JP2007065542A - Image projection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate and project an image which a viewer visually recognize in the same size, independently of a distance between the viewer and a screen on the basis of resolutions which the viewer can discriminate. <P>SOLUTION: A projector 1 includes; a zoom lens 162; a distance information acquisition part 52 for acquiring distance information between a viewer 80 viewing an image projected on a screen SC and the screen SC; a resolution determination part 54 for determining a display resolution based on a maximum resolution which the viewer can visually discriminate, on the basis of the distance information; and a projection lens control means 66 for driving a focus position of an optical system of the zoom lens 162 to project the image with the display resolution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image projection apparatus that projects and displays an image.

Conventionally, the display means of an image display device that displays an image has a resolution determined by the number of pixels constituting a display device such as a liquid crystal panel or a plasma display panel, and always displays an image with the same resolution regardless of the distance to the viewer. It was displayed.
In addition, the apparatus described in Patent Document 1 below enlarges the display image when the distance between the viewer and the display unit increases, and when the distance between the viewer and the display unit decreases, By reducing the display image and displaying it, the apparent resolution of the image viewed by the viewer is kept constant.

JP 2000-276123 A

  However, the above-described apparatus maintains the apparent resolution of the image viewed by the viewer without changing the size of the display screen composed of the pixels constituting the display means. Cannot display a part of Therefore, there arises a problem that the viewer cannot see all the information of the input image data. Further, due to the reduction of the display image, an area in which no image is displayed is generated in the peripheral portion of the display screen. Therefore, the viewer felt unnaturalness with respect to the displayed image.

In order to solve the above-described problems, an image projection apparatus according to the present invention is an image projection apparatus that projects an image generated based on a video signal onto a projection target, and changes the display resolution of the projected image. The viewer visually identifies the lens based on the distance information, a distance information acquisition unit that acquires distance information between the viewer who sees the image projected on the projection object and the projection object, and the distance information acquisition unit. A resolution determining unit that determines the display resolution based on the maximum possible resolution, and a projection lens control unit that controls the projection lens to project the image at the display resolution.
According to the present invention, the image projection apparatus projects an image with a display resolution based on the maximum resolution that can be identified by the viewer according to the distance between the viewer and the projection target. A visually suitable image can be visually recognized regardless of the position. Further, since the display resolution of the projected image is smoothly changed by the projection lens, the overall size of the image can be changed with a natural feeling against a change in the position of the viewer.

In the image projection apparatus according to the aspect of the invention, it is preferable that the resolution determination unit determines the resolution based on the maximum resolution at which a product with a distance indicated by the distance information is constant.
According to the present invention, the resolution determination unit can determine an appropriate resolution according to the distance between the viewer who sees the projected image and the projection object.

In the image projection apparatus of the present invention, the resolution determination unit determines the maximum resolution when determining the maximum resolution.
Y x Z = k
Y: distance between the projection object and the viewer (unit: centimeter)
Z: Maximum resolution (unit: PPI [number of pixels per inch])
k: constant (when the viewer's visual acuity is 1.0, 2.54 / tan (1/60 degrees))
It may be determined based on the arithmetic expression shown by

The image projection apparatus according to the aspect of the invention preferably further includes a projection light amount control unit that keeps the brightness of the projected image substantially constant by changing the light amount to be projected according to the display resolution.
According to the present invention, the image projection apparatus can keep the brightness of the projected image constant regardless of the display resolution.

In the image projection apparatus according to the aspect of the invention, it is preferable that the resolution determination unit includes a correction unit.
According to the present invention, the image projection apparatus can correct the display resolution.

  In the image projection apparatus of the present invention, the distance information acquisition unit may acquire the distance information based on a signal emitted from a remote controller to instruct the image projection apparatus.

Hereinafter, an embodiment of the present invention will be described using a liquid crystal light valve projector 1 as an example of an image projection apparatus.
(Embodiment)

(Hardware configuration)
FIG. 1 is a diagram illustrating a hardware configuration of the projector 1. The projector 1 includes a CPU (Central Processing Unit) 30, a ROM (Read Only Memory) 28, a RAM (Random Access Memory) 26, a video decoder 12, a video processor 14, an image memory 10, and a light valve drive. A circuit 16, a lamp control circuit 18, a zoom lens driving circuit 20, a distance detection circuit 22, an angle detection circuit 24, and an input I / F (Interface) 32 are provided. These hardware are connected to each other by a bus 34 so that each signal can be exchanged.

  The CPU 30 reads various programs and data such as a basic control program stored in the ROM 28, develops and executes these various programs and data in a main memory area provided in the RAM 26, and controls each unit included in the projector 1. Execute.

  The input I / F 32 is an interface for inputting a signal of the receiving circuit 42 that receives an operation signal superimposed on light, a sound wave, or the like transmitted from the operation remote controller 44 and an image signal input to the image signal input terminal 40. is there.

  The video decoder 12 performs A / D conversion on the analog image signal input to the image signal input terminal 40 and converts the analog image signal into a digital image signal that can be input to the video processor 14. In addition, the video processor 14 receives the digital image signal input from the image signal input terminal 40 or the digital image signal converted by the video decoder 12 and executes various image processing. By this image processing, for example, each pixel of a digital image is decomposed into red, green, and blue color light, and an image signal is generated for each color light, or a trapezoidal distortion (keystone generated in a projected image) ) Is removed. Furthermore, the image memory 10 is a memory for temporarily storing digital image signals in order to perform these image processes.

  The light valve driving circuit 16 supplies a driving voltage to each pixel constituting the liquid crystal light valve 140 for each color light according to the image signal for each color light generated by the video processor 14. Details of the liquid crystal light valve 140 will be described later.

  The lamp control circuit 18 adjusts the illuminance of the projected image by controlling the power supplied to the light source 111.

  The zoom lens driving circuit 20 drives the lens moving unit 164 of the zoom lens 162. The zoom lens 162 will be described later.

  The distance detection circuit 22 receives the electrical signal output from the in-focus position detection unit 166 of the zoom lens 162 and the electrical signal output from the distance sensor 48, and detects information related to the distance. For example, the distance sensor 48 is installed in the projector 1 and has a light receiving unit (not shown). The distance sensor 48 is connected to the projector 1 depending on the position, intensity, etc., of light emitted from the operation remote controller 44. Then, an electric signal including distance information with respect to the viewer 80 (FIG. 4A) who operates the operation remote controller 44 is output. The distance sensor 48 is not limited to a method using light, and a method using ultrasonic waves, radio waves, or the like can also be employed.

  The angle detection circuit 24 detects information related to the angle from the electrical signal output from the angle sensor 46. For example, the angle sensor 46 is installed in the projector 1 and outputs an electrical signal including angle information between the projector 1 and the viewer 80 based on a signal from the operation remote controller 44 described above. Further, the operation remote controller 44 may be provided with position detection means such as GPS (Global Positioning System), and may be detected from position information included in the instruction signal issued from the operation remote controller 44.

  Although the details will be described later, the distance sensor 48 and the angle sensor 46 are installed to detect the viewing distance Y (FIG. 4A) between the screen SC and the viewer 80. For example, It can be assumed that the angle sensor 46 and the angle detection circuit 24 are not provided by installing the distance sensor 48 near the screen SC and receiving the electric signal from the distance sensor 48 by the projector 1. In addition, the distance sensor 48 and the angle sensor 46 may be integrated. For example, the screen SC and the viewer 80 are taken in an overhead view with an image pickup device such as a CCD (Charge Coupled Device), and image processing is performed. The viewing distance described above may be calculated as follows.

(Configuration of optical system)
FIG. 2 is a configuration diagram for explaining the configuration of the optical system of the projector 1, and shows the optical path from the light emitted from the light source to the screen. As shown in FIG. 2, the optical device 100 includes an illumination optical system 110, a projection image generation unit 170, and a projection optical system 160.

  The illumination optical system 110 includes a light source 111, a first lens array 112, a second lens array 113, a polarization conversion element 114, and a superimposing lens 115, and a light bundle emitted from the light source 111 is The minute lenses 112a are divided into a large number of minute light bundles by the first lens array 112 arranged in a matrix. The second lens array 113 and the superimposing lens 115 are provided such that each of the divided light bundles irradiates the entire three liquid crystal light valves 140R, 140G, and 140B that are illumination targets. For this reason, the light beams are superimposed by the liquid crystal light valves 140R, 140G, and 140B, and the entire liquid crystal light valves 140R, 140G, and 140B are irradiated almost uniformly. The illuminance of the light beam emitted from the light source 111 is increased or decreased according to an instruction from the projection light amount control unit 60 (FIG. 3).

  The polarization conversion element 114 has a function of aligning light having a specific polarization direction so that non-polarized light from the light source 111 can be efficiently used by the liquid crystal light valves 140R, 140G, and 140B. The light emitted from the illumination optical system 110 enters the color light separation optical system 120.

  The projection image generation unit 170 includes a color light separation optical system 120, a relay optical system 130, three liquid crystal light valves 140R, 140G, and 140B as light modulation devices, and a cross dichroic prism 150. The projection image generation unit 170 generates an optical image based on the image signal input from the image signal generation unit 70 (FIG. 3) in a projectable manner.

  The color light separation optical system 120 separates the light emitted from the illumination optical system 110 into light of three colors having different wavelength ranges. The first dichroic mirror 121 transmits substantially red light and reflects light having a shorter wavelength than the transmitted light. The red light R transmitted through the first dichroic mirror 121 is reflected by the reflection mirror 122 and irradiates the liquid crystal light valve 140R for red light.

  Of the light reflected by the first dichroic mirror 121, the green light G is reflected by the second dichroic mirror 123 and irradiates the liquid crystal light valve 140G for green light. Further, the blue light B passes through the second dichroic mirror 123, passes through the relay optical system 130, and irradiates the blue light liquid crystal light valve 140B.

  Since the path of the blue light B is longer than the paths of the other color lights, the path of the blue light B is suppressed in order to suppress a decrease in illumination efficiency to the liquid crystal light valve 140B due to the divergence of the light beam. Is provided with a relay optical system 130.

  The relay optical system 130 includes an incident side lens 131, a first reflection mirror 132, a relay lens 133, a second reflection mirror 134, and an emission side lens 135. The blue light B emitted from the color light separation optical system 120 is converged in the vicinity of the relay lens 133 by the incident side lens 131 and diverges toward the emission side lens 135.

  Each of the liquid crystal light valves 140R, 140G, and 140B includes a liquid crystal panel 141, an incident-side polarizing plate 142, and an emitting-side polarizing plate 143, and modulates incident light to form an image (optical image). .

  An incident side polarization plate 142 and an emission side polarization plate 143 are attached to the incident side surface and the emission side surface of the liquid crystal panel 141, respectively. The incident side polarizing plate 142 and the exit side polarizing plate 143 can transmit only light polarized in a specific direction, respectively, and the incident side polarizing plate 142 can transmit light polarized in the direction aligned by the polarization conversion element 114. It is said. For this reason, most of each color light incident on the liquid crystal light valves 140R, 140G, and 140B is transmitted through the incident-side polarizing plate 142 and incident on the liquid crystal panel 141.

  Here, when a driving voltage corresponding to an image signal is applied to each pixel of the liquid crystal panel 141, the light incident on the pixel region of the liquid crystal panel 141 is modulated according to the driving voltage, and the polarization direction differs for each pixel. It becomes light with. Of this light, only the polarization component that can be transmitted through the emission-side polarizing plate 143 is emitted from the liquid crystal light valves 140R, 140G, and 140B. That is, the liquid crystal light valves 140R, 140G, and 140B transmit incident light with different transmittances for each pixel according to the image signal, so that an optical image having a gradation is formed for each color light. Optical images made up of the respective color lights emitted from the liquid crystal light valves 140R, 140G, and 140B are incident on the cross dichroic prism 150.

  The cross dichroic prism 150 combines the optical images of the respective colors emitted from the liquid crystal light valves 140R, 140G, and 140B for each pixel to form an optical image representing a color image. The optical image synthesized by the cross dichroic prism 150 enters the projection optical system 160.

  The projection optical system 160 displays the projection image on the screen SC or the like by enlarging and projecting the incident optical image. In the present embodiment, the zoom lens 162 is applied to the projection optical system 160. In the zoom lens 162, for example, a first predetermined lens constituting the optical system moves in accordance with the driving of the lens moving unit 164 including a linear actuator. As a result, the focal position of the constituent optical system moves while keeping the image formation position on the same plane, and the display resolution indicating the size of the image projected by the zoom lens 162 varies according to this movement. . As a method for moving such a predetermined lens, an optical correction type in which the predetermined lens moves as a unit, or a mechanical correction type in which the predetermined lens moves in cooperation with each other can be applied.

  In addition, when the image projected on the screen SC is focused, the amount of movement of the second predetermined lens corresponds to the distance to the screen SC. The detecting means 166 detects the distance to the screen SC based on the moving amount of the lens. The zoom lens 162 is not limited to the method of moving these predetermined lenses internally, and a method of changing the focal position by continuously changing the thickness of the lens can also be applied.

(Functional configuration)
FIG. 3 is a functional block diagram showing a functional configuration of the projector 1. The projector 1 includes an operation signal input unit 50, a distance information acquisition unit 52, a resolution determination unit 54, a visual acuity input unit 58, a projection light amount control unit 60, a projection distance detection unit 64, and a projection lens control unit 66. A video signal processing unit 68, an image signal generation unit 70, and a video signal input unit 72. These functional units are realized by organic cooperation between the hardware resources and software described above.

  The operation signal input unit 50 inputs a signal transmitted from the operation remote controller 44 and transfers the input signal to each function unit.

  The video signal processing unit 68 generates a digital image signal composed of time-series continuous image frames from the video signal input from the video signal input unit 72. The generated signal is sent to the image signal generator 70.

  The image signal generation unit 70 generates a projectable image signal from the digital image signal input from the video signal processing unit 68. The generated signal is sent to the projection image generation unit 170 of the optical device 100.

  The projection distance detection unit 64 calculates the distance between the projector 1 and the screen SC based on the focus position detected by the focus position detection unit 166. Information on the calculated distance is sent to the distance information acquisition unit 52.

  The distance information acquisition unit 52 acquires distance information between the viewer 80 who views the image projected on the screen SC and the screen SC. Specifically, the distance information acquisition unit 52 acquires distance information between the projector 1 and the viewer 80 detected by the distance sensor 48 and angle information formed by the projector 1 and the viewer 80 detected by the angle sensor 46. At the same time, by obtaining the distance information between the projector 1 and the screen SC output from the projection distance detector 64, the calculation is performed using the information, and the distance between the screen SC and the viewer 80, that is, the screen SC is calculated. The viewing distance Y of the viewing viewer 80 is calculated. Information on the calculated viewing distance Y is sent to the resolution determination unit 54.

  The resolution determination unit 54 determines the display resolution of the image projected by the projector 1 based on the viewing distance Y sent from the distance information acquisition unit 52. Here, the relationship between the display resolution of the image to be projected and the viewing distance suitable for this resolution will be described.

It is known that the resolution of the human eye is 60 [pixel / degree] when the visual acuity is 1.0. Here, assuming that the display resolution of the projected image is Z [ppi] (ppi is the number of pixels per inch), the relationship between the optimal viewing distance Y0 [cm] for humans and the display resolution of the projected image From the trigonometric theorem, it can be expressed as a relational expression in which the product of both is constant as in the following equation.
Y0 × Z = k “Expression 1”
However, k is a constant and k = 2.54 / tan (1/60 degrees).

Further, from the above equation, the maximum resolution Z0 [ppi] that can be identified by a human can be obtained for an arbitrary viewing distance Y. Furthermore, if the viewing distance of the viewer 80 with respect to the screen SC is Y [cm] and the current screen size is W [cm] × H [cm], the optimum screen size PW [cm] to maintain this maximum resolution Z0. XPH [cm] can be expressed by the following equation.
PW = W × Y / Y0 “Equation 2”
PH = H × Y / Y0 “Equation 3”

  In the present embodiment, the number of pixels of the liquid crystal panel 141 to be projected is 1920 [pixel] × 1080 [pixel], and FIG. 5 corresponds to the viewing distance Y using “Expression 1” to “Expression 3”. The relationship between the maximum resolution Z0 and the optimum screen size PW × PH is shown.

  As described above, the resolution determination unit 54 calculates the value of the maximum resolution Z0 at the viewing distance Y and then considers the ability of the zoom lens 162, and is as substantially as possible the screen size PW × PH based on the maximum resolution Z0. A display resolution capable of projecting an image on the screen SC with a suitable size is determined. Information on the determined display resolution is sent to the projection lens control unit 66 and the projection light quantity control unit 60.

  In addition, the resolution determination unit 54 includes visual acuity correction means 56. This visual acuity correction means 56 receives the visual acuity of the viewer 80 itself from the visual acuity input unit 58 and appropriately corrects the value of k described above. Specifically, the value of k is increased or decreased by inputting the eye resolution according to the visual acuity. As a result, the display resolution corresponding to the distance from the viewer 80 is determined in consideration of the visual acuity of the viewer 80. Thus, in determining the display resolution, various correction processes may be performed on the value of the maximum resolution Z0 according to the characteristics of the projector 1 and the installation environment of the projector 1.

  The projection lens control unit 66 drives the lens moving unit 164 of the zoom lens 162 to project at the display resolution sent from the resolution determination unit 54. Specifically, information indicating the relationship between the position of the first predetermined lens of the zoom lens 162 and the display resolution is stored in advance in the ROM 28 or the like, and the projection lens control unit 66 performs the first operation based on this information. 1 determines the position of a predetermined lens and instructs the lens moving means 164 to move to that position.

  When projecting an image with the display resolution sent from the resolution determination unit 54, the projection light amount control unit 60 adjusts the light amount of the light source 111 so that the brightness of the image is constant. Specifically, information indicating the relationship between the display resolution and the set illuminance is stored in advance in the ROM 28 or the like, and the projection light quantity control unit 60 determines the light quantity emitted from the light source 111 based on this information. The lamp control circuit 18 is instructed.

  In the above-described configuration, the change in the size of the display image when the viewer 80 viewing the screen SC moves will be described with reference to FIG. In order to facilitate explanation and understanding, it is assumed that the viewer 80 moves on the optical axis of the projector 1. FIG. 4A shows the positional relationship among the viewer 80, the screen SC, and the projector 1. FIG. 4B shows a projected image on the screen SC at the viewing distance Y1, and FIG. 4C shows a projected image on the screen SC at the viewing distance Y2. First, when viewing the screen SC from the position of the viewer 80A whose viewing distance is Y1, the distance information acquisition unit 52 acquires the viewing distance Y1, and the projection lens control means 66 displays according to the viewing distance Y1. By setting the resolution, a projected image 82A having a width PW1 and a height PH1 is displayed on the screen SC.

  Next, when moving to the position of the viewer 80B, the distance information acquisition unit 52 acquires the viewing distance Y2, and the projection lens control unit 66 sets the display resolution according to the viewing distance Y2. The projection light quantity control unit 60 controls the illuminance of the light source 111 to display a projection image 82B having a width of PW2 and a height of PH2 on the screen SC. As a result, the viewer 80 visually recognizes that the projection image 82A viewed before the movement and the projection image 82B viewed after the movement have the same size and the same brightness. Note that the viewer 80 can set whether to change the display resolution continuously or to change the display resolution intermittently after a certain period of time in a moving state. Further, when the viewer 80 moves in an area other than the optical axis of the projector 1, the same effect as described above is obtained.

(Processing flow)
FIG. 6 is a flowchart showing the flow of processing of the projector 1, and the flow of processing for displaying a moving image on the projector 1 will be described with reference to this figure.

  When the processing by the projector 1 is started, first, the distance information acquisition unit 52 measures the viewing distance of the viewer 80 who looks at the screen SC (step S200).

  Next, the resolution determination unit 54 determines the display resolution of the image to be projected from the viewing distance information (step S205).

  Subsequently, the projection lens control unit 66 drives the zoom lens to set the focal position in order to display at the determined display resolution (step S210).

  Next, the projection light quantity control unit 60 sets the light quantity of an image to be displayed with the determined display resolution (step S215).

  Next, the image frame of the digital image data input to the video signal input unit is read (step S220).

  Next, the read image frame is converted into an optical image by the optical device 100 and projected (step S230).

  Subsequently, the presence / absence of an image frame to be processed is checked (step S235). Here, when there is no image frame to be processed, that is, when the moving image data to be displayed is completed (Yes in step S235), the series of processing is ended.

  On the other hand, when the image frame to be processed remains, that is, when the moving image data to be displayed has not ended (No in step S235), the distance information acquisition unit 52 measures the viewing distance of the viewer 80. (Step S240), it is determined whether or not the position of the viewer 80 has changed (Step S245).

  If there is a change in the position of the viewer 80 (Yes in step S245), the process returns to the step of determining the display resolution of the image to be projected (step S205). On the other hand, if there is no change in the position of the viewer 80 (No in step S245), the process returns to the step of reading the next image frame of the digital image data (step S220).

  Through the above-described processing flow, the viewer 80 can watch a moving image whose size and brightness do not change even when the viewing distance is changed while the projector 1 is projecting the moving image.

As mentioned above, although this invention was demonstrated based on embodiment shown in figure, this invention is not limited to this embodiment, The modification as described below can also be assumed.
(1) The light modulation method of the image projection apparatus 1 is not limited to the method using the transmissive liquid crystal light valve 140, and the light modulation method using LCOS (Liquid Crystal On Silicon) which is a reflective liquid crystal element, or micro A light modulation method using DMD (Digital Micromirror Device) using a mirror may be used.
(2) The direction in which the image is projected is not limited to the front surface of the screen SC, but may be projected from the back surface.

1 is a diagram showing a hardware configuration of a projector according to an embodiment of the invention. FIG. 2 is a configuration diagram for explaining a configuration of an optical system of a projector according to an embodiment of the invention. FIG. 2 is a functional block diagram showing a functional configuration of a projector according to an embodiment of the invention. (A) shows the positional relationship between the viewer, the screen and the projector, (b) shows the projected image on the screen at the viewing distance, and (c) shows the projected image on the screen at the viewing distance. . The figure which shows the relationship between display resolution and the optimal screen size according to viewing distance. 6 is a flowchart showing a process flow of the projector according to the embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Image memory, 12 ... Video decoder, 14 ... Video processor, 16 ... Light valve drive circuit, 18 ... Lamp control circuit, 20 ... Zoom lens drive circuit, 22 ... Distance detection circuit, 24 ... Angle detection circuit , 26 ... RAM, 28 ... ROM, 30 ... CPU, 32 ... input I / F, 34 ... bus, 40 ... image signal input terminal, 42 ... receiving circuit, 44 ... operation remote control, 46 ... angle sensor, 48 ... distance sensor , 50 ... operation signal input unit, 52 ... distance information acquisition unit, 54 ... resolution determination unit, 56 ... visual acuity correction means, 58 ... visual acuity input unit, 60 ... projection light quantity control unit, 64 ... projection distance detection unit, 66 ... projection Lens control means, 68 ... Video signal processing section, 70 ... Image signal generation section, 72 ... Video signal input section, 80 ... Viewer, 82 ... Projected image, 100 ... Optical device, 110 ... Illumination Academic system, 111 ... light source, 112 ... first lens array, 112a ... lens, 113 ... second lens array, 114 ... polarization conversion element, 115 ... superimposed lens, 120 ... colored light separation optical system, 121 ... first Dichroic mirror, 123 ... second dichroic mirror, 130 ... relay optical system, 131 ... incident side lens, 132 ... first reflecting mirror, 133 ... relay lens, 134 ... second reflecting mirror, 135 ... exit side lens, DESCRIPTION OF SYMBOLS 140 ... Liquid crystal light valve, 141 ... Liquid crystal panel, 142 ... Incident side polarizing plate, 143 ... Ejection side polarizing plate, 150 ... Cross dichroic prism, 160 ... Projection optical system, 162 ... Zoom lens, 164 ... Lens moving means, 166 ... In-focus position detection means, 170... Projected image generation unit.

Claims (6)

An image projection apparatus for projecting an image generated based on a video signal onto a projection target,
A projection lens that changes the display resolution of the projected image;
A distance information acquisition unit for acquiring distance information between a viewer who sees an image projected on the projection object and the projection object;
A resolution determining unit that determines the display resolution based on a maximum resolution that the viewer can visually identify based on the distance information;
An image projection apparatus comprising: a projection lens control unit that controls the projection lens to project the image at the display resolution. The image projection apparatus according to claim 1,
The resolution determination unit
An image projection apparatus, wherein the image projection apparatus is determined based on the maximum resolution at which a product of the distance indicated by the distance information is constant. The image projection apparatus according to claim 2,
When determining the maximum resolution, the resolution determination unit
Y x Z = k
Y: distance between the projection object and the viewer (unit: centimeter)
Z: Maximum resolution (unit: PPI [number of pixels per inch])
k: constant (when the viewer's visual acuity is 1.0, 2.54 / tan (1/60 degrees))
An image projection apparatus characterized by being determined based on an arithmetic expression represented by: In the image projection device according to any one of claims 1 to 3,
By changing the amount of light to be projected according to the display resolution,
An image projection apparatus, further comprising: a projection light amount control unit that keeps the brightness of the projected image substantially constant. In the image projection device according to any one of claims 1 to 4,
The resolution determination unit
An image projection apparatus comprising correction means for correcting the display resolution. The image projection device according to any one of claims 1 to 5,
The distance information acquisition unit
The distance information is acquired based on a signal emitted from a remote controller to instruct the image projection apparatus.

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