CN109587461B - Laser scanning projection equipment and projection method thereof - Google Patents
Laser scanning projection equipment and projection method thereof Download PDFInfo
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- CN109587461B CN109587461B CN201811261263.2A CN201811261263A CN109587461B CN 109587461 B CN109587461 B CN 109587461B CN 201811261263 A CN201811261263 A CN 201811261263A CN 109587461 B CN109587461 B CN 109587461B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3141—Constructional details thereof
- H04N9/315—Modulator illumination systems
- H04N9/3161—Modulator illumination systems using laser light sources
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
- H04N9/3135—Driving therefor
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3138—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using arrays of modulated light sources
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3191—Testing thereof
Abstract
The embodiment of the application provides laser scanning projection equipment and a projection method thereof. The method comprises the following steps: acquiring the resonance frequency of the scanning mirror; generating a pixel clock signal according to the resonance frequency in combination with a reference clock signal; driving the laser light source according to the pixel clock signal; wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection. The technical scheme provided by the embodiment of the application can automatically adjust the pixel clock signal for driving the laser light source according to the actual resonance frequency of different scanning mirrors, so that the influence of factors such as difference existing in equipment hardware or temperature change during operation on the image projection effect is reduced, and the equipment performance is improved.
Description
Technical Field
The embodiment of the application relates to the technical field of electronics, in particular to laser scanning projection equipment and a projection method thereof.
Background
Compared with common LCD (liquid crystal micro projection technology) transmission micro projection, DLP (digital light processing technology) reflection micro projection and LCOS (liquid crystal on silicon) reflection micro projection, the laser scanning projector (LBS) has the advantages of simple structure, small volume, small optical path loss, low power consumption, wide color range, large contrast, high resolution, no need of focusing and the like.
In the LBS projection system, the scanning mirror and the laser source are the main components. The scanning mirror respectively rotates in a reciprocating manner by taking two orthogonal shafts as axes, deflects the combined light beams along two vertical directions and projects the deflected light beams to a preset area, and a projection image is generated. The scanning mirror includes a micro-electromechanical system (i.e., MEMS) that drives the scanning mirror to rotate back and forth about two orthogonal axes.
The operation in a first direction (often referred to as the transverse direction) of the scanning mirror is a line signal HS of the projected image; the motion in the second direction (often referred to as the portrait direction) is a frame signal VS of the projected image. To reduce the power consumption of the system, the operating frequency in the first direction is the resonance frequency of the MEMS. However, there is some difference in MEMS in production, and there is difference in transverse resonance frequency of each MEMS; and the resonance frequency shift phenomenon of the MEMS can occur due to temperature change and the like after long-time operation. The distortion of the projected image may be abnormal due to the difference of the resonance frequencies or the shift of the resonance frequencies.
Disclosure of Invention
In view of the above, the present application is proposed to provide a laser scanning projection apparatus and a projection method thereof that solve the above problems, or at least partially solve the above problems.
In one embodiment of the present application, a projection method of a laser scanning projection apparatus is provided. The method comprises the following steps:
acquiring the resonance frequency of the scanning mirror;
generating a pixel clock signal according to the resonance frequency in combination with a reference clock signal;
driving the laser light source according to the pixel clock signal;
wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection.
Optionally, the method further includes:
generating a transverse driving signal according to the resonance frequency in combination with the reference clock signal;
and driving the scanning mirror to perform transverse scanning according to the transverse driving signal.
Optionally, generating a lateral drive signal according to the resonance frequency in combination with the reference clock signal comprises:
determining a first frequency division coefficient according to the resonance frequency;
according to the first frequency division coefficient, frequency division processing is carried out on the reference clock signal to obtain a first frequency division clock signal;
looking up a sine wave table to generate the lateral drive signal based on the first divided clock signal, wherein a frequency of the lateral drive signal is equal to the resonant frequency.
Optionally, determining a first frequency-division coefficient according to the resonance frequency includes:
and taking the ratio of the product of the number of sampling points of the sine wave waveform table and the resonance frequency to the clock frequency of the reference clock signal as a first frequency division coefficient.
Optionally, generating a pixel clock signal according to the resonance frequency in combination with a reference clock signal, includes:
determining a first frequency multiplication multiple according to the projection resolution and the number of sampling points of the sine wave waveform table;
and performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
Optionally, the method further includes:
generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal;
and driving the scanning mirror to perform longitudinal scanning according to the longitudinal driving signal.
Optionally, generating a vertical driving signal according to the projection frame frequency in combination with the reference clock signal includes:
determining a second frequency division coefficient according to the projection frame frequency;
performing frequency division processing on the reference clock signal according to the second frequency division coefficient to obtain a second frequency division clock signal;
based on the second frequency-divided clock signal, a sawtooth waveform table is looked up to generate a longitudinal driving signal.
Optionally, determining the second frequency-dividing coefficient according to the projection frame frequency includes:
and taking the ratio of the product of the projection frame frequency and the number of sampling points of the sawtooth wave form table to the clock frequency of the reference clock signal as a second frequency division coefficient.
Optionally, acquiring the resonant frequency of the scanning mirror comprises:
collecting a transverse operation signal of a scanning mirror;
determining a time difference between the lateral run signal and a current lateral drive signal of the scan mirror based on the current lateral drive signal;
and calculating the resonance frequency of the scanning mirror according to the time difference.
In another embodiment of the present application, a laser scanning projection device is provided. The laser scanning projection device comprises:
the first signal generating module is used for generating a reference clock signal;
the second signal generation module is respectively connected with the first signal generation module and used for acquiring the resonance frequency of the scanning mirror; generating a pixel clock signal according to the resonance frequency by combining the reference clock signal;
the light source driving module is connected with the laser light source and used for driving the laser light source according to the pixel clock signal;
wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection.
Optionally, the second signal generating module is further configured to: generating a transverse driving signal according to the resonance frequency in combination with the reference clock signal;
and the scanning mirror is connected with the second signal generating module and is used for transverse scanning under the driving of the transverse driving signal.
Optionally, the second signal generating module includes:
the first arbitrary frequency division unit is used for determining a first frequency division coefficient according to the resonance frequency; according to the first frequency division coefficient, frequency division processing is carried out on the reference clock signal to obtain a first frequency division clock signal;
a first signal generating unit connected to the first arbitrary frequency dividing unit, for searching a sine wave waveform table based on the first frequency-divided clock signal to generate the lateral driving signal.
Optionally, the second signal generating module further includes:
the first frequency doubling unit is connected with the first arbitrary frequency dividing unit and used for determining a first frequency doubling multiple according to the projection resolution and the number of sampling points of the sine wave waveform table; and performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
Optionally, the second signal generating module is further configured to:
generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal;
the scanning mirror is also used for longitudinal scanning under the driving of the longitudinal driving signal.
Optionally, the second signal generating module includes:
the second arbitrary frequency division unit is used for determining a second frequency division coefficient according to the projection frame frequency; performing frequency division processing on the reference clock signal according to the second frequency division coefficient to obtain a second frequency division clock signal;
and the second signal generating unit is connected with the second arbitrary frequency dividing unit and used for searching a sawtooth wave form table based on the second frequency dividing clock signal so as to generate a longitudinal driving signal.
According to the technical scheme provided by the embodiment of the application, the corresponding pixel clock signal is generated according to the obtained actual resonance frequency of the scanning mirror, and the pixel clock signal is accurate and stable; and driving the laser light source to emit the light of the pixel point according to the pixel clock signal. Therefore, the pixel clock signal for driving the laser light source can be automatically adjusted according to the actual resonance frequency of different scanning mirrors, so that the influence of factors such as difference existing in equipment hardware or temperature change during operation on the image projection effect is reduced, and the equipment performance is improved. In addition, according to the technical scheme provided by the embodiment of the application, the synchronization of the vibration position of the scanning mirror and the lighting of the laser light source is realized in a software mode, so that a hardware circuit is simplified, the miniaturization of a system is facilitated, and the production cost is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic structural diagram of a laser scanning projection apparatus according to an embodiment of the present application;
fig. 2 is a signal diagram of a horizontal driving signal, a vertical driving signal and a clock signal according to an embodiment of the present disclosure;
fig. 3 is a schematic flowchart of a projection method according to an embodiment of the present application;
fig. 4 is a schematic circuit diagram of a laser scanning projection apparatus according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
In some of the flows described in the specification and claims of this application and in the above-described figures, a number of operations are included that occur in a particular order, but it should be clearly understood that these operations may be performed out of order or in parallel as they occur herein, the number of operations, e.g., 101, 102, etc., merely being used to distinguish between various operations, and the number itself does not represent any order of performance. Additionally, the flows may include more or fewer operations, and the operations may be performed sequentially or in parallel. It should be noted that, the descriptions of "first", "second", etc. in this document are used for distinguishing different messages, devices, modules, etc., and do not represent a sequential order, nor limit the types of "first" and "second" to be different.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Before the technical solution provided by the embodiment of the present application is introduced, a simple description is made on the structure of the laser scanning projection apparatus.
A laser scanning projection device as shown in fig. 1, comprising: a laser light source 1, an optical assembly 2 and a scanning mirror 3. The laser light source 1 is used for emitting laser light. In specific implementation, the number of the laser light sources 1 may be three, and the three laser light sources are red, green and blue laser light sources respectively, and are used for providing red, green and blue diffracted laser beams to generate a color image through projection. The optical component 2 can be used for projecting a laser beam emitted by the laser light source to the scanning mirror 3 according to a set light path, and then the laser beam is deflected by the scanning mirror 3 and is projected to a preset area to generate a projection image. The scanning mirror 3 rotates reciprocally about two orthogonal axes, deflects the projected light beam in two perpendicular directions, and projects the deflected light beam onto a predetermined area to generate a projection image. The scanning mirror 3 includes a micro-electromechanical system (MEMS) that drives the scanning mirror 3 to rotate back and forth about two orthogonal axes, i.e., the first direction of operation and the second direction of operation mentioned above, in response to a received drive signal.
Here, it should be noted that: the optical assembly 2 may include: a focusing lens 4, a combination prism 5, a reflecting mirror 6, and the like, which are not particularly limited in this embodiment.
The resonance frequency of the MEMS is adopted as the operation frequency of the scanning mirror 3 in the first direction; the resonance frequencies of different MEMS are different, and are influenced by temperature change, so that the operation position of the scanning mirror and the lighting of the laser light source are difficult to synchronize. Therefore, the embodiment of the present application monitors the resonant frequency of the scanning mirror, so as to adjust the pixel clock signal for driving the laser light source according to the acquired resonant frequency, so that the operation position of the scanning mirror and the lighting of the laser light source are kept synchronous.
Fig. 2 shows signal diagrams of the pixel clock signal Pclk, the lateral driving signal HS, and the longitudinal driving signal VS.
Fig. 3 shows a schematic flowchart of a projection method of a laser scanning projection apparatus according to an embodiment of the present application. As shown in fig. 3, the method includes:
101. the resonant frequency of the scan mirror is acquired.
102. And generating a pixel clock signal according to the resonance frequency by combining a reference clock signal.
103. And driving the laser light source according to the pixel clock signal.
Wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection.
In the above 101, the resonant frequency of the scanning mirror may be obtained by testing before projection, for example: the scanning mirror is driven by driving signals with the same amplitude and different frequencies to vibrate, and the frequency of the driving signal corresponding to the maximum motion amplitude of the scanning mirror is determined as the resonance frequency of the scanning mirror; or detected during the projection.
Because the scanning mirror can generate the resonance frequency shift phenomenon due to temperature change and the like in the operation process, in order to ensure the scanning position of the scanning mirror and the lighting synchronism of the laser light source in the whole projection process, the resonance frequency of the scanning mirror can be detected in real time in the projection process, so that the pixel clock signal for driving the laser light source can be adjusted in real time according to the resonance frequency of the scanning mirror detected in real time.
The specific implementation of detecting the resonant frequency during the projection process will be described in detail in the following embodiments.
In the above 102, the laser scanning projection device is provided with a crystal oscillator, and the crystal oscillator provides the reference clock signal f for the laser scanning projection device1. Can convert the reference clock signal f1As the above-mentioned reference clock signal f2(ii) a Or, for the reference clock signal f1Performing frequency multiplication to obtain the clock signal after frequency multiplication as the reference clock signal f2. For reference clock signal f1The second frequency multiplication factor used for frequency multiplication is k2，k2The value of (b) can be set according to actual needs, and the application is not particularly limited thereto. I.e. the reference clock signal f2And a reference clock signal f1The following relationship is satisfied:
f2＝k2×f1 (1)
it should be noted that, by using the clock signal after the frequency multiplication, i.e., the clock signal with a higher frequency, as the reference clock signal, the accuracy of the pixel clock signal generated based on the reference clock signal can be effectively improved. The crystal oscillator may be an active crystal oscillator.
The scanning mirror is operated transversely according to its resonant frequency, and the frequency f of the generated pixel clock signal is used to synchronize the scanning position of the scanning mirror with the lighting of the laser light sourcepclkWith resonant frequency f0The following relationships are required:
fpclk＝K×f0 (2)
K＝2G (3)
wherein G is the projection horizontal resolution. I.e. the frequency f of the pixel clock signalpclkIs the resonance frequency f0K times of.
Typically, the projection resolution includes a projection horizontal resolution and a projection vertical resolution. The projection horizontal resolution is equal to the sum of the pixel point number of the effective area in the horizontal direction and the compensation point number of the front edge and the back edge in the horizontal direction; the projection vertical resolution is equal to the sum of the number of pixel points of the effective area in the vertical direction and the number of compensation points of the front edge and the back edge in the vertical direction. It should be noted that the number of compensation points added to the leading edge and the trailing edge is to avoid distortion of the projected image edge.
In 103, the driving of the laser light source according to the pixel clock signal is as follows: the laser light source is driven by the pixel clock signal to sequentially read pixel point information of the image to be projected, modulate the laser beam according to the read pixel point information and emit the modulated laser beam. The laser beam emitted by the laser light source is emitted to the projection area by the scanning mirror to realize projection.
According to the technical scheme provided by the embodiment of the application, the corresponding pixel clock signal is generated according to the obtained actual resonance frequency of the scanning mirror, and the pixel clock signal is accurate and stable; and driving the laser light source to emit the light of the pixel point according to the pixel clock signal. Therefore, the pixel clock signal for driving the laser light source can be automatically adjusted according to the actual resonance frequency of different scanning mirrors, so that the influence of factors such as difference existing in equipment hardware or temperature change during operation on the image projection effect is reduced, and the equipment performance is improved. In addition, according to the technical scheme provided by the embodiment of the application, the synchronization of the vibration position of the scanning mirror and the lighting of the laser light source is realized in a software mode, so that a hardware circuit is simplified, the miniaturization of a system is facilitated, and the production cost is reduced.
In practice, the transverse driving signal for driving the scanning mirror to perform transverse scanning can also be generated by combining the reference clock signal. In this way, phase synchronization of the lateral driving signal and the pixel clock signal can be ensured. Specifically, the method may further include:
104. generating a lateral drive signal from the resonant frequency in conjunction with the reference clock signal.
105. And driving the scanning mirror to perform transverse scanning according to the transverse driving signal.
At 104 above, the frequency of the generated lateral drive signal is equal to the resonant frequency of the scan mirror. The transverse driving signal may be a sine wave signal, a square wave signal, or the like, which is not particularly limited in this embodiment.
In an implementation manner, the above-mentioned "generating the lateral driving signal according to the resonant frequency in combination with the reference clock signal" in 104 can be implemented by the following steps:
1041. and determining a first frequency division coefficient according to the resonance frequency.
1042. And according to the first frequency division coefficient, carrying out frequency division processing on the reference clock signal to obtain a first frequency division clock signal.
1043. Looking up a sine wave table based on the first divided clock signal to generate the lateral driving signal.
Wherein the frequency of the lateral drive signal is equal to the resonant frequency.
In this embodiment, the horizontal driving signal is generated by a table lookup method. The frequency of the lateral drive signal to be generated can be determined in advance based on the resonant frequency of the scan mirror. According to the frequency of the transverse driving signal to be generated (equal to the resonance frequency f)0) And the number of sampling points of the sine wave waveform table can determine a first table look-up clock signal required by table look-up, namely the frequency of the first frequency division clock signal. Determining the ratio of the frequency of the first divided clock signal to the frequency of the reference clock signal as a first division factor m/n, i.e. the frequency f of the first divided clock signal3With frequency f of the reference clock signal2The following relationship is satisfied:
f3＝f2×m/n (4)
frequency f of the first divided clock signal3With transverse drive signalsFrequency fsinThe following relationship is satisfied:
f0＝fsin＝f3/n1 (5)
wherein n is1The number of sampling points is the sine wave waveform table.
By the above equations (4) and (5), it is possible to obtain:
that is, the number n of sampling points of the sine wave waveform table is set1And the resonance frequency f0With the clock frequency f of the reference clock signal2The ratio of (d) is taken as the first frequency-dividing coefficient m/n.
The step 1042 can be implemented by any frequency dividing unit, that is, the reference clock signal is used as an input signal of any frequency dividing unit, and the reference clock signal is frequency-divided by the any frequency dividing unit according to the first frequency dividing coefficient to obtain the first frequency-divided clock signal. The specific implementation of any frequency dividing unit can be found in the prior art, and is not described in detail here.
In the above 1043, the first frequency-dividing clock signal can drive the table look-up counter to look up the sine wave table, and the horizontal driving signal can be output by the Direct Digital Synthesizer (DDS) principle. The table lookup counter is specifically configured to: and counting the first frequency division clock output by any frequency division, and looking up the sine wave form table according to the count value, thereby realizing the output of the transverse driving signal. The sine wave table stores sine wave data.
Further, in the above 102, "generating the pixel clock signal according to the resonance frequency in combination with the reference clock signal" may specifically be implemented by:
1021. and determining a first frequency multiplication multiple according to the projection resolution and the number of sampling points of the sine wave waveform table.
1022. And performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
Namely: frequency f of pixel clock signalpclkWith the frequency f of the first divided clock signal3The following relationship is satisfied:
fpclk＝k1×f3 (7)
which is in k1Is the first frequency multiplication factor.
From equations (2), (3), (5) and (7), one can obtain:
k1＝2G/n1
namely: and determining the ratio of the double value of the projection horizontal resolution in the projection resolution to the number of sampling points of the sine wave waveform table as a first frequency multiplication factor.
When the laser scanning projection equipment is used for projection, the scanning mirror not only performs transverse scanning, but also performs longitudinal scanning. A longitudinal drive signal for driving the scan mirror for longitudinal scanning can also be generated based on the reference clock signal. Specifically, the method may further include:
106. and generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal.
107. And driving the scanning mirror to perform longitudinal scanning according to the longitudinal driving signal.
In 106, the frequency of the generated vertical driving signal is equal to the projection frame frequency. Typically, the projection frame frequency is a fixed value, such as: 60 Hz.
In an implementation, the above 106 can be implemented by the following steps:
1061. and determining a second frequency division coefficient according to the projection frame frequency.
1062. And according to the second frequency division coefficient, carrying out frequency division processing on the reference clock signal to obtain a second frequency division clock signal.
1063. Based on the second frequency-divided clock signal, a sawtooth waveform table is looked up to generate a longitudinal driving signal.
In this embodiment, the vertical driving signal is generated by a table lookup method. The frequency of the vertical driving signal to be generated can be determined in advance according to the projection frame frequency. According to the desired longitudinal directionThe frequency of the driving signal (i.e. the projection frame frequency f) and the number of sampling points of the sawtooth waveform table can determine the second table look-up clock signal required by table look-up, i.e. the frequency of the second frequency-divided clock signal. Determining the ratio of the frequency of the second divided clock signal to the frequency of the reference clock signal as a second division factor j/i, i.e. a second divided clock signal f4With frequency f of the reference clock signal2The following relationship is satisfied:
f4＝f2×j/i (8)
frequency f of the second divided clock signal4With frequency f of the longitudinal drive signalsawThe following relationship is satisfied:
f＝fsaw＝f4/n2 (9)
wherein n is2The number of sampling points of the sawtooth wave form table.
By the above equations (8) and (9), it is possible to obtain:
that is, the projection frame frequency f and the number n of sampling points of the sawtooth waveform table are set2With the clock frequency f of the reference clock signal2The ratio of (d) is taken as the second frequency-dividing coefficient j/i.
The step 1062 may be implemented by any frequency dividing unit, that is, the reference clock signal is used as an input signal of any frequency dividing unit, and the reference clock signal is subjected to frequency division processing by the any frequency dividing unit according to the second frequency dividing coefficient to obtain the second frequency divided clock signal. The specific implementation of any frequency dividing unit can be found in the prior art, and is not described in detail here.
In the above 1063, the second frequency-divided clock signal may drive the table look-up counter to look up the saw-tooth waveform table, and the vertical driving signal is output according to a Direct Digital Synthesizer (DDS) principle. The table lookup counter is specifically configured to: and counting the second frequency division clock output by any frequency division, and looking up a sawtooth wave form table according to the count value so as to realize the output of the longitudinal driving signal. Wherein, the sawtooth wave form table stores the waveform data of the sawtooth wave.
The detection of the resonant frequency of the scan mirror during projection will now be described. That is, in the above 101, "acquiring the resonant frequency of the scanning mirror" may be specifically realized by the following steps:
1011. and collecting a transverse running signal of the scanning mirror.
1012. A time difference between the lateral run signal and the current lateral drive signal is determined based on the current lateral drive signal of the scan mirror.
1013. And calculating the resonance frequency of the scanning mirror according to the time difference.
In 1011 above, the lateral movement signal may be generated by a sensor provided in the laser scanning projection apparatus for monitoring the movement of the scanning mirror in the lateral direction. For example, the sensor is a piezoelectric sensor, and when the scanning mirror is transversely moved to different positions, the piezoelectric sensor is correspondingly deformed, and then a corresponding voltage signal is generated.
When the transverse operation signal is a voltage signal collected by a sensor, the step 1012 "determining the time difference between the transverse operation signal and the current transverse driving signal based on the current transverse driving signal of the scanning mirror" may be specifically implemented by the following steps:
and S11, comparing the voltage signal with a preset voltage signal.
S12, generating a first pulse signal according to the comparison result.
And S13, acquiring a second pulse signal which is synchronous with the phase of the current transverse driving signal.
And S14, determining the time difference according to the first pulse signal and the second pulse signal.
The 1013 can be implemented by the following steps:
and S21, acquiring the phase shift equivalent time inherent in the hardware circuit.
And S22, calculating the difference value between the time difference and the equivalent time of the phase shift.
And S23, calculating the resonant frequency of the scanning mirror according to the difference and the frequency of the current driving signal.
Namely, the above implementation process can be simply understood as being implemented by the following calculation formula (11):
wherein t is the time difference; Δ t is the inherent phase shift equivalent time of the hardware circuit; m is the number of sampling points of the sine wave waveform table; fnIs the resonant frequency of the scanning mirror, Fn-1The frequency of the current lateral drive signal. f () is a preset function. In specific implementation, the specific formula implementation of f () may be derived based on basic theory in the prior art, or may be an empirical formula, which is not specifically limited in this embodiment.
The technical scheme provided by the embodiment of the application can automatically adjust the pixel clock signal for driving the laser light source according to the actual resonance frequency of each scanning mirror in the projection process so as to reduce the influence on the image projection effect caused by the difference of equipment hardware or the temperature change and other factors during operation and improve the equipment performance. In addition, by adopting the technical scheme provided by the embodiment of the application, the implementation can be realized through an FPGA (Field-Programmable Gate Array) program without adding a hardware circuit, and the complexity of the hardware circuit is reduced, so that the miniaturization of the hardware circuit is realized.
Fig. 4 shows a schematic circuit diagram of a laser scanning projection apparatus according to another embodiment of the present application. As shown in fig. 4, the laser scanning projection apparatus includes: the laser scanning device comprises a first signal generation module 20, a second signal generation module 30, a light source driving module 40, a laser light source 50 and a scanning mirror 60. Wherein the content of the first and second substances,
a first signal generating module 20 for generating a reference clock signal;
the second signal generation module 30 is connected with the first signal generation module 20 and is used for acquiring the resonance frequency of the scanning mirror; generating a pixel clock signal according to the resonance frequency by combining the reference clock signal;
the light source driving module 40 is connected with the laser light source 50 and used for driving the laser light source according to the pixel clock signal;
wherein the scanning mirror 60 is used to reflect the light from the laser light source 50 to realize projection.
According to the technical scheme provided by the embodiment of the application, the corresponding pixel clock signal is generated according to the obtained actual resonance frequency of the scanning mirror, and the pixel clock signal is accurate and stable; and driving the laser light source to emit the light of the pixel point according to the pixel clock signal. Therefore, the pixel clock signal for driving the laser light source can be automatically adjusted according to the actual resonance frequency of each scanning mirror, so that the influence of factors such as difference of hardware of the equipment or temperature change during operation on the image projection effect is reduced, and the performance of the equipment is improved. In addition, according to the technical scheme provided by the embodiment of the application, the synchronization of the vibration position of the scanning mirror and the lighting of the laser light source is realized in a software mode, so that a hardware circuit is simplified, the miniaturization of a system is facilitated, and the production cost is reduced.
Further, the second signal generating module 30 is further configured to: generating a transverse driving signal according to the resonance frequency in combination with the reference clock signal;
the scanning mirror 60 is connected to the second signal generating module 30, and is configured to perform a transverse scanning under the driving of the transverse driving signal.
In specific implementation, the second signal generating module 30 includes: a first arbitrary frequency dividing unit 301 and a first signal generating unit 302.
A first arbitrary frequency dividing unit 301, configured to determine a first frequency dividing coefficient according to the resonance frequency; according to the first frequency division coefficient, frequency division processing is carried out on the reference clock signal to obtain a first frequency division clock signal;
a first signal generating unit 302, connected to the first arbitrary frequency dividing unit 301, for searching a sine wave waveform table based on the first frequency-divided clock signal to generate the lateral driving signal.
The first signal generating unit 302 includes a first lookup table counter 3021 and a sine wave table 3022. The first look-up table counter 3021 looks up the sine wave form table 3022 according to the count value by counting the first frequency-divided clock signal output from the first arbitrary frequency dividing unit 301, thereby realizing the output of the horizontal driving signal.
The first arbitrary frequency dividing unit 301 is specifically configured to: and taking the ratio of the product of the number of sampling points of the sine wave waveform table and the resonance frequency to the clock frequency of the reference clock signal as a first frequency division coefficient.
Further, the second signal generating module 30 further includes:
the first frequency doubling unit 303 is connected with the first arbitrary frequency dividing unit 301, and is configured to determine a first frequency doubling multiple according to the projection resolution and the number of sampling points of the sine wave waveform table; and performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
Further, the second signal generating module 30 is further configured to:
generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal;
the scanning mirror is also used for longitudinal scanning under the driving of the longitudinal driving signal.
Specifically, the second signal generating module 30 includes:
a second arbitrary frequency division unit 304, configured to determine a second frequency division coefficient according to the projection frame frequency; performing frequency division processing on the reference clock signal according to the second frequency division coefficient to obtain a second frequency division clock signal;
a second signal generating unit 305, connected to the second arbitrary frequency dividing unit, for searching a sawtooth waveform table based on the second divided clock signal to generate a vertical driving signal.
Wherein, the second signal generation unit 305 includes: a second look-up table counter 3051 and a sawtooth waveform table 3052.
It should be noted that, in order to simplify the circuit and ensure phase synchronization of the horizontal driving signal, the vertical driving signal, and the pixel clock signal, the first arbitrary frequency dividing unit 301 and the second arbitrary frequency dividing unit 304 are the same unit.
The second arbitrary frequency dividing unit 304 is specifically configured to: and taking the ratio of the product of the projection frame frequency and the number of sampling points of the sawtooth wave form table to the clock frequency of the reference clock signal as a second frequency division coefficient.
Further, the laser scanning projection apparatus may further include: a detection module (not shown). The detection module is connected with the second signal generation module 30 and is used for collecting transverse operation signals of the scanning mirror; determining a time difference between the lateral run signal and a current lateral drive signal of the scan mirror based on the current lateral drive signal; according to the time difference, the resonant frequency of the scanning mirror is calculated and provided to the second signal generation module 30.
Further, the first signal generating module 20 may include: a crystal oscillator 201 and a second frequency multiplying unit 202.
Here, it should be noted that: the laser scanning projection apparatus provided in the above embodiments may implement the technical solutions described in the above method embodiments, and the specific implementation principle of each module or unit may refer to the corresponding content in the above method embodiments, and is not described herein again.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (11)
1. A projection method for a laser scanning projection apparatus, comprising:
acquiring the resonance frequency of the scanning mirror; wherein, the resonance frequency is detected in real time in the projection process;
generating a pixel clock signal according to the resonance frequency in combination with a reference clock signal;
driving a laser light source according to the pixel clock signal;
wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection;
generating a transverse driving signal according to the resonance frequency in combination with the reference clock signal;
driving the scanning mirror to perform transverse scanning according to the transverse driving signal;
generating a lateral drive signal from the resonant frequency in combination with the reference clock signal, comprising:
determining a first frequency division coefficient according to the resonance frequency;
according to the first frequency division coefficient, frequency division processing is carried out on the reference clock signal to obtain a first frequency division clock signal;
looking up a sine wave table to generate the lateral drive signal based on the first divided clock signal, wherein a frequency of the lateral drive signal is equal to the resonant frequency.
2. The method of claim 1, wherein determining a first frequency-division coefficient based on the resonant frequency comprises:
and taking the ratio of the product of the number of sampling points of the sine wave waveform table and the resonance frequency to the clock frequency of the reference clock signal as a first frequency division coefficient.
3. The method of claim 1 or 2, wherein generating a pixel clock signal from the resonant frequency in conjunction with a reference clock signal comprises:
determining a first frequency multiplication multiple according to the projection resolution and the number of sampling points of the sine wave waveform table;
and performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
4. The method of claim 1 or 2, further comprising:
generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal;
and driving the scanning mirror to perform longitudinal scanning according to the longitudinal driving signal.
5. The method of claim 4, wherein generating a vertical drive signal from a projection frame frequency in conjunction with the reference clock signal comprises:
determining a second frequency division coefficient according to the projection frame frequency;
performing frequency division processing on the reference clock signal according to the second frequency division coefficient to obtain a second frequency division clock signal;
based on the second frequency-divided clock signal, a sawtooth waveform table is looked up to generate a longitudinal driving signal.
6. The method of claim 5, wherein determining the second frequency-dividing coefficient based on the projection frame frequency comprises:
and taking the ratio of the product of the projection frame frequency and the number of sampling points of the sawtooth wave form table to the clock frequency of the reference clock signal as a second frequency division coefficient.
7. The method of claim 1 or 2, wherein acquiring the resonant frequency of the scan mirror comprises:
collecting a transverse operation signal of a scanning mirror;
determining a time difference between the lateral run signal and a current lateral drive signal of the scan mirror based on the current lateral drive signal;
and calculating the resonance frequency of the scanning mirror according to the time difference.
8. A laser scanning projection device, comprising:
the first signal generating module is used for generating a reference clock signal;
the second signal generation module is connected with the first signal generation module and used for acquiring the resonance frequency of the scanning mirror; generating a pixel clock signal according to the resonance frequency by combining the reference clock signal; wherein, the resonance frequency is detected in real time in the projection process;
the light source driving module is connected with the laser light source and used for driving the laser light source according to the pixel clock signal;
wherein the scanning mirror is used for reflecting the light from the laser light source to realize projection;
the second signal generation module is further configured to: generating a transverse driving signal according to the resonance frequency in combination with the reference clock signal;
the scanning mirror is connected with the second signal generating module and is used for transverse scanning under the driving of the transverse driving signal;
the second signal generation module includes:
the first arbitrary frequency division unit is used for determining a first frequency division coefficient according to the resonance frequency; according to the first frequency division coefficient, frequency division processing is carried out on the reference clock signal to obtain a first frequency division clock signal;
a first signal generating unit connected to the first arbitrary frequency dividing unit, for searching a sine wave waveform table based on the first frequency-divided clock signal to generate the lateral driving signal.
9. The apparatus of claim 8, wherein the second signal generation module further comprises:
the first frequency doubling unit is connected with the first arbitrary frequency dividing unit and used for determining a first frequency doubling multiple according to the projection resolution and the number of sampling points of the sine wave waveform table; and performing frequency multiplication processing on the first frequency division clock signal based on the first frequency multiplication factor to obtain the pixel clock signal.
10. The apparatus of claim 8 or 9, wherein the second signal generating module is further configured to:
generating a longitudinal driving signal according to the projection frame frequency by combining the reference clock signal;
the scanning mirror is also used for longitudinal scanning under the driving of the longitudinal driving signal.
11. The apparatus of claim 10, wherein the second signal generating module comprises:
the second arbitrary frequency division unit is used for determining a second frequency division coefficient according to the projection frame frequency; performing frequency division processing on the reference clock signal according to the second frequency division coefficient to obtain a second frequency division clock signal;
and the second signal generating unit is connected with the second arbitrary frequency dividing unit and used for searching a sawtooth wave form table based on the second frequency dividing clock signal so as to generate a longitudinal driving signal.
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| CN201811261263.2A CN109587461B (en) | 2018-10-26 | 2018-10-26 | Laser scanning projection equipment and projection method thereof |
| PCT/CN2018/120483 WO2020082534A1 (en) | 2018-10-26 | 2018-12-12 | Laser scanning projection device and projection method thereof |
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| CN109584761A (en) * | 2018-10-31 | 2019-04-05 | 歌尔股份有限公司 | A kind of signal adjusting method and laser scanning projection device |
| CN110161784B (en) * | 2019-05-20 | 2021-07-09 | 歌尔光学科技有限公司 | Clock synchronization method and device for laser beam scanning projector and projector |
| CN113176550B (en) * | 2019-12-30 | 2023-04-07 | 上海禾赛科技有限公司 | Frame synchronization method for scanning galvanometer and laser radar |
| CN111508383B (en) * | 2020-04-23 | 2022-03-25 | 歌尔光学科技有限公司 | Imaging method, imaging apparatus, and computer-readable storage medium |
| CN111540306B (en) * | 2020-04-23 | 2022-03-25 | 歌尔光学科技有限公司 | Display method, display device, and computer-readable storage medium |
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| CN102656500A (en) * | 2009-11-25 | 2012-09-05 | 日本电气株式会社 | Optical scanning device, optical scanning method, program, and image display device |
| CN103201668A (en) * | 2010-11-08 | 2013-07-10 | 船井电机株式会社 | Image display device |
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| AU2001214632A1 (en) * | 2000-11-03 | 2002-05-15 | Microvision, Inc. | Scanned display with variation compensation |
| US8619167B2 (en) * | 2010-04-28 | 2013-12-31 | Microsoft Corporation | Scanned beam display and image capture |
| JP2013140224A (en) * | 2011-12-28 | 2013-07-18 | Jvc Kenwood Corp | Image display device, control method therefor, and information output apparatus |
| US8902346B2 (en) * | 2012-10-23 | 2014-12-02 | Intersil Americas LLC | Systems and methods for controlling scanning mirrors for a display device |
| JP6119201B2 (en) * | 2012-11-08 | 2017-04-26 | ソニー株式会社 | Control device, control method, drive device, and electronic apparatus |
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| CN102656500A (en) * | 2009-11-25 | 2012-09-05 | 日本电气株式会社 | Optical scanning device, optical scanning method, program, and image display device |
| CN103201668A (en) * | 2010-11-08 | 2013-07-10 | 船井电机株式会社 | Image display device |
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