CN108307188B - Shutter type liquid crystal glasses for multi-picture stereoscopic projection playing system and control method - Google Patents
Shutter type liquid crystal glasses for multi-picture stereoscopic projection playing system and control method Download PDFInfo
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Abstract
The invention discloses shutter type liquid crystal glasses for a multi-picture stereoscopic projection playing system and a control method thereof, wherein lenses of the multi-picture stereoscopic glasses are opened in a corresponding bit plane image projection time period to form lens opening time sequences with different duty ratios, and meanwhile, under a multi-picture projection mode, false pulses are filtered by adopting a form detection means to eliminate synchronous light pulse interference caused by superposition of simultaneous projection images of multiple projectors and false pulse interference caused by image burr interference, correct synchronous pulses are extracted, and the opening and closing time sequences of the multi-picture stereoscopic glasses and the stereoscopic picture time sequence of the multi-picture projection system are ensured to realize phase synchronization. The invention ensures that the opening and closing time sequence of the multi-picture stereo glasses and the stereo picture time sequence of the multi-picture projection system realize phase synchronization, thereby correctly distinguishing and watching each path of independent stereo video.
Description
Technical Field
The invention relates to shutter type liquid crystal glasses for a multi-picture stereoscopic projection playing system and a control method.
Background
The stereoscopic image is a common constantly-playing display form in the current movie and television works and virtual reality contents, and can enable audiences to have a strong experience of being personally on the scene. However, 3D stereoscopic display playing technology used in movies and televisions is based on single viewpoint rendering at present, and when a plurality of groups of users watch and interact with the system at the same time, only a group of stereoscopic images with fixed viewpoints can be played and displayed in a screen area, and thus, users in a group cannot generate real immersion feeling at the same time. The system realizes the function of playing three paths of stereo videos in the same screen area in a time-sharing way by changing the structure of a projector and the projection playing time sequence, but correspondingly needs to design special shutter type liquid crystal glasses for the system, so that the opening and closing time sequence of a liquid crystal lens is matched with the projection time sequence of the multi-picture stereo video, and each path of independent stereo video can be correctly distinguished and watched.
When a conventional DLP type stereoscopic projector projects and plays a stereoscopic video, a left-eye picture and a right-eye picture are projected alternately with 8.3ms as an image projection period to form a stereoscopic video image, wherein one image projection period is divided into three bit plane projection periods to project R, G, B three bit plane images of the same frame of image respectively. The projection type multi-picture stereo display playing system changes the existing stereo projection mode and projection time sequence, 3 projectors are grouped into one group, in the first bit plane projection time period, the 3 projectors are enabled to respectively project R, G, B bit plane images of the first path of stereo video images to form a complete color image, in the second bit plane projection time period and the third bit plane projection time period, the 3 projectors are enabled to respectively project R, G, B bit plane images of the second path of stereo video images and the third path of stereo video images, so that three paths of different video images are sequentially and uniquely displayed on a screen in three different projection time periods, and independent time-sharing playing of the three paths of stereo video images is realized.
The existing shutter-type liquid crystal glasses are matched with the existing stereoscopic projection playing time sequence, and the opening and closing states of the left lens and the right lens are alternately switched according to the image projection period of 8.3ms, so that the aliasing phenomenon of three paths of video images can be generated in the multi-picture stereoscopic projection mode, and therefore, the shutter-type liquid crystal glasses equipment special for the multi-picture stereoscopic projection playing system and a control method are required to be designed, and each path of independent stereoscopic video can be correctly distinguished and watched. Meanwhile, since three DLP projectors project images simultaneously, superposition of projected images on a screen area interferes with a synchronous light pulse signal, and therefore, in the design of special shutter-type liquid crystal glasses, interference-free processing needs to be performed on the synchronous light pulse signal.
Disclosure of Invention
The invention provides shutter type liquid crystal glasses for a multi-picture stereoscopic projection playing system and a control method thereof in order to solve the problems.
The first purpose of the present invention is to provide shutter type liquid crystal glasses for a multi-picture stereoscopic projection playing system, which can control the opening and closing timing of the liquid crystal lenses to be synchronous with the playing timing of the corresponding group of stereoscopic videos, so as to correctly distinguish and watch each path of independent stereoscopic videos.
The second objective of the present invention is to provide a method for controlling the above shutter-type liquid crystal glasses, in which an anti-interference processing method for waveform detection is performed when extracting the 3D synchronization optical pulse signal, so as to eliminate interference caused by simultaneous projection and superposition of three projectors, and improve the problems in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the shutter type liquid crystal glasses for the multi-picture stereoscopic projection playing system comprise a glasses body, wherein the glasses body is provided with:
the optical pulse synchronous signal extraction module is used for receiving a synchronous optical pulse signal of a projector in the multi-picture projection system, converting the synchronous optical pulse signal into a digital pulse signal and forming a synchronous pulse input of the control module;
the control module is used for forming a driving signal for controlling the switching of the left eye liquid crystal lens and the right eye liquid crystal lens of the glasses body according to the synchronous pulse signal of the multi-picture projection system, and ensuring that the switching time sequence of the liquid crystal lenses is synchronous with the playing time sequence of the multi-picture projection system;
the liquid crystal lens opening and closing voltage driving module generates driving voltage of the liquid crystal lens according to the opening and closing control signal output by the control module and controls the opening and closing state of the liquid crystal lens;
and the DC-DC power supply module converts the battery voltage into various DC voltages and supplies power to the control module and the liquid crystal lens switching voltage driving module.
Further, the optical pulse synchronizing signal extraction module comprises a photoelectric amplifier, a direct current clamping circuit, a fixed gain amplifier, a reverse comparator and a limiting circuit which are sequentially connected, an optical signal is converted into an analog electric signal through the photoelectric amplifier, a direct current component in the signal is filtered by the direct current clamping circuit, the fixed gain amplifier amplifies the analog signal, the signal is guaranteed to have enough amplitude to counteract attenuation of the optical-electric signal caused by the change of the distance between the observation and the shadow, and the amplified analog signal is subjected to binarization processing by the reverse comparator and converted into a digital signal.
Furthermore, the control module comprises a driving module and a phase synchronization module, wherein the driving module determines the time window parameters for opening and closing the liquid crystal lens according to the group serial number of the user, generates corresponding liquid crystal lens opening and closing control signals with unequal duty ratios, the phase synchronization module performs shape detection on the generated interrupt pulses, filters false pulses generated after signal burrs are amplified, retains and extracts correct photoelectric synchronization pulses, and performs phase synchronization on the liquid crystal lens opening and closing control signals according to the false pulses.
Furthermore, the driving module is connected with a timer, and the timer period is used as a basic time unit for timing to generate a time window for controlling the opening of the liquid crystal lens.
Further, the morphology detection condition of the phase synchronization module includes a signal width condition, a signal front and back level plateau condition, a pulse interval condition, and a pulse interval uniformity condition.
Furthermore, the liquid crystal lens opening and closing voltage driving module adopts two driving chips to respectively drive the opening and closing voltage of the liquid crystal lens of the left eye and the liquid crystal lens of the right eye, takes the liquid crystal lens opening and closing control signal generated in the control module as input, keeps the waveform of the opening and closing signal and ensures the switching speed of the opening and closing state of the liquid crystal lens.
Furthermore, the DC-DC power module converts the battery voltage into various DC voltages to supply power to the control module and the liquid crystal lens on-off voltage driving module, and converts the DC voltage supplied by the system into various output voltages to supply power to the control module and the liquid crystal lens on-off voltage driving module.
Furthermore, a microswitch of the control module starts a left and right eye switching function, control variables of a left lens and a right lens in the single chip microcomputer are switched, and the liquid crystal lenses are enabled to be switched on and off in a left-right-left sequence when the multi-picture stereoscopic glasses are opened.
Based on the working method of the system, the lenses of the multi-picture stereo glasses are opened in the projection time interval of the corresponding bit plane images to form lens opening time sequences with different duty ratios, and meanwhile, under the multi-picture projection mode, false pulses are filtered by adopting a form detection means to eliminate synchronous light pulse interference caused by superposition of simultaneous projection images of multiple projectors and false pulse interference caused by image burr interference, correct synchronous pulses are extracted, and the opening and closing time sequences of the multi-picture stereo glasses and the stereo picture time sequence of the multi-picture projection system are ensured to realize phase synchronization.
Further, the waveform shape detection conditions are distinguished:
(1) width condition: setting a width value of a synchronous pulse signal, namely maintaining a zero level state of the width value time after the falling edge of the synchronous pulse starts;
(2) front and rear platform conditions: the real synchronous pulse signal has obvious front and back platform structures, after reverse processing, the synchronous pulse is a negative pulse, and high level intervals with certain widths are arranged before and after the pulse, and are respectively called as the front and back platforms of the synchronous pulse;
(3) the interval condition is as follows: the time interval between the synchronization pulses is measured by the number of times the timer is interrupted;
(4) uniformity conditions: the interval condition is satisfied by a plurality of continuous synchronous pulse intervals before the current pulse.
Determining the starting and stopping range [ N ] of the opening time window of the liquid crystal lens according to the read user group signal1，N2]The time unit is a timer period, namely in a stereo projection left-right eye switching period, when the timer generates the Nth1Starting the liquid crystal lens when the interruption is repeated until the timer generates the Nth time2And turning off the liquid crystal lens when the interruption is performed again.
Compared with the prior art, the invention has the beneficial effects that:
the multi-picture stereo glasses are special equipment for multi-picture stereo projection system, and can ensure that the opening and closing time sequence of liquid crystal lens is synchronous with the playing time sequence of stereo video of correspondent group so as to correctly distinguish and watch the independent stereo video of every channel. The essential difference is that the lenses of the multi-picture stereo glasses are opened in the projection time period of the corresponding bit plane image, and the lens opening time sequences with different duty ratios are formed. Meanwhile, in a multi-picture projection mode, in order to eliminate synchronous light pulse interference caused by superposition of images projected by three projectors simultaneously and false pulse interference caused by image burr interference, a form detection means is adopted to filter the false pulse, correct synchronous pulse is extracted, and the opening and closing time sequence of multi-picture stereoscopic glasses and the stereoscopic picture time sequence of a multi-picture projection system are ensured to realize phase synchronization, so that each path of independent stereoscopic video is distinguished and watched correctly.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a functional diagram of each module of a multi-picture stereoscopic eyewear apparatus;
FIG. 2 is a schematic diagram of the photo-electric signal of a single DLP type stereoscopic projector during one left-and-right eye image switching period;
FIG. 3 is a schematic diagram of the photo-electric signal during a left-eye and right-eye image switching period in a multi-picture projection mode;
FIG. 4 is a schematic circuit diagram of an optical pulse synchronization signal extraction module;
FIG. 5 is a flowchart of the external interrupt response routine of the single-chip microcomputer in the control module;
FIG. 6 is a flowchart of the SCM timer interrupt response routine in the control module;
fig. 7 is a flow chart of a main program of a single chip microcomputer in the control module.
The specific implementation mode is as follows:
the invention is further described with reference to the following figures and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As described in the background art, the prior art has a disadvantage that the aliasing phenomenon of three paths of video images can be generated in the current multi-picture stereoscopic projection mode, and in order to solve the above technical problems, the present application provides a shutter type liquid crystal glasses device and a control method specially used for a projection type multi-picture stereoscopic display playing system.
To explain the operation principle of the present invention, the principle of the multi-view stereoscopic projection/playback system and the morphological structure of the multi-view stereoscopic image need to be explained. For convenience of description, hereinafter, the "multi-picture stereoscopic projection and playback system" will be referred to simply as "multi-picture projection system", and the "shutter type liquid crystal glasses dedicated to the projection type multi-picture stereoscopic display and playback system" will be referred to simply as "multi-picture stereoscopic glasses".
When the DLP type projector is in a stereo playing state, the image refresh rate is 120Hz, namely 120 frames of pictures are projected every second, wherein 60 frames of left-eye images and 60 frames of right-eye images are contained, and a stereo video is formed by projection according to the sequence of left-right-left-right. One left-right eye picture switching period is 8.33 ms. In the DLP stereoscopic projector adopting the DLP LINK standard, the DLP projector projects a synchronous light pulse signal with the width of 20 mu s at the beginning of each period, the synchronous light pulse signal is used as a mark of the beginning of the period, the intensity of the synchronous light pulse is obviously higher than that of an image signal, but the duration is extremely short, and the video playing cannot be influenced. In each period, the projection imaging process of the color image is divided into 3 periods, R, G, B three bit planes of the image are projected in each period respectively, and finally the color image is formed by using the persistence of vision. The multi-picture projection system is based on the time-sharing projection and synthesis imaging process, and redesigns the color wheel structure and the play mode of the projector: the method comprises the steps of compiling 3 DLP type projectors into a group, enabling the 3 projectors to respectively project R, G, B bit plane images of a first path of three-dimensional video image in a first projection time interval to form a complete color image of a user 1, and enabling the 3 projectors to respectively project R, G, B three bit plane images of the user 2 and the user 3 in a second projection time interval and a third projection time interval, so that three paths of different video images are sequentially and uniquely displayed on a screen in three different projection time intervals, and independent time-sharing playing of three paths of three-dimensional video images is achieved.
In the multi-picture projection mode, special multi-picture stereo glasses need to be designed to correctly distinguish and watch each path of independent stereo video. Firstly, a user serial number is set through an external dial switch, a time window for opening the liquid crystal lens is determined according to the user serial number, the liquid crystal lens is opened in a first projection time interval if the liquid crystal lens is in a user 1 state, and the liquid crystal lens is opened in a second projection time interval or a third projection time interval if the liquid crystal lens is in a user 2 or user 3 state, so that the time window for opening the liquid crystal lens is matched with the corresponding projection time interval, and the function is realized through the programming of a single chip microcomputer device serving as a multi-picture glasses control module.
In order to determine the time window parameters for opening the liquid crystal lens, the start time of each projection period from the synchronous light pulse signal and the length of each projection period need to be determined, and it needs to be pointed out that the time window parameters of each surface projection period of projectors of different models are different and need to be obtained through experimental measurement, so when designing and realizing multi-picture glasses, the measurement should be performed according to the specific projector model used by the multi-picture projection system, and the time window parameters are set accordingly. The present representative DLP commercial projector mingi MS524 type stereoscopic projector is employed in a multi-picture projection system, and the time window parameter measurement results of this type of projector are described in detail below.
Firstly, parameter measurement is carried out on a single bright base MS524 type stereo projector: starting a projector stereoscopic playing mode and playing a stereoscopic video, converting a projector image brightness signal into an analog electrical signal through a photodiode, observing and measuring the form of the analog electrical signal through an oscilloscope, wherein the acquired analog electrical signal contains a direct current component due to ambient light components, filtering the direct current component by using a direct current clamping circuit, measuring the analog electrical signal mode in a left-eye and right-eye picture switching period of 8.33ms as shown in figure 1, firstly, a synchronous light pulse signal with the width of 20 mus, then, a zero level interval with the width of 1.6ms, then, R, G, B three bit plane projection time intervals with the widths of 1.7ms, changing the voltage of the analog electrical signal along with the image brightness, and finally, ending the period, wherein the width of the zero level interval is 1.63 ms. From the above measurement results, the time windows corresponding to the respective facet projection periods can be determined, as shown in fig. 2.
Since the above-mentioned patterns occur periodically, a zero level interval of 1.63ms before each synchronization light pulse is called a front stage of the synchronization pulse, and a zero level interval of 1.6ms after the synchronization light pulse is called a rear stage of the synchronization pulse, which is a remarkable feature of the front and rear structures of the optical synchronization pulse. When the single projector works, the peak value of the image signal amplitude of each surface projection period is obviously lower than the synchronous light pulse amplitude and is about 2/3 of the synchronous light pulse amplitude.
Under the multi-picture projection mode, the synchronous projection and image superposition of the three projectors can obviously influence the form and signal amplitude characteristics of synchronous light pulses: due to the difference of internal devices of the projectors, the accurate coincidence of the synchronous light pulses of the three projectors cannot be ensured, but two or three pulses with short intervals are formed, and are called as synchronous pulse groups for convenience, and the width of each synchronous pulse group is about 0.23ms from the rising edge of the first synchronous pulse to the falling edge of the last synchronous pulse, as shown in fig. 2; due to the superposition of the synchronous projection images of the three projectors, the amplitude of the image signal of each bit plane projection period reaches or is higher than the amplitude of the synchronous light pulse signal, as shown in fig. 2. Although the synchronous light pulse signal loses the obvious characteristic of amplitude advantage in the multi-picture projection mode, the synchronous light pulse signal has the morphological characteristics of a front platform and a rear platform which are basically kept unchanged, and a long rear platform structure of about 1.3ms is still kept even after the synchronous light pulse is changed into a synchronous pulse group in the multi-picture projection mode, as shown in fig. 2, in the design implementation of the multi-picture stereo glasses, the filtering of false pulses is ensured by detecting the morphological conditions of the front platform and the rear platform, and the synchronous light pulse signal is correctly extracted.
The technical scheme adopted by the invention is described below, and the multi-picture stereoscopic glasses device comprises four modules: (1) the optical pulse synchronous signal extraction module is used for receiving a synchronous optical pulse signal of a projector in the multi-picture projection system, converting the synchronous optical pulse signal into a digital pulse signal and forming synchronous pulse input of the multi-picture glasses control module.
(2) The control module is realized by an embedded single chip microcomputer, and has the function of forming a driving signal for controlling the switching of the opening and closing of the liquid crystal lens of the left eye and the right eye according to a synchronous pulse signal of the multi-picture projection system, so that the opening and closing time sequence of the liquid crystal lens is ensured to be synchronous with the playing time sequence of the multi-picture projection system.
(3) The liquid crystal lens opening and closing voltage driving module generates driving voltage of the liquid crystal lens according to the opening and closing control signal output by the control module and controls the opening and closing state of the lens.
(4) And the DC-DC power supply module converts the battery voltage into various DC voltages and supplies power for the embedded single chip microcomputer and the liquid crystal lens switching voltage driving module. Fig. 3 shows a schematic diagram of functional modules of multi-view stereoscopic glasses.
The working principle of each module is described in detail as follows:
(1) and the optical pulse synchronous signal extraction module is used for receiving and extracting synchronous optical pulse signals of the multi-picture projection system and converting the optical signals into analog electric signals through the photodiode. And then the direct current component in the signal is filtered by the direct current clamp. And then amplifying the analog signal by fixed gain amplification to ensure that the signal has enough amplitude so as to counteract the attenuation of the optical-electrical signal caused by the change of the distance between the observation and the observation. And finally, performing binarization processing on the amplified analog signal by using a reverse comparator, converting the analog signal into a digital signal, wherein the output at the moment when the signal amplitude is greater than the reference potential is 0, and the output at the moment when the signal amplitude is greater than the reference potential is 1, for convenience of expression, the output is called as an optical-electrical digital signal and is respectively connected to two I/O terminals P0.3 and P0.11 of the single chip microcomputer, wherein the former is used as external interrupt trigger of the single chip microcomputer, the falling edge of the optical-electrical digital signal triggers external interrupt, the latter is used for sampling the optical-electrical digital signal by the single chip microcomputer, and a circuit schematic diagram of the optical pulse synchronous signal extraction.
Under the ideal condition, the rising edge of the synchronous light pulse appearing every 8.33ms is changed into a falling edge after being processed in a reverse mode, and the falling edge is used as an interrupt trigger signal and input into a single chip microcomputer and used as an external synchronous reference for generating a lens opening and closing control time sequence. However, since the image signal contains glitch interference after being subjected to photoelectric conversion, and a false interference pulse is generated after the signal is amplified, the generated interrupt pulse contains both a real synchronization pulse corresponding to the synchronization light pulse and a false interference pulse, and therefore further form detection needs to be performed on the interrupt pulse signal to filter the false pulse.
(2) And the control module comprises a driving function and a phase synchronization function, wherein the driving function is used for determining time window parameters according to the user group serial numbers and generating corresponding liquid crystal lens opening and closing control signals with unequal duty ratios. The phase synchronization function is used for detecting the form of the interrupt pulse generated at the previous stage, filtering the false pulse generated due to burr amplification, retaining and extracting the correct photoelectric synchronization pulse, and performing phase synchronization on the opening and closing control signal of the liquid crystal lens. The control module is realized by an embedded single chip microcomputer.
The implementation method of the driving function comprises the following steps: in the multi-picture stereo projection mode, the liquid crystal lens needs to be started within a specific bit plane projection time period, and therefore a timer is arranged in the single chip microcomputer, the timer period is used as a basic time unit for timing, and a time window for controlling the liquid crystal lens to be started is generated.
The typical value set by the timer is 11.0592MHz of crystal oscillator, the frequency multiplication of phase-locked loop 3, the frequency division coefficient 1/4, the time constant 160 of the timer, the corresponding frequency of the timer is 120X 432Hz, and the period of the timer is Tc19.29 mus, i.e. the stereoscopic projector completes exactly one left and right eye cut every 432 times the timer is interruptedAnd (5) changing the period.
With timer period TcThe single chip microcomputer is provided with two 32-bit integer variables Cnt1 and Cnt2 as counters for recording the interruption times of the timer, and the variable value is accumulated to be 1 when 1 timer interruption occurs. With timer period TcThe number of timer interrupts recorded in the counter variables Cnt1 and Cnt2 is counted for a basic unit of time.
The timer clears the count value of the Cnt1 and counts the count value again by accumulating every 432 times of interruption, the value of the Cnt1 is called a foldback counter, the value of the Cnt1 changes from 0 to 431 in a period, and one change period just corresponds to the left-eye and right-eye switching period of stereoscopic projection, so the count value of the Cnt1 can be used as a time scale to generate a time window for controlling the opening of the liquid crystal lens. The count value of Cnt2 is incremented from 0, and is called a non-wrap counter, which is used to provide an overall time scale for the system.
The user group serial number is set through a two-digit dial switch (DIP) of the peripheral equipment, wherein the 00 state corresponds to the user 1, the 01 state corresponds to the user 2, and the 10 state corresponds to the user 3. Different user group serial number settings correspond to different liquid crystal lens opening time window settings.
Determining the starting and stopping range [ N ] of the opening time window of the liquid crystal lens according to the read user group signal1，N2]The time unit is a timer period, namely in a stereo projection left-right eye switching period, when the timer generates the Nth1Starting the liquid crystal lens when the interruption is repeated until the timer generates the Nth time2The liquid crystal lens is closed during the secondary interruption, and the time length of the liquid crystal lens in the opening state in a stereoscopic projection left-right eye switching period is (N)2-N1) X 19.29 μ s, and a period of time in the OFF state of (432-N)2+N1)×19.29μs。
Performing liquid crystal lens drive control in a timer interrupt response routine in which the value of a return counter Cnt1 is read, when the number of interrupts recorded in Cnt1 is equal to N1Then the liquid crystal lens is turned on, and when the interruption number recorded in Cnt1 is equal to N2Then is turned offAnd closing the liquid crystal lens.
In the above control method, it is necessary to ensure that the count period of the foldback counter Cnt1 is phase-synchronized with the left and right eye switching periods of the stereoscopic projection, that is, the count value of Cnt1 is 0 when the projector generates the synchronization light pulse. In an actual working state, due to the difference between the starting time of the projector and the starting time of the liquid crystal glasses, the projector and the liquid crystal glasses cannot ensure phase synchronization, and therefore phase synchronization needs to be performed in the control module according to the detection result of the synchronous light pulse of the projector.
The method for realizing the phase synchronization function comprises the following steps:
in the case of a burst of synchronization light pulses in the multi-picture projection mode, it is provided for this purpose that the first pulse in the burst of synchronization pulses is used as the synchronization pulse for the multi-picture stereo glasses.
Because the image signal has glitch interference, in the interrupt pulse generated by the optical pulse synchronous signal extraction module, there are both real synchronous pulses corresponding to the synchronous optical pulse and false interference pulses, so that form detection is required to filter the false pulses, and correct phase synchronization can be realized.
In order to distinguish real synchronous pulse signals from false pulse signals caused by glitch interference, the following waveform form detection conditions are adopted for distinguishing:
1. width condition: the width of the synchronous pulse signal is fixed to 20 mus, namely after the falling edge of the synchronous pulse starts, the zero level state of 20 mus is maintained, and part of the false pulses are transient pulses, and the condition is not satisfied when the width is extremely short.
2. Front and rear platform conditions: the real synchronous pulse signal has obvious front and back platform structures, after reverse processing, the synchronous pulse is a negative pulse, high level intervals with the width of 1.6ms are arranged before and after the pulse, the high level intervals are respectively called as the front and back platforms of the synchronous pulse, and no obvious front and back edge structures are arranged before and after the false pulse.
3. The interval condition is as follows: the current real sync pulse should be 8.33ms apart from the last sync pulse, which is measured by the number of timer interrupts, and the dummy pulse does not satisfy this condition.
4. Uniformity conditions: to enhance the interval condition detection, it is required that the interval of three consecutive synchronization pulses before the current pulse is 8.33 ms.
And detecting the signal forms before and after the falling edge every time when the optical-electric digital signal generates a falling edge to trigger the external interruption, and if the form conditions are met, judging the signal form to be a real synchronous pulse, otherwise, judging the signal form to be a false interference pulse.
In order to realize the detection of the front and rear platform conditions, the singlechip needs to read and record the optical-electric digital signal for sampling, in the interrupt response program of the timer, the optical-electric digital signal is sampled through an I/O port P0.11d, the sampling value is 1bit, and the sampling period is the timer period Tc19.29 mus. A64-bit shift register RC is arranged in a singlechip, after sampling each time, the RC shifts one bit to the left, and the current sampling value is read into the lowest bit. Recording 64 sampling results of the stored photoelectric digital signals in RC, wherein the corresponding sampling time is TcX 64 ≈ 1.23ms for detecting the structural conditions of the front and rear stages.
The above morphological conditions were detected one by one in the following order: the method comprises the following steps of 1, front platform condition detection, 2 width condition detection, 3 rear platform condition detection, 4 interval condition detection and 5 uniformity condition detection. 1 and 2 are executed in a response program of an external interrupt, 3, 4 and 5 are executed in a main program, and the specific implementation method is described as follows:
1, detecting the condition of a front platform: when the external interruption is triggered by a falling edge generated by the optical-electric digital signal, the numerical value in the shift register RC is read immediately in an interruption response program, if the numerical value is 0 xfffffffffh, namely 64 bits are all 1, the numerical value indicates that a high level interval with the width of about 1.23ms exists before the pulse, namely the structural condition of the front platform is judged to be met, otherwise, the pulse is judged to be interfered.
2, width condition detection: and executing in an interrupt response program, if the structural condition of the front platform is judged to be met, reading the value of the current optical-electrical digital signal through a port P0.11 of the single chip microcomputer immediately, delaying for a certain time from the leading edge of the pulse at the moment, if the value of the optical-electrical digital signal is 0 (reverse direction) at the moment, indicating that the current pulse has a certain width, judging that the width condition is met, otherwise, judging that the false instantaneous interference pulse is judged.
If the two detection results are true, the current pulse is called a 'candidate synchronous pulse', the flag variable of the candidate pulse set in the singlechip is set to be 1, otherwise, the flag variable is set to be 0, the non-retracing counter Cnt2 at the current moment is set, and then the external interrupt response program is stopped and returns to the main program.
And 3, detecting the condition of the rear platform: and judging the value of a candidate pulse mark variable in the main program, if the value is 0, indicating that a candidate synchronous pulse meeting the front platform condition and the width condition does not appear, continuing to wait, and if the value is 1, indicating that a candidate synchronous pulse appears, and starting the main program to carry out rear platform condition detection. At this time, a delay waiting process is required, and after sampling the photo-electric digital signal for a sufficient period of time, the sampling value recorded in the shift register RC is read to determine whether the back platform structure exists.
As mentioned above, in the multi-frame projection mode, the synchronization light pulse is split into the synchronization pulse group (as shown in fig. 2), there are two pulse structures within 0.22ms after the first pulse of the pulse group is ended, and then there is an obvious post-stage structure, so that when the post-stage condition is detected, an additional delay of about 0.2ms is needed to perform the function of overriding and ignoring other pulses in the pulse group, and when the detection is specific, the delay time is set to 76 timer periods, i.e. TcX 64 ≈ 1.47ms, during which 76 times of sampling are performed on the photo-electric digital signal, while only the last 64 times of sampling values are retained in the 64-bit shift register SR, and the first 12 times of sampling values are discarded, wherein the discarded part corresponds to the time length TcX 12 ≈ 0.23ms, which serves to override and ignore other pulses in the burst. If the numerical value in the shift register SR is 0 xfffffffffh, that is, 64 bits are all 1, it indicates that a high level interval with a width of about 1.23ms exists after the pulse, that is, it is determined that the structural condition of the rear stage is satisfied.
As previously mentioned, the sampling and timing of the opto-electronic digital signal is a timer period TcThe number of timer interrupts recorded in the counter variables Cnt1 and Cnt2 is counted for a basic unit of time. To achieve afterThe time delay waiting in platform detection adopts a timing method, when the external interruption is triggered, the value in a non-retrace counter Cnt2 is recorded in an interruption response program to be used as the starting time of the current pulse, if the current pulse is judged as a candidate synchronous pulse, the value in the non-retrace counter Cnt2 is continuously read in a circular waiting mode after the current pulse returns to a main program, Cnt2 is continuously accumulated along with the interruption of a timer until the difference between the current pulse and the counting value of the starting time of the pulse is 76, which indicates that T is completedcAnd 4, a delay process of multiplied by 64 and approximately equal to 1.47ms, reading the value in the shift register SR immediately, and detecting the condition of the rear platform.
If a new external interrupt occurs during the delay wait and is marked as a candidate sync pulse, the previous candidate sync pulse is discarded and the post-platform condition detection is performed after the delay wait is performed again.
4, detection of interval conditions: if the current pulse meets the condition of the rear platform, immediately carrying out interval condition detection in the main program, namely if the difference between the starting time of the current pulse and the starting time of the last synchronous pulse is 432 units, corresponding to the time length TcAnd when the time interval of the current pulse and the last synchronous pulse is 8.33ms, the time interval of the current pulse and the last synchronous pulse meets the DLP LINK standard, the interval condition is judged to be met, otherwise, the current pulse is judged to be a false interference pulse.
5, detecting uniformity conditions: and finally, for strengthening interval condition detection, requiring that the interval of three continuous synchronous pulses before the current pulse is 8.33ms, namely detecting the interval between the start time of the current pulse and the start time of three continuous synchronous pulses before the current pulse, if the interval is not met, judging that the current pulse is a false interference pulse, clearing the record of the start time of three continuous synchronous pulses before the current pulse, and restarting the record.
If the current pulse meets the form condition 1-5, the current pulse is judged to be a real synchronous pulse, the mark variable of the synchronous pulse is set to be 1, at the moment, the foldback counter Cnt2 can be calibrated according to the current synchronous pulse, namely, the value of the foldback counter Cnt2 is ensured to be 0 at the moment when the current synchronous pulse starts, namely, the switching period of the left eye and the right eye recorded by the counter Cnt2 is synchronous with the switching period of the left eye and the right eye of the multi-picture stereoscopic projection system, and the process is called as a phase table for the convenience of expression.
As described above, since the detection of the morphological condition 1 to 5 is performed, when the current pulse is determined to be the true synchronization pulse, the time is delayed by 76 timer cycles from the start time of the pulse, and therefore, when the phase table is performed, the value of the foldback counter Cnt2 should be set to 76 instead of 0, and the count cycle corresponding to the Cnt2 is also synchronized with the projector left-eye image switching cycle. The phase table counting function is executed in the timer interrupt response program, if the value of the synchronization pulse mark variable is 1, the real synchronization pulse is detected, the value in the retrace counter Cnt2 is set to 76, the phase table counting is completed, the synchronization pulse mark variable is cleared, and the phase table counting is carried out again after the next synchronization pulse comes.
When the multi-picture stereo glasses are opened, the default liquid crystal lenses are switched on and off in a left-right-left sequence, but because the starting time of the multi-picture stereo glasses and the multi-picture projection system cannot be accurately synchronized, the situation that the opening sequence of the left and right lenses in the stereo glasses is opposite to the playing sequence of a stereo projection left picture and right picture can occur, namely, a right eye image is seen when the left lens is opened, a left eye image is seen when the right lens is opened, and a user can visually feel the disorder of the stereo pictures.
The above-mentioned driving function and phase synchronization function are respectively implemented in the timer interrupt response program, the external interrupt response program, and the main program of the single chip microcomputer, and the flowcharts of the timer interrupt response program, the external interrupt response program, and the main program of the single chip microcomputer are shown in fig. 5, fig. 6, and fig. 7.
(3) The liquid crystal lens switching voltage driving module adopts two LM393NG chips to respectively drive the switching voltage of the liquid crystal lenses of the left eye and the right eye, takes the liquid crystal lens switching control signal generated in the control module as input, keeps the waveform of the switching signal, and raises the liquid crystal lens switching control voltage to 15V, thereby ensuring the switching speed of the switching state of the liquid crystal lenses.
(4) The DC-DC power supply module converts the battery voltage into various DC voltages to supply power for the embedded single chip microcomputer and the liquid crystal lens switching voltage driving module, the module is realized by an SDB628 chip, 3.7V direct-current voltage of a lithium battery powered by a system is converted into three output voltages of 3.3V, 1.8V and 15V, the former two output voltages supply power for the single chip microcomputer, and the latter supplies power for the liquid crystal lens switching voltage driving module.
The implementation method of 4 modules of the multi-picture stereo glasses is described above, and compared with the existing stereo liquid crystal glasses, the multi-picture stereo glasses are special equipment for a multi-picture stereo projection system, and ensure that the opening and closing time sequence of the liquid crystal lenses is synchronous with the playing time sequence of the stereo video of the corresponding group, so that each path of independent stereo video can be distinguished and watched correctly. The essential difference is that the lenses of the multi-picture stereo glasses are opened in the projection time period of the corresponding bit plane image, and the lens opening time sequences with different duty ratios are formed. Meanwhile, in a multi-picture projection mode, in order to eliminate synchronous light pulse interference caused by superposition of images projected by three projectors simultaneously and false pulse interference caused by image burr interference, a form detection means is adopted to filter the false pulse and extract correct synchronous pulse, so that the opening and closing time sequence of the multi-picture stereoscopic glasses and the stereoscopic picture time sequence of the multi-picture projection system are ensured to realize phase synchronization.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (8)
1. A shutter type liquid crystal glasses for a multi-picture stereoscopic projection playing system is characterized in that: including the glasses body, be provided with on the glasses body:
the optical pulse synchronous signal extraction module is used for receiving a synchronous optical pulse signal of a projector in the multi-picture projection system, converting the synchronous optical pulse signal into a digital pulse signal and forming a synchronous pulse input of the control module;
the control module is used for forming a driving signal for controlling the opening and closing switching of the left eye liquid crystal lens or/and the right eye liquid crystal lens of the glasses body according to the synchronous pulse signal of the multi-picture projection system, and ensuring that the opening and closing time sequence of the liquid crystal lens is synchronous with the playing time sequence of the multi-picture projection system;
the liquid crystal lens opening and closing voltage driving module generates driving voltage of the liquid crystal lens according to the opening and closing control signal output by the control module and controls the opening and closing state of the liquid crystal lens;
the DC-DC power supply module converts the battery voltage into various DC voltages and supplies power to the control module and the liquid crystal lens switching voltage driving module;
the control module further comprises a driving module and a phase synchronization module, wherein the driving module determines time window parameters according to the user group serial number and generates corresponding liquid crystal lens opening and closing control signals with unequal duty ratios, the phase synchronization module performs shape detection according to generated interrupt pulses, filters false pulses generated due to burr amplification in the liquid crystal lens opening and closing control signals, reserves and extracts correct photoelectric synchronization pulses, and performs phase synchronization on the liquid crystal lens opening and closing control signals according to the false pulses;
the implementation process of the driving module comprises the following steps: in the multi-picture three-dimensional projection mode, a timer period is used as a basic time unit for timing, a time window for controlling the opening of the liquid crystal lens is generated, and the liquid crystal lens is controlled to be opened in a specific position surface projection time period.
2. The shuttered liquid crystal glasses for a multi-picture stereoscopic projection and playback system as claimed in claim 1, wherein: the optical pulse synchronous signal extraction module comprises a photoelectric amplifier, a direct current clamper, a fixed gain amplifier, a reverse comparator and an amplitude limiting circuit which are sequentially connected, wherein an optical signal is converted into an analog electric signal through the photoelectric amplifier, the direct current clamper is used for filtering a direct current component in the signal, the fixed gain amplifier amplifies the analog signal to ensure that the signal has enough amplitude so as to counteract the optical-electric signal attenuation caused by the change of the viewing distance, and the reverse comparator is used for carrying out binarization processing on the amplified analog signal and converting the analog signal into a digital signal.
3. The shuttered liquid crystal glasses for a multi-picture stereoscopic projection and playback system as claimed in claim 1, wherein: the form detection conditions of the phase synchronization module comprise a signal width condition, a signal front and back level platform condition, a pulse interval condition and a pulse interval uniformity condition.
4. The shuttered liquid crystal glasses for a multi-picture stereoscopic projection and playback system as claimed in claim 1, wherein: the liquid crystal lens opening and closing voltage driving module adopts two driving chips to respectively drive the opening and closing voltage of the liquid crystal lenses of the left eye and the right eye, takes a liquid crystal lens opening and closing control signal generated in the control module as input, keeps the waveform of the opening and closing signal and ensures the switching speed of the opening and closing state of the liquid crystal lenses.
5. The shuttered liquid crystal glasses for a multi-picture stereoscopic projection and playback system as claimed in claim 1, wherein: the DC-DC power supply module converts the battery voltage into various DC voltages to supply power for the control module and the liquid crystal lens opening and closing voltage driving module, converts the direct current voltage supplied by the system into various output voltages and supplies power for the control module and the liquid crystal lens opening and closing voltage driving module.
6. The shuttered liquid crystal glasses for a multi-picture stereoscopic projection and playback system as claimed in claim 1, wherein: a microswitch of the control module starts a left-right eye switching function, control variables of a left eyeglass and a right eyeglass in the single chip microcomputer are switched, and the liquid crystal eyeglasses are switched in a left-right-left sequence when the shutter type liquid crystal eyeglasses are opened.
7. The working method of the shutter-type liquid crystal glasses for the multi-picture stereo projection playing system according to any one of claims 1-6, characterized in that: the lenses of the shutter type liquid crystal glasses are opened in the corresponding bit plane image projection time interval to form lens opening time sequences with different duty ratios, and meanwhile, under the multi-picture projection mode, false pulses are filtered by adopting a form detection means to eliminate synchronous light pulse interference caused by superposition of simultaneous projection images of multiple projectors and false pulse interference caused by image burr interference, correct synchronous pulses are extracted, and the opening and closing time sequences of the shutter type liquid crystal glasses and the stereoscopic picture time sequence of a multi-picture projection system are ensured to realize phase synchronization.
8. The method of operation of claim 7, wherein: the following morphological detection conditions were used for differentiation:
(1) width condition: setting a width value of a synchronous pulse signal, namely maintaining a zero level state of the width value time after the falling edge of the synchronous pulse starts;
(2) front and rear platform conditions: the real synchronous pulse signal has obvious front and back platform structures, after reverse processing, the synchronous pulse is a negative pulse, and high level intervals with certain widths are arranged before and after the pulse, and are respectively called as the front and back platforms of the synchronous pulse;
(3) the interval condition is as follows: the time interval between the synchronization pulses is measured by the number of times the timer is interrupted;
(4) uniformity conditions: the interval condition is satisfied by a plurality of continuous synchronous pulse intervals before the current pulse.
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| CN110267418B (en) * | 2019-06-17 | 2023-12-26 | 浙江大邦科技有限公司 | Projection system based on intelligent street lamp and control method |
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