WO2023112485A1 - Dispositif d'affichage d'image et circuit de commande de source de lumière - Google Patents

Dispositif d'affichage d'image et circuit de commande de source de lumière Download PDF

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Publication number
WO2023112485A1
WO2023112485A1 PCT/JP2022/039381 JP2022039381W WO2023112485A1 WO 2023112485 A1 WO2023112485 A1 WO 2023112485A1 JP 2022039381 W JP2022039381 W JP 2022039381W WO 2023112485 A1 WO2023112485 A1 WO 2023112485A1
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Prior art keywords
value
brightness
duty
output
normalized
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PCT/JP2022/039381
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English (en)
Japanese (ja)
Inventor
雄大 山本
章 黒塚
敬史 濱野
光隆 山口
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パナソニックＩｐマネジメント株式会社
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Publication of WO2023112485A1 publication Critical patent/WO2023112485A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/66—Transforming electric information into light information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor

Definitions

  • the present invention relates to an image display device that displays an image modulated by a video signal and a light source control circuit suitable for the image display device.
  • An image display device that projects an image onto an indoor wall or a screen installed indoors is known. Further, in an image display device mounted on a vehicle, an image is projected and displayed on the windshield in front of the driver's seat. For example, illumination light is modulated using a reflective liquid crystal panel and projected onto a windshield or the like.
  • the brightness of the displayed image is changed according to the ambient brightness. For example, the brighter the surroundings, the higher the brightness of the displayed image. This makes the displayed image easier to see.
  • the brightness of the displayed image is controlled by changing the amount of light emitted from the light source.
  • Patent Document 1 describes a configuration for controlling the amount of emitted light from a light source by changing the duty of pulsed light emission for the light source and the output of the light source. Specifically, in the range from zero to a predetermined brightness, the duty of pulse emission is linearly increased to 100% while the output of the light source is kept constant. Further, when this range is exceeded, the output of the light source is linearly increased to the maximum output while the duty of pulse emission is maintained at 100%.
  • an object of the present invention to provide an image display device and its light source control circuit capable of controlling the brightness of a displayed image without giving the user a sense of discomfort.
  • a first aspect of the present invention relates to an image display device.
  • An image display device includes a light source, a display element that modulates light emitted from the light source based on a video signal, an illumination optical system that guides the light emitted from the light source to the display element, and a display and a control unit that controls the duty and output of the pulse light emission of the light source according to the brightness of the image.
  • the control unit changes one of the duty and the output in one direction from a minimum value to a maximum value in accordance with the change in brightness, and changes the other of the duty and the output to the corresponding brightness. is changed to obtain a gamma correction value of
  • one of the duty and the output changes in one direction from the minimum value to the maximum value according to changes in brightness.
  • the other of the duty and the output is changed so as to obtain the corresponding brightness gamma correction value. Therefore, the other of duty and output also changes in one direction from the minimum value to the maximum value according to the change in brightness.
  • neither the duty nor the output has an inflection point. Therefore, it is possible to control the brightness of the display image without giving the user a sense of discomfort.
  • the other of the duty and the output changes so as to obtain the corresponding brightness gamma correction value, so it is possible to change the brightness of the display image to suit human vision. Therefore, it is possible to effectively suppress the discomfort of the user when the brightness of the display image changes.
  • a second aspect of the present invention relates to a light source control circuit for controlling a light source of an image display device.
  • the light source control circuit according to this aspect minimizes one of the duty and the output according to the change in brightness in the control processing for controlling the duty and the output of the pulse light emission of the light source according to the brightness of the display image. value to a maximum value, and the other of the duty and the output is varied to obtain the corresponding gamma correction value of the brightness.
  • the same control as in the first aspect is performed. Therefore, an effect similar to that of the first mode is achieved.
  • an image display device and its light source control circuit capable of controlling the brightness of a displayed image without giving the user a sense of discomfort.
  • FIG. 1 is a plan view showing the configuration of an optical system of an image display device according to an embodiment.
  • FIG. 2 is a block diagram showing the configuration of the circuit section of the image display device according to the embodiment.
  • FIG. 3A is a graph showing the relationship between brightness and duty of pulse emission according to a comparative example.
  • FIG. 3B is a graph showing the relationship between brightness and light source output duty, according to a comparative example.
  • FIG. 4A is a graph showing the relationship between brightness and duty of pulsed light emission according to the embodiment.
  • FIG. 4B is a graph showing the relationship between brightness and light source output duty, according to the embodiment.
  • FIG. 5(a) is a diagram showing the configuration of a duty table according to the embodiment.
  • FIG. 5(b) is a diagram showing the configuration of an output table according to the embodiment.
  • FIG. 6A is a graph showing the relationship between brightness input and output when gamma correction is applied, according to an embodiment.
  • FIG. 6(b) is a diagram showing the relationship between the input value and the output value of brightness in each plot on the graph of FIG. 6(a).
  • FIG. 7A is a graph showing an example of the relationship between the drive current of the light source and the light emission output according to the embodiment.
  • FIG. 7B is a diagram showing the relationship between the normalized input value of brightness and the normalized output value of the light source according to the embodiment.
  • FIG. 8 is a diagram showing the relationship between the normalized input value of brightness and the normalized duty value of pulse emission according to the embodiment.
  • FIG. 9A is a graph showing the relationship between the normalized input value of brightness and the normalized duty value of pulse emission according to the embodiment.
  • FIG. 9B is a graph showing the relationship between the normalized input value of brightness and the normalized output value of the light source according to the embodiment.
  • FIG. 10 is a flow chart showing a method of generating a duty table and an output table according to the embodiment.
  • FIG. 11 is a flowchart illustrating processing for controlling brightness of a displayed image, according to an embodiment.
  • 12 is a plan view showing the configuration of the optical system of the image display device according to Modification 1.
  • FIG. 13 is a flowchart for controlling the brightness of a display image according to Modification 1.
  • FIG. 14 is a plan view showing the configuration of the optical system of the image display device according to Modification 2.
  • FIG. 15 is a graph schematically showing the relationship between the driving current of the light source and the light emission output when the temperature changes, according to Modification 2.
  • FIG. 16 is a flowchart illustrating a process of selecting a duty table and an output table used for light source control according to Modification 2;
  • FIG. 17 is a flowchart showing a method of generating a duty table and an output table according to Modification 3.
  • FIG. 16 is a flowchart illustrating a process of selecting a duty table and an output table used for light source control according to Modification 2;
  • FIG. 17 is a flowchart showing a method of generating a duty table and an output table according to Modification 3.
  • each figure is labeled with mutually orthogonal X, Y, and Z axes.
  • the Y-axis negative direction is the projection direction of laser light modulated by a video signal
  • the X-axis direction is the vertical direction of the optical system.
  • FIG. 1 is a plan view showing the configuration of the optical system of the image display device 1.
  • FIG. 1 the optical axis of the optical system is indicated by a dashed-dotted line, and the optical paths of laser beams of respective colors are schematically indicated by dotted lines.
  • the image display device 1 includes light sources 11 to 13, an illumination optical system 20, a display element 30, and a projection lens unit 40 as an optical system configuration. Furthermore, the image display device 1 includes an actuator 50 that vibrates the cylindrical lens array 25 in the Y-axis direction.
  • the light sources 11, 12, and 13 emit laser light in a red wavelength band, a green wavelength band, and a blue wavelength band, respectively.
  • Light sources 11, 12, and 13 are, for example, semiconductor lasers.
  • the light sources 11 and 12 emit laser light in the positive Z-axis direction, and the light source 13 emits laser light in the positive Y-axis direction.
  • the output optical axes of the light sources 11, 12, 13 are contained in the same plane parallel to the YZ plane.
  • the light sources 11 , 12 , 13 are arranged such that the polarization direction is S-polarized with respect to the plane of polarization of the polarization beam splitter 28 .
  • the illumination optical system 20 guides the laser light of each color emitted from the light sources 11 , 12 and 13 to the display element 30 .
  • the illumination optical system 20 includes collimator lenses 21a to 21c, dichroic mirrors 22a and 22b, a fly-eye lens 23, a collimator lens 24, a cylindrical lens array 25, a diffusion plate 26, a field lens 27, and a polarizing beam splitter. 28.
  • the collimator lenses 21a-21c converge the laser beams emitted from the light sources 11-13 into substantially parallel beams, respectively.
  • the dichroic mirror 22a transmits the laser light in the red wavelength band that has passed through the collimator lens 21a, and reflects the laser light in the green wavelength band that has passed through the collimator lens 21b.
  • the dichroic mirror 22b transmits laser light in the red and green wavelength bands incident from the dichroic mirror 22a side, and reflects laser light in the blue wavelength band that has passed through the collimator lens 21c.
  • the dichroic mirror 22a is arranged at a position where the emission optical axes of the light sources 11 and 12 intersect, and the dichroic mirror 22b is arranged at a position where the emission optical axes of the light sources 11 and 13 intersect.
  • the optical axes of the light sources 11, 12, 13 are aligned with each other by the dichroic mirrors 22a, 22b. Therefore, the laser beams in the respective wavelength bands of red, green, and blue go through the same optical path in the positive Z-axis direction after passing through the dichroic mirror 22b.
  • the fly-eye lens 23 homogenizes the intensity distribution of the incident laser light.
  • the fly-eye lens 23 is composed of a microlens array in which a large number of microlenses are arranged in a matrix.
  • the laser light incident on each microlens of the fly-eye lens 23 is diffused through the collimator lens 24 so as to spread over the same incident area of the cylindrical lens array 25 . Thereby, the intensity distribution of the laser light of each color is made uniform in the incident area of the cylindrical lens array 25 .
  • the collimator lens 24 collimates the laser light incident from the fly-eye lens 23 and guides it to the cylindrical lens array 25 .
  • a large number of cylindrical lenses 25a and 25b are formed on the incident surface and the exit surface of the cylindrical lens array 25, respectively.
  • a large number of cylindrical lenses 25a are formed on the incident surface of the cylindrical lens array 25 so that the generatrix is parallel to the X-axis.
  • a large number of cylindrical lenses 25b are formed on the output surface of the cylindrical lens array 25 so that the generatrix is parallel to the Y-axis.
  • each lens unit converges the laser light in the Y-axis direction by the cylindrical lens 25a on the entrance surface, and converges the laser light in the X-axis direction by the cylindrical lens 25b on the exit surface. Due to this lens action of each lens part and the lens action of the field lens 27 on the rear side, the laser light transmitted through each lens part is guided to the display element 30 so as to spread over the entire display area of the display element 30 .
  • the diffusion plate 26 diffuses the laser light incident from the cylindrical lens array 25 side at a predetermined diffusion angle. A large number of fine lenses are formed on the entrance surface or the exit surface of the diffuser plate 26 with almost no space therebetween. The diffusing action of the diffusing plate 26 further homogenizes the intensity distribution of the laser light.
  • the polarizing beam splitter 28 reflects the S-polarized components of the laser beams incident from the field lens 27 side and guides them to the display element 30, and transmits and projects the P-polarized components of the laser beams incident from the display element 30 side. It leads to the lens unit 40.
  • the display element 30 is a reflective liquid crystal panel.
  • the display element 30 changes the polarization direction of the laser light incident on the display area for each pixel according to the video signal. As a result, the amount of laser light that passes through the polarization beam splitter 28 changes for each pixel. Thus, the laser light of each color is modulated according to the video signal.
  • the projection lens unit 40 projects the modulated laser light of each color incident from the polarization beam splitter 28 side in the Y-axis negative direction.
  • the projection lens unit 40 includes a plurality of projection lenses 41 for projecting laser light of each color, and a lens barrel 42 that holds the projection lenses 41 .
  • the actuator 50 includes a support portion 51 and a drive portion 52, and drives the drive portion 52 to vibrate the support portion 51 in the Y-axis direction.
  • Drive unit 52 is, for example, an electromagnetic actuator that drives support unit 51 by an electromagnetic force generated between a coil and a magnet.
  • the drive unit 52 may be configured to drive the support unit 51 by another method.
  • the projection lens 41 projects the laser light of each color wavelength band modulated by the display element 30 based on the video signal.
  • the light sources 11, 12, and 13 are driven in a time division manner, and the display element 30 displays an image of that color during the driving period of the light source of each color.
  • a color projection image is displayed on the rear stage side of the projection lens unit 40 .
  • the actuator 50 finely vibrates the cylindrical lens array 25 in the Y-axis direction. This suppresses speckle noise that occurs in the projected image due to interference of laser light.
  • FIG. 2 is a block diagram showing the configuration of the circuit section of the image display device 1 according to the embodiment.
  • the image display device 1 includes a control section 101, light source drive sections 102 to 104, a display element drive section 105, and an actuator drive section 106 as the configuration of the circuit section.
  • a light source control circuit 200 is configured by the control unit 101 and the light source driving units 102 to 104 .
  • the control unit 101 includes an arithmetic processing circuit such as a CPU and a memory, and controls each unit according to a program stored in the memory.
  • the light source driving units 102 to 104 drive the light sources 11 to 13 under the control of the control unit 101, respectively.
  • the display element driving section 105 drives the display element 30 under the control of the control section 101 .
  • Actuator driving section 106 drives actuator 50 under the control of control section 101 .
  • the control unit 101 controls the light source driving units 102 to 104 to drive the light sources 11, 12, and 13 in a time division manner, controls the display element driving unit 105, and controls the driving period of each light source.
  • a modulation pattern for modulating the laser light from the light source is displayed on the display element 30 .
  • the control unit 101 drives the display element 30 so as to generate a modulation pattern corresponding to one frame of an image in each time division period. As a result, the images of each color are integrated to display a color image.
  • control is performed to change the brightness of the display image according to the brightness of the surroundings of the display image.
  • the brightness of the displayed image can be controlled by changing the amount of light emitted from the light sources 11-13.
  • control unit 101 causes the light sources 11 to 13 to emit pulsed light at a predetermined duty, and changes the duty and the output of the light sources 11 to 13 to change the amount of light emitted from the light sources 11 to 13.
  • duty means the ratio of the period of pulsed light emission to one cycle of pulsed light emission
  • output means the intensity of pulsed light emission.
  • the maximum duty of the light emission period of each color with respect to one frame period is 1/3 or about 33%.
  • the time division does not necessarily have to be set evenly for the three colors, for example, the maximum duration of red is set to 50% of one frame period, and the maximum duration of green and blue are each set to one frame period. It may be set to 25%. In this case, the maximum duty of the red emission period is 50%, and the maximum duty of the blue and green emission periods is 25%.
  • the control unit 101 sets the duty and output according to the input brightness for each of the light sources 11 to 13 within the range up to the maximum duty and maximum output, and controls the light sources 11 to 13 with the set duty and output. drive each. Thereby, the brightness of the display image is adjusted to a predetermined brightness.
  • FIG. 3(a) is a graph showing the relationship between the brightness and the duty of pulse emission according to the comparative example.
  • FIG. 3B is a graph showing the relationship between brightness and light source output duty, according to a comparative example.
  • the output of the light source in the comparative example, in the range from zero to the predetermined brightness L0, the output of the light source is maintained at a constant value P0, and the pulse emission duty is It is increased linearly up to a maximum value D_max. Further, when this range is exceeded, the output of the light source is linearly increased to the maximum output PW_max while the duty of pulse emission is maintained at D_max.
  • an inflection point occurs at the position of brightness L0 in both duty and output. Therefore, if the brightness of the display image is changed across the brightness L0, which is the point of inflection, as described above, the user may feel uncomfortable.
  • the duty of pulse light emission and the outputs of the light sources 11 to 13 are controlled so that such an inflection point does not occur.
  • the control unit 101 changes one of the duty and the output in one direction from the minimum value to the maximum value according to the change in brightness, and changes the other of the duty and the output to gamma-correct the corresponding brightness. Vary to obtain a value.
  • FIG. 4(a) is a graph showing the relationship between the brightness and the duty of pulse emission according to the embodiment.
  • FIG. 4B is a graph showing the relationship between brightness and light source output duty, according to the embodiment.
  • the duty increases in a curve from the minimum value D_min to the maximum value D_max as the brightness increases over the entire brightness range.
  • the light source output increases in a curve from the minimum value Pw_min to the maximum value Pw_max as the brightness increases over the entire brightness range.
  • the control unit 101 acquires the duty and output corresponding to the input brightness value from the relationships shown in FIGS. 4(a) and 4(b), and drives the light sources 11 to 13 with the acquired duty and output.
  • the relationship between brightness, duty, and output may be defined for each light source.
  • the control unit 101 acquires the duty and the output corresponding to the input brightness value for each light source from the relationship defined for each light source, and controls each light source.
  • the relationship between brightness, duty, and output may be obtained from information that associates brightness values with duty and output in advance.
  • the control unit 101 holds this information in memory in advance. This information may be prepared for each light source. As shown in FIG. 2, this information can be held in the control section 101 as a duty table 101a and an output table 101b.
  • FIG. 5(a) is a diagram showing the configuration of the duty table 101a.
  • FIG. 5B is a diagram showing the configuration of the output table 101b.
  • the duty table 101a brightness values and duty values are associated with each other.
  • the output table 101b brightness values and light source output values are associated with each other.
  • the brightness is set in 100 steps.
  • a duty table 101a and an output table 101b may be held for each of the light sources 11-13.
  • one of the pulse emission duty and the light source output is changed from its minimum value to its maximum value with the same change tendency as the change tendency from the minimum value to the maximum value of the gamma correction value of brightness. More specifically, one of the pulse emission duty and the light source output is changed from its minimum value to its maximum value so as to have correlation with the change from the minimum value to the maximum value of the gamma correction value of brightness. Then, the other of the pulse emission duty and the light source output is changed so as to obtain the corresponding brightness gamma correction value.
  • the light source output is varied from its minimum value to its maximum value with the same variation trend as the brightness gamma correction value from its minimum value to its maximum value, and the duty of the pulse emission is adjusted to the corresponding brightness.
  • Gamma correction is a conventionally well-known correction process that corrects the brightness input value to a value suitable for human perception based on the non-linearity of human perception of brightness.
  • gamma correction is defined by the following formula.
  • Equation (1) X is the input brightness value, and Y is the brightness value after gamma correction (gamma correction value).
  • the gamma value ⁇ depends on the illumination optical system 20 and the display element 30. FIG. Generally, in image display devices, the gamma value ⁇ is set to approximately 1.8 to 2.2.
  • FIG. 6(a) is a graph showing the relationship between brightness input and output when gamma correction is applied.
  • FIG. 6(b) is a diagram showing the relationship between the input value and the output value of brightness in each plot on the graph of FIG. 6(a).
  • FIGS. 6A and 6B show broken line graphs showing the relationship between brightness input and output when the gamma value ⁇ is 1.0, that is, when no gamma correction is performed. Output values are shown.
  • the brightness input value is divided into 100 levels from 1 to 100, and the brightness input value is standardized with 1 as the maximum brightness value. Therefore, the gamma correction value of brightness is also normalized with 1 as the maximum value.
  • the gamma correction value graph (solid line) is curved downward in the range other than both ends, compared to the graph (broken line) without gamma correction. That is, the gamma correction value is smaller than the brightness input value in the range between the minimum value and the maximum value.
  • the outputs of the light sources 11 to 13 for each brightness are calculated so as to have the same changing tendency as the gamma correction value.
  • a method of setting the duty and output for the light source 11 that emits laser light in the red wavelength band is shown below.
  • the duties and outputs of the other light sources 12 and 13 are also set by a similar setting method.
  • FIG. 7(a) is a graph showing an example of the relationship between the driving current of the light source 11 and the light emission output.
  • the light source 11 does not emit light until the drive current reaches the light emission threshold, and when the drive current exceeds the light emission threshold, the output increases as the drive current increases. Therefore, the output and driving current of the light source 11 are set within ranges W1 and W2 in which the light source 11 stably emits light exceeding the light emission threshold.
  • the output range W1 of the light source 11 is set within the range of 80 mW to 800 mW. Thus, the minimum and maximum values of the output of the light source 11 are set.
  • the minimum and maximum values are each normalized with the maximum value being 1.
  • the minimum and maximum output values are 80 mW and 800 mW, respectively, so the normalized minimum and maximum values are 0.1 and 1, respectively.
  • normalized output values of the light sources 11 to 13 for each brightness are calculated so as to have the same changing tendency as the gamma correction value.
  • the normalized output value is changed from the minimum value to the maximum value so as to have correlation with the change from the minimum value to the maximum value of the gamma correction value. That is, the normalized output value of the range between the upper limit and the lower limit of the output of the light source 11 is calculated so as to be linear with the normalized gamma correction value (normalized gamma value).
  • Calculation of the normalized output value can be performed by the following formula.
  • L ⁇ is the normalized gamma correction value for each brightness
  • L ⁇ min and L ⁇ max are the minimum and maximum normalized gamma correction values, respectively.
  • Pw is the normalized output value of each brightness
  • Pwmin and Pwmax are the minimum and maximum normalized output values, respectively.
  • FIG. 7(b) is a diagram showing the relationship between the normalized input value of brightness and the normalized output value of the light source 11.
  • the normalized input value of each brightness is calculated by the above formula (2).
  • a normalized output value of the light source 11 is associated.
  • the normalized value of duty (normalized duty value) associated with each normalized input value is Calculated.
  • FIG. 8 is a diagram showing the relationship between the normalized input value of brightness and the normalized duty value of pulse emission.
  • the normalized duty value is calculated by dividing the corresponding normalized gamma correction value by the corresponding normalized output value. That is, by multiplying the normalized output value for each brightness by the normalized duty value, the normalized gamma correction value for that brightness is obtained.
  • FIG. 9(a) is a graph showing the relationship between the normalized input value of brightness and the normalized duty value of pulse emission.
  • FIG. 9B is a graph showing the relationship between the normalized input value of brightness and the normalized output value of the light source 11. As shown in FIG.
  • the brightness input value The duty and output values increase as the The tendency of change from the minimum value to the maximum value in the graph of FIG. 9(b) is similar to the tendency of change from the minimum value to the maximum value of the graph of FIG. 6(a). That is, the output of the light source 11 changes from the minimum value to the maximum value so as to have correlation with the change from the minimum value to the maximum value of the normalized gamma correction value.
  • the normalized duty value for each normalized input value of brightness is, as described above, the normalized output value of FIG. 9(a) corresponding to the normalized input value.
  • the normalized gamma correction value shown in FIG. 6A corresponding to the normalized input value is obtained.
  • FIG. 10 is a flow chart showing a method of generating the duty table 101a and the output table 101b when the above setting method is used.
  • step S11 the gamma correction of the above formula (1) is applied to each normalized input value of brightness to calculate the normalized gamma correction value of each brightness.
  • the normalized gamma correction value corresponding to each normalized input value of brightness is acquired.
  • step S12 as described with reference to FIG. 7A, the minimum and maximum values of the output of the light source 11 are set, and the set minimum and maximum values are normalized by the maximum value. be.
  • step S13 the normalized output value in the range between the maximum value (upper limit) and the minimum value (lower limit) of the normalized output is linear with the normalized gamma correction value.
  • the normalized output value corresponding to each normalized input value of brightness is acquired.
  • step S14 the normalized duty value corresponding to each normalized output value is calculated so that the multiplied value with the normalized output value becomes the gamma correction value corresponding to the normalized output value. Thereby, as shown in FIG. 8, the normalized duty value corresponding to each normalized input value of brightness is obtained.
  • each normalized duty value is multiplied by the maximum pulse emission duty value (eg, 33%) to generate a duty table.
  • an output table is generated by multiplying the normalized output value by the maximum value of the light emission output of the light source 11 (800 mW, for example).
  • the duty table 101a and the output table 101b configured as shown in FIGS. 5(a) and 5(b) are generated.
  • FIG. 11 is a flow chart showing processing for controlling the brightness of the display image.
  • the brightness of the displayed image is automatically set according to the ambient brightness, for example.
  • an illuminance sensor is used to detect ambient brightness.
  • the system controller acquires the brightness level corresponding to the detection value of the illuminance sensor from a relational expression or table that defines the relationship between the illuminance and the brightness level, and converts the acquired brightness level to the brightness level shown in FIG. Output to the control unit 101 .
  • the brightness of the displayed image may be set by the user via the input interface. In this case, the system controller outputs a default brightness value to the control unit 101 in FIG. Output to the unit 101 .
  • control unit 101 holds a duty table 101a and an output table 101b for each of the light sources 11-13.
  • control unit 101 stores the duty values and output values corresponding to the processing brightness values input at the start of the operation, for each of the light sources 11 to 13, in the duty table 101a and the output table. 101b, and sets the acquired duty value and output value to each light source (S101).
  • the control unit 101 causes each light source to emit pulse light according to the duty value and output value set in step S101 (S103). Then, the control unit 101 determines whether or not the display operation has ended (S104), and if the display operation has not ended (S104: NO), determines whether or not the brightness setting has been changed. (S105).
  • the control unit 101 If the brightness setting has not been changed (S105: NO), the control unit 101 returns the process to step S102 and performs the same process. On the other hand, if the brightness setting has been changed (S105: YES), the control unit 101 returns the process to step S101. Then, the control unit 101 acquires the duty value and the output value corresponding to the new brightness value from the duty table 101a and the output table 101b for each of the light sources 11 to 13, and stores the acquired duty value and output value in each Set the light source. Thus, the brightness of the displayed image is changed.
  • the control unit 101 repeats similar processing until the display operation is completed (S104: NO). After that, when the display operation ends (S104: YES), the control unit 101 ends the processing of FIG.
  • the control unit 101 changes the outputs of the light sources 11 to 13 in one direction from the minimum value to the maximum value according to the change in brightness, and the duty of pulse emission. is varied so as to obtain the gamma correction value for the corresponding brightness.
  • the duty value for each brightness is set so that the gamma correction value for that brightness can be obtained from the duty value and the output value corresponding to that brightness. .
  • the brightness of the display image can be changed so as to be suitable for human vision. Therefore, it is possible to effectively suppress the discomfort of the user when the brightness of the display image changes.
  • the control unit 101 adjusts the outputs of the light sources 11 to 13 with the same change tendency as the change tendency from the minimum value to the maximum value of the gamma correction value. Vary from its minimum value to its maximum value. More specifically, the control unit 101 changes the outputs of the light sources 11 to 13 from the minimum value to the maximum value so as to have correlation with the change from the minimum value to the maximum value of the gamma correction value. That is, the control unit 101 sets the output values of the light sources 11 to 13 so as to be linear with the gamma correction value of each brightness based on the above equation (2). This allows the outputs of the light sources 11 to 13 to follow changes in the gamma correction value. Therefore, the outputs of the light sources 11 to 13 can be changed so as to suit the human vision for brightness.
  • the multiplied value obtained by multiplying the normalized duty value and the normalized output value for each brightness is the normalized gamma correction value for that brightness.
  • the control unit 101 holds a duty table 101a and an output table 101b in which a brightness value is associated with a duty and an output value. Get the duty and output values for a brightness value. As a result, the control unit 101 can easily acquire the duty and output values without performing calculations for acquiring the duty and output values when the brightness is changed.
  • the image display device 1 includes a plurality of light sources 11 to 13 having different emission wavelengths, and as shown in FIG. Control (S101) for setting duty and output is performed.
  • S101 for setting duty and output is performed.
  • inflection points such as those shown in FIGS. 3A and 3B do not occur in any of the light sources 11-13. Therefore, it is possible to effectively suppress the discomfort of the user when the brightness of the display image changes, and to change the brightness of the display image so as to be suitable for human vision.
  • Modification 1 a photodetector for detecting the amount of light emitted from the light sources 11 to 13 is further arranged, and the amount of light emitted from each light source detected via the photodetector and the amount of light corresponding to the brightness to be set are detected. At least one of the duty and the output is corrected so that the difference in is suppressed.
  • the target brightness may not be obtained due to conditions such as the temperature of the light sources 11-13. Therefore, in Modification 1, the actual emitted light amount of each light source is detected by the photodetector when the duty and output are set as described above and the light sources 11 to 13 emit pulsed light, and the detected actual emitted light amount is detected by the photodetector. At least one of the duty and the output is corrected so that the difference between the amount of light and the amount of light corresponding to the brightness to be set is suppressed.
  • FIG. 12 is a plan view showing the configuration of the optical system of the image display device 1 according to Modification 1.
  • a spectral element 29 and a photodetector 60 are added as compared with FIG.
  • the spectroscopic element 29 transmits most of the light of each color incident from the dichroic mirror 22b side, and reflects only part of the light.
  • a flat glass plate is used as the spectral element 29 .
  • the photodetector 60 receives the light of each color reflected by the spectral element 29 and outputs a signal corresponding to the received light intensity.
  • FIG. 13 is a flowchart for controlling the brightness of the display image according to Modification 1.
  • the flowchart of FIG. 13 has steps S111 to S113 added. Processing in steps other than steps S111 to S113 is the same as the corresponding steps in FIG.
  • the control unit 101 integrates the detection value of the photodetector 60 over the pulse emission period, and acquires the integrated value as the received light amount ( S111).
  • the control unit 101 preliminarily holds, for each of the light sources 11 to 13, a table in which each brightness value is associated with a reference value of the amount of received light (integrated value) for realizing the brightness.
  • the control unit 101 acquires the reference value corresponding to the currently set brightness from the table of the light sources to be controlled, and calculates the difference between the acquired reference value and the integrated value acquired in step S111 (S112). . Then, the control unit 101 corrects the output of the light source to be controlled so that this difference is suppressed (S113).
  • the control unit 101 executes steps S111 to S113 each time light of each color is pulsed. As a result, the emitted light amount of each color converges to the light amount corresponding to the brightness setting value. Therefore, even if the temperature of the light sources 11 to 13 changes, the display image can be displayed with the set brightness.
  • step S113 the outputs of the light sources 11 to 13 are corrected, but instead of or together with this, the pulse emission duty of each light source may be corrected so as to suppress the difference value. .
  • a temperature sensor for detecting the temperature near the light sources 11 to 13 is further arranged, and the duty table and the output table used for setting are changed according to the temperature detected by the temperature sensor. That is, the control unit 101 holds a duty table and an output table for a plurality of temperatures, and uses the duty table and the output table corresponding to the temperature detected by the temperature sensor to determine the brightness value to be set. Get duty and output values.
  • FIG. 14 is a plan view showing the configuration of the optical system of the image display device 1 according to Modification 2.
  • a temperature sensor 70 is added compared to FIG. A temperature sensor 70 is placed close to the light sources 11-13 to detect the temperature in the vicinity of the light sources 11-13. In the configuration of FIG. 14, one temperature sensor 70 detects the temperature near the light sources 11-13. Alternatively, a temperature sensor may be arranged for each of the light sources 11-13 and the temperature of each light source may be detected individually.
  • FIG. 15 is a graph schematically showing the relationship between the driving current of the light source 11 and the light emission output when the temperature changes.
  • FIG. 15 shows respective graphs when the temperature of the light source 11 is t1 to t7.
  • the output range W1 of the light source 11 shown in FIG. 7(a) may be changed according to the temperature. It should be changed according to the temperature.
  • the output range of light source 11 can be set to range W11 when the temperature is in the range of t1 to t3.
  • the power range of the light source can be set to range W12.
  • the normalized output value for each brightness is set from the above equation (2) based on the minimum output value Pw_min1 and the maximum output value Pw_max1. Further, when the temperature is t7, the normalized output value for each brightness is set from the above equation (2) based on the minimum output value Pw_min2 and the maximum output value Pw_max2. Similarly, when the temperatures are at t4, t5, and t6, the minimum output value and maximum output value are adjusted, and the normalized output value for each brightness is set from the above equation (2). Therefore, the normalized duty value of each brightness also changes for each temperature. As a result, the duty table and output table of each light source also differ for each temperature.
  • the duty table and output table of each light source are defined for each temperature. That is, the control unit 101 of FIG. 2 holds a plurality of types of duty tables 101a and output tables 101b with different target temperatures for each of the light sources 11-13.
  • FIG. 16 is a flowchart showing selection processing of the duty table and the output table used for controlling the light sources 11 to 13 according to Modification 2.
  • the control unit 101 acquires the temperature from the temperature sensor 70 (S201), and selects the duty table and the output table corresponding to the acquired temperature as tables to be used for control (S202). .
  • the control unit 101 performs the control shown in FIG. 11 or 12 using the selected duty table and output table.
  • the control unit 101 repeatedly executes the process of step S201 until the operation of the image display device 1 is completed (S203: NO).
  • the tables used for control are changed to the duty table and output table corresponding to the new temperature in step S202.
  • the table used for the control in FIG. 11 or 12 can be switched at any time.
  • the duty table and the output table suitable for the temperature of the light source 11 are used for controlling the light sources 11 to 13, so that the light sources 11 to 13 can be controlled more appropriately and smoothly. Therefore, it is possible to appropriately control the brightness of the display image to a predetermined brightness.
  • the normalized output value is calculated by applying the formula (2) to the normalized gamma correction value, A normalized duty value was calculated based on the output value.
  • the normalized duty value is first calculated so as to be linear with the normalized gamma correction value, and then the normalized output value is calculated based on the normalized gamma correction value and the normalized duty value. may be calculated.
  • the normalized duty value of each brightness can be calculated by the following formula.
  • L ⁇ is the normalized gamma correction value for each brightness
  • L ⁇ min and L ⁇ max are the minimum and maximum normalized gamma correction values, respectively.
  • D is the normalized duty value of each brightness
  • Dmin and Dmax are the minimum and maximum normalized duty values, respectively.
  • the normalized output value is calculated so that the multiplied value by the normalized duty value of each brightness becomes the normalized gamma value of that brightness.
  • the product of the minimum normalized output value and the maximum light source output value 800 mW in the example of FIG. 7A
  • the minimum and maximum normalized duty values are set so as to satisfy this condition.
  • FIG. 17 is a flow chart showing a method of generating the duty table 101a and the output table 101b according to the third modification.
  • steps S12-S14 of the flowchart of FIG. 10 are replaced with steps S21-S23.
  • the processes of steps S11, S15, and S16 in FIG. 17 are the same as the corresponding steps in FIG.
  • step S21 the minimum and maximum values of the pulse emission duty are set, and the set minimum and maximum values are normalized by the maximum value.
  • step S22 the normalized duty value in the range between the maximum value (upper limit) and minimum value (lower limit) of the normalized duty is calculated so as to be linear with the normalized gamma correction value. This calculation is performed by the above formula (3). As a result, a normalized duty value corresponding to each normalized input value of brightness is obtained.
  • step S23 the normalized output value corresponding to each normalized duty value is calculated so that the multiplied value with the normalized duty value becomes the normalized gamma correction value corresponding to the normalized duty value. As a result, a normalized output value corresponding to each normalized input value of brightness is obtained.
  • each normalized duty value is multiplied by the maximum value of the pulse emission duty to generate a duty table.
  • the normalized output value is multiplied by the maximum value of the light emission output of the light source 11 to generate an output table.
  • the duty table 101a and the output table 101b may be generated for each of the light sources 11 to 13, as in the above embodiment. Further, as in the second modification, a duty table 101a and an output table 101b may be generated for each temperature of the light sources 11-13.
  • the output value for each brightness is set so as to be linear with respect to the gamma correction value for each brightness. It may not be linear with respect to the brightness gamma correction value, and may be set by other methods as long as it changes in one direction from the minimum value to the maximum value. For example, each brightness output value may change so as to change linearly from the minimum value to the maximum value.
  • the duty value for each brightness should be set so that the output value for that brightness and the gamma correction value for that brightness are obtained. That is, the normalized duty value for each brightness may be set so that the normalized gamma correction value for that brightness is obtained when multiplied by the normalized output value for that brightness. Similarly, in Modification 3, the duty value of each brightness does not have to be linear with respect to the gamma correction value of each brightness. may be set by the method of
  • the duty value and output value of the brightness to be set are obtained from the duty table 101a and the output table 101b. It may be obtained by calculation.
  • the control unit 101 calculates, for example, the normalized gamma correction value from the brightness value to be set by the above formula (1), and the calculated normalized gamma correction value, the normalized minimum value of the light emission output, and the standard By applying the normalized maximum value to the above equation (2), the normalized output value of the brightness to be set is calculated.
  • the control unit 101 sets the normalized duty value of the brightness to be set so that the multiplied value by the calculated normalized output value becomes the normalized gamma correction value calculated from the above equation (1). calculate.
  • the control unit 101 multiplies the calculated normalized output value and normalized duty value by the maximum value of the output value and the maximum value of the duty value, respectively, to calculate the output value and the duty value for the brightness to be set. .
  • the output value and duty value for the brightness to be set may be calculated directly from the brightness setting value by omitting the intermediate steps in the above calculation process. Also in the third modification, the duty value and the output value of the brightness to be set may be similarly calculated.
  • the control unit 101 holds information (table) in which each brightness shown in FIG. 8 is associated with the normalized output value and the normalized duty value.
  • the control unit 101 obtains the normalized output value and the normalized duty value corresponding to the brightness to be set from this information (table), and outputs the normalized output value and the normalized duty value to the obtained normalized output value and the normalized duty value.
  • the output value and duty value corresponding to the brightness to be set are calculated.
  • the three light sources 11 to 13 that respectively emit laser light in the red, green, and blue wavelength bands are used to display images. type is not limited to this.
  • the image display device 1 may include only one of the light sources 11-13.
  • the control section 101 may hold the duty table 101a and the output table 101b only for this light source.
  • a light source that emits laser light in other color wavelength bands may be used for image display. .
  • the duty of pulse emission and the emission output of laser light sources of wavelength bands of other colors may be controlled in the same manner as described above.
  • the configuration of the optical system of the image display device 1 is not limited to the configurations shown in the first embodiment and the first to third modifications.
  • a display element may be arranged individually for each of the light sources 11 to 13, and the laser light of each color modulated by each display element may be integrated by a plurality of dichroic mirrors.
  • a reflective liquid crystal panel is used as a display element for modulating laser light, but the display element for modulating laser light is limited to this. isn't it.
  • a transmissive liquid crystal panel or a display element of another type such as a digital mirror device (DMD) may be used to modulate the laser light.
  • DMD digital mirror device
  • the configuration of the optical system may be changed in accordance with the change in the method of the display element.
  • the image display device 1 is an image display device that projects a laser beam modulated by a display element. It may be an image display device of the system.
  • the light sources 11 to 13 are not necessarily laser light sources, and may be other types of light sources such as LEDs (Light Emitting Diodes).

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Abstract

L'invention concerne un dispositif d'affichage d'image (1) qui comprend : des sources de lumière (11-13); un élément d'affichage (30) qui module la lumière émise par les sources de lumière (11-13) sur la base d'un signal vidéo; un système optique d'éclairage qui guide la lumière émise par les sources de lumière (11-13) vers l'élément d'affichage (30); et une unité de commande (101) qui commande le cycle et la sortie de l'émission de lumière pulsée à partir des sources de lumière (11-13) en fonction de la luminosité d'une image affichée. L'unité de commande (101) change l'un du cycle et de la sortie de la valeur minimale à la valeur maximale dans une direction en fonction du changement de la luminosité et change l'autre du cycle et de la sortie de sorte à obtenir une valeur de correction gamma de luminosité correspondante.
PCT/JP2022/039381 2021-12-15 2022-10-21 Dispositif d'affichage d'image et circuit de commande de source de lumière WO2023112485A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014050497A1 (fr) * 2012-09-26 2014-04-03 日本精機株式会社 Dispositif d'affichage
JP2014106420A (ja) * 2012-11-28 2014-06-09 Seiko Epson Corp 表示装置及び表示装置の制御方法
US20160203774A1 (en) * 2013-09-03 2016-07-14 Lg Electronics Inc. Liquid crystal display and method for driving the same
US20180061333A1 (en) * 2016-03-25 2018-03-01 Boe Technology Group Co., Ltd. Backlight control method, backlight module and display apparatus
WO2018097121A1 (fr) * 2016-11-24 2018-05-31 日本精機株式会社 Appareil d'affichage d'images et afficheur tête haute
WO2018123554A1 (fr) * 2016-12-26 2018-07-05 日本精機株式会社 Dispositif d'affichage

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014050497A1 (fr) * 2012-09-26 2014-04-03 日本精機株式会社 Dispositif d'affichage
JP2014106420A (ja) * 2012-11-28 2014-06-09 Seiko Epson Corp 表示装置及び表示装置の制御方法
US20160203774A1 (en) * 2013-09-03 2016-07-14 Lg Electronics Inc. Liquid crystal display and method for driving the same
US20180061333A1 (en) * 2016-03-25 2018-03-01 Boe Technology Group Co., Ltd. Backlight control method, backlight module and display apparatus
WO2018097121A1 (fr) * 2016-11-24 2018-05-31 日本精機株式会社 Appareil d'affichage d'images et afficheur tête haute
WO2018123554A1 (fr) * 2016-12-26 2018-07-05 日本精機株式会社 Dispositif d'affichage

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