Galvanometer power supply control circuit and laser projection equipment

Abstract

The embodiment of the invention provides a galvanometer power supply control circuit and laser projection equipment, and relates to the technical field of laser projection. The galvanometer power supply control circuit comprises a DLP unit circuit, a time delay circuit and a switching circuit. A command signal output end of the DLP unit circuit is connected with an input end of the delay circuit, an output end of the delay circuit is connected with a control end of the switching circuit, an input end of the switching circuit is connected with a power supply, and an output end of the switching circuit is connected with a power input end of the galvanometer driving circuit; the time delay circuit is configured to output a starting signal to the control end of the switching circuit after preset time delay when the input end of the time delay circuit receives a configuration success command signal output by the DLP unit circuit; the switching circuit is configured to conduct the electrical connection between the input end and the output end when the control end of the switching circuit receives the opening signal. The embodiment of the invention is used for solving the problem that the galvanometer coil is easy to burn out.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of laser projection technology, and more specifically, to a galvanometer power supply control circuit and a laser projection device. Background Art

[0002] Laser projection equipment is a display technology that uses solid-state lasers of red, green and blue (R, G, B) as light sources. It has the advantages of low power consumption and longer service life. The service life of laser projection equipment is almost 10 times that of traditional light bulbs. Laser projection equipment can truly reproduce the rich and bright colors of the objective world and provide excellent expression. The color gamut coverage of laser display can reach more than 90% of the color space that the human eye can recognize, which is more than twice the color gamut coverage of traditional display technology, breaking through the shortcomings of the color gamut space of the first three generations of display technology.

[0003] Resolution is also an important indicator of the performance of laser projection equipment. The higher the resolution, the higher the precision of the image that can be projected onto the screen, the more information is displayed, and the clearer the picture is. However, the resolution of laser projection equipment is limited by hardware technology, and it is difficult to improve the resolution. At present, many laser projection devices use digital micromirror devices (DMD) as key components, and the resolution of laser projection equipment is mainly determined by the resolution of DMD. With the help of micro-oscillating reflector (referred to as galvanometer) technology, low-resolution DMD can be used to project high-resolution images. By dividing a high-resolution frame image into two low-resolution sub-images, and then controlling the galvanometer in the DMD to flip repeatedly, the two sub-images are sequentially displaced in one image display cycle, so as to achieve high-resolution image projection. During the high-speed vibration of the galvanometer, DC high-voltage drive is prone to occur when the galvanometer is switched on and off, causing the galvanometer coil to burn out and the galvanometer to fail to work properly. Summary of the invention

[0004] The exemplary embodiments of the present application provide a galvanometer power supply control circuit and a laser projection device, which are used to solve the problem that the galvanometer coil is easily burned out.

[0005] The technical solutions provided by the embodiments of this application are as follows:

[0006] In a first aspect, an embodiment of the present application provides a galvanometer power supply control circuit, including a DLP unit circuit, a delay circuit, and a switch circuit;

[0007] The command signal output end of the DLP unit circuit is connected to the input end of the delay circuit, the output end of the delay circuit is connected to the control end of the switch circuit, the input end of the switch circuit is connected to the power supply, and the output end of the switch circuit is connected to the power input end of the galvanometer drive circuit;

[0008] The delay circuit is configured to output a start signal to the control end of the switch circuit after a preset delay when the input end of the delay circuit receives the configuration success command signal output by the DLP unit circuit;

[0009] The switch circuit is configured to conduct the electrical connection between the input end and the output end when the control end of the switch circuit receives a start signal.

[0010] In a second aspect, an embodiment of the present application provides a laser projection device, including a galvanometer, a galvanometer drive circuit, and the galvanometer power supply control circuit described above;

[0011] The output end of the galvanometer power supply control circuit is connected to the power supply input end of the galvanometer drive circuit, and the output end of the galvanometer drive circuit is connected to the galvanometer coil.

[0012] It can be seen from the above technical solutions that the galvanometer power supply control circuit and laser projection equipment provided in the embodiment of the present application control the power supply of the galvanometer drive circuit through the DLP unit circuit, the delay circuit and the switch circuit. The DLP unit circuit can only output a configuration success command signal to the delay circuit when the configuration is successful. At this time, the DLP unit circuit also outputs a galvanometer mirror frame synchronization signal to the galvanometer drive circuit. After receiving the configuration success command signal, the delay circuit will output an opening signal to the control end of the switch circuit after a preset delay, so that the power supply supplies power to the galvanometer drive circuit. By setting the delay, it can be ensured that the galvanometer mirror frame synchronization signal is first transmitted to the galvanometer drive circuit, and then the power supply supplies power to the galvanometer drive circuit. It can avoid the phenomenon that the power supply is turned on first to generate a DC high-voltage pulse when the galvanometer mirror frame synchronization signal has not been transmitted to the galvanometer drive circuit, causing the galvanometer coil to burn out, thereby solving the problem that the galvanometer coil is easy to burn out and improving the reliability of the laser projection equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the implementation methods in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technology descriptions. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.

[0014] Figure 1 A schematic diagram showing the structure of a laser projection device in some embodiments is shown;

[0015] Figure 2 A schematic structural diagram of another laser projection device in some embodiments is shown;

[0016] Figure 3A schematic structural diagram of another laser projection device in some embodiments is shown;

[0017] Figure 4 A diagram showing the position of a first sub-image when the galvanometer mirror is deflected in some embodiments;

[0018] Figure 5 A diagram showing the position of the second sub-image when the galvanometer mirror is deflected in some embodiments;

[0019] Figure 6 A schematic diagram of a galvanometer drive circuit in some embodiments is shown;

[0020] Figure 7 A schematic diagram of a galvanometer power supply control circuit in some embodiments is shown;

[0021] Figure 8 Schematic diagrams of galvanometer power supply control circuits in other embodiments are shown;

[0022] Fig. 9 Schematic diagrams of galvanometer power supply control circuits in some other embodiments are shown;

[0023] Fig.10 Schematic diagrams of galvanometer power supply control circuits in some other embodiments are shown;

[0024] Fig.11 A partial circuit diagram of a laser projection device in some embodiments is shown. DETAILED DESCRIPTION

[0025] In order to make the purpose and implementation method of the present application clearer, the exemplary implementation method of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0026] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0027] The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0028] An embodiment of the present application provides a galvanometer power supply control circuit, which is applied to laser projection equipment. Figure 1 This is a schematic diagram of the structure of the laser projection device provided in the embodiment of the present application. Figure 2is a schematic diagram of the structure of another laser projection device provided in an embodiment of the present application, Figure 3 Schematic diagram of the structure of the lens assembly of the laser projection device provided in the embodiment of the present application. Figure 1 , Figure 2 and Figure 3 As shown, the projection device may include a processor 10, at least one laser driving component 20, a light source 30, a light valve 40, a galvanometer driving circuit 50, a galvanometer 60, a display screen 130, and a detector 101. The light source 30 may include at least one group of lasers corresponding to the at least one laser driving component 20. The at least one refers to one or more, and the multiple refers to two or more. The at least one group refers to one or more groups, and the multiple groups refer to two or more groups, and each group of lasers may include one or more lasers.

[0029] The processor 10 may be a digital light processing (DLP) chip. The light source 30 may be a laser light source, for example, Figure 1 , the laser light source may include a blue laser 301, a red laser 302 and a green laser 303. The light valve 40 may be a digital micromirror device (DMD). The galvanometer 60 may be used to shift sub-images of different frames to different positions of the projection screen, thereby realizing the superposition display of the multiple frames of sub-images, thereby achieving the effect of expanding the resolution of the projection device. In the embodiment of the present application, the galvanometer 60 has two deflection positions, that is, the galvanometer 60 can shift the sub-image to two different display positions of the projection screen. The detector 101 may be a camera or a charge-coupled device (CCD).

[0030] Multiple sub-images are obtained by splitting the target image to be projected. The resolution of the target image is greater than the resolution of the light valve. The resolution of each frame of the sub-image after splitting is not greater than the resolution of the light valve, for example, it can be equal to the resolution of the light valve. For example, the resolution of the target image can be M×N, where M is the number of pixels in each row of the target image, and N is the number of pixels in each column. The resolution of the light valve is M1×N1, where M1 is the number of pixels in each row of the image that the light valve can project and display, and N1 is the number of pixels in each column. The resolution of each frame of the sub-image can be m1×n1, where m1 is the number of pixels in each row of the sub-image of each frame, and n1 is the number of pixels in each column. M, N, M1, N1, m1 and n1 are all positive integers greater than 1, and M is greater than M1, N is greater than N1, m1 is not greater than M1, and n1 is not greater than N1.

[0031] For example, the resolution of the target image can be 3840×2160, that is, M is 3840 and N is 2160. The resolution of the light valve can be 2880×1620, that is, M1 is 2880 and N1 is 1620. The resolution of the subframe image is 2715×1527, that is, m1 is 2715 (approximately 3840). One-tenth of 2160), n1 is 1527 (about 2160 The resolution of the target image is 3840×2160, which is greater than the resolution of the light valve, and the resolution of each sub-image is 2715×1527, which is less than the resolution of the light valve, 2880×1620.

[0032] In the embodiment of the present application, during the calibration phase of the galvanometer, the processor 10 is configured to split the galvanometer calibration image into a first sub-image and a second sub-image. In the first sub-frame, the galvanometer 60 in the lens assembly is moved to the first position, and the first sub-image is projected at the first display position of the display screen 130 through the lens assembly; in the second sub-frame, the galvanometer 60 in the lens assembly is moved to the second position, and the second sub-image is projected at the second display position of the display screen 130 through the lens assembly. Then, according to the offset between the first sub-image and the second sub-image captured by the detector 101, the first position and the second position of the galvanometer 60 are calibrated.

[0033] The laser projection device may also include a main control chip 00, referring to Figure 2 , the processor 10 can be connected to the main control chip 00. When the laser projection device projects and displays the galvanometer calibration image to be projected, the main control chip 00 can decode the image signal of the galvanometer calibration image and send the decoded image signal of the galvanometer calibration image to the processor 10 at a frequency of 60 Hz. Correspondingly, the processor 10 can receive the image signal of the decoded galvanometer calibration image sent by the main control chip 00. Afterwards, the processor 10 can split the received decoded image signal of the galvanometer calibration image into signals of the first sub-image and the second sub-image, so as to realize dividing the galvanometer calibration image into two frame sub-images.

[0034] In the embodiment of the present application, the processor 10 is connected to each laser driving assembly 20. After the processor 10 divides the galvanometer calibration image to be projected into the first sub-image and the second sub-image, it can output at least one enable signal corresponding to the three primary colors of each frame of the sub-image, and transmit the at least one enable signal to the corresponding laser driving assembly 20. The laser current control signal is used to instruct the laser driving assembly 20 to provide the corresponding laser driving current to the laser connected thereto to drive the laser to emit laser light. Among them, the laser current control signal can be a pulse width modulation (PWM) signal.

[0035] like Figure 2 As shown, the laser projection device may further include a power supply 150, a start control component 160 and a program storage component 170. The main control chip 100 is connected to the start control component 160 and the processor 10 respectively, the power supply 150 is connected to the laser drive component 20, and the program storage component 170 is connected to the processor 10.

[0036] The main control chip 100 sends a start command to the start control component 160. The start control component 160 starts working after receiving the start command, and outputs 1.1 volts (V), 1.8V, 3.3V, 2.5V and 5V to the display control component in sequence according to the power-on timing of the start control component 160 to power the processor 10. After that, when the power supply voltage and timing are correct, the start control component 160 sends a reset signal to the processor 10, reads the program from the external program storage component 170 and initializes it, and then the entire projection device starts working. The processor 10 configures the start control component 160 through the serial peripheral interface (SPI) communication, and instructs the start control component 160 to start powering the light valve 40. Then, the control component 160 is started to output three voltages to the light valve 40, namely, voltage bias (VBIAS) is 18V, voltage reset (VRST) is -14V, and voltage offset (VOFS) is 10V. After the voltage of the light valve 40 is normal, the light valve 40 starts to work. The processor 10 sends the primary color scale value of the sub-image to the light valve 40 through the LVDS communication method to realize the sub-image. The power supply in the laser projection device is converted from 100V to 240V AC to DC by the power board to power each component.

[0037] like Figure 1As shown, the laser projection device includes three laser driving components 20, and accordingly, the light source 30 includes three groups of lasers corresponding to the three laser driving components 20, and the three groups of lasers can be blue laser 301, red laser 302 and green laser 303, respectively, and the blue laser 301, red laser 302 and green laser 303 are respectively connected to the corresponding laser driving components 20. Among them, the blue laser 301 is used to emit blue laser, the red laser 302 is used to emit red laser, and the green laser 303 is used to emit green laser. The laser projection device can be called a three-color laser projection device.

[0038] The processor 10 outputs a blue PWM signal B_PWM corresponding to the blue laser 301 based on the blue primary color component of each frame of the sub-image, and outputs an enable signal B_EN corresponding to the blue laser 301 based on the lighting duration of the blue laser 301 in the driving cycle. Then, the blue PWM signal B_PWM and the enable signal B_EN corresponding to the blue primary color component of each frame of the sub-image are transmitted to the laser driving component 20, which is the driving component corresponding to the blue laser 301. The laser driving component 20 corresponding to the blue laser 301 can respond to the blue PWM signal B_PWM and the enable signal B_EN to provide the blue laser 301 with a corresponding laser driving current to drive the blue laser 301 to emit a blue laser.

[0039] The processor 10 outputs a red PWM signal R_PWM corresponding to the red laser 302 based on the red primary color component of each frame of the sub-image, and outputs an enable signal R_EN corresponding to the red laser 302 based on the lighting duration of the red laser 302 in the driving cycle. Then, the red PWM signal R_PWM and the enable signal R_EN corresponding to the red primary color component of each frame of the sub-image are transmitted to the laser driving component 20, which is the driving component corresponding to the red laser 302. The laser driving component 20 corresponding to the red laser 302 can respond to the red PWM signal R_PWM and the enable signal R_EN to provide the corresponding laser driving current to the red laser 302 to drive the red laser 302 to emit red laser.

[0040] The processor 10 outputs a green PWM signal G_PWM corresponding to the green laser 303 based on the green primary color component of each frame of the sub-image, and outputs an enable signal G_EN corresponding to the green laser 303 based on the lighting duration of the green laser 303 in the driving cycle. Then, the green PWM signal G_PWM and the enable signal G_EN corresponding to the green primary color component of each frame of the sub-image are transmitted to the laser driving component 20, which is the driving component corresponding to the green laser 303. The laser driving component 20 corresponding to the green laser 303 can respond to the green PWM signal G_PWM and the enable signal G_EN to provide the green laser 303 with a corresponding laser driving current to drive the green laser 303 to emit green laser.

[0041] After controlling the laser to start emitting laser, the processor 10 can control the light valve 40 to flip according to the primary color gradation value of the pixel in each frame of the sub-image, and realize the primary color gradation value by the length of time the micromirror in the light valve 40 flips, and forms the gray scale of the three primary colors of the corresponding pixel in conjunction with the corresponding color light irradiated on the light valve 40, and then project multiple frames of sub-images in sequence onto the display screen 130, and display the frame of sub-image to different positions of the display screen 130 by controlling the deflection of the galvanometer 60.

[0042] In the embodiment of the present application, the multiple sub-images include two sub-images. When the laser light emitted by each laser irradiates the light valve 40, the processor 10 can control the light valve 40 to flip according to the primary color gradation value of the pixel in each sub-image, so as to project the two sub-images sequentially onto the display screen 130. For example, the primary color gradation value can be a red, green, blue (RGB) gradation value.

[0043] like Figure 3As shown, if the light source 30 in the laser projection device includes two groups of red lasers 302, a group of blue lasers 301 and a group of green lasers 303 that are integrated. The projection device can be called a full-color laser projection device. The blue laser 301 in the laser projection device is arranged between the red laser 302 and the green laser 303. Since the blue laser 301 can withstand a higher temperature, the blue laser 301 is arranged between the red laser 302 and the green laser 303. This arrangement is more conducive to the rapid heat dissipation of the red laser 302 and the green laser 303, so that the reliability of the integrated multiple groups of lasers is higher. The full-color laser projection device can also include four reflective lenses 70, a lens assembly 80, a diffusion wheel 90, a light pipe 100, a total internal reflection (TIR) ​​lens 110, a projection lens 120 and a display screen 130. Among them, the lens assembly 80 includes a first lens 801, a second lens 802 and a third lens 803, and each group of lasers is correspondingly provided with a reflective lens 70.

[0044] In the process of projecting and displaying the first sub-image, the blue laser light emitted by the blue laser 301 is reflected by the reflective lens 70 at the corresponding position, and is focused by the first lens 801, is homogenized by the diffusion wheel 90, and is homogenized by total reflection through the light guide 100. The red laser light emitted by the red laser 302 is reflected by the reflective lens 70 at the corresponding position, and is focused by the first lens 801, is homogenized by the diffusion wheel 90, and is homogenized by the total reflection through the light guide 100. The green laser light emitted by the green laser 303 is reflected by the reflective lens 70 at the corresponding position, and is focused by the first lens 801, is homogenized by the diffusion wheel 90, and is homogenized by the total reflection through the light guide 100. The blue laser, red laser and green laser after being homogenized by the light pipe 100 are shaped by the second lens 802 and the third lens 803 in a time-sharing manner and enter the TIR lens 110 for total reflection. During the process of the three primary color lights being irradiated to the light valve 40 in a timely manner, the processor 10 controls the light valve 40 to flip according to the primary color gradation value of the pixel in the first sub-image. The flipped light valve 40 reflects the light that has been totally reflected by the TIR lens 110, passes through the TIR lens 110 again, is deflected by the galvanometer 60, and is finally projected onto the display screen 130 through the projection lens 120, so as to display the first sub-image on the display screen 130.

[0045] Afterwards, the second sub-image is projected and displayed in sequence.

[0046] In the process of projecting and displaying each frame of sub-image, the processor 10 can transmit the galvanometer current control signal corresponding to a frame of sub-image to the galvanometer drive circuit 50, and the galvanometer current control signal is used to control the galvanometer drive circuit 50 to provide the galvanometer drive current to the galvanometer 60 to drive the galvanometer 60 to deflect. Among them, the galvanometer current control signals corresponding to different frame sub-images are different, thereby realizing the projection of multiple frame sub-images to different positions on the projection screen, thereby realizing the superposition display of the multiple frame sub-images, and then realizing the display of the target image on the display screen 130. In addition, in the process of projecting and displaying multiple frame sub-images, the current direction of the galvanometer drive current can change alternately, and the changing waveform of the galvanometer drive current can be a sine wave.

[0047] In the process of projecting and displaying each frame of sub-image, the light valve 40 receives the irradiation of the three primary colors of light in a timely manner, and when the light valve 40 receives the irradiation of the target primary color of the three primary colors of light, the processor 10 can transmit the galvanometer current control signal of the corresponding sub-image to the galvanometer drive circuit 50, and the galvanometer current control signal is used to control the galvanometer drive circuit to provide the galvanometer drive current to the galvanometer to drive the galvanometer 60 to deflect, and then the galvanometer 60 remains unchanged, thereby completing the display of a frame of sub-image. Then, when displaying the next frame of sub-image, the display control component 10 and the galvanometer drive circuit 50 can drive the galvanometer 60 to deflect again, and so on, so as to realize the projection and display of different frames of sub-images to different positions of the projection screen.

[0048] In the process of projecting and displaying the first sub-image, the light valve 40 receives the irradiation of the three primary color lights in a timely manner, and when the light valve 40 receives the irradiation of the target primary color light among the three primary color lights, the processor 10 can transmit the first galvanometer current control signal to the galvanometer drive circuit 50. The first galvanometer current control signal is used to control the galvanometer drive circuit 50 to drive the galvanometer 60 to rotate to the first position.

[0049] In the process of projecting and displaying the second sub-image, the light valve 40 receives the irradiation of the three primary colors of light sequentially, and when the light valve 40 receives the irradiation of the target primary color of the three primary colors of light, the processor 10 can transmit the second galvanometer current control signal to the galvanometer drive circuit 50. The second galvanometer current control signal is used to control the galvanometer drive circuit 50 to drive the galvanometer 60 to rotate to the second position.

[0050] like Figure 4As shown, in the process of projecting and displaying the first frame sub-image P1, the light valve 40 receives the irradiation of the three primary colors of light in a timely manner, and when the light valve 40 receives the irradiation of the blue primary color light among the three primary colors of light, the processor 10 can transmit the first galvanometer current control signal to the galvanometer drive circuit 50, and the galvanometer drive circuit 50 provides the first galvanometer drive current to the coil in the galvanometer 60, and the galvanometer 60 can rotate a certain angle under the drive of the first galvanometer drive current. In this way, the center point pixel in the first sub-image P1 can be offset by a certain distance relative to the coordinate origin o in the positive direction of the A axis, that is, the center point pixel in the first sub-image P1 is located at the position a of the A axis.

[0051] like Figure 5 As shown, in the process of projecting and displaying the second frame sub-image P2, the light valve 40 receives the irradiation of the three primary colors of light in a timely manner, and when the light valve 40 receives the irradiation of the blue primary color light among the three primary colors of light, the processor 10 can transmit the second galvanometer current control signal to the galvanometer drive circuit 50, and the galvanometer drive circuit 50 provides the second galvanometer drive current to the coil in the galvanometer 60, and the galvanometer 60 can rotate a certain angle under the drive of the second galvanometer drive current. In this way, the center point pixel in the second sub-image P2 can be offset by a certain distance relative to the coordinate origin o in the negative direction of the A axis, that is, the center point pixel in the second sub-image P2 is located at the b position of the A axis.

[0052] The galvanometer current control signals corresponding to different frame sub-images are different, so the galvanometer 60 can be driven to deflect to different positions, so that the multiple frame sub-images are superimposed and displayed on the display screen 130, and the high-resolution target image can be displayed on a low-resolution laser projection device without losing the pixel information of the target image.

[0053] The present application embodiment takes a two-dimensional voltage driven galvanometer as an example for explanation. The galvanometer driving circuit is as follows: Figure 6As shown, the video image processing chip N1 of the laser projection device can adopt a field programmable gate array (FPGA). After receiving the galvanometer mirror frame synchronization signal of the DLP chip, N1 outputs the galvanometer mirror synchronization signal WG_SYNCz, clock signal WG_CLK and driving waveform data WG_DATA. The driving waveform data is converted from VCCA (1.8V) to VCCB (3.3V) by the level conversion chip N2, and then converted to a matching level that can be recognized by the back-end digital-to-analog converter N3, and the synchronization signal SYNCz, clock signal DAC_CLK and driving waveform data DAC_DATA are output to the digital-to-analog converter N3. The driving waveform data is converted from digital quantity to analog quantity Vi by the digital-to-analog converter N3 and output to the operational amplifier circuit N4. The analog drive waveform Vi is simultaneously input to the two operational amplifiers A1 and A2 in N4. On the one hand, it is input to the inverting input terminal of operational amplifier A1, and after amplification by operational amplifier A1, the output voltage waveform V_p is the positive terminal voltage of the galvanometer. On the other hand, it is input to the non-inverting input terminal of operational amplifier A2, and after amplification by operational amplifier A2, the output voltage V_n of the galvanometer is output. Therefore, the driving voltage at both ends of the galvanometer is V_p-V_n. During normal operation, the galvanometer moves under the drive of the analog drive voltage waveform of V_p-V_n. When the FPGA outputs the drive waveform data of the galvanometer, the normal drive circuit design is Figure 6 The power supplies VCCA and VCCB of N2, V_DAC of N3, P12V of N4, V_DAC of the voltage divider resistor at the in-phase end of operational amplifier A1, and V_DAC of the pull-up resistor of operational amplifier A2 are all powered on immediately when the power is turned on. At this time, the galvanometer drive waveform data sent by the FPGA has not been correctly output, so there will be a period of high-voltage pulse output to the galvanometer when the power is turned on. However, the galvanometer specification requires that the DC voltage does not exceed 1.2V. In the DC voltage mode, if the voltage at both ends of the galvanometer is higher than 1.2V, the coil of the galvanometer will be burned. The higher the DC voltage, the shorter the time of burning the coil and the higher the probability. Similarly, not only is DC high voltage not allowed to exist when the power is turned on, but DC high voltage is not allowed to exist at any time when the galvanometer is working, such as when the power is turned off, or when the DLP fails and the FPGA does not output the galvanometer drive waveform data, but the power supplies of the galvanometer drive circuit are not turned off at this time, so the output of DC high voltage will also cause the galvanometer coil to burn.

[0054] The specific reason for the generation of the DC high voltage is that the video image processing chip N1 has not output the drive waveform data WG_SYNCz, WG_CLK, WG_DATA due to power-on, power-off or malfunction, but the power supply of each chip of the galvanometer drive circuit has been supplied. In this case, each chip of the galvanometer drive circuit works normally, but there is no galvanometer drive waveform data output, so the output Vi of the digital-to-analog converter N3 has no output, which is equivalent to the disconnected state.

[0055] N4 contains two operational amplifiers A1 and A2, such as Figure 6 As shown, the configuration resistors of the operational amplifiers and the corresponding resistance values ​​have been marked in the circuit schematic. The following is the calculation of the two outputs V_p and V_n of the two operational amplifiers based on the working principle of the operational amplifier.

[0056] The voltage V_A1+ at the non-inverting input terminal A1+ of the operational amplifier A1 is

[0057]

[0058] Substituting the resistance parameters of R4 and R5 into the above formula, the V_DAC voltage is 3.3V, then

[0059]

[0060] According to the virtual short and virtual disconnection principle, V_A1-=V_A1+=2.726V,

[0061] The current flowing through R2 and R3 is the same, so

[0062] Substituting the resistance parameters of R2, R6, R7 and the voltage parameters of V_DAC and V_A1- into the above formula, we get

[0063]

[0064] Then the voltage drop across resistor R3 is V_R3

[0065] V _R3 =I R3 ×R3=5.639×10 -6 ×121×10 3 =0.682V

[0066] The output voltage V_p of the operational amplifier A1 is equal to the voltage V_A1 at the inverting terminal of the operational amplifier minus the voltage V_R3 on the resistor R3.

[0067] V _p =V _A1- -V _R3 =2.726-0.682=2.044V

[0068] The non-inverting input voltage V_A2+ of operational amplifier A2 is

[0069] V_A2+=V_DAC-I R3 ×R7

[0070] Substituting the actual parameters into the above formula, we get

[0071] V_A2+=3.3-5.639×10 -6 ×56×10 3 =2.984V

[0072] Then the voltage at the inverting input terminal of operational amplifier A2 is V_A2-=V_A2+=2.984V

[0073] Then the output voltage V_n of operational amplifier A2 can be obtained

[0074]

[0075] Substitute the actual parameters,

[0076] Therefore, when the galvanometer drive waveform data has not been output, the operational amplifier is working, and the output DC voltage is added to the two ends of the galvanometer. The voltage is V_p-V_n=10.005-2.044=7.961V, and the coil resistance of the galvanometer is usually only 12.1 ohms. Therefore, the coil of the galvanometer generates heat flow under a high current of about 0.7A, and eventually burns out the fixing glue of the coil. The fixing glue melts and causes the coil to collapse, making the galvanometer unusable.

[0077] The embodiment of the present application provides a galvanometer power supply control circuit applied to a laser projection device to protect the galvanometer coil and prevent the galvanometer coil from burning. Figure 6 The galvanometer driving circuit shown avoids outputting DC high-voltage pulses, that is, when the input voltage V_DAC of the operational amplifier circuit N4 and the power supply P12V are powered on, it is ensured that the driving waveform data of the galvanometer must be output, and the operational amplifier is not allowed to work but the driving waveform Vi is not output.

[0078] like Figure 7 As shown, the galvanometer power control circuit provided in the embodiment of the present application includes a DLP unit circuit 501, a delay circuit 502 and a switch circuit 503. The command signal output end of the DLP unit circuit is connected to the input end of the delay circuit, the output end of the delay circuit is connected to the control end of the switch circuit, the input end of the switch circuit is connected to the power supply, and the output end of the switch circuit is connected to the power input end P12V of the galvanometer drive circuit.

[0079] The delay circuit is configured such that when the input end of the delay circuit receives the configuration success command signal output by the DLP unit circuit, after a preset delay, an on signal is output to the control end of the switch circuit.

[0080] The switch circuit is configured to conduct the electrical connection between the input end and the output end when the control end of the switch circuit receives a start signal.

[0081] In some embodiments, Figure 8 As shown, the delay circuit includes MCU N10, the command signal output end of the DLP unit circuit is connected to the input end of the MCU, and the output end of the MCU is connected to the control end of the switch circuit. The MCU is configured so that when the input end of the MCU receives the configuration success command signal output by the DLP unit circuit, after a preset delay, it outputs a start signal to the control end of the switch circuit.

[0082] In some embodiments, the MCU further includes a fan fault signal port and an overheat signal port. The MCU is configured such that when the input terminal IO1 of the MCU receives the configuration success command signal output by the DLP unit circuit and does not receive the fan fault signal and the overheat signal, after a preset delay, the output terminal IO2 outputs a start signal to the control terminal of the switch circuit, ensuring that the MCU will output a start signal only when the system has no fan, overheat, or other faults.

[0083] In other embodiments, the MCU may also include only a fan fault signal port, or only an overheat signal port.

[0084] In some embodiments, Figure 8 As shown, the DLP unit circuit includes a master DLP chip N5 and a slave DLP chip N6. The DLP unit circuit is configured to output a configuration success command signal to the input end of the delay circuit when both the master DLP chip and the slave DLP chip are configured successfully.

[0085] In some embodiments, the DLP unit circuit further includes a first transistor N7, a second transistor N8, and an AND gate circuit N9. The first transistor is configured to output a high-level configuration success command signal to the first input terminal of the AND gate circuit when receiving a low-level configuration success signal output by the master DLP chip. The second transistor is configured to output a high-level configuration success command signal to the second input terminal of the AND gate circuit when receiving a low-level configuration success signal output by the slave DLP chip. The AND gate circuit is configured to output a configuration success command signal to the input terminal of the delay circuit when both the first input terminal and the second input terminal of the AND gate circuit receive a high-level configuration success command signal.

[0086] Specifically, the command signal output terminal of the master control DLP chip is connected to the base of the first transistor through a resistor R10, the collector of the first transistor is connected to a 3.3V high-level power supply through a resistor R11, the base of the first transistor is grounded through a resistor R12, the collector of the first transistor is also connected to the first input terminal of the AND gate circuit, and the emitter of the first transistor is grounded. The command signal output terminal of the slave control DLP chip is connected to the base of the second transistor through a resistor R13, the collector of the second transistor is connected to a 3.3V high-level power supply through a resistor R14, the base of the second transistor is grounded through a resistor R15, the collector of the second transistor is also connected to the second input terminal of the AND gate circuit, and the emitter of the second transistor is grounded. The output terminal of the AND gate circuit is connected to the input terminal of the MCU.

[0087] The configuration success signals output by the master DLP chip and the slave DLP chip are usually valid at low level. Through the first transistor and the second transistor, the configuration success signal is pulled up to a 3.3V high-level configuration success command signal, and then output to the MCU after passing through the AND gate circuit, so that the MCU can receive and identify it.

[0088] In some embodiments, Figure 8 As shown, the switch circuit includes a transistor, and the transistor is configured to conduct the electrical connection between the source and the drain when the gate of the transistor receives a start signal.

[0089] Specifically, the transistor is a PMOS N12, and the switch circuit further includes a third transistor N11. The base of the third transistor is connected to the output end of the MCU through a resistor R16, and is also grounded through a resistor R17, the emitter of the third transistor is grounded, the collector of the third transistor is connected to the gate of the PMOS through a resistor R18, the source of the PMOS is connected to the power supply VIN, a capacitor C5 and a resistor R19 are connected in parallel between the gate and the source of the PMOS, and the drain of the PMOS is connected to the power input terminal P12V of the galvanometer drive circuit.

[0090] When the base of the third transistor receives a high-level start-up signal, the third transistor is turned on and grounded, the gate of the PMOS is at a low level, the PMOS is turned on, and the system's 12V power supply VIN is input to P12V, and the power supply P12V of the operational amplifier circuit N4 of the galvanometer drive circuit is powered on to provide a driving voltage for the galvanometer.

[0091] The embodiment of the present application can ensure that the galvanometer mirror frame synchronization signal is transmitted to the galvanometer mirror drive circuit first by setting a preset delay, and the galvanometer mirror drive circuit is powered by the power supply only after that. This can avoid the phenomenon that the power supply is turned on first to generate a DC high-voltage pulse when the galvanometer mirror frame synchronization signal has not yet been transmitted to the galvanometer mirror drive circuit, causing the galvanometer mirror coil to burn out. This solves the problem that the galvanometer mirror coil is easily burned out, and improves the safety and reliability of the laser projection equipment.

[0092] In some embodiments, the preset delay time can be 20-500 ms, thereby providing sufficient time for the galvanometer mirror frame synchronization signal to be transmitted to the galvanometer mirror drive circuit, thereby ensuring the safety and reliability of the laser projection device.

[0093] The working process of the laser projection device provided in the embodiment of the present application is as follows:

[0094] After powering on, the master DLP chip and slave DLP chip of the laser projection device are initialized and configured first. If the configuration is successful and there is no fault interruption, the configuration success signal mHOST_IRQ (issued by the master DLP chip) and sHOST_IRQ (issued by the slave DLP chip) are output.

[0095] mHOST_IRQ and sHOST_IRQ are 1.8V signals, which are low level valid. The collectors of the first N-type transistor N7 and the second N-type transistor N8 are pulled up to 3.3V. Therefore, the low level of the mHOST_IRQ and sHOST_IRQ signals output after the master control chip and the slave control chip are successfully configured after startup are converted to a high level valid at 3.3V through the first N-type transistor N7 and the second N-type transistor N8. After the two high-level outputs pass through the AND gate circuit N9, a high-level configuration success command signal is output to the MCU, that is, mHOST_IRQ and sHOST_IRQ must be output at the same time, and they are high level after passing through the AND gate circuit. As long as one of the control chips is not successfully configured or both are not successfully configured at the same time, the system will not start. The master DLP chip and the slave DLP chip must be successfully configured at the same time for the system to start normally, otherwise the system will not start.

[0096] Under the premise that the detection port IO1 of the single-chip microcomputer MCU obtains a high level and there is no system error, fan failure error, or overheating error, the MCU will output a high level through IO2 after a delay. Under the control of the high level, the third transistor N11 is turned on and grounded, the gate of the PMOS N12 is at a low level, the PMOS is turned on, and the system's 12V power supply VIN is input to P12V, and the power supply P12V of the operational amplifier chip N4 of the galvanometer drive circuit is powered on and starts working.

[0097] During the above delay time, when the detection port IO1 of the MCU obtains a high level, the main control DLP chip sends a synchronization signal of the galvanometer drive waveform output to FPGAN1, such as Figure 6As shown, FPGA starts to output the galvanometer drive waveform data under the control of the synchronization signal. After the level conversion circuit N2 and the digital-to-analog converter N3, the drive waveform data is earlier than the power-on time of the power supply P12V of the operational amplifier circuit N4, so no DC high-voltage pulse is output to the galvanometer coil. When the output signal IO2 of the MCU has no output, the base of N11 is pulled down through the resistor R17, N11 is not turned on, the gate of N12 is at a high level, so N12 is also not turned on, P12V has no voltage output, N4 does not work, and no DC high-voltage pulse is output.

[0098] When an error or failure occurs in the DLP system, one or both of mHOST_IRQ and sHOST_IRQ will be pulled high, one or both of N7 and N8 will be turned on, and one or both inputs of the AND gate circuit N9 will be low level, so the output of N9 is low level. At this time, the input terminal IO1 of the MCU obtains a low level, and the output terminal IO2 of the MCU outputs a low level, turning off the P12V power supply of the operational amplifier circuit N4. When the system fails, the drive waveform data output by the FPGA is turned off after the master DLP chip or the slave DLP chip stops working, and the P12V power supply of N4 is disconnected later.

[0099] When the laser projection device has a complete machine failure, such as a fan failure, an over-temperature failure, or a normal shutdown, the P12V power supply of the operational amplifier chip N4 of the galvanometer is first turned off in the shutdown timing control to turn off the galvanometer, and then a shutdown command is sent to turn off the DLP chip. Therefore, when a fan failure, an over-temperature failure, or any shutdown command such as a normal shutdown occurs, the output terminal IO2 of the MCU will output a low level, turn off the P12V power supply of the galvanometer operational amplifier circuit N4, and turn off the galvanometer, thereby avoiding the problem of the DC high-voltage pulse generated by the output of the non-driving waveform data burning the galvanometer.

[0100] The embodiment of the present application eliminates the DC high voltage pulse by changing the timing between the galvanometer drive waveform data WG_SYNCz, WG_CLK, WG_DATA outputs and the power supply P12V of the operational amplifier circuit N4.

[0101] The power-on timing of the embodiment of the present application is that the galvanometer drive waveform data WG_SYNCz, WG_CLK, and WG_DATA are output first, followed by the power supply V_DAC of the digital-to-analog converter N3, and then the power supply P12V of the operational amplifier circuit N4, or the power supply V_DAC of the digital-to-analog converter N3 and the power supply P12V of the operational amplifier circuit N4 are output simultaneously.

[0102] The power-off timing of the embodiment of the present application is that when a fault or shutdown occurs during the operation of the product, the power supply P12V of the operational amplifier circuit N4 is turned off first, then the power supply V_DAC of the digital-to-analog converter N3 is turned off, and then the galvanometer drive waveform data is turned off. Or the power supply V_DAC of the digital-to-analog converter N3 and the power supply P12V of the operational amplifier circuit N4 are turned off at the same time. Figure 6 As shown, P12V is the power supply of the operational amplifier circuit N4. If the power supply P12V of the operational amplifier circuit N4 is turned off directly first, the operational amplifier circuit N4 will not work, so there is no output voltage. Even if the power supply V_DAC of the digital-to-analog converter N3 and the galvanometer drive waveform are not turned off, there will be no DC high-voltage pulse, and the galvanometer coil will not be burned.

[0103] The power supply P12V of the operational amplifier circuit N4 directly controls whether N4 works, that is, the power supply P12V is the key to whether the DC high-voltage pulse is output. Therefore, the key to eliminating the DC high-voltage pulse is to control the timing of the power supply P12V of the operational amplifier circuit N4. The optimal timing control of the power-on timing and the power-off timing is to control the power supply P12V of the operational amplifier circuit N4. The embodiment of the present application is to solve the problem of the galvanometer coil burning. Figure 6 Based on the galvanometer drive circuit shown in the figure, the Figure 7 The galvanometer power supply control circuit shown in the figure controls Figure 6 The operational amplifier in the circuit controls the power-on and power-off timing of the power supply P12V of N4, thereby eliminating the DC high-voltage pulse that drives the galvanometer.

[0104] In some embodiments, Fig. 9 As shown, the DLP unit circuit may also include only one DLP chip N5 and a first transistor N7. The first transistor is configured to output a high-level configuration success command signal to the input end of the delay circuit when receiving a low-level configuration success signal output by the DLP chip.

[0105] Specifically, the command signal output terminal of the DLP chip is connected to the base of the first transistor through a resistor R10, the collector of the first transistor is connected to a 3.3V high-level power supply through a resistor R11, the base of the first transistor is grounded through a resistor N12, the collector of the first transistor is also connected to the input terminal of the delay circuit, and the emitter of the first transistor is grounded. The configuration success signal output by the DLP chip is usually low-level valid, and the configuration success signal is pulled up to a 3.3V high-level configuration success command signal through the first transistor N7, so that the MCU can receive and identify it.

[0106] In some embodiments, Fig.10As shown, the MCU does not have a delay function, and a delay circuit N13 is separately set between the output terminal IO2 of the MCU and the third transistor N11. After the delay circuit receives the start signal output by the MCU, it transmits the start signal to the base of the third transistor after a preset delay.

[0107] The embodiment of the present application also provides a laser projection device, including a galvanometer, a galvanometer drive circuit and a galvanometer power control circuit provided in the above embodiment. The output end of the galvanometer power control circuit is connected to the power input end of the galvanometer drive circuit, and the output end of the galvanometer drive circuit is connected to the galvanometer coil.

[0108] The laser projection device provided in the embodiment of the present application has the same technical features as the galvanometer power supply control circuit provided in the above-mentioned embodiment of the present application, so it can also solve the same technical problems and achieve the same technical effects.

[0109] In some embodiments, Fig.11 As shown, a voltage-dividing resistor R20 is connected in series between the galvanometer drive circuit and the galvanometer coil. The figure only shows the local circuit between the output terminals V_p and V_n of the galvanometer drive circuit and the galvanometer. The output terminal of the galvanometer drive circuit is connected to the galvanometer through a connector, and the voltage-dividing resistor R20 is connected in series between the output terminal V_p and the connector.

[0110] A voltage-dividing resistor R20 is added in series in the path of the galvanometer. The voltage-dividing resistor R20 can be equal to the resistance of the galvanometer coil and is used to divide the voltage with the galvanometer coil. When a DC high-voltage pulse appears, the DC voltage applied to both ends of the galvanometer coil is reduced, that is, the current of the galvanometer coil is reduced in the DC mode, thereby reducing the heating of the galvanometer coil and further reducing the possibility of burning the galvanometer coil. For example, the galvanometer coil resistance is 12.1 ohms. A 12.1 ohm series resistor is added in the path of the output end V_p of the operational amplifier circuit. After voltage division with the galvanometer coil, the voltage applied to both ends of the galvanometer coil is reduced to half of the original voltage, so that the DC voltage applied to the galvanometer coil is reduced, and the heat generated by the galvanometer coil is reduced, thereby further protecting the galvanometer coil.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0112] For the convenience of explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific use considerations.

Claims

1. A galvanometer power supply control circuit, characterized in that: It includes a DLP unit circuit, a delay circuit and a switch circuit; The command signal output end of the DLP unit circuit is connected to the input end of the delay circuit, the output end of the delay circuit is connected to the control end of the switch circuit, the input end of the switch circuit is connected to the power supply, and the output end of the switch circuit is connected to the power input end of the galvanometer drive circuit; The delay circuit is configured to output a start signal to the control end of the switch circuit after a preset delay when the input end of the delay circuit receives the configuration success command signal output by the DLP unit circuit; The switch circuit is configured to conduct the electrical connection between the input end and the output end when the control end of the switch circuit receives a start signal.

2. The galvanometer power supply control circuit according to claim 1, characterized in that: The delay circuit includes an MCU, the command signal output end of the DLP unit circuit is connected to the input end of the MCU, and the output end of the MCU is connected to the control end of the switch circuit; The MCU is configured to output a start signal to the control end of the switch circuit after a preset delay when the input end of the MCU receives a configuration success command signal output by the DLP unit circuit.

3. The galvanometer power supply control circuit according to claim 2, characterized in that: The MCU also includes a fan fault signal port and / or an overheat signal port; The MCU is configured to output an on signal to the control end of the switch circuit after a preset delay when the input end of the MCU receives a configuration success command signal output by the DLP unit circuit and does not receive a fan fault signal and / or an overheating signal.

4. The galvanometer power supply control circuit according to claim 1, characterized in that: The DLP unit circuit includes a DLP chip and a first transistor; The first transistor is configured to output a high-level configuration success command signal to the input end of the delay circuit upon receiving a low-level configuration success signal output by the DLP chip.

5. The galvanometer power supply control circuit according to claim 1, characterized in that: The DLP unit circuit includes a master control DLP chip and a slave control DLP chip; The DLP unit circuit is configured to output a configuration success command signal to the input end of the delay circuit when both the master DLP chip and the slave DLP chip are configured successfully.

6. The galvanometer power supply control circuit according to claim 5, characterized in that: The DLP unit circuit also includes a first triode, a second triode and an AND gate circuit; The first transistor is configured to output a high-level configuration success command signal to the first input terminal of the AND gate circuit upon receiving a low-level configuration success signal output by the master control DLP chip; The second transistor is configured to output a high-level configuration success command signal to the second input terminal of the AND gate circuit upon receiving a low-level configuration success signal output by the slave control DLP chip; The AND gate circuit is configured to output a configuration success command signal to the input end of the delay circuit when both the first input end and the second input end of the AND gate circuit receive a high-level configuration success command signal.

7. The galvanometer power supply control circuit according to claim 1, characterized in that: The switch circuit includes a transistor; The transistor is configured to conduct electrical connection between the source and the drain when the gate of the transistor receives an on signal.

8. The galvanometer power supply control circuit according to claim 7, characterized in that: The transistor is a PMOS, and the switch circuit further includes a third triode; The base of the third transistor is connected to the output end of the delay circuit, the emitter of the third transistor is grounded, the collector of the third transistor is connected to the gate of the PMOS, the source of the PMOS is connected to the power supply, and the drain of the PMOS is connected to the power input end of the galvanometer drive circuit.

9. A laser projection device, characterized in that: It comprises a galvanometer, a galvanometer driving circuit and a galvanometer power supply control circuit as claimed in any one of claims 1 to 8; The output end of the galvanometer power supply control circuit is connected to the power supply input end of the galvanometer drive circuit, and the output end of the galvanometer drive circuit is connected to the galvanometer coil.

10. The laser projection device according to claim 9, characterized in that: A voltage-dividing resistor is connected in series between the galvanometer drive circuit and the galvanometer coil.

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