; 2. a comparison module; 3. an adjustment module; 4. a control module; 100. an active pixel sensor.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Techniques and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
According to a first aspect of the present application, there is provided a control method for an active pixel sensor of a global shutter. It is noted that the active pixel sensors in the present application are all referred to as electron bombardment type active pixel sensors.
In the active pixel sensor of the global shutter, the whole image completes exposure at the same time, and all detection modules of the active pixel sensor of the global shutter collect incident light at the same time and expose at the same time.
As shown in fig. 1, the control method includes: step S101, repeatedly detecting the current illumination intensity according to the detection period.
Specifically, the detection period in the embodiment of the application refers to that the current illumination intensity is detected once every a certain number of frame periods, so as to obtain the current illumination intensity. According to different illumination intensity detection requirements, different detection periods can be selected to correspondingly detect the illumination intensity. According to the embodiment of the application, the current illumination intensity can be repeatedly detected according to the detection period by setting a certain detection period, so that the illumination intensity reflecting the current actual illumination environment can be obtained under the condition that the illumination environment changes. The setting of the detection period also enables the illumination intensity detection process to be more flexible, and avoids the influence on the power consumption of the active pixel sensor caused by overlarge data volume due to real-time detection. Wherein, can adopt a plurality of detection module to detect current illumination intensity to improve the detection accuracy to current illumination intensity.
Step S102, the current illumination intensity is compared with a predetermined illumination intensity.
The predetermined illumination intensity is data pre-configured in a register of the active pixel sensor, and the data can be adjusted by a computer program according to requirements. The predetermined illumination intensity in the embodiment of the present application is used as a criterion for distinguishing between the first operation mode and the second operation mode described below, and is also used as a criterion for distinguishing between a low illumination level and a high illumination level. The embodiment of the application can compare the current illumination intensity with the preset illumination intensity through a comparator in the active pixel sensor.
Step S201, if the current illumination intensity is smaller than the preset illumination intensity, the active pixel sensor is adjusted to enter a first working mode.
Specifically, after the current illumination intensity is less than the predetermined illumination intensity obtained in step S102, the active pixel sensor is adjusted to enter a first operation mode, which may be a night operation mode. According to the embodiment of the application, under the condition that the current illumination intensity is smaller than the preset illumination intensity, the current night environment or low illumination environment is judged, and the active pixel sensor is adjusted to enter the first working mode.
When the current illumination intensity is smaller than the preset illumination intensity and the active pixel sensor is adjusted to enter a first working mode, namely a night working mode, a photocathode of the active pixel sensor is electrified, and electrons can be excited out by the photocathode under the irradiation of light. In general, the active pixel sensor is set to maintain ground potential, the photocathode is set to low potential, and a high-voltage electric field is additionally arranged between the photocathode and the pixel device layer of the active pixel sensor, so that electrons excited by the photocathode can be accelerated by the high-voltage electric field, the electrons collide to the pixel device layer, electron multiplication occurs in the pixel device layer and the electrons are collected, the active pixel sensor can conveniently detect weak light under night environment or low illumination environment, and the detection capability and application range of the active pixel sensor are improved.
Step S202, applying a high voltage pulse signal of a predetermined period to the photocathode of the active pixel sensor in a subsequent frame period according to the current illumination intensity, and controlling a low level duration of the high voltage pulse signal, the predetermined period being equal to the frame period of the active pixel sensor.
Specifically, the predetermined period is a period of a high-voltage pulse signal applied to the photocathode of the active pixel sensor. According to the embodiment of the application, after the active pixel sensor is adjusted to enter the first working mode, namely the night working mode, a high-voltage pulse signal with a preset period can be applied to the photocathode of the active pixel sensor in a subsequent frame period according to the current illumination intensity, so that the photocathode of the active pixel sensor is electrified, and then the photocathode can be excited to emit electrons under the irradiation of light. For example, in two consecutive frame periods in fig. 3, a high voltage pulse signal of a predetermined period is applied to the photocathode of the active pixel sensor, and the low level duration of the high voltage pulse signal in the latter predetermined period is longer, that is, the photocathode on duration is longer, than the low level duration of the high voltage pulse signal in the former predetermined period.
In general, the active pixel sensor is kept at ground potential, and a high-voltage pulse signal applied to the photocathode is a negative-voltage pulse signal, so that when the high-voltage pulse signal is at a low level, a high-voltage electric field is formed on a gap between the photocathode and a pixel device layer of the active pixel sensor to accelerate electrons excited by the photocathode, so that the electrons collide to the pixel device layer to generate electron multiplication and electron collection in the pixel device layer, and the active pixel sensor detects weak light under a night environment.
In addition, the low level duration of the high voltage pulse signal is the on time of the photocathode in a predetermined period, in which the photocathode can be excited to emit electrons under the irradiation of light, and the high voltage electric field provided between the photocathode and the pixel device layer of the active pixel sensor can also accelerate electrons emitted from the photocathode. The embodiment of the application can change the opening time of the photocathode in a preset period by changing the low-level duration of the high-voltage pulse signal, further can change the quantity of electrons excited by the photocathode under the irradiation of light and the quantity of electrons accelerated by a high-voltage electric field formed between the photocathode and the pixel device layer, thereby adjusting the total quantity of electrons impinging on the pixel device layer, further changing the detection capability of the active pixel sensor on weak light under the night environment and facilitating the imaging of the active pixel sensor under the low-illumination environment.
According to the embodiment of the application, the low-level duration of the high-voltage pulse signal is controlled in the subsequent frame period according to the current illumination intensity, so that the quantity of electrons excited by the photocathode in the subsequent frame period due to light irradiation and the quantity of electrons accelerated by the high-voltage electric field formed between the photocathode and the pixel device layer can be controlled, and the detection capability of the active pixel sensor on weak light in the subsequent frame period is controlled. It is noted that in the embodiment of the present application, according to the current illumination intensity, the low-level duration of the high-voltage pulse signal is controlled in the subsequent frame period, while the low-level duration of the high-voltage pulse signal in the current frame period is kept unchanged, and the delay control can avoid the problem that gains of pixels in the frame period are inconsistent, so as to ensure the image gain level stability of the frame period. Furthermore, the error of the detection illumination intensity result caused by the unstable gain level of each pixel of the image in one frame can be avoided, the control confusion of the low-level duration of the subsequent frame period caused by the error is avoided, and the imaging reliability and the imaging controllability of the active pixel sensor are improved.
Meanwhile, the preset period is set to be equal to the frame period of the active pixel sensor, namely the period of the high-voltage pulse signal applied to the photocathode is equal to the frame period of the active pixel sensor, so that exposure and reading of all pixels in one frame of the active pixel sensor can be ensured, and the low-level duration of the high-voltage pulse signal in the subsequent frame period can be conveniently controlled.
The embodiment of the application can change the low-level duration of the high-voltage pulse signal in the subsequent frame period through delay control so as to change the starting time of the photocathode in the subsequent frame period, further change the quantity of electrons excited by the photocathode under the irradiation of light and the quantity of electrons accelerated by the high-voltage electric field formed between the photocathode and the pixel device layer, thereby adjusting the total quantity of electrons impinging on the pixel device layer, further changing the detection capability of the active pixel sensor on weak light under the night environment and facilitating the imaging of the active pixel sensor under the low-illumination environment.
Optionally, the step S202 includes:
According to the current illumination intensity and the light intensity standard, the duty ratio of the low-level duration corresponding to the high-voltage pulse signal in the subsequent frame period is obtained;
And adjusting the low-level duration in the subsequent frame period according to the duty ratio.
Specifically, the light intensity standard is a basis for measuring the current illumination intensity, and the embodiment of the application can match the current illumination intensity to a light intensity value according to the light intensity standard, and different illumination intensities correspond to different light intensity values, namely, the light intensity value can represent the current illumination intensity. According to the embodiment of the application, the duty ratio of the low-level duration corresponding to the high-voltage pulse signal in the subsequent frame period can be calculated according to the light intensity value, and the low-level duration in the subsequent frame period is adjusted according to the calculated duty ratio, so that the proportion of the opening duration of the photocathode in the subsequent frame period relative to the preset period meets the duty ratio.
The embodiment of the application can adjust the low-level duration in the subsequent frame period according to the current illumination intensity and the duty ratio obtained by the light intensity standard, further can change the starting time of the photocathode in the subsequent frame period, so as to change the quantity of electrons excited by the photocathode under the illumination of light and the quantity of electrons accelerated by a high-voltage electric field formed between the photocathode and a pixel device layer, thereby adjusting the total quantity of electrons impinging on the pixel device layer, further changing the detection capability of the active pixel sensor on weak light under the night environment and facilitating the imaging of the active pixel sensor under the low illumination environment.
Optionally, the light intensity standard is embodied in gray scale values;
The step S202 includes calculating an average gray value of the pixels of the current frame period of the active pixel sensor.
Specifically, because of the different colors and brightnesses of the points of the scene, the points on the black-and-white photograph taken by the camera or the black-and-white image reproduced by the television receiver appear gray to different extents. Based on this, the logarithmic relationship between white and black is divided into several stages. The gray values typically range from 0 to 255, with white being 255 and black being 0. The embodiment of the application sets the light intensity standard to be embodied by adopting the gray value, namely the light intensity standard can correspond to an appropriate and standard gray value. And, the current illumination intensity can also be matched to one gray value, different illumination intensities corresponding to different gray values, i.e. the current illumination intensity can be represented by using the gray values.
According to the embodiment of the application, the average gray value of the pixels in the current frame period of the active pixel sensor is calculated, so that the duty ratio of the low-level duration of the high-voltage pulse signal in the subsequent frame period can be obtained, and further the low-level duration in the subsequent frame period can be adjusted according to the duty ratio, so that the starting time of the photocathode in the subsequent frame period is changed, and the detection capability of the active pixel sensor on weak light under a night environment is finally adjusted.
According to the arrangement of the actual detection module or the detection requirement, the average gray value of the pixels of the active pixel sensor in the specific area can be calculated, the average gray value of the pixels of the active pixel sensor scattered in the array can be calculated, the duty ratio of the low-level duration of the high-voltage pulse signal in the subsequent frame period can be obtained, and the low-level duration in the subsequent frame period can be adjusted according to the duty ratio.
In another embodiment of the application, the light intensity criterion may also be embodied in terms of time instant, i.e. the light intensity criterion can correspond to an appropriate, standard time instant. And different illumination intensities can be matched to different moments, i.e. the utilization moment can also represent the current illumination intensity. Step S202 includes calculating a median of the active pixel sensor at the moment of the current frame period, acquiring a duty ratio of a low-level duration corresponding to the high-voltage pulse signal in a subsequent frame period according to the median of the moment of the current frame period, and adjusting the low-level duration in the subsequent frame period according to the duty ratio.
Optionally, the average gray value is converted to the duty cycle by a preset function such that the duty cycle is inversely proportional to the average gray value.
Specifically, the average gray value may be converted by a preset function pre-configured in a register of the active pixel sensor, converted into a duty ratio inversely proportional thereto, and adjusted according to the duty ratio for a low level duration in a subsequent frame period. As shown in fig. 5 and fig. 6, the duty ratio is set to be inversely proportional to the average gray value, and the smaller the average gray value is, the lower the current illumination intensity is, the stronger the detection capability of the corresponding active pixel sensor is required, that is, the longer the low level duration corresponding to the high voltage pulse signal is, and the larger the duty ratio is. The larger the average gray value is, the higher the current illumination intensity is, and the weaker the detection capability of the corresponding active pixel sensor is required, namely the shorter the low-level duration corresponding to the high-voltage pulse signal is, and the smaller the duty ratio is.
According to the embodiment of the application, the duty ratio is inversely proportional to the average gray value, so that the duty ratio can be adjusted according to different illumination intensities to adjust the low-level duration corresponding to the high-voltage pulse signal, thereby avoiding the service life damage caused by long-time starting of the photocathode while adapting to different night environments or low-illumination environments with different degrees, and prolonging the service life of the active pixel sensor. The embodiment of the application can conveniently adjust the low-level duration corresponding to the high-voltage pulse signal by utilizing the duty ratio, and the adjustment process is simple and controllable.
In addition, the embodiment of the application can convert the gray value representing the current illumination intensity into the required duty ratio according to the preset function so as to control the subsequent frame period. That is, the duty cycle is dynamically variable in response to the detected current light intensity, such that the active pixel sensor is capable of automatically adjusting the duty cycle to accommodate a changing low light environment in the first mode of operation.
Optionally, the duty cycle remains unchanged during one of the frame periods.
Specifically, in the embodiment of the present application, the duty ratio is set to be constant within one frame period, for example, as shown in fig. 4, when a new duty ratio is calculated at point a, it is also necessary to wait for the rising edge time of the exposure signal at point B of the next frame to correspondingly adjust the low level duration of the high voltage pulse signal, where the rising edge time of the exposure signal is consistent with the falling edge time of the reset signal of the first exposure line. Based on the setting, the embodiment of the application can ensure that the low-level duration of the high-voltage pulse signals is the same in the exposure process of all images in one frame period, can avoid the problem that the gains of pixels in the current frame period are inconsistent, and ensures the image gain level stability of the current frame period. Furthermore, the error of the detection illumination intensity result caused by the unstable image gain level in one frame can be avoided, the control confusion of the low-level duration of the subsequent frame period caused by the error is avoided, and the detection reliability and the detection controllability of the active pixel sensor on light rays are improved.
Optionally, the detection period is N times a frame period, and N is an integer of any one of 1 to 5.
Specifically, the embodiment of the application sets the detection period of the current illumination intensity to be a frame period which is N times of the detection period of the current illumination intensity, namely, once illumination intensity is detected every N frame periods, and subsequent steps are carried out according to the illumination intensity. Wherein N may be an integer of any one of 1 to 5 according to factors such as an actual operation rate and power consumption of the active pixel sensor. When the active pixel sensor is required to be flexibly adapted to different night environments or low-illumination environments with different degrees, smaller N can be selected so that the detection of the current illumination intensity is more frequent; when the night environment or the low-light environment tends to be stable, a larger N can be selected to avoid the detection of the current light intensity from being too frequent, and the power consumption of the active pixel sensor is reduced.
Optionally, the step S202 includes: a high voltage pulse signal is applied to the photocathode and a low level duration is controlled from the following mth frame period, M being an integer of any one of 1 to 5.
Specifically, after the illumination intensity is detected, the embodiment of the application applies a high-voltage pulse signal to the photocathode from the subsequent Mth frame period from the current frame and controls the low-level duration to correspondingly adjust the starting time of the photocathode from the subsequent Mth frame period, so that the detection capability of the active pixel sensor from the subsequent Mth frame period on weak light under the night environment is adjusted, and the active pixel sensor can adapt to different night environments.
According to actual design and image detection requirements, M can be an integer of any one of 1 to 5, and when the active pixel sensor is required to flexibly adapt to different night environments or low-light environments so as to clearly detect images, smaller M can be selected, so that the adjustment of low-level time is more frequent to enhance the detection capability; when the night environment or the low light environment tends to be stable, a larger M can be selected to maintain a constant low level time in a plurality of continuous frame periods so as to avoid frequent adjustment of the power-on time, and thus excessive power consumption of the active pixel sensor can be avoided.
In addition, for the foregoing N and M, N and M may be set to be 1, that is, each frame period detects the light intensity once, and from the immediately next frame period, a high voltage pulse signal is applied to the photocathode and the low level duration is controlled, so that the on duration of the photocathode of the next frame can be quickly adjusted according to the continuously changing light intensity, thereby adjusting the detection capability of the active pixel sensor. It is also possible to set N and M to other combinations of numbers, for example, N is 2 and M is 1, that is, the illumination intensity is detected once every 2 frame periods, and a high voltage pulse signal is applied to the photocathode and the duration of the low level is controlled from the immediately next frame period, where the detection period is 2 and the control delay is 1; or N is 2, M is 2, namely the illumination intensity is detected every 2 frame periods, and a high-voltage pulse signal is applied to the photocathode from the next second frame period and the low-level duration is controlled, so that the excessive power consumption of the active pixel sensor can be avoided, the detection period is 2, and the control delay is 2. In order to detect and reduce the amount of computation by using the illumination intensity that best reflects the current illumination environment, M may be set to be N or less.
Optionally, each frame period includes an exposure interval, and each predetermined period includes a pulse interval to which a high voltage pulse signal is applied;
and configuring the pulse interval in the exposure interval, wherein the duration of the pulse interval is smaller than or equal to the exposure interval.
As shown in fig. 3, the embodiment of the present application sets each frame period F to include an exposure interval E in which all images can be simultaneously exposed. The pulse interval is a time interval for turning on the photocathode within a predetermined period T, and in view of the negative high voltage applied to the photocathode, the time interval for turning on the photocathode is the low level interval in fig. 3.
The embodiment of the application configures the pulse interval in the exposure interval, so that the quantity of electrons excited by the photocathode in the corresponding exposure interval and the quantity of electrons accelerated by the high-voltage electric field can be adjusted by adjusting the duration of the pulse interval in a preset period, and the detection capability of the active pixel sensor on weak light in a night environment or a low-illumination environment is further adjusted. The embodiment of the application sets the duration of the pulse interval to be less than or equal to the exposure interval, can ensure that the active pixel sensor realizes imaging, avoids the service life damage caused by long-time starting of the photocathode, and prolongs the service life of the active pixel sensor.
The embodiment of the application can adjust the duration of the pulse interval in a preset period by adjusting the duty ratio so as to adjust the detection capability of the active pixel sensor on weak light under night environments, thereby being suitable for different night environments. For example, in fig. 3, in two consecutive predetermined periods T1 and T2, the duration of the corresponding pulse intervals is different, and when the illumination environment is detected to be darker in T1, the duration of the pulse interval in T2 is set to be longer correspondingly, that is, the on time of the photocathode in T2 is longer, so as to enhance the gain level of the active pixel sensor in T2.
Optionally, each frame period further comprises a read interval;
The pulse interval is completely staggered from the read interval.
As shown in fig. 3, each frame period in the embodiment of the present application further includes a reading section, which is located after the exposure section, that is, after all the image exposure is completed to collect the electrical signals, the readout circuit in the active pixel sensor can output the electrical signals in the form of video. The pulse interval and the reading interval are completely staggered, so that when a reading circuit in the active pixel sensor works, the photocathode is kept in a closed state, the service life of the photocathode can be prevented from being damaged due to long-time opening, and the service life of the active pixel sensor is prolonged.
Optionally, the control method further includes:
Step S301, if the current illumination intensity is larger than the preset illumination intensity, the active pixel sensor is adjusted to enter a second working mode;
Step S302, the application of the high voltage pulse signal to the photocathode of the active pixel sensor is canceled.
As shown in fig. 2, after the current illumination intensity is repeatedly detected according to the detection period and compared with the predetermined illumination intensity, if the current illumination intensity is greater than the predetermined illumination intensity, it is determined that the current daytime environment or the high illumination environment is present, the active pixel sensor is adjusted to enter a second operation mode, that is, the daytime operation mode. When the active pixel sensor enters a daytime working mode, the application of a high-voltage pulse signal to the photocathode of the active pixel sensor is canceled to prevent the photocathode from being excited to emit electrons, at the moment, incident light can penetrate through the photocathode, and a pixel device layer of the active pixel sensor can directly receive the incident light to image.
According to the embodiment of the application, after the current illumination intensity is larger than the preset illumination intensity, the active pixel sensor is adjusted to enter a daytime working mode, the application of a high-voltage pulse signal to the photocathode of the active pixel sensor is canceled, the service life of the photocathode caused by the working in the daytime with stronger illumination can be prevented from being damaged, and the service life of the active pixel sensor is prolonged.
Optionally, adjusting the active pixel sensor into the first mode of operation includes: adjusting the lens assembly to focus the image on the photocathode;
Adjusting the active pixel sensor into the second mode of operation includes: the lens assembly is adjusted to focus the image on the pixel device layer of the active pixel sensor.
Specifically, when the current illumination intensity is smaller than the preset illumination intensity, the active pixel sensor is adjusted to enter a first working mode, namely a night working mode, and a high-voltage pulse signal is applied to the photocathode of the active pixel sensor to enable the photocathode to start working. The lens assembly is adjusted to focus an image on the photocathode, so that the electrified photocathode can be irradiated by light to excite electrons, and a high-voltage electric field formed on a gap between the photocathode and the pixel device layer accelerates the electrons entering the gap, so that the electrons collide to the pixel device layer to generate electron multiplication and electron collection in the pixel device layer, and imaging in a night environment or a low-illumination environment is realized.
And after comparing that the current illumination intensity is larger than the preset illumination intensity, adjusting the active pixel sensor to enter a second working mode, namely a daytime working mode, and canceling the application of a high-voltage pulse signal to the photocathode of the active pixel sensor so as to close the electronic function of the active pixel sensor excited by the illumination of light. The adjusting lens component enables the image to be focused on the pixel device layer of the active pixel sensor, and at the moment, the photocathode only plays a role of light transmission, so that the pixel device layer of the active pixel sensor can directly receive incident light to image.
According to different working modes of the active pixel sensor, the embodiment of the application can correspondingly adjust the lens assembly to adjust the focusing position of the image, and control the opening and closing of the photocathode to realize imaging in different environments in daytime and at night, so that the detection capability of the active pixel sensor is improved. In addition, by controlling the opening and closing of the photocathode, the service life of the photocathode can be prevented from being damaged due to the fact that the photocathode works in the daytime with strong illumination, and the service life of the active pixel sensor is prolonged.
According to a second aspect of the present application, there is provided an active pixel sensor 100 for a global shutter for performing the control method of any one of the above, the active pixel sensor 100 comprising:
the detection module 1 is used for repeatedly detecting the current illumination intensity according to a detection period;
the comparison module 2 is used for comparing the current illumination intensity with the preset illumination intensity;
an adjustment module 3, where the adjustment module 3 is configured to adjust the active pixel sensor 100 into the first operation mode when the current illumination intensity is less than the predetermined illumination intensity;
and a control module 4, wherein the control module 4 is used for applying a high-voltage pulse signal with a preset period to the photocathode of the active pixel sensor 100 in a subsequent frame period according to the current illumination intensity, and controlling the low-level duration of the high-voltage pulse signal, and the preset period is equal to the frame period of the active pixel sensor 100.
Optionally, the adjusting module 3 is further configured to adjust the active pixel sensor 100 into the second operation mode when the current illumination intensity is greater than a predetermined illumination intensity;
the control module 4 is further configured to cancel the application of the high voltage pulse signal to the photocathode of the active pixel sensor 100.
As shown in fig. 7, the active pixel sensor 100 according to the embodiment of the present application includes a detection module 1, a comparison module 2, an adjustment module 3, and a control module 4. Based on the cooperation of the modules, the active pixel sensor 100 of the embodiment of the application can change the low-level duration of the high-voltage pulse signal in the subsequent frame period through delay control, so as to change the quantity of electrons excited by the photocathode irradiated by light and the quantity of electrons accelerated by the high-voltage electric field formed between the photocathode and the pixel device layer, thereby adjusting the total quantity of electrons impinging on the pixel device layer, further changing the detection capability of the active pixel sensor 100 on weak light in a night environment, and facilitating the imaging of the active pixel sensor 100 in a low-illumination environment.
According to a third aspect of the present application, there is provided an electronic device comprising an active pixel sensor as described above, the electronic device comprising all technical effects of the active pixel sensor as described above.
The foregoing embodiments mainly describe differences between the embodiments, and as long as there is no contradiction between different optimization features of the embodiments, the embodiments may be combined to form a better embodiment, and in consideration of brevity of line text, no further description is given here.
While certain specific embodiments of the invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (14)
1. A control method for an active pixel sensor of a global shutter, comprising:
Step S101, repeatedly detecting the current illumination intensity according to the detection period;
step S102, comparing the current illumination intensity with a preset illumination intensity;
Step S201, if the current illumination intensity is smaller than the preset illumination intensity, the active pixel sensor is adjusted to enter a first working mode;
Step S202, according to the current illumination intensity, applying a high-voltage pulse signal with a preset period to the photocathode of the active pixel sensor in a subsequent frame period, and controlling the low-level duration of the high-voltage pulse signal, wherein the preset period is equal to the frame period of the active pixel sensor, and the low-level duration of the high-voltage pulse signal in the current frame period is kept unchanged.
2. The control method according to claim 1, characterized in that said step S202 includes:
According to the current illumination intensity and the light intensity standard, the duty ratio of the low-level duration corresponding to the high-voltage pulse signal in the subsequent frame period is obtained;
And adjusting the low-level duration in the subsequent frame period according to the duty ratio.
3. The control method according to claim 2, wherein the light intensity criterion is embodied in gray values;
the step S202 includes calculating an average gray value of the pixels of the active pixel sensor in the current frame period.
4. A control method according to claim 3, characterized in that the average gray value is converted into the duty ratio by a preset function such that the duty ratio is inversely proportional to the average gray value.
5. The control method according to claim 2, characterized in that the duty ratio remains unchanged during one of the frame periods.
6. The control method according to claim 1, wherein the detection period is N times a frame period, N being an integer of any one of 1 to 5.
7. The control method according to claim 1, characterized in that said step S202 includes: a high voltage pulse signal is applied to the photocathode and a low level duration is controlled from the following mth frame period, M being an integer of any one of 1 to 5.
8. The control method according to claim 1, wherein each frame period includes an exposure interval, and each predetermined period includes a pulse interval in which a high-voltage pulse signal is applied;
and configuring the pulse interval in the exposure interval, wherein the duration of the pulse interval is smaller than or equal to the exposure interval.
9. The control method according to claim 8, wherein each frame period further includes a read interval;
The pulse interval is completely staggered from the read interval.
10. The control method according to claim 1, characterized by further comprising:
Step S301, if the current illumination intensity is larger than the preset illumination intensity, the active pixel sensor is adjusted to enter a second working mode;
Step S302, the application of the high voltage pulse signal to the photocathode of the active pixel sensor is canceled.
11. The method of claim 10, wherein adjusting the active pixel sensor into the first mode of operation comprises: adjusting the lens assembly to focus the image on the photocathode;
Adjusting the active pixel sensor into the second mode of operation includes: the lens assembly is adjusted to focus the image on the pixel device layer of the active pixel sensor.
12. An active pixel sensor for a global shutter for performing the control method of any one of claims 1 to 11, characterized in that the active pixel sensor (100) comprises:
The detection module (1) is used for repeatedly detecting the current illumination intensity according to a detection period;
The comparison module (2) is used for comparing the current illumination intensity with the preset illumination intensity;
the adjusting module (3) is used for adjusting the active pixel sensor (100) to enter a first working mode when the current illumination intensity is smaller than the preset illumination intensity;
And the control module (4) is used for applying a high-voltage pulse signal with a preset period to the photocathode of the active pixel sensor (100) in a subsequent frame period according to the current illumination intensity and controlling the low-level duration of the high-voltage pulse signal, wherein the preset period is equal to the frame period of the active pixel sensor (100).
13. The active pixel sensor according to claim 12, wherein the adjustment module (3) is further configured to adjust the active pixel sensor (100) into the second operation mode when the current illumination intensity is greater than a predetermined illumination intensity;
the control module (4) is also used for canceling the application of a high-voltage pulse signal to the photocathode of the active pixel sensor (100).
14. An electronic device characterized by comprising an active pixel sensor (100) according to claim 12 or 13.
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