JP2006084991A - Projecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projecting device having a focusing section that immediately informs a user of the cause of focusing failure. <P>SOLUTION: The projecting device projects a display image onto a projection surface by using illuminating light emitted from a light source. The projecting device has the focusing section for automatically focusing the projecting device relative to the projection surface. The focusing section includes: a measuring means for measuring the luminance of the projection surface; a judging means for judging whether or not the luminance measured by the measuring means is sufficient to bring into automatic focus; and an informing means by which, when the judging means judges that the luminance is not sufficient to bring into automatic focus, a user is informed of that. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In general, the present invention relates to a projection apparatus that enlarges and projects a display image displayed on a display device such as a liquid crystal panel onto a projection surface using a projection light system using irradiation light from a light source, In particular, the present invention relates to a focusing unit that automatically focuses the projection apparatus on the projection surface.

  In recent years, projection devices such as projectors have not only improved functionality but also demanded improvement in operability, and projection devices including a focusing unit that automatically adjusts the focal position of the projection device with respect to the projection surface (screen) have been developed. Proposed. The focusing unit captures a screen with an imaging device such as a CCD camera, drives the projection lens from a signal processed by processing the captured image, and automatically performs focusing.

As a conventional focusing unit, an image having a predetermined pattern prepared in advance is projected on a screen, and a distance signal between the projection device and the screen is obtained by receiving a pattern contrast signal by a line sensor. There is a focusing section (see, for example, Patent Document 1). In the in-focus portion of Patent Document 1, even when the contrast on the screen is low or the change is small, the position of the maximum contrast value can be found, so that accurate focusing can be performed. In addition, as another focusing unit, there is a focusing unit (for example, see Patent Document 2) that displays that automatic focusing is being performed when focusing is in progress. In the in-focus portion of Patent Document 2, it is easy to determine whether the in-focus state or the in-failure state, so that the work can be performed efficiently.
JP-A-5-188282 JP-A-8-285691

  However, in Patent Document 1, when the luminance on the screen is high, the luminance of the screen also overlaps the projected pattern, the pattern contrast becomes low, and it becomes difficult to detect the maximum contrast value. As a result, the focusing unit cannot focus, and in some cases, there is a problem that focusing is continued for a long time.

  Further, Patent Document 2 has a problem that the cause cannot be specified when focusing cannot be performed.

  Therefore, an object of the present invention is to provide a projection apparatus including a focusing unit that immediately informs the user of the cause when focusing cannot be performed.

  A projection apparatus according to an aspect of the present invention is a projection apparatus that projects a display image on a projection surface using irradiation light from a light source, and includes a focusing unit that focuses the projection surface. The focusing unit includes a measuring unit that measures the luminance of the projection surface, a determining unit that determines whether the luminance measured by the measuring unit is a focusable luminance, and the determining unit is in focus. And notifying means for notifying that the brightness is not focusable when it is determined that the brightness is not possible.

  A projection device according to another aspect of the present invention is a projection device that projects a display image on a projection surface via a projection optical system, and includes a focusing unit that focuses on the projection surface. The focusing unit includes a driving unit that drives a focusing lens in the projection optical system, and a position storage unit that stores a history of the focal position of the focusing lens driven by the driving unit. When the projection device is used, focusing is performed based on the history.

  A focusing device as another aspect of the present invention is a focusing device that is used in a projection device that projects a display image on a projection surface using irradiation light from a light source, and focuses the projection surface. A measuring unit for measuring the luminance of the projection surface; a determining unit for determining whether the luminance measured by the measuring unit is a focusable luminance; and the determining unit determines that the focusing is not possible. And a notification means for notifying that the brightness is not focusable.

  A focusing method according to another aspect of the present invention is used in a projection apparatus that projects a display image on a projection surface using irradiation light from a light source, and performs the focusing on the projection surface. The step of measuring the luminance of the projection surface, the step of determining whether the luminance measured by the measuring unit is a focusable luminance, and the determination unit determining that the focusing is not possible And a step of notifying that the brightness is not focusable.

  According to another aspect of the present invention, there is provided a projection apparatus for projecting a display image on a display device onto a projection surface via a projection optical system using irradiation light from a light source, the light source and the display device. , A driving means for moving the focusing lens of the projection optical system, a distance measuring means for measuring the distance between the projection device and the projection surface to be projected, and a projection image for distance measurement are stored. Storage means, measurement means for measuring the brightness of the projection surface of the image projected from the projection device, and brightness on the projection surface of the stored projection image for distance measurement projected from the projection optical system. And measuring means for determining whether or not the projection surface has an illuminance at which the projection surface can be focused, projecting images with different brightness values, and reflecting the reflected luminance from the projection surface of the images with different brightness values. Metering and focusing is possible from the difference in metering values Judgment whether the brightness is illuminating and calculating the edge part of the projected image of the image having different brightness from the line sensor of the distance measuring device, the transition of the luminance difference of the edge part is represented by the line sensor as the horizontal axis and the luminance as the vertical axis. When the calculation is performed using the graph, if the projection surface is represented by a curve having an angle from a predetermined angle, the focusing lens is driven to perform the focusing operation even when the projection surface has a brightness other than the focusable brightness. It is characterized by that.

  According to another aspect of the present invention, there is provided a projection apparatus for projecting a display image on a display device onto a projection surface via a projection optical system using irradiation light from a light source, the light source and the display device. , A driving means for moving the focusing lens of the projection optical system, a distance measuring device for measuring the distance between the projection device and the projection surface to be projected, and a projection image for distance measurement are stored. Storage means, measurement means for measuring the brightness of the projection surface of the image projected from the projection device, storage means for storing projection distance information to be compared with the photometric data, and projection distance information is derived from the photometric data. Whether or not the luminance on the projection surface of the stored projection image for distance measurement projected from the projection optical system is measured by the measurement unit, and whether or not the projection surface has an illuminance that allows focusing. Judgment to judge Means for projecting the memorized projection image for distance measurement, and measuring the reflected luminance from the projection surface. If it is determined that the illuminance cannot be focused from the photometric value, the projection is performed from the reflected luminance value. Calculation is performed by a calculation means for deriving distance information, a focusing lens is driven from information stored in the storage means for storing the projection distance information, a focusing assist operation is performed, and distance measurement is performed again by the distance measuring device. To do.

  Further objects or other features of the present invention will become apparent from the preferred embodiments described with reference to the accompanying drawings.

  According to the present invention, it is possible to provide a projection apparatus including a focusing unit that immediately notifies the user of the cause when focusing cannot be performed.

  Hereinafter, a projection apparatus 10 that is an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a block diagram showing a configuration of the projection apparatus 10. FIG. 2 is a block diagram illustrating a configuration of the focusing unit 100.

  The projection device 10 projects the display image on the projection surface (screen) 300 using the irradiation light from the light source, the light source 20, the illumination optical system 30, the liquid crystal light valve 40, the projection optical system 50, A focusing unit 100. In the present embodiment, the projector 10 will be described using a liquid crystal projector. However, the present invention is not limited to the liquid crystal projector, and may be applied to projector apparatuses having various configurations such as a CRT projector and a DLP (Digital Light Processing) projector. Good. The liquid crystal projector of this embodiment will be described using a front projection type projector.

  The light source 20 illuminates the display image. The light source 20 generally uses a lamp. For example, a high intensity discharge (HID) lamp such as an ultra-high pressure mercury lamp, a metal halide lamp, or a xenon lamp is integrated with a reflecting mirror. The light source 20 may be a compact solid-state laser that is a highly directional light source, a microwave-excited electrodeless HID lamp, a lamp composed of a carbon nanotube electron source and a phosphor, or the like.

  The illumination optical system 30 color-separates light from the light source 20. The illumination optical system 30 separates the three primary colors of red (R), green (G), and blue (B). Therefore, the illumination optical system 30 includes a color separation optical system such as an optical integrator, a polarization conversion optical system, a dichroic mirror, and various lens systems such as a condenser lens. The illumination optical system 30 is combined with a lens system so that the liquid crystal light valve 40 is illuminated uniformly and efficiently.

  The liquid crystal light valve 40 modulates light incident from the illumination optical system 30. The liquid crystal light valve 40 is an element that controls optical characteristics (transmission, reflection, phase, scattering, diffraction, refraction, and absorption) at each spatial position in a two-dimensional plane, and forms image information by changing the optical characteristics. To do. The address (writing) method of the input signal (image information) to the liquid crystal light valve 40 is an electric address method using a semiconductor integrated circuit such as p-Si TFT or c-Si MOSFET, an optical image of a small display element, or a laser beam. There are an optical addressing method for writing information by an electron beam addressing method and an electron beam addressing method for writing information by electron beam scanning in a vacuum. These methods control the luminous flux from an independent light source and display it on the screen in an enlarged manner, so that the size and brightness of the displayed image can be increased by the light source used compared to the self-luminous CRT projector. Suitable for screen display.

  The projection optical system 50 has a function of projecting the display image, and synthesizes light modulated by the liquid crystal light valve 40. The projection optical system 50 combines the three primary colors of red (R), green (G), and blue (B). The projection optical system 50 includes a color synthesis optical system and a projection lens.

  The focusing unit 100 has a function of automatically focusing the projection device 10 on the screen 300, and includes an AF switch 110, a measurement device 120, a line sensor 130, a focus encoder 140, a driving unit 150, And a control unit 160. The focusing unit 100 is built in the projection apparatus 10 and is disposed at a position where the focusing lens in the projection optical system 50 can be driven. Further, in the focusing unit 100, a part of the measuring device 120 and the line sensor 130 described later are exposed to the outside of the casing of the projection device 10. In this case, a part of the measuring device 120 and the line sensor 130 is disposed on a surface facing the screen.

  The AF switch 110 generates a signal for performing an automatic focusing operation. The AF switch 110a is formed on the surface of the projection apparatus 10 so that the user can easily perform an operation, and a button type or a slide type is adopted. Further, in the present embodiment, not only the AF switch 110a formed on the surface of the projection apparatus 10, but also a remote controller type AF switch 110b is introduced so that automatic focusing can be performed remotely. In this case, the projection device 10 is provided with a receiving unit for receiving the transmission signal of the AF switch 110b. In addition to the AF switch 110b, various functions such as the brightness, contrast, volume adjustment, and angle adjustment of the projected image can be added to the remote controller.

  The measuring device (measuring means) 120 measures the luminance on the screen 300 and is provided in the projection device 10. Two measuring devices 120 are further mounted for measuring the left and right and black and white image luminance. In this case, the measuring device 120 may be a single device as long as it can be divided into a plurality of sensors. The measuring device 120 can also measure the luminance on the screen 300 while driving the projection optical system 50 by the driving unit 150. In the measuring device 120, a detection unit (not shown) is exposed from the outside of the casing of the projection device 10. The detection unit is arranged at a position facing the screen 300 in order to detect the luminance of the screen 300. Further, the measuring device 120 is electrically connected to the CPU 162. In this case, the measuring device 120 measures the luminance of left and right and black and white projected on the screen 300 and transmits the measured luminance to the CPU 162. The measuring device 120 can measure not only the luminance on the screen 300 but also the external luminance (light quantity) including natural light or room light.

  The line sensor 130 acquires a target image by an optical sensor (CCD) arranged in a horizontal row. Thereby, the line sensor 130 captures luminance information of the acquired image. The line sensor 130 mainly includes a CCD image sensor element, a lens, and a driver / control circuit, and is electrically connected to an A / D conversion circuit 164 described later. Therefore, the line sensor 130 is exposed from the outside of the housing of the projection device 10 at a position where a detection unit (not shown) faces the screen 300. Two line sensors 130 are further mounted to measure the left and right and black and white image brightness. In this case, the number of line sensors 130 may be one as long as the sensor can be divided and measured.

  The focus encoder 140 detects the position of the projection optical system 50. Therefore, the focus encoder 140 is built in the projection optical system 50. Alternatively, the focus encoder 140 may be built in the driving unit 150.

  The driving unit 150 drives the lens in the projection optical system 50. Therefore, the driving unit 150 holds the projection optical system 50 so that it can be driven. The driving unit 150 may be automatically driven based on positional information between the screen 300 and the projection optical system 50. Further, when the driving means 150 is driven manually, it is adjusted by a dial type knob (not shown). Further, the driving unit 150 may be provided with a mechanism for adjusting the irradiation position by driving the projection optical system 50 in the vertical and horizontal directions as well as the focal position between the screen 300 and the projection optical system 50.

  The control unit 160 summarizes the overall operation of the automatic focusing function, and includes an image storage circuit 161, a CPU 162, a luminance comparison operation circuit 163, an A / D conversion circuit 164, an image output circuit 165, and a luminance. A storage circuit 166, a distance calculation circuit 167, and a projection position storage circuit 168 are included.

  The image storage circuit 161 functions as a memory for storing images. In this embodiment, the image storage circuit 161 stores left and right and black and white image luminances measured by the measurement device 120. The stored image in the image storage circuit 161 is referred to by the CPU 162 as appropriate.

  The CPU 162 has a function of calculating and outputting based on input information, and includes an AF switch 110, a measuring device 120, a focus encoder 140, a driving unit 150, an image storage circuit 161, and a luminance comparison calculation circuit. 163, an A / D conversion circuit 164, an image output circuit 165, a luminance storage circuit 166, a distance calculation circuit 167, and a projection position storage circuit 168 are electrically connected. The CPU 162 performs a calculation for the focusing unit 100, but a calculation function for the projection apparatus 10 may be added.

  The luminance comparison arithmetic circuit (determination unit) 163 has a function of comparing the luminance information measured by the measuring device 120 with the CPU 162 as to whether automatic focusing is possible. In the present embodiment, the luminance comparison operation circuit 163 compares the measured luminance information with reference luminance information stored in a luminance storage circuit 166 described later. In this case, when it is determined that the brightness is capable of automatic focusing, the luminance comparison arithmetic circuit 163 causes the driving unit 150 to perform focusing. Let the measurement take place. Note that the function of the luminance comparison arithmetic circuit 163 may be performed by the CPU 162.

  The A / D conversion circuit 164 has a function of converting luminance information of the line sensor 130 from an analog value to a digital value. Therefore, the A / D conversion circuit 164 is electrically connected to the line sensor 130. The digitally converted luminance information is transmitted to the CPU 162. The A / D conversion circuit 164 may not be built in the control unit 160 but may be built in the line sensor 130.

  The image output circuit (notification means) 165 has a function of outputting an image to the outside, and in this embodiment, when the luminance comparison calculation circuit 163 determines that automatic focusing is not possible, the luminance is not capable of automatic focusing. To inform. In addition, the luminance comparison arithmetic circuit 163 projects an image or character string stored in advance on the screen 300 when the difference in luminance between the left and right measured by the measuring device 120 is maximized. The image output circuit 165 is used to notify the user of the cause when focusing cannot be performed, but can also be used as an image output circuit for a projection image of the projection apparatus 10. Further, the image output circuit 165 not only projects an image or character string onto the screen 300, but also outputs a cause that the liquid crystal display unit cannot be focused by forming a liquid crystal display unit in the projection device 10, for example. May be.

  The luminance storage circuit 166 has a function as a memory that stores the luminance measured by the measuring device 120. The luminance storage circuit 166 is electrically connected to the CPU 161 and refers to the stored luminance as appropriate. Further, the luminance storage circuit 166 may be the same memory as the image storage circuit 161.

  The distance calculation circuit 167 has a function of calculating a distance. In the present embodiment, the distance calculation circuit 167 calculates the distance between the screen 300 and the projection optical system 50 based on the image luminance acquired by the line sensor 130. The calculated distance is transmitted to the driving unit 150 via the CPU 162.

  The projection position storage circuit 168 has a function of storing the projection position. In the present embodiment, the projection position storage circuit 168 stores a history of focal positions adjusted by the driving unit 150. This history is used to focus the projection device 10 next time. The projection position storage circuit 168 may be the same memory as the image storage circuit 161, as with the luminance storage circuit 166.

  With the above configuration, the focusing unit 100 can identify the cause of inability to focus, eliminate the problem of continuing focusing for a long time, and can immediately notify the user of the cause when focusing cannot be performed. .

  Hereinafter, the automatic focusing method 500 of the present embodiment will be described with reference to FIG. Here, FIG. 4 is a flowchart for explaining the automatic focusing method 500.

  First, a trigger for entering an autofocus operation is generated by pressing the AF switch 110 (step S502). When the AF switch 110 is pressed, the projection apparatus 10 projects the black and white sample image divided into the left and right screens stored in the image storage circuit 161 onto the screen 300 by the image output circuit 10.

  Next, after the sample image is projected, the luminance on the screen 300 is measured by the measurement device 120 provided in the projection device 10 (step S504). The luminance measurement here is performed to determine whether the luminance on the screen 300 is a brightness that can be focused. In this case, the luminance to be measured is the luminance of the sample image added to the original luminance on the screen 300. Further, various images can be used as long as they are projected images without using sample images. Note that it is possible to use not only the measurement device 120 but also the line sensor 130 as the measurement device.

  Thereafter, it is determined whether or not the measured luminance information is bright enough to be focused by the CPU 162 and the luminance comparison operation circuit 163 (step S506). Here, the brightness on the screen 300 is measured to determine whether focusing is possible, but external brightness (light quantity) including natural light or room light is measured to determine whether focusing is possible. It is also possible. If it is determined in step S506 that the brightness is in focus, the process proceeds to a normal autofocus operation.

  In the normal focusing operation, first, image information is acquired by the line sensor 130 (step S528). In this case, the information acquired by the line sensor 130 is luminance information on the screen 300. Thereafter, the luminance information is converted into an analog value by the A / D conversion circuit 164 (step S530). The digitally converted luminance information is sent to the CPU 162. The luminance information sent to the CPU 162 calculates the luminance difference between the left and right line sensors inside the CPU 162, calculates from the difference between the line sensors, and calculates the distance between the projection optical system 50 and the screen 300 by the distance calculation circuit 167 (step). S532).

  The current position of the projection optical system 50 is grasped (step S534), and the drive amount of the projection optical system 50 is calculated from the calculated data (step S536). At the same time, the movement target position of the projection optical system 50 is also set according to the calculation result (step S538). Then, the projection optical system 50 is moved to the movement target position using the driving unit 150 (step S540). At that time, the projection optical system 50 includes a focus encoder 140 that detects an absolute position, and the position of the projection optical system 50 can be determined from the CPU 162.

  While the drive unit 150 is being driven, the position of the projection optical system 50 is read by the focus encoder 140 (step S542), and the drive unit 150 is driven until the projection optical system 50 reaches the movement target position (step S544). When the projection optical system 50 reaches the movement target position, the driving unit 150 is stopped (step S546). Then, the focusing operation is finished, and a desired image is projected on the screen 300.

  On the other hand, if it is determined in step S506 that the brightness is not focusable, the left and right and black and white brightness on the screen 300 is measured (step S508). The luminance measurement here is performed to determine the maximum contrast value. Moreover, in this embodiment, although the measuring apparatus 120 is used for the apparatus used for a measurement, you may use the line sensor 130. FIG. Next, the measured luminance is stored in the luminance storage circuit 166 (step S510). Thereafter, the projection optical system 50 is driven (step S512). Then, the luminance is measured again and stored in the luminance storage circuit 166. This process is performed a plurality of times, and the position with the highest contrast among the stored luminances is specified (step S514). Then, the projection optical system 50 is driven to a position having the highest contrast. In this case, when comparing the difference between when the image is projected on the screen 300 and when the image is in focus, the ideal condition when the image is in focus is the right and left monochrome images. This is when the brightness difference of the image is maximized. The projection optical system 50 is moved so as to satisfy such conditions.

  Steps S508 to S514 are performed in order to ensure the minimum projection accuracy in a situation where the brightness on the screen 300 cannot be focused. Thereby, for example, when the brightness on the screen 300 is lowered, if the focus lens is adjusted in advance to a position where the contrast of the projected image is the highest, an advantage that the projected image can be viewed immediately. There is. Even when the brightness on the screen 300 cannot be focused, an image or character string that informs the user that automatic focusing cannot be achieved by adjusting the focus lens in advance to a position where the contrast of the projected image is the highest. Can be easily recognized on the screen 300.

  When the projection optical system 50 is moved to a position where the left / right luminance difference is maximized, the notification image or notification character string stored in advance is output onto the screen 300 by the image output circuit 165 (step S516). Thereby, the user can know that automatic focusing cannot be performed.

  Thereafter, when a certain time has elapsed, the luminance on the screen 300 is measured again (step S518). The brightness measurement here is performed to determine whether the brightness on the screen 300 has changed to a focusable brightness. Therefore, the luminance measurement in this case may examine the luminance (light quantity) of external light such as natural light or room light.

  Then, it is determined whether or not the measured luminance information is bright enough to be focused by the CPU 162 and the luminance comparison calculation circuit 163 (step S520). Here, when the brightness has changed and the brightness conditions allow automatic focusing, the routine proceeds to the normal automatic focusing operation (step S528) described above.

  If it is determined in step S520 that the brightness is not focusable, the counter counts the number of measurements (step S524). Then, it is determined whether the measurement has reached a predetermined number of times (step S524). If the measurement is less than or equal to the predetermined number of times, the process returns to step S518.

  Through the above steps, the focusing unit 100 can identify the cause of inability to focus, solve the problem of continuing focusing for a long time, and can immediately notify the user of the cause when focusing cannot be performed. .

  Hereinafter, an automatic focusing method 600 according to the second embodiment will be described with reference to FIG. Here, FIG. 5 is a flowchart for explaining an automatic focusing method 600 according to the second embodiment.

  The automatic focusing method 600 is substantially the same as the automatic focusing method 500 described above, but steps S522 and S524 of the automatic focusing method 500 are different. Therefore, the description of the same steps is omitted.

  When it is determined in step S620 that the brightness is not focusable, the measurement time is counted by a timer (step S624). Then, it is determined whether the measurement has reached a predetermined time (step S624). If the measurement is less than or equal to the predetermined time, the process returns to step S618, and when the predetermined time is reached, the automatic focusing ends.

  Through the above steps, the focusing unit 100 can identify the cause of inability to focus, solve the problem of continuing focusing for a long time, and can immediately notify the user of the cause when focusing cannot be performed. .

  Hereinafter, an automatic focusing method 700 according to the third embodiment will be described with reference to FIG. Here, FIG. 6 is a flowchart for explaining an automatic focusing method 700 according to the third embodiment.

  First, a trigger for entering an autofocus operation is generated by pressing the AF switch 110 (step S702). When the AF switch 110 is pressed, the projection apparatus 10 projects the black and white sample image divided into the left and right screens stored in the image storage circuit 161 onto the screen 300 by the image output circuit 10.

  Next, image information is acquired by the line sensor 130 (step S704). In this case, the information acquired by the line sensor 130 is luminance information on the screen 300. Thereafter, the luminance information is converted into an analog value by the A / D conversion circuit 164 (step S706).

  The digitally converted luminance information is sent to the CPU 162. The luminance information sent to the CPU 162 calculates the luminance difference between the left and right line sensors inside the CPU 162, calculates the white / black level difference (contrast difference) from the difference between the line sensors (step S708), and determines whether automatic focusing is possible. Judgment is made (step S710). In this case, the data captured by the left and right line sensors 130 is as shown in the graph in FIG. Here, FIG. 3 is a graph showing the contrast difference between the left and right.

  Since the optical axes of the right and left lenses of the line sensor 130 are configured in parallel, when one image is captured at the same time, the capture position of the left and right line sensors 130 is displayed at a position different from the reference position of the sensor. The

  When the contrast is high on the left and right sides of the screen and the focus is in the vicinity of the in-focus state, a graph with a high brightness difference and a wide edge contrast difference, that is, FIG. In this case, the graph indicates that the focus accuracy of the projection apparatus 10 is good when the angle θ is large. Further, although the contrast is high on the left and right sides of the screen, when the focal point is not in the vicinity of the in-focus state, the luminance difference is high and the angle θ is small, that is, a graph as shown in FIG. 5B. Here, when the screen 300 is irradiated with external light such as natural light or room light, the difference in luminance becomes small as shown in FIGS. It becomes difficult to distinguish.

  When the level difference between the black and white is equal to or greater than a certain level (in this case, FIG. 5A and FIG. 5B correspond), the distance calculation circuit 167 calculates the distance between the projection optical system 50 and the screen 300. (Step S712). In this case, the distance between the screen 300 and the projection device 10 is calculated by calculating the difference in luminance in FIG.

  The current position of the projection optical system 50 is grasped (step S714), and the drive amount of the projection optical system 50 is calculated from the calculated data (step S716). At the same time, the movement target position of the projection optical system 50 is also set according to the calculation result (step S718). Then, the projection optical system 50 is moved to the movement target position using the driving unit 150 (step S720). At that time, the projection optical system 50 includes a focus encoder 140 that detects an absolute position, and the position of the projection optical system 50 can be determined from the CPU 162.

  While the driving unit 150 is being driven, the position of the projection optical system 50 is read by the focus encoder 140 (step S722), and the driving unit 150 is driven until the projection optical system 50 reaches the movement target position (step S724). When the projection optical system 50 reaches the movement target position, the driving unit 150 is stopped (step S726). Then, the focusing operation is finished, and a desired image is projected on the screen 300.

  On the other hand, if the black / white level difference is below a certain level (in this case, FIG. 5 (c) and FIG. 5 (d) correspond), the slope of the black / white density change of the reference edge is calculated by the calculation circuit (step S728). In the present embodiment, the function of the arithmetic circuit is performed by the luminance comparison arithmetic circuit 163 or the distance arithmetic circuit 167. A black-and-white edge is determined from information obtained from the line sensor 130, and the defocus amount of the image projected by the comparison means for comparing the inclination obtained by the arithmetic circuit with a predetermined inclination is within a reference value. Is determined (step S730). When the angle θ is small, the defocus amount is other than the reference value, and when the angle θ is larger than the reference value, the defocus amount is small. In the present embodiment, the function of the comparison means is performed by the luminance comparison operation circuit 163.

  When the angle θ is larger than the reference, the density difference between black and white is small due to external light, and the focusing condition is poor. However, when the distance is measured with a small defocus amount, the calculation from the distance measurement data is performed. Since the result is reliable, the same focusing operation as the above-described normal automatic focusing operation is performed.

  On the other hand, the calculation result from the distance measurement data in a state where the defocus amount is large and out of focus includes a distance measurement error, and the data is not reliable. When the edge angle θ is smaller than the reference, the brightness of the screen is measured by the measuring device 120 (step S732). Thereafter, the luminance information is converted into an analog value by the A / D conversion circuit 164 (step S734). At the same time, the movement target position of the projection optical system 50 is also set according to the calculation result (step S742). Then, the projection optical system 50 is moved to the movement target position using the driving unit 150 (step S744).

  While the drive unit 150 is being driven, the position of the projection optical system 50 is read by the focus encoder 140 (step S746), and the drive unit 150 is driven until the projection optical system 50 reaches the movement target position (step S748). When the projection optical system 50 reaches the movement target position, the driving unit 150 is stopped (step S750). Then, the image information is acquired again by the line sensor 130 (step S752). In this case, the information acquired by the line sensor 130 is luminance information on the screen 300. Thereafter, the luminance information is converted into an analog value by the A / D conversion circuit 164 (step S754). Then, the process returns to step S712.

  Through the above steps, the focusing unit 100 can identify the cause of inability to focus, solve the problem of continuing focusing for a long time, and can immediately notify the user of the cause when focusing cannot be performed. .

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

It is a schematic block diagram which shows the structure of the projection apparatus of this invention. It is a block diagram which shows the structure of the focusing part of the projection apparatus shown in FIG. It is a graph which shows the contrast difference of right and left. It is a flowchart for demonstrating the automatic focusing method of the focusing part shown in FIG. It is a flowchart for demonstrating the automatic focusing method which is 2nd Embodiment shown in FIG. It is a flowchart for demonstrating the automatic focusing method which is 3rd Embodiment shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Projection apparatus 20 Light source 30 Illumination optical system 40 Liquid crystal light valve 50 Projection optical system 100 Focusing part 110 AF switch 120 Measuring apparatus 130 Line sensor 140 Focus encoder 150 Driving means 160 Control part

Claims (8)

A projection device for projecting a display image onto a projection surface using irradiation light from a light source, and having a focusing unit for focusing on the projection surface,
The focusing unit includes a measuring unit that measures the luminance of the projection surface;
Determining means for determining whether the brightness measured by the measuring means is a focusable brightness;
And a notifying means for notifying that the brightness is not in focus when the determining means determines that focusing is not possible. The projection apparatus according to claim 1, wherein the focusing unit performs focusing on the projection surface when the determination unit determines that the brightness is in focus. The projection device has a projection optical system for projecting the display image,
The focusing unit includes a driving unit that drives a focusing lens in the projection optical system,
3. The measurement unit according to claim 1, wherein the measurement unit measures the luminance again while driving the focusing lens by the driving unit before the notification unit notifies that the luminance is not in focus. Projection device. A projection device that projects a display image on a projection surface via a projection optical system, and has a focusing unit that focuses on the projection surface,
The focusing unit includes a driving unit that drives a focusing lens in the projection optical system;
And a position storage unit that stores a history of the focal position of the focusing lens driven by the driving unit, and performs focusing based on the history when the projection apparatus is used next time. Projection device. A focusing device that is used in a projection device that projects a display image onto a projection surface using irradiation light from a light source, and performs focusing on the projection surface,
Measuring means for measuring the brightness of the projection surface;
Determining means for determining whether the brightness measured by the measuring means is a focusable brightness;
And a notifying means for notifying that the brightness is not focusable when the determining means determines that focusing is not possible. A focusing method used to project a display image on a projection surface using irradiation light from a light source, and performs focusing on the projection surface,
Measuring the brightness of the projection surface;
Determining whether the brightness measured by the measuring means is a focusable brightness;
And a step of notifying that the brightness is not focusable when the determination means determines that focus is not possible. In the projection device that projects the display image on the display device onto the projection surface via the projection optical system using the irradiation light from the light source,
A housing containing the light source and the display device;
Driving means for moving the focusing lens of the projection optical system;
Distance measuring means for measuring the distance between the projection device and the projection surface to be projected;
Storage means for storing a projection image for distance measurement;
Measuring means for measuring the brightness of the projection surface of the image projected from the projection device;
The brightness on the projection surface of the stored projection image for distance measurement projected from the projection optical system is measured by the measurement means to determine whether the projection surface has an illuminance that allows focusing. A judgment means,
Project an image with different brightness, measure the reflected brightness from the projection surface of the image with different brightness, determine the illuminance that can be focused from the difference in the photometric value, and edge of the projected image of the image with different brightness Calculated from the line sensor of the distance measuring device, and the transition of the luminance difference at the edge is calculated with a graph with the line sensor as the horizontal axis and the luminance as the vertical axis, it is represented by a curve with an angle from a predetermined angle. In the case where the projection surface has a brightness other than the focusable brightness, the projection device is characterized in that the focusing lens is driven to perform the focusing operation. In the projection device that projects the display image on the display device onto the projection surface via the projection optical system using the irradiation light from the light source,
A housing containing the light source and the display device;
Driving means for moving the focusing lens of the projection optical system;
A distance measuring device for measuring a distance between the projection device and a projection surface to be projected;
Storage means for storing a projection image for distance measurement;
Measuring means for measuring the brightness of the projection surface of the image projected from the projection device;
Storage means for storing projection distance information to be compared with the photometric data;
Computing means for deriving projection distance information from the photometric data;
The brightness on the projection surface of the stored projection image for distance measurement projected from the projection optical system is measured by the measurement means to determine whether the projection surface has an illuminance that allows focusing. Comprising a determining means, projecting the stored projection image for distance measurement, photometrically measuring the reflected luminance from the projection surface, and determining from the photometric value that the illuminance cannot be focused, Calculation is performed by a calculation means for deriving projection distance information, a focusing lens is driven from information stored in the storage means for storing the projection distance information, a focusing assist operation is performed, and distance measurement is performed again by the distance measuring device. Projection device.