JP2005165140A - Projector, automatic focusing system for projector and automatic focusing method for projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the automatic focusing of a projector by a new method different from the conventional one. <P>SOLUTION: In the projector 2 projecting image light to a screen 1 at a fixed divergent angle, detecting light and detecting sound outputted simultaneously from an electronic pen 3 pointing a projection point X projected to the screen 1 are received by a sensor part 25, and the length of a 1st line L1 linking the sensor part 25 and the projection point X in the shortest distance is obtained based on a time difference in a period from receiving the detecting light until receiving the detecting sound, and the length of a 2nd line L2 linking the sensor part 25 and the screen 1 in the shortest distance is obtained by multiplying the length of the 1st line L1 by a predetermined constant, whereby a projection optical system is focused based on the length of the 2nd line L2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector, and more particularly to an automatic focus adjustment mechanism of a projection optical system.

  Conventionally, projectors have been used for presentations in places where a large number of people gather, such as conferences, academic conferences, and exhibitions, and recently projectors have also been used in ordinary homes.

  The projector generates image light by modulating a light beam emitted from a light source by a light valve, and can be roughly divided into two types according to the type of the light valve. One is a transmissive projector using a transmissive liquid crystal panel or the like as a light valve. The other is a reflective projector that uses a DLP (registered trademark of Texas Instruments (TI)) or a reflective liquid crystal panel as a light valve. However, both types of projectors are common in that the image light generated by the light valve is enlarged and projected onto the projection surface (screen surface, wall surface, etc.) by the projection optical system. Therefore, it is necessary to adjust the focus of the projection optical system according to the distance to the projection surface, and many projectors are provided with an automatic focus adjustment mechanism.

  For example, Patent Literature 1 includes a light emitting system including a light emitting element, a lens, a prism, and a light emitting window, and a light receiving system including a light receiving element, a lens, a prism, and a light receiving window, and a side for detecting the distance to the screen. A projector having a distance mechanism and a focus adjustment mechanism that adjusts the position of a lens for focus adjustment according to the distance to the screen detected by the side distance mechanism is disclosed. The light emitting system provided in the lateral distance mechanism condenses the infrared rays emitted from the light emitting elements with a lens, changes the optical axis in the center direction of the screen with a prism, and then changes the optical axis from the light emitting window having infrared transmission characteristics to the screen. Project to the top. On the other hand, the light receiving system receives the infrared light projected on the screen by the light emitting system by the light receiving element through the light receiving window and the lens, and detects the distance to the screen based on the light receiving intensity.

Patent Document 2 discloses a projection lens having a focus adjustment unit, a focus adjustment mechanism that adjusts the focus of the projection lens, a movable reflector unit installed between a dichroic mirror or a dichroic prism, and the projection lens. A light receiving element that receives reflected light from the screen via the movable reflecting mirror means, converts it into a light receiving output signal, and is disposed at a position equivalent to the optical axis distance between the projection lens and the three LCDs; Disclosed is a liquid crystal projector including a focus adjustment control unit that detects and calculates a focus position up to a screen based on a received light output signal and performs drive control of the focus adjustment mechanism, and a position detector that detects an adjustment position of the focus adjustment mechanism. ing.
JP-A-11-264963 Japanese Patent Laid-Open No. 11-119185

  There is no particular problem with the automatic focus adjustment mechanism provided in the conventional projector. The present invention intends to realize automatic focus adjustment of a projection optical system by a novel method completely different from the conventional one.

  The present invention obtains a distance between the projector and the projection surface based on a time difference until sound and light simultaneously emitted from the projection surface reach the projector, and adjusts the focus of the projector based on the obtained distance. It is characterized by performing. Therefore, even if the distance between the projector and the projection surface changes, the focus of the projector can be easily adjusted.

  The projector of the present invention having the above features has a projection optical system that projects image light at a constant divergence angle with respect to the projection surface, and from the vicinity of the projection point projected onto the projection surface via the projection optical system. A projector that performs focus adjustment using a pointing unit that can output detection light and detection sound simultaneously, and a light receiving unit that receives detection light output from the pointing unit on the projection surface, and a light output that is output from the pointing unit Based on the time difference between the receiving means that receives the detection sound and the detection light received by the light receiving means until the detection sound is received by the receiving means, the light receiving means or the receiving means and the projection point are at the shortest distance. A first calculating means for determining the length of the first straight line to be connected, and a second straight line for connecting the light receiving means or the receiving means and the projection surface at the shortest distance by multiplying the length of the first straight line by a predetermined constant. Long The finding has a second calculation unit, and a focus adjusting means based on the length of the second straight line performs focus adjustment of the projection optical system.

  An automatic focus adjustment system for a projector according to the present invention having the above-described features includes a projector having a projection optical system that projects image light at a constant divergence angle with respect to a projection surface, and a projection projected on the projection surface by the projector. And pointing means capable of outputting detection light and detection sound simultaneously from the vicinity of the point, and the pointing means outputs detection sound in synchronization with the detection light output means and detection light output means for outputting the detection light. The projector includes a light receiving unit that receives the detection light output from the pointing unit, a receiving unit that receives the detection sound output from the pointing unit, and a receiver that receives the detection light after the light receiving unit receives the detection light. Based on the time difference until the detection sound is received by the means, the light receiving means or the receiving means and the projection point are connected at the shortest distance. A first calculating means for determining the length of the straight line, and a length of the second straight line connecting the light receiving means or the receiving means and the projection surface with the shortest distance by multiplying the length of the first straight line by a predetermined constant. Second calculating means to be obtained; and focus adjusting means for adjusting the focus of the projection optical system based on the length of the second straight line.

  The method for automatically adjusting the focus of a projector according to the present invention having the above-described features includes a step in which a projector having a projection optical system that projects image light at a constant divergence angle with respect to a projection surface projects a projection point on the projection surface; The pointing means on the projection surface simultaneously outputs detection light and detection sound from the vicinity of the projection point, the light receiving means provided in the projector receives the detection light output from the pointing means, and the reception provided in the projector A time difference between the step in which the means receives the detection sound output from the pointing means and the first calculation means included in the projector from when the detection light is received by the light reception means until the detection sound is received by the reception means; A step of obtaining a length of the first straight line connecting the light receiving means or the receiving means and the projection point with the shortest distance based on A calculating means for multiplying a length of the first straight line by a predetermined constant to obtain a length of a second straight line connecting the light receiving means or the receiving means and the projection surface at the shortest distance; and focus adjustment provided in the projector And means for adjusting the focus of the projection optical system based on the length of the second straight line.

  According to the present invention, since the focus of the projector is automatically adjusted even if the distance between the projector and the projection surface changes, it is possible to always view a beautiful image. Such an effect is particularly effective in a projector in which the distance from the screen changes every time it is installed, such as a portable projector. In addition, according to the present invention, the above-described effect can be obtained with a very simple configuration, which is advantageous for realizing a projector having an automatic focus adjustment function at a low cost or downsizing.

  Hereinafter, an example of an automatic focus adjustment system (hereinafter sometimes abbreviated as “system”) for a projector according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of the system of this example. FIG. 2 is a schematic diagram showing a schematic structure of the electronic pen constituting the system of this example. FIG. 3 is a schematic diagram showing an outline of the structure of the projector constituting the system of this example. FIG. 4 is a functional block diagram relating to the automatic focus adjustment mechanism of the projector shown in FIG.

  As shown in FIG. 1, the system of this example is composed of a projector 2 that projects image light at a constant divergence angle toward a projection surface (screen 1 in this example), and an electronic pen 3 as pointing means. ing.

  As shown in FIG. 2, the electronic pen 3 has a pen-type main body 10, and the main body 10 is a circuit board on which at least an oscillator driving circuit 11, a light emitting element driving circuit 12, and a power supply circuit 13 are formed. 14 is built-in. In addition, an ultrasonic oscillator 15 including a magnetic circuit driven by an oscillator driving circuit 11, an ultrasonic speaker excited by the magnetic circuit, and infrared light emission driven by a light emitting element driving circuit 12 are provided at the tip of the main body 10. An element (semiconductor light emitting element) 16 is provided. When a push button 17 provided near the rear end of the main body 10 is pressed, a voltage supplied from a power source (not shown) is applied to the oscillator driving circuit 11 and the light emitting element driving circuit 12 via the power circuit 13. The ultrasonic oscillator 15 outputs an ultrasonic wave as a detection sound, and the infrared light emitting element 16 emits light to output an infrared ray as a detection light. Here, the oscillator driving circuit 11 and the light emitting element driving circuit 12 are set so as to simultaneously drive the ultrasonic oscillator 15 or the infrared light emitting element 16 based on a timing signal output from a timing circuit (not shown). Therefore, while the push button 17 is being pressed, ultrasonic waves and infrared rays are continuously output from the electronic pen 3 in synchronization. The oscillator drive circuit 11 and the ultrasonic oscillator 15 may be modularized. Further, the light emitting element driving circuit 12 and the infrared light emitting element 16 may be modularized. Further, a switch corresponding to the push button 17 is provided at the front end of the main body 10, and when the front end of the main body 10 is pressed against the surface of the screen 1, the switch is pressed and turned on, and the front end of the main body 10 is connected to the screen 1. When the pressing is released, the switch can be automatically turned off. Also in this case, it is desirable that the ultrasonic wave and the infrared light are continuously output from the electronic pen 3 while the switch is in the ON state (while the tip of the main body 10 is pressed against the screen 1).

  As shown in FIG. 3, the projector 2 has a substantially rectangular parallelepiped casing 20, and the casing 20 includes a light source device 21, an illumination optical system 22, a light valve 23, and a projection optical system 24. A sensor unit 25 including an infrared sensor that receives infrared rays output from the electronic pen 3 and an ultrasonic sensor that receives ultrasonic waves output from the electronic pen is provided.

  The light source device 21 includes a light source 30 such as a halogen lamp, a metal halide lamp, or a xenon lamp, and a reflector 31 that guides light emitted from the light source 30 in a predetermined direction.

  The illumination optical system 22 is a color wheel that separates light emitted from the light source device 21 into three color lights of R (red), G (green), and B (blue) in a time division manner, and light that has passed through the color wheel. Are integrated with an integrator optical system for making the luminance distribution uniform in a plane perpendicular to the optical axis of the light, and are the same as those provided in a conventional projector. Is omitted.

  The light valve 23 is a so-called DLP having a large number of micromirrors whose inclination angles can be individually controlled. Each micromirror corresponds to each pixel of the image displayed on the screen, and desired image light can be generated by controlling the tilt angle of each micromirror based on the image data. Specifically, an angle is controlled so that the reflected light does not enter the projection optical system 24 for a certain micromirror, and the angle is set so that the reflected light enters the projection optical system 24 for a certain micromirror. By performing the control, desired image light can be generated. Angle control of each micromirror is input from the outside via an interface (not shown), and a predetermined process (conversion to R / G / B data, processing to repair an interlaced field, etc.) by a processor (not shown) ) Is selectively performed on the basis of the image data subjected to.

  The projection optical system 24 includes a first reflection mirror 40 on which image light generated by the light valve 23 (light modulated by the light valve 23) is incident, and a first reflection mirror on which image light reflected by the first reflection mirror 40 is incident. The second reflection mirror 41, the third reflection mirror 42 on which the image light reflected by the second reflection mirror 41 is incident, and the fourth reflection mirror 43 on which the image light reflected by the third reflection mirror 42 is incident. These first to fourth reflecting mirrors 41 to 43 all have an aspheric reflecting surface. Further, the first reflection mirror 40 and the second reflection mirror 41 are arranged in a positional relationship in which the above-described incident reflection is realized inside the housing 20. Further, the third reflection mirror 42 and the fourth reflection mirror 43 are erected so as to face each other with a predetermined inclination angle on the upper surface of the housing 20. Here, the second reflecting mirror 41 also functions as a focusing optical element that adjusts the focus of the projection optical system 24 by reciprocating in the direction of the arrow in the drawing. The fourth reflection mirror 42 functions as a projection mirror that finally projects the image light toward the screen 1, and the divergence angle is always constant.

  The sensor unit 25 is provided on the side portion of the fourth reflection mirror 43. When the infrared sensor that constitutes the sensor unit 25 detects infrared rays output from the electronic pen 3 shown in FIG. 1, the infrared sensor outputs an electrical signal (infrared detection signal), and the ultrasonic sensor outputs an ultrasonic signal output from the electronic pen 3. When a sound wave is detected, an electrical signal (ultrasonic detection signal) is output.

  Next, the operation of the system of this example will be described with reference to FIGS. 1 and 4, and the operation of each unit shown in FIG. 4 will also be described. When automatic focus adjustment of the projector 2 is performed in the system of this example, first, the projection point X is projected onto the screen 1 by the projector 2. Specifically, when an autofocus button (not shown) provided on the operation panel of the projector 2 is pressed by the operator, the projector 2 uses the same principle as that for displaying a normal image on the screen 1. 1 shows the projection point X. In FIG. 1, the projection point X is projected onto the center of the screen 1, but the projection position of the projection point X is not particularly limited, and the shape, size, color, and the like are not particularly limited.

Next, when the operator presses the push button 17 (see FIG. 2) while pointing the projection point X displayed on the screen 1 with the tip of the electronic pen 3 and outputs infrared rays and ultrasonic waves from the electronic pen 3, it is output. Infrared and ultrasonic waves are detected by the sensor unit 25 of the projector 2 as described above. Specifically, infrared rays are detected by the infrared sensor 25a shown in FIG. 4, ultrasonic waves are detected by the ultrasonic sensor 25b shown in FIG. 4, and infrared detection signals and ultrasonic detection signals are received from the infrared sensors 25a and 25b. Are output respectively. Then, the output infrared detection signal and ultrasonic detection signal are input to the first calculation means 50. Here, since there is a difference in the propagation speed of light and sound, among infrared rays and ultrasonic waves simultaneously output from the electronic pen 3 shown in FIG. 1, the infrared rays first reach the infrared sensor 25a, and then the ultrasonic waves Reaches the ultrasonic sensor 25b. Therefore, a time difference corresponding to the difference in the propagation speed of light and sound between the input of the infrared detection signal and the input of the ultrasonic detection signal to the first calculation means 50 occurs. Therefore, the first calculation means 50 starts the time measurement by operating the timer means 51 using the input of the infrared detection signal as a trigger, and the elapsed time until the ultrasonic detection signal is input, that is, the input of the infrared detection signal. The time difference from the input of the ultrasonic signal is obtained. Further, the first calculation means 50 performs a calculation of multiplying the time difference (Δbt [sec]) obtained as described above by the ultrasonic wave propagation velocity (in this example, 340 [m / sec]). By this calculation, the length L ₁ (m) of the straight line L1 connecting the sensor unit 25 of the projector 2 shown in FIG. 1 and the projection point X on the screen 1 with the shortest distance is obtained.

Next, the second calculation means 52 shown in FIG. 4 performs a calculation by multiplying the length L ₁ of the straight line L1 obtained by the calculation of the first calculation means 50 by a predetermined constant COSθ. Here, as shown in FIG. 1, the angle θ is a straight line that connects the straight line L1 passing through the sensor unit 25 and the projection point X and the sensor unit 25 and the plane including the screen 1 with the shortest distance (that is, the sensor unit 25 A straight angle perpendicular to the plane including the screen) L2 is an included angle. As shown in FIG. 5, since the projector 2 projects image light toward the screen 1 with a constant divergence angle, an element on the light valve used to project the projection point X (the light valve is DLP). If the micromirror in this case and the liquid crystal cell in the case of a liquid crystal panel) are not changed, the angle θ is always constant even if the distance between the projector 2 and the screen 1 changes. Therefore, in this example, the angle θ is measured in a state where the projector 2 and the screen 1 are arranged at an arbitrary distance, and the value of COSθ is stored in advance in the memory 53 (see FIG. 4) of the projector 2 as data. It is. Therefore, the second calculation means 52 shown in FIG. 4 reads the value of COSθ from the memory 53 and performs the above calculation. Thus, the length L _{2 of the} straight line L2 that connects the sensor unit 25 shown in FIG. 1 and the screen 1 on which the projection point X is projected with the shortest distance is obtained. The second calculation means 52 outputs the above calculation result to the focus adjustment means 54.

Then, the focus adjusting unit 54 drives the mirror driving means 55 a length L ₂ that is input as the focal length, moving the second reflecting mirror 41 shown in FIG. 3 in the direction of the arrow in FIG. Specifically, the correspondence relationship between the length L ₂ and the position of the second reflecting mirror 41 is stored in advance in the memory 53 as data, while the projector 2 is not able to detect the current position of the second reflecting mirror 41. The illustrated position detection means is provided. Therefore, the focus adjusting unit 54 includes the second reflecting mirror 41 on the data corresponding to the current position of the second reflecting mirror 41 detected by the position detecting unit and the length L ₂ obtained by the second calculating unit 52. And a command to move the second reflecting mirror 41 as long as the deviation is eliminated is output to the mirror driving means 55. The mirror driving means 55 includes a motor as a driving source and a moving mechanism for moving the second reflecting mirror 41 forward and backward in the optical axis direction by the rotational driving force of the motor, and drives the motor in accordance with an input command. Then, the second reflecting mirror 41 is advanced and retracted by a necessary amount. In the system of this example, automatic focus adjustment of the projector 2 is performed as described above. Note that one or more of the plurality of means shown in FIG. 4 is realized by a processor (not shown) executing a program stored in the memory 53.

  In this example, the second reflecting mirror 41 shown in FIG. 3 can be moved in the optical axis direction to function as a focusing optical element. However, other reflecting mirrors can function as a focusing optical element. You can also. Further, when an optical element other than the optical element shown in the figure is added, the optical element can also function as an optical element for focusing. Furthermore, in this example, the system of the present invention has been described by taking a projector whose light valve is a DLP as an example, but the light valve of the projector may be another light valve such as a reflective liquid crystal panel or a transmissive liquid crystal panel. . Further, in this example, the system of the present invention has been described by taking as an example a so-called mirror projector in which the projection optical system is configured by a mirror. May be. In this case, the focus adjustment can be realized by obtaining the necessary moving amount of the focusing lens by the same method as described above and moving the focusing lens forward and backward in the optical axis direction by that amount.

  In this example, the system of the present invention has been described by taking the case where the pointing means is an electronic pen as an example. However, the pointing means has a configuration capable of simultaneously outputting light and sound that can be detected by the light receiving means and the receiving means provided in the projector. As long as it is provided, there are no other limitations. However, in order to realize more accurate focusing, it is desirable that the light and sound can be output from a position as close as possible to the projection point projected on the projection surface by the projector. Further, it is desirable from the viewpoint of accurate focusing that the sensor unit is provided as close as possible to the optical axis of the projection optical system of the projector. However, if for some reason the sensor unit must be provided at a position away from the optical axis of the projection optical system, the calculation results of the first calculation means and the second calculation means shown in FIG. It is also possible to achieve accurate focusing by correcting according to.

It is a schematic diagram which shows the structure of the automatic focus adjustment system of the projector of this invention. It is a schematic diagram which shows the structure of the electronic pen which comprises the system shown in FIG. It is a schematic diagram which shows the structure of the projector which comprises the system shown in FIG. It is a functional block of the projector shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen 2 Projector 3 Electronic pen 10 Main body 11 Oscillator drive circuit 12 Light emitting element drive circuit 13 Power supply circuit 14 Circuit board 15 Ultrasonic oscillator 16 Infrared light emitting element 17 Push button 20 Housing 21 Light source device 22 Illumination optical system 23 Light valve 24 Projection Optical system 25 Sensor unit 25a Infrared sensor 25b Ultrasonic sensor 30 Light source 31 Reflector 40 First reflection mirror 41 Second reflection mirror 42 Third reflection mirror 43 Fourth reflection mirror 50 First calculation means 51 Timer means 52 Second calculation means 53 Memory 54 Focus adjustment means 55 Mirror drive means

Claims (6)

It has a projection optical system that projects image light at a fixed divergence angle with respect to the projection surface, and can simultaneously output detection light and detection sound from the vicinity of the projection point projected onto the projection surface via the projection optical system A projector that performs focus adjustment using pointing means,
A light receiving means for receiving the detection light output from the pointing means on the projection surface;
Receiving means for receiving the detection sound output from the pointing means;
Based on the time difference from when the detection light is received by the light receiving means to when the detection sound is received by the receiving means, the light receiving means or the receiving means and the projection point are connected at the shortest distance. First calculating means for determining the length of one straight line;
A second computing means for multiplying a length of the first straight line by a predetermined constant to obtain a length of a second straight line connecting the light receiving means or the receiving means and the projection surface with a shortest distance;
A projector having a focus adjustment unit configured to adjust a focus of the projection optical system based on a length of the second straight line; When the length of the first straight line is L ₁ , the length of the second straight line is L ₂ , and the included angle between the first straight line and the second straight line is θ, the second computing means the projector according to claim 1, wherein performing the calculation of L ₁ · COS .theta determine said L _2. A projector having a projection optical system for projecting image light at a fixed divergence angle with respect to the projection surface, and pointing means capable of simultaneously outputting detection light and detection sound from the vicinity of the projection point projected on the projection surface by the projector And
The pointing means comprises detection light output means for outputting detection light, and detection sound output means for outputting detection sound in synchronization with the detection light output means,
The projector includes a light receiving unit that receives the detection light output from the pointing unit, a receiving unit that receives the detection sound output from the pointing unit, and the detection light received by the light receiving unit. Based on a time difference until the detection sound is received by the receiving means, a first calculating means for obtaining a length of a first straight line connecting the light receiving means or the receiving means and the projection point with the shortest distance. And a second calculating means for multiplying the length of the first straight line by a predetermined constant to obtain the length of the second straight line connecting the light receiving means or the receiving means and the projection surface with the shortest distance; Focus adjusting means for adjusting the focus of the projection optical system based on the length of the second straight line;
Projector focus adjustment system. When the length of the first straight line is L ₁ , the length of the second straight line is L ₂ , and the included angle between the first straight line and the second straight line is θ, the second computing means It is the focal automatic adjustment system of a projector according to claim 3, wherein performing the calculation of the L ₁ · COS .theta determine said L ₂ A projector having a projection optical system for projecting image light at a constant divergence angle with respect to the projection surface, and projecting a projection point on the projection surface;
A step in which pointing means on the projection surface simultaneously outputs detection light and detection sound from the vicinity of the projection point;
A light receiving means provided in the projector receives the detection light output from the pointing means;
Receiving means provided in the projector, receiving the detection sound output from the pointing means;
Based on a time difference from when the detection light is received by the light receiving unit to when the detection sound is received by the receiving unit, the first calculation unit included in the projector is based on the light receiving unit or the receiving unit. Obtaining a length of a first straight line connecting the projection points with the shortest distance;
The second calculation means included in the projector multiplies the length of the first straight line by a predetermined constant, and the length of the second straight line connecting the light receiving means or the receiving means and the projection surface with the shortest distance. The process of seeking
A step of adjusting a focus of the projection optical system based on a length of the second straight line by a focus adjustment unit included in the projector;
A method for automatically adjusting the focus of a projector. When the length of the first straight line is L ₁ , the length of the second straight line is L ₂ , and the angle formed by the first straight line and the second straight line is θ, the second calculation means is the focal automatic adjustments to the projector of claim 5, wherein performing the calculation of the L ₁ · COS .theta determine said L _2.

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