JP2013251798A - Image projection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection apparatus which can easily improve distortion of a projected image due to a temperature gradient from an incident side to an emitting side in a projection optical system.SOLUTION: An image projection apparatus includes: first temperature detection means which is provided outside an emitting side of a projection optical system for projecting image light modulated by a light modulation element to a screen face when a side toward the screen face of the projection optical system is set to be the emitting side and a side nearer to the light modulation element to an incident side; second temperature detection means disposed inside; acquisition means for acquiring correction image data for correcting distortion of an image projected in accordance with output of the first and second temperature detection means; and input means for inputting data to the light modulation element.

Description

  The present invention relates to an image projection apparatus, and relates to an image projection apparatus that suppresses distortion of a projection image.

  In recent years, projectors have made significant progress in increasing screen size, resolution, and image quality. However, intensifying competition in the market and shortening the product development period have led to the need for inexpensive and simple system construction. Yes. A projector is a device that projects an image displayed on a liquid crystal panel as a light modulation element onto a screen using a projection optical system, and the projection optical system generally has a complex optical system including a plurality of lenses. There are many types of projection optical systems on the market that use wide-angle, standard, and telephoto single-focus lenses, lenses with zoom mechanisms, and interchangeable lenses, and users can zoom in optimally according to the installation environment and usage. Magnification and brightness can be selected.

  On the other hand, as these image projection apparatuses, those in which distortion of projected images is suppressed are desired. In order to realize this, there is a method of adopting an optical system in which lenses are configured in a multi-group and reducing aberrations related to distortion, and an optical system in which the lenses are aspherically processed and aberrations related to distortion are hardly generated with a small number of lenses. Alternatively, there is a method of using an expensive glass material that is less affected by distortion as a lens material. Separately, as a projector that corrects changes in optical performance due to temperature in the projection optical system, the change in focus deviation due to temperature is corrected by moving the lens in or near the projection optical system. An apparatus is known (Patent Document 1).

JP 2008-233550 A

  As a feature of the projector, first, it has a high-output light source for irradiating a liquid crystal panel as a light modulation element. For this reason, in order to suppress the temperature rise inside the projector, the heat generated from the light source is generally cooled by air blown by a fan and exhausted outside the apparatus.

  In addition, the projection optical system in a projector is usually composed of a plurality of lenses. The exit-side lens is in contact with the outside air, while the incident-side lens is exposed to heat from the light source and exhaust air from the fan, and is heated. Susceptible to. In other words, in the projection optical system of the projector, there is a high possibility that a large temperature gradient is generated between the exit-side lens exposed to the outside air and the entrance-side lens disposed in the apparatus. This temperature gradient varies depending on the outside air temperature and projector installation conditions, but due to the temperature gradient, each lens constituting the projection optical system expands and contracts depending on the temperature, and the aberration changes and is projected. The image will be distorted.

  In order to solve this, it is costly to use glass materials and lens barrel materials with excellent temperature characteristics (small thermal expansion), or to tighten the cooling conditions in the equipment so that there is no temperature gradient with the outside air. Become high. In addition, in order to perform temperature compensation of the generated distortion, configuring the projection optical system with a large number of lenses not only increases the cost by using a large number of lenses, but also increases the weight.

  In Patent Document 1, even if the change in focus shift with temperature can be corrected, image distortion with temperature cannot be corrected.

  An object of the present invention is to provide an image projection apparatus that can easily improve distortion of a projected image caused by a temperature gradient between an incident side and an exit side in a projection optical system.

  In order to achieve the above object, a typical configuration of an image projection apparatus according to the present invention is to project a light source, a light modulation element irradiated by the light source, and image light modulated by the light modulation element onto a screen surface. A projection optical system, and a side closer to the screen surface of the projection optical system as an emission side, and a side closer to the light modulation element as an incident side, the emission side of the projection optical system and the projection optical system First temperature detection means provided outside the projector, at least one second temperature detection means provided inside the projection optical system, outputs of the first temperature detection means and the second temperature detection means And obtaining means for obtaining corrected image data for correcting distortion of an image projected in response to the input, and input means for inputting the corrected image data to the light modulation element.

  According to the present invention, distortion of a projected image can be easily improved.

It is sectional drawing of the projection optical system of the projector which concerns on embodiment of this invention. It is explanatory drawing of the color separation / synthesis system of the projector which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a general view of the projector which concerns on embodiment of this invention, (a) is a top view, (b) is the side view seen from one side, (c) is the side view seen from the other side. It is a block diagram which shows the electric circuit structure of the projector which concerns on embodiment of this invention. It is a flowchart of the projector which concerns on embodiment of this invention.

  Hereinafter, the present invention will be described in detail based on illustrated embodiments.

<< First Embodiment >>
(Whole projector)
FIG. 3A is a top view showing a projector as an image projection apparatus according to the present embodiment, and FIGS. 3B and 3C are side views. In FIG. 3A, reference numeral 22 denotes a projection optical system, and 101 denotes a projector main body (image projection apparatus main body). Reference numeral 103 is a power button, 104 is a setting button for automatically adjusting the size and distortion of a projected image, 105 is a button for selecting input of a video signal, and 106 is a plurality of buttons for displaying, selecting, and determining a menu. In FIG. 3B, reference numeral 110 denotes a large exhaust port for exhausting the heat inside the projector, and a fin for adjusting the exhaust direction is attached. From here, the heat generated by the projection lamp and electric circuit in the equipment is exhausted.

  In FIG. 3C, 111 is an analog image data input terminal, 112 is a digital image data input terminal, and 113 is a high-speed data communication terminal for connecting to an image data input / output device such as a camera or an external storage device by wire. . Reference numeral 114 denotes a composite video signal input terminal, 115 denotes an S video signal input terminal, and 116 denotes a terminal for externally outputting an analog audio signal.

(Color separation / synthesis system)
FIG. 2 shows a color separation / synthesis system provided on the incident side of the projection optical system 22 and has a configuration known from Japanese Patent Application Laid-Open No. 2011-154381. White light emitted from a light source (a light source that emits non-polarized light) 1 is reflected by a reflector behind and becomes substantially parallel light 2. White light can be decomposed into three primary colors of red, green, and blue, and each of them is red light (light in the red wavelength region) 2r, green light (light in the green wavelength region) 2g, and blue light (light in the blue wavelength region). ) 2b.

  These lights are aligned by the polarization conversion element 3 into P-polarized light (polarized state in which the electric field vibrates in the paper surface), and become P-polarized red light 4r, P-polarized green light 4g, and P-polarized blue light 4b. Here, the non-polarized light is made to be P-polarized light of all colors (light in the visible light region) by the polarization conversion element 3, but the light of all colors may be S-polarized light. Absent. Alternatively, the polarization direction of one color light may be in a state that is substantially orthogonal to the polarization directions of the other two color lights.

  Further, if the light source is a light source (for example, a laser light source) configured to emit only light having a predetermined polarization direction, the polarization conversion element may be omitted. When a laser light source is used, only a polarizing plate may be arranged, or a light source of a different color from the polarization direction of light emitted from a light source of a certain color among laser light sources corresponding to each of the three colors. The light sources may be arranged so that the polarization directions of the light emitted from the light beams are orthogonal to each other.

  The dichroic mirror 5 has a characteristic of reflecting only the green light component, 4g is reflected, and 4r and 4b are transmitted. The light beams 4r and 4b transmitted through the dichroic mirror 5 are transmitted through the polarizing plate 6 to improve the degree of polarization, and enter the wavelength selective polarization rotation element 7.

  The wavelength-selective polarization rotating element 7 has a characteristic that the polarization direction of the red component is rotated by 90 degrees and the polarization direction of the blue component is not rotated. 4r and 4b transmitted through the wavelength-selective polarization rotating element 7 are S-polarized light. The red light 8r and the P-polarized blue light 8b enter the polarization beam splitter 9.

  8r incident on the polarization beam splitter 9 is reflected by the polarization separation surface 10 and irradiates a reflective liquid crystal panel 11r as an image display element (light modulation element). The reflective liquid crystal panels (11r, 11g, 11b) are turned on (bright display, light is guided to the projection optical system, and light is projected onto the projection surface such as a screen). In the off state (dark display, a state where light is shielded with respect to the projection optical system), the polarization is not rotated.

  Therefore, in the ON state, 8r becomes P-polarized red light 12r and enters the polarization beam splitter 9 again, and because of P-polarization, this time it passes through the polarization separation surface 10 and exits from the polarization beam splitter 9. In the off state, the light is reflected by the polarization separation surface. In some cases, a retardation plate (preferably a quarter-wave plate) is disposed between the polarizing beam splitter and the reflective liquid crystal panel for the purpose of correcting the polarization direction of obliquely incident light. Omits this.

  On the other hand, since 8b is P-polarized light, it passes through the polarization splitting surface 10 and enters the reflective liquid crystal panel 11b. When 11b is in the ON state, 8b becomes S-polarized blue light 12b and again enters the polarization beam splitter 9, and because of S-polarization, it is reflected by the polarization separation surface 10 and exits from the polarization beam splitter 9.

  4 g reflected by the dichroic mirror 5 passes through the polarizing plate 13 to improve the degree of polarization, and then enters the polarization beam splitter 14 and reaches the polarization separation surface 15. 4 g of P-polarized light passes through the polarization separation surface 15 and irradiates the reflective liquid crystal panel 11 g. When 11g is in the ON state, 4g becomes S-polarized green light 12g, which is incident again on the polarization beam splitter 14, and is reflected by the polarization separation surface 15 due to S-polarization, and then exits the polarization beam splitter 14.

  Here, each color light emitted from the polarization beam splitter 14 and directed to the color synthesis element (optical path synthesis element) 19 includes each color light in an ideal on state (each color ideally polarized by 90 degrees in the reflective liquid crystal panel). Light other than (light, image light) 12r, 12g, 12b is also included. That is, components that reduce the contrast of the image, such as leaked light that has leaked to the projection optical system side by the polarizing beam splitter, out of the light that should be guided to the light source side by the polarizing beam splitter through the off-state pixels Is actually included. The component light that lowers the contrast needs to be removed.

  Accordingly, a polarizing plate 16A (functioning as a polarizing plate for at least green light and red light or green light and blue light) 16A is disposed on the exit side of the polarizing beam splitter 14. As a result, the green light 12 g emitted from the polarization beam splitter 14 becomes S-polarized green light 18 g from which unnecessary polarization components have been removed, and enters the color composition element 19.

  Here, the polarizing plate 16A may absorb unnecessary polarized light, or may be configured to guide the reflected light out of the optical path after reflecting the unnecessary polarized light. Further, it may be configured to absorb unnecessary polarized light.

  A wavelength-selective polarization rotation element 17 having a characteristic that the polarization direction of the blue component is rotated by 90 degrees and the polarization direction of the red component is not rotated is disposed on the exit side of the polarization beam splitter 9, and the wavelength-selective polarization rotation is performed. A polarizing plate 16 </ b> B is disposed on the emission side of the element 17. With this configuration, 12r and 12b transmitted through the wavelength-selective polarization rotating element 17 become P-polarized red light 18r and P-polarized blue light 18b and enter the polarizing plate 16B. Then, unnecessary polarization components (here, S-polarized components of red light and blue light) are removed, and then incident on the color composition element 19.

  The color synthesizing surface 20 of the color synthesizing element 19 is a dielectric multilayer G reflective dichroic film, and 18 g is reflected by the color synthesizing surface 20 and 18 r and 18 b are transmitted. The color combining surface 20 combines the optical path of red light, blue light, and the optical path of green light. Regarding the RGB reflection and transmission bands at this time, the reflection wavelength band of the dichroic film is generally wider for S-polarized light than for P-polarized light (the transmission band is wider for P-polarized light than for S-polarized light). In this embodiment, since the green light 18g is S-polarized light and 18r and 18b are P-polarized light, the use bands of the respective colors overlap with each other, and the use efficiency of the colors can be improved.

  The three color lights 18r, 18g, and 18b that have undergone optical path synthesis pass through the color synthesis element 19 through the phase plate (quarter wavelength plate) 21 and include a projection optical system (not limited to a lens, but also a mirror or the like). The image may be projected onto a screen (not shown). Although a front projector is assumed here, of course, a rear projector may be used, so that an image may be projected onto a screen member including a lenticular lens, a Fresnel lens, and the like by the projection optical system 22 described above.

  The phase plate 21 has a phase difference of approximately a quarter wavelength. As a result, the polarization direction of the return light that has once entered the projection optical system 22 via the phase plate 21 and then has been reflected by any transmission surface of the projection optical system 22 and returned to the phase plate is the first phase. The state is rotated by 90 degrees with respect to the polarization direction when entering the plate 21. For this reason, of the green light 18g, for example, the return light reflected and returned by the projection optical system 22 is reflected by the color synthesis element 19 in the state of P-polarized polarized light and enters the polarizing plate 16A. Absorbed by the polarizing plate 16A.

  Similarly, the return lights of 18r and 18b are absorbed by the polarizing plate 16B. That is, the return light reflected and returned by the projection optical system 22 is re-reflected with respect to any color light and is absorbed by the polarizing plate without returning to the projection optical system 22 again. Thereby, it is possible to prevent image degradation (decrease in contrast) on the screen due to light reflection by the projection optical system 22.

(Block diagram of the entire projector)
FIG. 4 is a block diagram showing components such as an electronic circuit, a sensor, an actuator, a lamp, and a power supply built in the projector main body 101 shown in FIG. 3 in terms of electrical signal flow. Reference numeral 201 denotes a one-chip microcomputer for scaling a video signal input from an external video signal output device in an analog or digital format to the resolution of the liquid crystal panel of the projector (hereinafter referred to as a video signal processing microcomputer). .

  When the video signal processing microcomputer 201 detects an input from the analog video input terminal 111 or the digital video input terminal 112, the video signal processing microcomputer 201 decodes the video signal input from the input terminal. Then, resolution conversion (scaling) is performed so that the display sizes of the liquid crystal panels 11r, 11g, and 11b are obtained, and data is sent to the liquid crystal panel driver 213. The liquid crystal panels 11r, 11g, and 11b receive signals from a liquid crystal panel driver 213 as input means for inputting image data, and display an image on the liquid crystal panel. In the present embodiment, the liquid crystal panel is a three-plate type of R, G, and B, and each has a liquid crystal panel driver IC.

  A microcomputer 202 converts image data received from the wired high-speed digital data communication port 113 into a video signal format and outputs the data to the video signal processing microcomputer 201 (hereinafter referred to as a communication control microcomputer). A projector control microcomputer 203 performs the following control. That is, control of the buttons 103 to 106 arranged on the touch panel, cooling fan 214, AC power supply 209, lamp 215, a plurality of temperature sensors 216 mounted inside the projector such as around the lamp, drive control of the projection optical system, etc. To do. In other words, the overall control of the sensors and actuators attached to the projector is performed.

  Here, the detection outputs of the temperature sensors 221 to 224 provided in or near the projection optical system are configured to be input to the video signal processing microcomputer 201 via the projector control microcomputer 203. This will be described in detail later.

  Reference numeral 210 denotes an AF sensor for measuring the distance to the projection surface of the projector. The projector control microcomputer 203 receives a signal from the AF sensor 210, controls the motor driver 212 and drives the focus motor 211 so that the projected image is focused on the screen surface, and appropriately controls the lens unit 217.

  When an instruction for zoom control is issued from the button 106 arranged on the touch panel, the projector control microcomputer 203 controls the motor driver 212 to drive the zoom motor 220 and optimally control the lens unit 217. Reference numerals 221 to 224 denote temperature sensors (temperature detection means) for measuring the temperature inside and outside the projection optical system, and are arranged in each part of the projection optical system as will be described later.

  Reference numeral 216 denotes a temperature sensor attached to the inside of the projector, and the projector control microcomputer detects the temperature in the main body and controls the rotation speed of the cooling fan 214. A control circuit 215 for controlling the light source 1 controls lighting / extinguishing of the lamp. Reference numeral 209 denotes an AC power source for the projector. The projector control microcomputer detects the power source switching of the power button 103 on the touch panel, and the AC power source is turned on / off. Reference numerals 206, 207, and 208 denote volatile or non-volatile memories, which respectively store a program of a connection destination microcomputer or are used as a frame buffer of a projection image.

(Projection optical system)
Next, a sectional view of the projection optical system 22 is shown in FIG. The projection optical system 22 of the present embodiment is a zoom lens, the lenses 301 to 304 are the first group, 305 is the second group, 306 is the third group, 307 and 308 are the fourth group, and 309 to 311 are the fifth group. , 312 constitute the sixth group. At zoom magnification, the second to fifth groups move in the front-rear direction, and the first group and the sixth group are fixed. The first group is a focus group and moves in the front-rear direction during focus adjustment.

  In FIG. 1, reference numerals 221 to 224 denote non-contact temperature sensors (temperature detection means). The temperature sensor should be arranged at a position where the temperature gradient in the projection optical system becomes the largest. In the present embodiment, the lens is disposed on the part exposed to the outside air (221) and the inside of the projection optical system (222), the inside of the projection optical system on the lamp light incident side (223), and the side facing the projector body (224). It is configured.

  That is, the sensor 221 is disposed at the front of the first group, the sensor 222 is in the vicinity of the first group between the first group and the second group, the sensor 223 is in the vicinity of the sixth group between the fifth and sixth groups, and the sensor 224. Is arranged near the lens mount in the projector body. In other words, the sensor 221 is disposed on the side of the projection optical system 22 facing the screen (exit side) and outside the projection optical system 22. The sensor 224 is disposed on the light modulation element side (incident side) of the projection optical system 22 and outside the projection optical system 22.

  In addition, regarding the arrangement position, the temperature of a lens using a glass material in which the temperature change of the physical property value is large in each lens group as compared with others may be measured. Further, in terms of configuration, if the aberration of a part of the lens of the projection optical system is made of a material extremely sensitive to temperature change, the lens may be arranged near the lens. Here, the temperature sensor can measure the temperature of the lens surface in a non-contact manner.

(Image correction data acquisition flowchart)
Next, a flowchart of image correction data acquisition according to the present embodiment is shown in FIG. Here, it is shown that image correction is performed using both information of the temperature gradient between the outside air temperature and the projection optical system, and the temperature gradient between the projector main body side (image projection apparatus main body side) and the projection optical system.

  First, the lens aberration correction function is turned on (S401). The projector reads temperature data (a, b, c, d, respectively) as detection outputs of the temperature sensors 221 to 224 attached to the projection optical system (S402). The sensor 221 as the first temperature detection means reads the temperature a of the portion where the lens is exposed to the outside air, and the sensors 222 and 223 as the second temperature detection means read out the lens temperatures b and c in the projection optical system, respectively. . Further, the sensor 224 as the third temperature detecting means reads the lens temperature d on the projector main body side. The temperature data is taken into the projector control microcomputer (203) and notified to the video signal processing microcomputer (201).

  In the video signal processing microcomputer (201), the aberration correction coefficient of the first group lens is different depending on whether the temperature a of the portion where the first group lens is in contact with the outside air is smaller than a certain threshold Ta (first threshold) or not. The (first aberration correction coefficient) can be selected (S403). If the temperature a is lower than Ta, then the temperature b in the projection optical system of the first lens group is compared with a certain threshold value T1 (second threshold value), and according to the comparison result. An aberration correction coefficient for the first lens group can be selected (S404).

  Here, when the temperature b is smaller than T1, α1 is selected as the aberration correction coefficient to be selected for the aberration correction of the first lens group. Conversely, when b is equal to or larger than T1, β1 is selected as the aberration correction coefficient. (S405).

  On the other hand, when the temperature a is equal to or greater than Ta, the aberration correction coefficient is determined by the same flow. That is, when the temperature b is smaller than a certain threshold value U1 (third threshold value), γ1 is selected as the aberration correction coefficient of the first group. Conversely, when b is equal to or larger than U1, δ1 is selected as the aberration correction coefficient. (S406).

  Further, the aberration correction coefficient of the sixth lens group is selected through the same flow as described above. That is, the video signal processing microcomputer (201) can determine the magnitude relationship between the temperature d on the projector body side of the sixth group lens and a certain threshold value Td, and can select an aberration correction coefficient (S408). Hereinafter, the aberration correction coefficients (α2, β2, γ2, δ2) of the sixth group are compared with the temperature d and the threshold value Td, and the temperature c inside the projection optical system of the sixth group lens and the threshold values T2 and U2. (S408 to S412).

  That is, in the video signal processing microcomputer (201), the external temperature d of the sixth group lens on the projector body side is smaller than a certain threshold value Td (fourth threshold value) or not smaller than a certain threshold value Td (fourth threshold value). An aberration correction coefficient (second aberration correction coefficient) can be selected. If the temperature d is smaller than Td, then the temperature c in the projection optical system of the sixth group lens is judged from the threshold T2 (fifth threshold), and the aberration of the sixth group lens is determined. Make it possible to select a correction factor. Here, when the temperature c is lower than T2, α2 is selected as the aberration correction coefficient selected for the aberration correction of the first lens group. Conversely, if c is equal to or greater than T2, β2 is selected as the aberration correction coefficient (S410).

  On the other hand, when the temperature d is equal to or greater than Td, the aberration correction coefficient is determined in the same flow. That is, when the temperature c is smaller than a certain threshold value U2 (sixth threshold value), γ2 is selected as the aberration correction coefficient of the sixth group. Conversely, when c is equal to or larger than U2, δ2 is selected as the aberration correction coefficient. Selected (S412). In this way, the corrected image data is calculated to correct the distortion of the projected image based on a plurality of temperature data in or near the projection optical system, and the correction value is uniquely determined.

  For example, when the temperature a is smaller than Ta and the temperature b is smaller than T1, the aberration correction coefficient is β1, and when the temperature d is smaller than Td and the temperature c is smaller than T2, the aberration correction coefficient is β2. In this case, the position Z of each pixel whose distortion is corrected as the corrected image data with respect to the position A of each pixel is obtained by calculation using, for example, the following expression.

Z = A + (β1 / 2 + β2 / 2) × A
The corrected image data is input to the liquid crystal panels 11r, 11g, and 11b as light modulation elements by a liquid crystal panel driver 213 as input means. When the projection optical system 22 is a zoom lens and the focal length is variable, the corrected image data is calculated further taking the focal length into consideration.

  In this embodiment, each threshold value is limited for the measurement temperatures a to d for simplicity, but the threshold value may be used when a more complicated aberration correction coefficient is required depending on the physical properties of the lens and the group configuration. It can be handled by increasing the number of conditional branches.

  Based on these aberration correction values, the video signal processing microcomputer 201 predicts in advance each aberration caused by the temperature inside the projection optical system, and performs an aberration correction calculation on the image data to be projected so as to cancel it. (S414). If the correction is turned off, the lens aberration correction calculation ends (S415). On the other hand, if the correction is not turned OFF, the temperature inside or near the projection optical system is acquired again (S402), and the above-described processing is repeated thereafter.

  As described above, even when a temperature change occurs in or near the projection optical system when the projector is turned on or during image projection, a good image with little deterioration due to aberration is projected. It is possible.

(Modification 1)
In the embodiment described above, it has been described that image correction is performed using both the temperature gradient between the outside air temperature and the projection optical system, and the temperature gradient between the image projection apparatus main body side and the projection optical system. It is also possible to correct the image using only the temperature gradient with the projection optical system.

  (Modification 2) The aberration correction coefficient predetermined according to the detection outputs of the temperature sensors 221 to 224 is stored in a memory (for example, a non-volatile memory) provided in the projection optical system (particularly, a replaceable projection optical system). You may do it. Then, the video signal processing microcomputer 201 as the acquisition unit is configured to communicate information between the projection optical system and the image projection apparatus main body, and the aberration correction stored in the memory is information specifying the exchanged projection optical system. A coefficient may be acquired.

22 .. Projection optical system, 101 Projector body, 221... Temperature detection means (first temperature detection means), 222 223... Temperature detection means (second temperature detection means), 224. Third temperature detection means)

Claims (9)

A light source;
A light modulation element irradiated by the light source;
A projection optical system for projecting image light modulated by the light modulation element onto a screen surface;
When the side toward the screen surface of the projection optical system is the exit side, and the side close to the light modulation element is the entrance side,
First temperature detection means provided on the output side of the projection optical system and outside the projection optical system;
At least one second temperature detecting means provided inside the projection optical system;
Obtaining means for obtaining corrected image data for correcting distortion of an image projected in accordance with outputs of the first temperature detecting means and the second temperature detecting means;
Input means for inputting the corrected image data to the light modulation element;
An image projection apparatus comprising:   Third temperature detection means provided on the incident side of the projection optical system and outside the projection optical system, the acquisition means includes the first temperature detection means, the second temperature detection means, and the The image projection apparatus according to claim 1, wherein correction image data for correcting distortion of an image to be projected is acquired according to an output of the third temperature detection unit.   The acquisition unit compares the detection output of the first temperature detection unit with a first threshold, and if the acquisition unit is smaller than the first threshold, the detection output of the second temperature detection unit is set to a second threshold. On the other hand, if it is equal to or larger than the first threshold value, the detection output of the second temperature detection means is compared with a third threshold value, and an aberration correction coefficient is selected according to the comparison result, The image projection apparatus according to claim 1, wherein the correction image data is calculated and acquired based on the aberration correction coefficient. The acquisition unit compares the detection output of the first temperature detection unit with a first threshold value, and if the output is smaller than the first threshold value, the detection unit outputs the detection output of the second temperature detection unit on the emission side. While comparing with the second threshold value, if it is equal to or larger than the first threshold value, the detection output of the second temperature detecting means on the emission side is compared with the third threshold value, and according to the result of the comparison Selecting a first aberration correction factor, and
The detection output of the third temperature detection means is compared with a fourth threshold value. If the detection output is smaller than the fourth threshold value, the detection output of the second temperature detection means on the incident side is set to the fifth threshold value. On the other hand, if it is equal to or larger than the fourth threshold value, the detection output of the second temperature detecting means on the incident side is compared with a sixth threshold value, and a second aberration correction is made according to the comparison result. Select a coefficient
The image projection apparatus according to claim 3, wherein the corrected image data is calculated based on the first aberration correction coefficient and the second aberration correction coefficient.   The image projection apparatus according to claim 1, wherein a focal length of the projection optical system is variable.   The image projection apparatus according to claim 1, wherein the projection optical system is replaceable, and includes a communication unit that communicates between the projection optical system and the image projection apparatus main body. .   The information for specifying the exchanged projection optical system and the outputs of the first temperature detection means and the second temperature detection means are connected to the projection optical system and the image projection apparatus main body via the communication means. The image projection apparatus according to claim 6, wherein communication is performed between the two.   The image projection apparatus according to claim 3, wherein the aberration correction coefficient corresponding to the output is stored in a memory included in the exchanged projection optical system.   The projection optical system is replaceable, and has communication means for communicating between the projection optical system and the image projection apparatus body, and the aberration correction coefficient is stored in a nonvolatile memory included in the exchanged projection optical system. The image projection apparatus according to claim 3 or 4, wherein the image projection apparatus is stored, and the acquisition unit acquires the aberration correction coefficient via the communication unit.