Projector controller and projection control method

Abstract

This application relates to a projector controller and a projection control method. A projector controller includes an object detector and control electronics and is configured to protect an audience member from intense light imposed by a no-entry zone in front of a projector. The object detector is configured to optically sense a presence of an object in a detection area under the no-entry zone and above the audience member. The control electronics is configured to control the projector when the object detector indicates the presence of the object in the detection area. A method for protecting an audience member from intense light imposed by a no-entry zone in front of an output of a projector includes (i) optically sensing a presence of an object in a detection area between the no-entry zone and the audience member, and (ii) controlling the projector when the presence of the object is sensed in the detection area.

Description

[0001] Related Application

[0002] This application is a divisional application of original Chinese patent application entitled “Projector Controller and Projection Control Method”. The original application has a Chinese application number of 201980042243.2; the original application has a filing date of May 14, 2019.

[0003] Cross Reference to Related Applications

[0004] This application claims priority to U.S. Provisional Application No. 62 / 672,288, filed May 16, 2018, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD

[0005] This application relates to cinema projectors and eye safety. BACKGROUND

[0006] For cinema applications, laser-based digital projectors are gradually replacing lamp-based digital projectors. Depending on the design and implementation, laser-based digital projectors can have several advantages over lamp-based projectors, such as enhanced picture quality, longer lifetime, improved reliability, and lower power draw.

[0007] Lasers can emit light at intensity levels sufficient to cause damage to viewers. For example, permanent eye damage can result from looking into a laser beam. To prevent such harm, lasers are classified according to the damage that they can cause, and their use in commercial products, such as laser-based digital projectors, is regulated accordingly. SUMMARY

[0008] In a first aspect, a projector controller includes an object detector and control electronics, and is configured to protect an audience member from intense light imposed by an exclusion zone in front of a projector. The object detector is configured to optically sense a presence of an object in a detection region under the exclusion zone and above the audience member. The control electronics is configured to control the projector when the object detector indicates the presence of the object in the detection region.

[0009] In a second aspect, a method for protecting an audience member from intense light imposed by an exclusion zone in front of an output of a projector is disclosed. The method includes optically sensing a presence of an object in a detection region between the exclusion zone and the audience member. The method also includes controlling the projector when the presence of the object is sensed in the detection region. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a side view of a theater showing removed seats under a danger zone at the output of a projector.

[0011] Figure 2 is a perspective view of a theater in an embodiment in which a high intensity projector has a projector controller communicatively coupled thereto.

[0012] Figure 3A is Figure 2 a side view of a projector controller and a projector of Figure 3B and 3C are example top views thereof in respective embodiments.

[0013] Figure 4 is Figure 2 a side view of a no-entry zone within illumination emitted by a high intensity projector of Figure 2

[0014] Figure 5 and 6 are each a cross-sectional view of a no-entry zone of Figure 4

[0015] Figure 7 is a schematic diagram of a projector controller configured in an embodiment to control a projector of Figure 2

[0016] Figure 8 is a functional block diagram of a projector controller based on time-of-flight measurements in an embodiment.

[0017] Figure 9 is a functional block diagram of a projector controlled based on optical phase shift ranging in an embodiment.

[0018] Figure 10 is an example plot of azimuth angle versus time of a laser beam of Figure 8 when using a beam steering mechanism of Figures 7 to 9

[0019] Figure 11 is an example plot of output signal versus time of an object detector of Figure 8 when detecting two objects using a beam steering mechanism of Figures 7 to 9

[0020] Figure 12 is a functional block diagram of a projector controller based on position sensitive detection using a single detector array in an embodiment.

[0021] Figure 13 is a functional block diagram of a projector controller based on position sensitive detection using two detector arrays in an embodiment.​​​​​

[0022] Figure 14 is a side view of a first optical relay configured in an embodiment to redirect projector illumination from a projector of Figure 2 .

[0023] Figure 15 is a side view of a second optical relay configured in an embodiment to redirect projector illumination from a projector of Figure 2 .

[0024] Figure 16 is a side view of a partially reflective optical relay configured in an embodiment to redirect projector illumination from a projector of Figure 2 .

[0025] Figure 17 is a side view of a theater of Figure 1 supplemented by a projector.

[0026] Figure 18 is a flowchart illustrating a method in an embodiment for protecting audience members from intense light imposed by an exclusion zone in front of a projector. DETAILED DESCRIPTION

[0027] Figure 1 is a side view of a projector 180 in a projection booth 192 of a theater 190. The projector 180 emits screen illumination 182 onto a screen 195. The screen illumination 182 includes an exclusion zone 184 in which the intensity exceeds an eye safety threshold. The projector 180 can produce screen illumination 182 with an intensity greater than illumination produced by a conventional projector having a corresponding conventional exclusion zone 124 that is less than the exclusion zone 184. The exclusion zone 184 thus extends over an area of the theater 190 that would otherwise accommodate theater patrons if the theater 190 were equipped with a projector having a lower luminance than the projector 180. To prevent injury to the eyes of theater patrons in the event that they happen to look toward the projector 180 from within the exclusion zone 184, a seatless zone 197 can be enforced below the exclusion zone 184 so that patrons’ seats are limited to rows 196 that are not below the exclusion zone 184. In the example shown in Figure 1 , the audience members 198 seated in row 196(1) are farther from the projector than the seatless zone 197.

[0028] Figure 2is a perspective view of theater 190, where projector controller 200 is communicatively coupled to projector 280, which is an instance of projector 180. Coordinate system 201 represents directions x, y, and z. Screen 195 can be parallel to the x-y plane, and the z direction can correspond to the optical axis of the lens of projector 280. Screen 195 is located at a screen distance 195D from projector 280, as measured in a plane parallel to the x-z plane. References herein, and unless otherwise stated, to a direction or plane represented by at least one of x, y, or z refer to coordinate system 201. Projector 280 can be located in projection booth 192.

[0029] Projector 280 includes light source 281. Projector 280 projects at least a portion of the light generated by light source 281 as screen illumination 282 toward screen 195, which is an instance of screen illumination 182. Light source 281 can include at least one laser that results in exclusion zone 184 that is larger than conventional exclusion zone 124. For example, exclusion zone 184 extends over several rows 193, whereas conventional exclusion zone 124 does not.

[0030] One way to remedy the increased risk associated with exclusion zone 184 is to provide seatless area 197 underneath exclusion zone 184. However, the introduction of seatless area 197 reduces the seating capacity of theater 190, and thus its revenue potential. Projector controller 200 provides an alternative means for maintaining seating capacity while protecting customers from high intensity projector illumination.

[0031] Projector controller 200 monitors detection area 286 for the presence of an object. Detection area 286 extends at least underneath exclusion zone 184, such that an object (e.g., a head of a theater customer) moving from a row 193 toward exclusion zone 184 is detected by projector controller 200 before reaching exclusion zone 184. Projector controller 200 is configured to control projector 280 when the presence of an object in detection area 286 is detected. Projector controller 200 can turn off or reduce screen illumination 282 in response to detecting the presence of an object in detection area 286.

[0032] Projector controller 200 can be positioned at different locations relative to projector 280. Figure 3A is a schematic side view of projector controller 200 positioned directly underneath projector 280, which can correspond to Figure 3B andthe relative positioning of projector controller 200 and projector 280 in either of the plan views of 3C Figure 3B is a plan view of projector controller 200 positioned directly underneath projector 280. Figure 3Cis a plan view of the theater 190 positioned below but laterally offset from the projector 280.

[0033] The theater 190 includes a sidewall 291. At least a portion of the projector controller 200 can be positioned such that it is not below the projector 280. For example, the optical receiver of the projector controller 200 can be closer to the sidewall 291 than to the projector 280.

[0034] Figure 4 is a side view of the theater 190 in a plane parallel to the y-z plane of the coordinate system 201. Figure 4 indicates the plane of the cross-sections 5 and 6 which are orthogonal to Figure 4 . Figure 5 is a view of the screen illumination 282 in the cross-section plane 5 parallel to the x-y plane. Figure 6 is a view of the theater 190 in the cross-section plane 6 parallel to the x-z plane. While the projector 280 and the projector controller 200 need not be located in the cross-section plane 6, they are included in Figure 6 for illustrative purposes. Together Figure 2 and 4 6 are best viewed in the following description.

[0035] Figure 5 and 6 illustrate the exclusion zone 184 in a plane parallel to the x-y plane and the z-x plane, respectively. Figure 5 The exclusion zone 184 is illustrated as having a smaller height (y-direction) than the screen illumination 282 and a smaller width (x-direction) than it. The exclusion zone 184 can have the same height as the screen illumination 282 and / or the same width as it.

[0036] The projector controller 200 is communicatively coupled to the projector 280 and includes an object detector 210 and control electronics 220. Without departing from the scope of embodiments of the present invention, at least a portion of the projector controller 200, such as the object detector 210 and / or the control electronics 220, can be integrated into the projector 280 or included with the projector, the combination being a projector system. The object detector 210 and the control electronics 220 can be collected in a common housing, for example, or can be spatially separated while communicatively connected through wired and / or wireless communication channels.

[0037] The object detector 210 is configured to optically sense the presence of an object in a detection region 286 that can be at least partially located below the exclusion zone 184 and above the audience member 198, as illustrated in Figure 2 and 4 For example, the audience member 198 is located Figure 2As illustrated in line 193, the restricted area 184 may be located above additional audience members (e.g., those audience members whose seats are adjacent to audience member 198 in line 193).

[0038] In a plane parallel to the xz plane, the detection region 286 may occupy the region directly below at least a portion of the forbidden zone 184. For example, the detection region 286 may occupy the region directly below the forbidden zone 184 between z... min With z max The region at z-values ​​between 1 and 2 is represented as Figure 6 In the middle. min The location corresponds to the minimum human reachable distance of 280 from the projector. max The position can correspond to the far end of the no-entry zone 184 in the positive z direction.

[0039] The detection area 286 can be defined by the beam 230 emitted by the object detector 210. Figure 4 The illustration illustrates object 413, for example, the hand or head of audience member 198. When object 413 is within detection area 286, it reflects a portion of the beam 230, which can be detected by projection controller 200.

[0040] The beam 230 may have a divergence angle 230D or a corresponding scanning range between the lower boundary 230L and the upper boundary 230U, the definition of which is as follows: Figure 4 The depression angle range in the yz plane. Beam 230 can traverse the xz plane by having a wide divergence angle and / or by performing a time-varying scan in the xz plane. Figure 6 The diagram illustrates the azimuth interval 661. The divergence angle 230D (in the yz plane) and the azimuth interval 661 (in the xz plane) define the detection area 286. In the xz plane, the screen illumination 282 can cross or span the azimuth interval 282D. The azimuth interval 661 can be less than or equal to the azimuth interval 282D.

[0041] The distant end of the no-entry zone 184, located in a direction parallel to beam 230 and within the reference object detector 210, is situated at a distance of no-entry range 287 from the object detector 210. For example, the no-entry range 287 may be between one and two meters or up to ten meters. At the distant end of the no-entry zone 184, located at a distance of no-entry range 287 from the projector 280, the intensity of the screen illumination 282 may be between 30 milliwatts per square centimeter and 40 milliwatts per square centimeter.

[0042] To prevent the projector controller 200 from detecting the scattered portion of the screen illumination 282, the light beams 230 can include electromagnetic wavelengths that are not included in the screen illumination 282. For example, the light beams 230 can include only electromagnetic wavelengths that are not included in the screen illumination 282. For example, the light beams 230 can have a spectral content that includes infrared light and does not include visible light, which provides the additional benefit that it is not visible to the audience members 198. The infrared light can have a wavelength between 0.8 microns and 1.2 microns. For example, the object detector 210 can include a laser diode that emits light having a spectral peak at λ = 905 nm.

[0043] The plane 560 intersects the projector 280 and is parallel to the y-z plane, as shown in Figure 5 and 6 The plane 560 can include or be parallel to a plane that includes the optical axis of the projection lens of the projector 280. The plane 560 can also be parallel to the y-z plane, which can be perpendicular to the screen 195. In the x-z plane, the exclusion zone 184 has an angular extent across an azimuthal interval 661.

[0044] The control electronics 220 are configured to control the projector 280 when the object detector 210 indicates that an object 413 is present at least partially in the detection region 286. The object detector 210 can emit a plurality of light beams 230, which can be arranged vertically (in the y-direction) to enable the object detector 210 to determine the extent of the object 413 in the exclusion zone 184.

[0045] The object 413 is located at an object angle 662 with respect to the plane 560, as shown in Figure 6 The object 413 is located at an object distance 664 from the projector controller 200, which determines an azimuthal angle 663 that the object 413 subtends. The subtended azimuthal angle 663 is the difference between an upper bound angle 663U and a lower bound angle 663L measured with respect to the plane 560. The control electronics 220 can be configured to measure at least one of the object angle 662, the subtended azimuthal angle 663, and the object distance 664. The object angle 662 has a corresponding vertex 662V. For example, the vertex 662V is located at the focal point of the projection lens of the projector 280.

[0046] Figure 5FIG. illustrates a no-go zone 184 that includes a region 502 having a horizontal position 562 and a width 504 determined by an object angle 662 and a subtended azimuth angle 663, respectively. The object angle 662 determines the horizontal position 562. The horizontal position 562 can be defined and / or measured with respect to a plane 560. The control electronics 220 can be configured to control the projector 280 by reducing an intensity of a screen illumination 282 projected by the projector 280. This intensity reduction can include at least one of the following operations: deactivating the light source 281, turning off an output of the projector 280 so that a high light point of an output image cannot be produced, and limiting a maximum intensity of the output image or the screen illumination 282. For example, a high light point of an output image is a high intensity region, such as a specular reflection off a surface in the image, direct sunlight, a glowing object, a region that is significantly brighter than other regions, or the like.

[0047] Limiting the maximum intensity can include globally limiting the intensity of the screen illumination 282 or limiting the intensity of only one or more regions (e.g., the region 502) of the screen illumination 282. The output image can be formed from the screen illumination 282; for example, the content of the output image is determined by video data received by the projector 280.

[0048] The control electronics 220 can reduce the screen illumination 282 at a selected propagation angle. For example, the control electronics 220 can reduce the screen illumination 282 in the projection direction between the angles 663L and 663U so that the screen illumination 282 in the region 502 is dim compared to other regions of the no-go zone 184. The degree to which the screen illumination 282 in the region 502 is attenuated by the control electronics 220 can depend on the object distance 664. For example, the degree of attenuation can monotonically increase as the object distance 664 decreases to ensure that the attenuation is sufficient to reduce the intensity of the screen illumination 282 at the object distance 664 below an eye damage threshold.

[0049] The control electronics 220 can attenuate the screen illumination 282 in only a portion of the region 502, such as a lower section 503 corresponding to a vertical position (x-direction) of the object 413 relative to the detection region 286. The projector controller 200 can have this functionality when it emits a plurality of light beams 230 that are arranged in the x-direction.

[0050] Figure 6A scanning light beam 630 emitted by certain embodiments of the projector controller 200 is also illustrated. The light beam 630 is an example of the light beam 230 and propagates at a propagation angle 632 with respect to the plane 560. The projector controller 200 can be configured to cause the light beam 630 to scan such that the propagation angle 632 traverses the azimuthal interval 661 at a distance 286H below the keep-out zone 184. For example, when the size of the keep-out zone 184 varies over time according to the time-dependent intensity of the screen illumination 282, the scan can be periodic with a scan frequency that exceeds the frame rate of the projector 280. For example, the distance 286H is between zero and 50 centimeters.

[0051] In one implementation, the projector controller 200 causes the light beam 630 to scan to sequentially traverse the azimuthal interval 661 at a number of different distances 286H below the keep-out zone 184. This implementation can allow determining the vertical position (x-direction) of the object 413 with respect to the detection region 286 and thus allow attenuating the screen illumination 282 in only a portion of the region 502, e.g., a lower section 503 corresponding to the vertical position of the object 413. In another implementation, the projector controller 200 causes a plurality of light beams 630 to scan to each traverse the azimuthal interval 661 at a different respective distance 286H below the keep-out zone 184. This implementation can also allow determining the vertical position (x-direction) of the object 413 with respect to the detection region 286 and thus allow attenuating the screen illumination 282 in only a portion of the region 502, e.g., a lower section 503 corresponding to the vertical position of the object 413. In one embodiment, the azimuthal interval 661 exceeds the azimuthal interval 282D. For example, the projector controller 200 can include a test object 613 located outside the azimuthal interval 282D enabling monitoring in real-time whether the projector controller 200 is functioning properly. For example, the test object 613 is a diffuse reflector and can be mounted on a side wall 291 of the theater 190 as illustrated in FIG. 6B. The test object 613 can be positioned at a fixed location corresponding to a particular value of the propagation angle 632, i.e., a value outside the azimuthal interval 282D, such that the projector controller 200 can distinguish whether the light detected by the object detector 210 corresponds to light reflected by the object 413 or the test object 613. Figure 6

[0052] Figure 7 is a schematic diagram of a projector controller 700 configured to control a projector 280 operating in a theater 190 including an object 413. The projector controller 700 is an example of the projector controller 200 of FIG. 6A and includes an object detector 710 and control electronics 720, which are examples of the object detector 210 and the control electronics 220, respectively. Figure 2 ​​

[0053] Object detector 710 includes light source 712, optical receiver 714, and positioning electronics 716. Light source 712 can be a laser and can include an infrared light source, and is configured, for example, to operate in at least one of a pulsed mode of operation or a continuous wave mode of operation. Optical receiver 714 can include at least one of a silicon photodiode, an avalanche photodiode, a photomultiplier tube, and a multi-photon pixel counter. Positioning electronics 716 can include at least one of signal conditioning electronics (also referred to as a signal conditioner), a transimpedance amplifier, a time-difference circuit, a lock-in amplifier, and an analog-to-digital converter.

[0054] Distance 286H can depend on the response time of optical receiver 714, which in one embodiment is 100 ± 50 ms. For example, the minimum value of distance 286H is determined by the speed at which object 413 crosses beam 630. The quotient of distance 286H and this speed corresponds to a time interval. This time interval can exceed the response time of receiver 714, so that projector controller 700 has sufficient time to change screen illumination 282 before object 413 reaches screen illumination 282.

[0055] Light source 712 is configured to emit beam 630, a portion of which is reflected or scattered by object 413 as scattered light 735. Scattered light 735 includes scattered light 736 that propagates toward optical receiver 714. Optical receiver 714 is configured to receive at least a portion of scattered light 735, e.g., scattered light 736. Positioning electronics 716 is configured to receive the output of optical receiver 714 and generate signal 738 that indicates the presence of scattered light 736 at optical receiver 714. Signal 738 can indicate Figure 6 at least one of the following angles shown in FIG. 6B: the subtended azimuth angle 663, the upper bound angle 663U, and the lower bound angle 663L.

[0056] Object detector 710 can include optical filter 715 located in front of optical receiver 714 to prevent detection of stray light that is not reflected by object 413. Optical filter 715 can be configured to block light at the wavelength of screen illumination 282. In one example, optical filter 715 transmits infrared light and blocks visible light. Optical filter 715 can be an edge filter or a bandpass filter that transmits only one or more wavelength ranges emitted by light source 712 and / or blocks other wavelength ranges or screen illumination 282.

[0057] The control electronics 720 can include at least one of a processor 722 and a memory 750 communicatively coupled thereto. The memory 750 can be transitory and / or non-transitory and can include one or both of a volatile memory (e.g., SRAM, DRAM, compute RAM, other volatile memory, or any combination thereof) and a non-volatile memory (e.g., FLASH, ROM, magnetic media, optical media, other non-volatile memory, or any combination thereof). A portion or all of the memory 750 can be integrated into the processor 722. The memory 750 can store at least one of the exclusion zone 287 and software 752.

[0058] The object detector 710 can include a beam manipulator 740 configured to scan the light beam 630 across the azimuthal interval 661 at a beam scan rate via changing the propagation angle 632. The beam manipulator 740 can include at least one of a rotating polygon mirror, a scanning galvanometer mirror, and a MEMS mirror array. The control electronics 720 can be communicatively coupled to the beam manipulator 740 and configured to at least one of (a) control or determine the time dependence of the propagation angle 632, (b) determine the value of the propagation angle 632 corresponding to the time at which the optical receiver 714 receives the scattered light 736, and (c) measure the object angle 662, e.g., via machine-readable instructions of the software 752.

[0059] Figure 8 is a functional block diagram of a projector controller 800, which is an example of the projector controller 700. The projector controller 800 includes an object detector 810 and control electronics 820. The object detector 810 is an example of the object detector 710 and includes the optical receiver 714, the localization electronics 816, a laser 812, and the beam manipulator 740. The localization electronics 816 is an example of the localization electronics 716 and includes a time difference circuit 817. The time difference circuit 817 can be or include a time-to-digital converter. The laser 812 is an example of the light source 712 and can be considered a Class 1 laser as defined by the American National Standards Institute. The control electronics 820 is an example of the control electronics 720 and stores a memory 850, which is an example of the memory 750. The memory 850 includes software 852, which is an example of the software 752.

[0060] The software 852 of the memory 850 can store at least one of the exclusion zone 287, the propagation angle 632, the scan configuration 742, the range estimator 854, the distance comparator 856, the scan director 857, the direction estimator 858, and the angle map 842. The range estimator 854 can generate at least one of the time of flight 882 and the object distance 664. The distance comparator 856, the scan director 857, and the direction estimator 858 can generate and / or determine, respectively, the hazard indicator 866, the angle control signal 867, and the object angle 662. The scan director 857 can generate the angle control signal 867 based on the scan configuration 742, which can include at least one of a sweep frequency and a sweep magnitude. The scan configuration 742 can be stored in a memory of the beam steerer 740.

[0061] In an example scenario, the object 413 is located within a field of view of the optical receiver 714 and at the object angle 662 relative to the plane 860. The plane 860 is an example of the plane 560 of Figure 5 and 6 Thus, the plane 860 can include an optical axis of the projector 280 communicatively coupled to the projector controller 800.

[0062] In operation, the laser 812 is configured to emit the optical pulse 830 and generate the start pulse 831 to be received by the time difference circuit 817. The generation of the start pulse 831 can be simultaneous with the emission of the optical pulse 830 or offset in time by a known value. In an example, the start pulse 831 is a pulse of light. Figure 8 In an example, the optical pulse 830 has an associated propagation angle 632 that the beam steerer 740 varies over time such that the propagation angle 632 traverses an azimuthal interval 661 of the exclusion zone 184 of Figure 6 In an example, the optical pulse 830 has an associated propagation angle 632 that the beam steerer 740 varies over time such that the propagation angle 632 traverses an azimuthal interval 661 of the exclusion zone 184 of Figure 8 The propagation angle 632 is illustrated to result in the optical pulse 830 being incident on the object 413. The object 413 reflects the optical pulse 830 as a scattered pulse 835 including a scattered pulse 836, at least a portion of which propagates toward the optical receiver 714. The optical pulse 830 is an example of the light beam 630. The scattered pulses 835 and 836 are examples of the scattered light 735 and 736, respectively.

[0063] The propagation angle 632 has a corresponding vertex 632V. For example, the vertex 632V is located on or proximate to a last optical surface of the beam steerer 740 that manipulates the optical pulse 830, e.g., via reflection or refraction, before the optical pulse 830 exits the beam steerer 740.

[0064] Upon detecting the scattered pulse 836, the optical receiver 714 can generate a stop pulse 837 to be received by the time difference circuit 817. Based on the start pulse 831 and the stop pulse 837, the localization electronics 816 generate, e.g., via the time difference circuit 817, a time-of-flight signal 838 to be received by the control electronics 820. The range estimator 854 processes the time-of-flight signal 838 to determine at least one of a time-of-flight 882 of the scattered pulse 836 and an object distance 664 between the object 413 and the optical receiver 714. Each of the time-of-flight 882 and the object distance 664 can be stored in the memory 850. The time-of-flight signal 838 is an example of the signal 738. Figure 7

[0065] The control electronics 820 can be configured to control the projector 280 by reducing the intensity of the screen illumination 282 based on the measured time-of-flight 882. For example, the control electronics 820 can be configured to reduce at least a spatial region, e.g., the region 502, of the screen illumination 282 when the time-of-flight 882 corresponds to an object distance 664 that is less than the exclusion range 287. The software 852 can include a distance comparator 856 that outputs a hazard indicator 866 when the object distance 664 is less than the exclusion range 287. Accordingly, the control electronics 820 can be configured to control the projector 280 by reducing the intensity of the screen illumination 282 based on a value of the hazard indicator 866.

[0066] The control electronics 820 can also be configured to determine a value of the object angle 662 from the scattered pulse 836. For example, the beam manipulator 740 can be configured to continuously transmit updated values of the propagation angle 632 to the control electronics 820. Further, the control electronics 820 can transmit an angle control signal 867 to the beam manipulator 740, which controls the propagation angle 632 at any given time.

[0067] The control electronics 820 can determine the object angle 662 based on a clock time corresponding to the stop pulse 837. For example, when the vertex of the propagation angle 632 and the vertex 662V of the object angle 662 are aligned in the x-z plane, the object angle 662 can be equal to a value of the propagation angle 632 corresponding to a time associated with the generation of the stop pulse 837.

[0068] ​More broadly, when this alignment is not applicable, the propagation angle 632 can be mapped to the object angle 662 via angle mapping 842. For example, angle mapping 842 is a lookup table or function that maps the range of possible propagation angles 632 to the corresponding measured object angle 662 based on the relative positions of vertices 662V and 632V in the xz plane. For example, at least one of plane geometry and trigonometry can be used to map the propagation angle 632 to the corresponding object angle 662 (or object angle 662).

[0069] Therefore, the control electronics 820 can be configured to control the projector 280 by reducing the intensity of the screen illumination 282 based on the value of the object angle 662 determined by the orientation estimator 858. For example, in response to the detection of an object 413 in the detection area 286 ( Figure 5 and 6 The intensity of screen illumination 282 can be reduced in the angular region centered on object angle 662, which causes at least a portion of region 502 to darken temporarily.

[0070] Figure 9 This is a functional block diagram of object detector 910, which is an example of object detector 710. Object detector 910 includes a light source 912, an optical receiver 714, and positioning electronics 916. Light source 912 and positioning electronics 916 are examples of light source 712 and positioning electronics 716, respectively. For example, light source 912 is a laser. Positioning electronics 916 may include at least one of phase detector 952, oscillator 953, and low-pass filter 954, each of which may be part of lock-in amplifier 950. Phase detector 952 may include at least one demodulator.

[0071] The light source 912 is configured to emit amplitude-modulated sensing light 930 at a modulation frequency 953F. For example, the oscillator 953 drives the light source 912 with an oscillator signal 953S, causing the light source 912 to emit amplitude-modulated sensing light 930.

[0072] Object 413 causes the amplitude-modulated sensing light 930 to be reflected as amplitude-modulated scattered light 935. The amplitude-modulated scattered light 935 has a group velocity v. g The modulation frequency 953F corresponds to the time period T, making the product v g T is more than Figure 2 The screen distance is 195D. This configuration achieves a precise match between the peak amplitude of the amplitude-modulated sensing light 930 and its reflected component in the amplitude-modulated scattered light 935 detected by the optical receiver 714.

[0073] The amplitude-modulated scattered light 935 is phase-delayed relative to the amplitude-modulated sensing light 930 by a phase Δφ. The optical receiver 714 generates a signal 937 in response to detecting the amplitude-modulated scattered light 935. The positioning electronics 916 receives the signals 953s and 937 and determines the phase Δφ from them, e.g., via a phase detector 952, and generates a phase signal 938 that includes the phase Δφ. The phase signal 938 is Figure 7 an example of the signal 738.

[0074] The control electronics 720 can receive the phase signal 938 and determine at least one of the object distance 664 and the hazard indicator 866 from it. Thus, the control electronics 720 can be configured to control the projector 280 by reducing the intensity of the screen illumination 282 based on the value of the hazard indicator 866. The object detector 910 can include the beam manipulator 740 and can be configured to communicate with the control electronics 720 to determine the object angle 662, as explained with respect to Figure 8 .

[0075] Figure 10 is a plot showing the time dependence of the azimuth angle 1032 between the start time 1010 and the end time 1019. Figure 11 is a plot showing the time dependence of the optical receiver signal 1138 between the start time 1010 and the end time 1019. Together, the Figure 10 and 11 are best viewed in the following description. The azimuth angle 1032 is an example of the propagation angle 632. The optical receiver signal 1138 is an example of the signal 738. Figure 7 .

[0076] Figure 10 Each value of the azimuth angle 1032 within the azimuth angle interval 1061 is generated by the projector controller 200 of Figure 6 . The values of the azimuth angle 1032 span the azimuth angle interval 1061, which is an example of the azimuth angle interval 661. The optical receiver signal 1138 includes pulses 1101 and 1102. The pulse 1101 has a duration 1121 between times 1011 and 1012. The pulse 1102 has a duration 1122 between times 1013 and 1014.

[0077] The pulses 1101 and 1102 correspond to at least a portion of the object 413 entering the detection region 286, e.g., as explained with respect to Figure 4The case when the object 413 is a head of a person facing the projector 280. Since the object 413 can be a head of a person facing the projector 280, preventing eye damage requires the projector controller 200 to reduce the intensity of the screen illumination 282 at the object angle 662 corresponding to the azimuth angle 1032 at times corresponding to the pulses 1101 and 1102. Figure 10 These corresponding azimuth angles are denoted as angle ranges 1001 and 1002, which correspond to the pulses 1101 and 1102, respectively.

[0078] The propagation angle 632 can be equal to an angle within the angle ranges 1001 and 1002. The direction estimator 858 can determine that the object angle 662 spans an interval of the propagation angle of the light beam 630, which corresponds to at least one of the angle ranges 1001 and 1002 according to the angle mapping 842.

[0079] Figure 12 is a schematic block diagram of a projector controller 1200, which is an example of the projector controller 200 of Figure 2 is a schematic block diagram of a projector controller 1200, which is an example of the projector controller 200 of The projector controller 1200 includes an object detector 1210 and control electronics 1220, which are examples of the object detector 210 and the control electronics 220, respectively. The projector controller 1200 is configured to determine both the object angle 662 and the object distance 664 based on position-sensitive detection of scattered light. The projector controller 1200 does not require either the time-of-flight or phase detection techniques of the object detectors 810 and 910 or their associated projector controller 700.

[0080] The object detector 1210 includes the light source 712, the beam manipulator 740, and an optical receiver 1214, which is an example of the optical receiver 714. The optical receiver 1214 includes a position-sensitive detector 1270 and a lens 1218. The position-sensitive detector 1270 has a width 1271 and can include a plurality of photodetectors arranged in an x-z plane. Examples of the position-sensitive detector 1270 include commercially available multi-element photodiode arrays and multi-channel array photodetectors, such as those configured to detect infrared light. The lens 1218 has an optical axis 1218A, which can be normal to a front surface 1270F of the position-sensitive detector 1270. In the x-z plane, the optical axis 1218A intersects the plane 560 at a receiver angle 1219. The optical receiver 1214 generates a receiver signal 1279 indicative of an electrical response of the position-sensitive detector 1270 to scattered light incident thereon.

[0081] The beam manipulator 740 is separated from the optical receiver 1214 by a distance 1272 in the x-dimension in a direction 1261. For simplicity of explanation, the direction 1261 is perpendicular to the plane 560 in the following discussion. However, the direction 1261 can be at an oblique angle with respect to the plane 560 without departing from the scope of the application. The lens 1218 is oriented so that its optical axis 1218A is oriented at a receiver angle 1219C with respect to the direction 1261. The angles 1219 and 1219C are complementary angles.

[0082] The distance 1272 can be many times larger than a width 1271 of the position sensitive detector 1270. For example, the width 1271 can be less than 10 centimeters and the distance 1272 can be more than two meters. The distance 1272 can be large enough so that the optical receiver 1214 can be mounted on a side wall 291 of a theater 190 while the beam manipulator 740 is located below and / or directly below the projector 280. Figure 2

[0083] The beam manipulator 740 is configured to manipulate the light beam 630 emitted by the light source 712 so that the light beam 630 propagates at a propagation angle 632 with respect to the plane 560. In the example of FIG. 12, the light beam 630 reflects off of a surface 1241 of the beam manipulator 740. For example, the surface 1241 is a planar reflective surface of a rotating polygon mirror, a scanning galvanometer mirror, or a MEMS mirror array. The light beam 630 propagates at the propagation angle 632 with respect to the plane 560 and at an angle 1238 with respect to the direction 1261. In this example, the angles 1238 and 632 are complementary angles. Figure 12

[0084] The light beam 630 scatters off of the object 413 as scattered light 735. The scattered light 735 propagates toward the optical receiver 1214 is characterized by a chief ray 1236 with respect to the optical receiver 1214. The chief ray 1236 is an example of the scattered light 736. The chief ray 1236 differs from the propagation direction of the light beam 630 by an angle 1205. Upon reaching the optical receiver 1214, the chief ray 1236 immediately impinges on the lens 1218 at an incidence angle 1237 with respect to the optical axis 1218A. The sum of the angles 1237 and 1219C is a compound angle 1273. The angle 1238 and the propagation angle 632 are complementary angles. The sum of the angles 1238, 1273, and 1205 is π radians.

[0085] ​​The lens 1218 transmits the chief ray 1236 incident thereon and refracts the scattered light 735 onto the position sensitive detector 1270 at a position thereon determined by the angle of incidence 1237. Thus, the receiver signal 1279 can be processed, e.g., by the control electronics 720, to determine the angle of incidence 1237. The position sensitive detector 1270 enables determination of the object distance 664 in terms of at least one of the distance 1272, the angle 1205, the angle 1237, and the angle 1238, e.g., via trigonometric relationships, such as the law of sines.

[0086] The control electronics 1220 can include at least one of a processor 722 and a memory 1250 communicatively coupled thereto. The hardware properties of the memory 1250 are similar to those of the memory 750. The memory 1250 can store inputs 1251, software 1252, and outputs 1253.

[0087] The inputs 1251 include at least one of the scan configuration 742, the propagation angle 632, the angle map 842, the receiver calibration 1278, the receiver signal 1279, the distance 1272, the receiver angle 1219, and the exclusion range 287. The memory 1250 can receive the propagation angle 632 from the beam manipulator 740 or from the angle control signal 867. The memory 1250 can receive the receiver signal 1279 from the optical receiver 1214. The receiver calibration 1278 can include a mapping of positions of light detected by the position sensitive detector 1270 to the angle of incidence 1237.

[0088] The software 1252 includes a scan director 857, a direction estimator 858, and a distance comparator 856, each of which is described above with reference to the software 852 of Figure 8 The software 1252 also includes a direction estimator 1258 and a range estimator 1254.

[0089] The processor 722 executes the software 1252 to generate the outputs 1253 in dependence on the inputs 1251. The scan director 857 generates the angle control signal 867 in dependence on the scan configuration 742. The control electronics 1220 can control the beam manipulator 740 via the angle control signal 867. The direction estimator 858 generates the object angle 662 in dependence on at least one of the propagation angle 632, the angle map 842, and the angle control signal 867. The direction estimator 1258 generates the composite angle 1273 in dependence on the receiver signal 1279 and the receiver angle 1219.

[0090] The range estimator 1254 determines the object distance 664 from the distance 1272, the object angle 662, and the composite angle 1273. For example, the range estimator 1254 can employ the sine theorem to determine the object distance 664 from the angle 1238, the composite angle 1273, and the distance 1272, where the angle 1238 and 632 are complementary angles. The distance comparator 856 can generate the hazard indicator 866 when the object distance 664 is less than the exclusion zone 287.

[0091] In various embodiments, an object detector (e.g., object detector 1210) can be designed to detect objects in a hazard zone based on invisible infrared signals. The invisible infrared light can be emitted by, for example, one or more infrared lasers. In addition to or instead of infrared light detection, a visible light source with power at a safety level can also enter the hazard zone as a warning illumination for body parts or objects. When a person violates safety rules and enters the hazard zone or places an object into the hazard zone, the visible light reminds the person to move outside the hazard zone or remove the object from the hazard zone.

[0092] For example, in a theater, a red laser can be used to create a plane of red light (or any other color) above the head height of the audience as a warning device. In some embodiments, the red light can be disposed at the same (or slightly above or below) plane as the infrared light. When a body part or object extends across the plane of the infrared light, the red light can be turned on as a warning.

[0093] Figure 13 is a functional block diagram of a projector controller 1300 that is based on position sensitive detection with two detector arrays. The projector controller 1300 is an example of the projector controller 200 and includes an object detector 1310 and control electronics 1320.

[0094] The object detector 1310 includes a light source 1312, the optical receiver 1214, and a second optical receiver 1314. The second optical receiver 1314 is similar to the optical receiver 1214 and includes a position sensitive detector 1370 and a lens 1318 that are similar to the position sensitive detector 1270 and the lens 1218, respectively. The second optical receiver 1314 can be the same as the optical receiver 1214. The lens 1318 has an optical axis 1318A that is similar to the optical axis 1218A.

[0095] The control electronics 1320 can include at least one of the processor 722 and a memory 1350 communicatively coupled thereto. The hardware properties of the memory 1350 are similar to those of the memory 750. The memory 1350 can store inputs 1351, software 1352, and outputs 1353.

[0096] Light source 1312 is configured to emit a diverging beam 1330 that propagates in the x-z plane and is an instance of light beam 230. Diverging beam 1330 has a beam divergence angle 1331 that can span an azimuthal interval 661 of Figure 6 Light source 1312 is separated from second optical receiver 1314 in the x-direction by a distance 1372 in a direction 1261. The sum of distances 1272 and 1372 is a distance 1377, which can be included in input 1351. Figure 13 Projector controller 1300 is depicted behind an object 413 that intersects a portion of diverging beam 1330 that propagates at a propagation angle 632 relative to plane 560.

[0097] As in Figure 12 Optical receiver 1214 is oriented relative to plane 560 at a receiver angle 1219 that is complementary to angle 1219C (not shown in Figure 13 Second optical receiver 1314 is oriented relative to plane 560 at a receiver angle that is complementary to angle 1319C between optical axis 1318A and direction 1261. Input 1351 can include at least one of angles 1219C and 1319C or equivalently their respective complements. Input 1351 can also include a receiver calibration 1378 similar to receiver calibration 1278.

[0098] In an exemplary use scenario, a portion of diverging beam 1330 is scattered off object 413 as scattered light 735. Scattered light 735 propagates toward optical receivers 1214 and 1314 are characterized by respective chief rays 1236 and 1336 relative to optical receivers 1214 and 1314, respectively. Chief ray 1336 is an instance of scattered light 736 and forms an object angle 1373 relative to direction 1261. Optical receivers 1214 and 1314 produce respective receiver signals 1279 and 1379 indicative of electrical responses of position sensitive detectors 1270 and 1370 to respective chief rays 1236 and 1336 incident thereon. Input 1351 can include at least one of receiver signals 1279 and 1379.

[0099] Propagation directions of chief rays 1236 and 1336 differ by an angle 1305. Upon reaching optical receiver 1214, chief ray 1236 is incident on lens 1218 at an incidence angle 1237 relative to optical axis 1218A. Upon reaching second optical receiver 1314, chief ray 1336 is incident on lens 1218 at an incidence angle 1337 relative to optical axis 1318A. The sum of angles 1373 and 1337 is angle 1319C. The sum of angles 1273, 1373, and 1305 is π radians.

[0100] Lens 1318 transmits the chief ray 1336 incident thereupon and refracts the scattered light 735 onto position sensitive detector 1370 at a position thereupon determined by the angle of incidence 1337. Receiver signal 1379 can be processed, e.g., by control electronics 1320, to determine the angle of incidence 1337. Position sensitive detector 1270 enables determination of object distance 664 in terms of at least one of distance 1272, angle 1205, angle 1237, and angle 1238, e.g., via trigonometric relationships, such as the law of sines.

[0101] Processor 722 executes software 1352 to generate output 1353 in terms of input 1351. Software 1352 can include direction estimator 1354 that determines (a) angle of incidence 1237 in terms of receiver signal 1279 and receiver calibration 1278 and (b) angle of incidence 1337 in terms of receiver signal 1379 and receiver calibration 1378. Software 1352 can include direction estimator 1355 that determines (a) compound angle 1273 in terms of angle of incidence 1237 and receiver angle 1219C and (b) object angle 1373 in terms of angle of incidence 1337 and receiver angle 1319C. For example, object angle 1373 is equal to receiver angle 1319C minus angle of incidence 1337.

[0102] Software 1352 can include range estimator 1357, direction estimator 1358, and object angle estimator 1359. Range estimator 1357 determines object distance 664. For example, range estimator 1357 employs the law of sines to determine at least one of distance D 12 between object 413 and position sensitive detector 1270 and distance D 13 between object 413 and position sensitive detector 1370, from which the law of cosines can be employed to determine object distance 664. Direction estimator 1358 can determine propagation angle 632 by using the law of sines, distance D 12 , object distance 664, and angle 1273 to determine angle 1238 and its complement (propagation angle 632). Object angle estimator 1359 can determine object angle 662 in terms of propagation angle 632 and angle map 842.

[0103] Figure 14is a side view of a projector 280 operating in a theater 190, where an optical relay 1400 is configured to redirect screen illumination 282 (as redirected illumination 1482) away from a seat 196 and toward a screen 195 in order to increase a distance between the seat 196 and a no-entry zone 1484, which is an instance of the no-entry zone 184. At least a portion of the optical relay 1400 can be located in a projection booth 192. A portion of the optical relay 1400 can extend outside of the projection booth 192. The optical relay 1400 can include at least one of a mirror, a relay lens, a relay imaging system, a relay lens assembly, and an optical filter. The optical relay 1400 has an associated relay length corresponding to a distance that light propagates therein. The relay length can be between 1 meter and 10 meters.

[0104] Figure 15 is a side view of a projector 280 operating in a theater 190, where an optical relay 1500 is configured to redirect screen illumination 282 (as redirected illumination 1582) away from a seat 196 and toward a screen 195 in order to increase a distance between the seat 196 and a no-entry zone 1584, which is an instance of the no-entry zone 184. The optical relay 1500 is an instance of the optical relay 1400 and can include a periscope configured to redirect projector illumination away from the seat 196 and toward the screen 195.

[0105] Each of the optical relays 1400 and 1500 can include a partially reflective mirror. Figure 16 is a side view of a projector 280 operating in a theater 190, where an optical relay 1400 is configured to redirect screen illumination 282 (as redirected illumination 1482) away from a seat 196 and toward a screen 195 in order to increase a distance between the seat 196 and a no-entry zone 1484, which is an instance of the no-entry zone 184. At least a portion of the optical relay 1400 can be located in a projection booth 192. A portion of the optical relay 1400 can extend outside of the projection booth 192. The optical relay 1400 can include at least one of a mirror, a relay lens, a relay imaging system, a relay lens assembly, and an optical filter. The optical relay 1400 has an associated relay length corresponding to a distance that light propagates therein. The relay length can be between 1 meter and 10 meters.

[0106] Partially-reflective optical relay 1600 can be configured to vertically separate redirected illumination 1682 from transmitted illumination 282T by, e.g., a separation between mirrors 1610 and 1620 by a distance 1602. For example, distance 1602 is between 1 centimeter and 1 meter. In an embodiment, partially-reflective optical relay 1600 is configured to vertically and / or horizontally separate redirected illumination 1682 from transmitted illumination 282T, e.g., by a separation between mirrors 1610 and 1620.

[0107] Figure 16 Region corresponding to where redirected illumination 1682 and transmitted illumination 282T overlap is illustrated as a no-go zone 1684. In the absence of optical relay 1600, no-go zone 1684 would extend downward toward seat 196, and thus pose a hazard to an audience member 198 seated below. One benefit of optical relay 1600 is to enhance eye safety even when distance 1602 is sufficiently short (and / or has a component parallel to the x-direction) that no-go zone 1684 extends below the eye level of a viewer 198 when standing. Because redirected illumination 1682 and transmitted illumination 282T are spatially offset, the respective high-intensity regions of redirected illumination 1682 and transmitted illumination 282T are also spatially offset. Thus, when projector 280 is projecting a non-uniform intensity image, the effective maximum intensity incident on a viewer's eye is reduced due to the spatial offset introduced by optical relay 1600.

[0108] Optical relay 1600 can also vertically separate redirected illumination 1682 from transmitted illumination 282T so that no-go zone 284 is sufficiently above the eye level of a standing viewer (e.g., any viewer 198 standing below no-go zone 284). Distance 1602 can be determined at least in part by this eye level of a standing viewer (e.g., a viewer whose height exceeds a predetermined percentile of heights). In this embodiment, the optical intensity of redirected illumination 1682 can exceed that of transmitted illumination 282T.

[0109] Figure 17 is a side view of theater 190 configured with both projector 180 and a supplemental projector 1780. For example, supplemental projector 1780 is projector 280. Supplemental projector 1780 can be located outside of projection booth 192 and configured to emit projector illumination 1782. The addition of supplemental projector 1780 enables the reproduction of high-quality images (similar to those reproduced by high-intensity (e.g., laser-based) projectors) while maintaining the small no-go zone associated with low-intensity (e.g., non-laser) projectors.

[0110] The projector illumination 1782 can correspond to the same video data as the screen illumination 182 and be time synchronized with the screen illumination 182. Alternatively, the projector illumination 1782 can be complementary to the screen illumination 182, e.g., by including graphical overlay images and / or video (e.g., high light spots). The supplemental projector 1780 can be aligned so that the projector illumination 1782 aligns with the screen illumination 182 on the screen 195.

[0111] Figure 18 is a flowchart illustrating a method 1800 for protecting audience members from intense light emitted from a projector, which imposes a keep-out zone in front of the projector. The method 1800 can be implemented by the projection controller 200 and instances thereof described herein. The method 1800 includes at least one of steps 1810 and 1820.

[0112] Step 1810 includes optically sensing a presence of an object in a detection region between the keep-out zone and an audience member. In an instance of step 1810, the object detector 210 detects the object 413 in the detection region 286 between the keep-out zone 184 and the audience member 198. Step 1810 can include at least one of steps 1812, 1816, and 1818. Step 1812 can include step 1813, in which case step 1818 can also include step 1819.

[0113] Step 1812 includes emitting a sensing light at an elevation angle interval and within an azimuth angle interval, the elevation angle interval and the azimuth angle interval defining a detection region. In an instance of step 1812, the object detector 210 emits the light beam 230 at a fixed elevation angle interval and within the azimuth angle interval 282D, where the lower bound 230L and the upper bound 230U define the elevation angle interval. Step 1813 includes beam scanning the sensing light across the azimuth angle interval at a beam scan rate. In an instance of step 1813, the beam manipulator 740 scans the light beam 630 across the azimuth angle interval 661 at a beam scan rate that exceeds a frame rate of the projector 280.

[0114] Step 1816 includes receiving scattered light generated by the sensing light scattered from the object. In an instance of step 1816, the optical receiver 714 receives the scattered light 736 scattered by the object 413.

[0115] Step 1818 includes outputting an electrical signal indicative of a presence of the scattered light. Step 1819 includes outputting an electrical signal indicative of an azimuth angle range at which the object in the detection region is oriented. In an instance of step 1818, the object detector 710 outputs the signal 738. Figure 7

[0116] ​Step 1820 includes controlling the projector when the presence of an object is sensed in the detection region. In the example of step 1820, projector controller 200 controls projector 280 when object detector 210 detects an object 413 in detection region 286 and under or in exclusion zone 184. Step 1822 includes reducing the intensity of light projected by the projector. In the example of step 1822, projector controller 200 reduces the intensity of screen illumination 282. When step 1818 includes step 1819, step 1822 can include step 1823, which includes reducing the intensity of light projected by the projector in the azimuthal range of step 1819. In the example of step 1823, projector controller 700 reduces the intensity of screen illumination 282 in azimuthal range 663.

[0117] Changes can be made in the above methods and systems without departing from the scope of the application. Accordingly, it should be noted that the objects herein contained in the above description or shown in the drawings should be construed as illustrative only and not as limiting in any way. The adjective "exemplary" in this document means serving as an example, instance, or illustration. The appended claims are intended to cover all the features described herein, and all statements of the scope of the application methods and systems, which, and languages, may be argued to be between the method and system statements.

Claims

1. A projector controller for protecting an audience member from intense light imposed by a keep-out zone in front of a projector, the projector controller comprising: an object detector configured to optically sense a presence of an object in a detection area underneath the keep-out zone, wherein the object detector includes: a light source configured to emit a sensing light at an elevation angle interval and in an azimuth angle interval, the elevation angle interval and the azimuth angle interval defining the detection area; an optical receiver configured to receive a scattered light generated by the sensing light scattered off the object; and positioning electronics configured to receive an output of the optical receiver and generate a signal indicative of a presence of the scattered light on the optical receiver; and a beam steering assembly configured to scan the sensing light across the azimuth angle interval at a beam scanning rate higher than a frame rate of the projector; and control electronics configured to control the projector in response to the object detector indicating a presence of the object in the detection area.

2. The projector controller of claim 1, the controlling the projector comprising at least one of: deactivating a light source within the projector; turning off an output of the projector; deactivating a production of a highlight point of an output image projected by the projector; and limiting a maximum intensity of the output image.

3. The projector controller of claim 1, the object detector further configured to measure an angle subtended by the object in the detection area, the control electronics configured to reduce an intensity of light projected by the projector in a projection direction corresponding to the angle.

4. The projector controller of claim 1, the object detector further configured to measure position information of the object in the detection area, the control electronics configured to reduce an intensity of light projected by the projector in a projection direction corresponding to the position information.

5. The projector controller of claim 1, the object detector operating at a wavelength not emitted by the projector.

6. The projector controller of claim 1, wherein the positioning electronics are configured to determine a distance between the projector controller and the object in the detection area.

7. The projector controller of claim 1, the beam steering assembly selected from a group consisting of a rotating polygon mirror, a scanning galvanometer mirror, and a MEMS mirror array.

8. The projector controller of claim 6, wherein the control electronics are configured to increase a degree of attenuation of an intensity of light projected by the projector as the distance decreases.

9. The projector controller of claim 1, the object detector configured to measure an azimuth angle range subtended by the object in the detection area.

10. The projector controller of claim 9, the control electronics configured to control the projector by reducing an intensity of light projected by the projector in the azimuth angle range.

11. The projector controller of claim 1, the localization electronics configured to measure an azimuth angle at which the object is sensed in the detection region within the azimuth angle interval.

12. The projector controller of claim 11, the control electronics configured to control the projector by reducing an intensity of light projected by the projector at the azimuth angle.

13. The projector controller of claim 1, the light source comprising an infrared light source or a visible light source.

14. The projector controller of claim 1, the optical receiver comprising one of a silicon photodiode, an avalanche photodiode, a photomultiplier tube, and a multi-photon pixel counter.

15. The projector controller of claim 1, further comprising an optical filter positioned in front of the optical receiver, and the optical filter configured to block light at a wavelength emitted by the projector.

16. The projector controller of claim 1, the light source comprising a pulsed laser that emits pulsed sensing light, the localization electronics configured to measure a time of flight between the pulsed sensing light and pulsed scattered light originating from the pulsed sensing light scattering off the object.

17. The projector controller of claim 16, the control electronics configured to control the projector by reducing an intensity of light projected by the projector based on the measured time of flight.

18. The projector controller of claim 1, the light source configured to emit amplitude modulated sensing light that produces amplitude modulated scattered light, the localization electronics configured to measure a phase delay between the amplitude modulated sensing light and the amplitude modulated scattered light.

19. The projector controller of claim 18, the localization electronics configured to derive a distance between the light source and the object in the detection region from the phase delay by phase sensitive detection at a modulation frequency of the amplitude modulated sensing light.

20. The projector controller of claim 18, the light source configured to emit the sensing light at a wavelength not emitted by the projector.

21. The projector controller of claim 1, the optical receiver comprising a position sensitive detector and a lens assembly positioned and oriented to measure a position of the scattered light on the position sensitive detector.

22. The projector controller of claim 21, the position sensitive detector comprising an array of photodetectors.

23. The projector controller of claim 21, the localization electronics configured to process the position of the scattered light on the position sensitive detector to triangulate position information of the object, the position information comprising at least an azimuth angle of the object in the detection region within the azimuth angle interval.

24. The projector controller of claim 23, the control electronics configured to dim an output of the projector in a direction determined by the azimuth angle.

25. A projector system, comprising: A projector controller according to claim 1; and The projector.

26. A method for protecting an audience member from light emitted by a projector, comprising: optically sensing a presence of an object in a detection region between an exclusion zone and the audience member, the exclusion zone being above the audience member and within the emitted light; and controlling the projector when the presence of the object is sensed in the detection region, wherein optically sensing the presence of the object comprises: emitting a sensing light at a depression angle interval and within an azimuth angle interval, the depression angle interval and the azimuth angle interval defining the detection region, wherein emitting the sensing light comprises scanning the sensing light across the azimuth angle interval at a beam scan rate that is higher than a frame rate of the projector; receiving scattered light produced by the sensing light scattered off the object; and outputting an electrical signal indicative of a presence of the scattered light.

27. The method of claim 26, wherein controlling the projector comprises: determining a distance between a projector controller and the object in the detection region; and increasing a degree of attenuation of an intensity of light projected by the projector as the distance decreases.

28. The method of claim 27, optically sensing further comprises outputting an electrical signal indicative of an azimuth angle range subtended by the object in the detection region.

29. The method of claim 28, controlling the projector further comprises decreasing an intensity of light projected by the projector within the azimuth angle range.

Images