JP5304843B2 - Light source driving method and projector - Google Patents

Description

  The present invention relates to a light source driving method for supplying power to a light source of a projector, and a projector using the light source driving method.

  The light source of a projector generally emits high-luminance light using a discharge lamp. However, if the discharge of electrons between the electrodes of the lamp is continued for a long time, the discharge trajectory becomes unstable and flickering occurs in the projected image. Therefore, on the side of the light source driving device that supplies power to the lamp to light (drive) it, the drive of supplying a normal current and a current larger than the normal current is periodically performed to stabilize the discharge trajectory. There is a light source driving device having a function of preventing flicker (see Patent Document 1 (FIG. 4)). Alternatively, it is considered that a larger amount of current flows than in the initial period (see Patent Document 2 (FIG. 3) to (FIG. 6)).

  Also, in a projector, as a method for autofocusing a projected image, a test pattern projected on a screen is captured by a monitor camera, and a place where the peak value of the amplitude of the horizontal signal of the captured image (image data) is high is detected. Has proposed a method for obtaining a focus position (see Patent Document 3).

Japanese National Patent Publication No. 10-501919 Japanese translation of PCT publication No. 2002-532867 JP 2000-241874 A

Here, when the autofocus adjustment of Patent Document 3 is performed using the light source driving apparatus that prevents flickering of the projected image of Patent Document 1, the monitor camera is within the period of the drive waveform output by the light source driving apparatus. Since an increase in luminance caused by changing the current is detected, flickering occurs in the captured image data, and the brightness of each image data becomes unstable. Therefore, when the autofocus method using the brightness difference of the image data is used, there is a problem that accurate processing cannot be performed.
In order to avoid this instability of brightness, a method of taking an image of a plurality of images with the focus lens stopped and calculating an average value is also considered and executed. However, it takes time to achieve focus, and manual focus adjustment may be performed in a shorter time.

In addition, it may be possible to determine whether the brightness difference is increased or decreased while moving the focus lens while recognizing the instability of the brightness of the image data, but the focus accuracy is significantly reduced.
In order to avoid instability in brightness of the image data, if the drive for supplying a larger current than the normal current is not performed periodically during the drive waveform period, as described above, Flickering occurs, making the image difficult to see for the user viewing the projected image. For this reason, it is necessary to always perform driving for supplying a larger current than the normal current periodically in the period of the driving waveform.

  SUMMARY An advantage of some aspects of the invention is that it provides a light source driving method for supplying power to a light source of a projector and a projector using the light source driving method.

In order to achieve the above-described object, the present invention provides a light source driving method for a projector that projects light by modulating light from a light source with a spatial light modulator, and driving the light source during autofocus adjustment and during normal operation. It is characterized by different waveforms.
According to such a light source driving method, the light source is driven with different driving waveforms at the time of autofocus adjustment and at the normal time.

  Therefore, when performing autofocus adjustment, for example, the brightness of image data obtained by capturing a projected image with an image sensor or the like can be made constant by driving the light source with a drive waveform for autofocus adjustment. . Further, by driving the light source with a normal driving waveform at normal times, it is possible to project a flicker-free projection image, for example.

According to a preferred aspect of the present invention, there is provided a second light source driving method in which a light source is driven with a first drive waveform during autofocus adjustment, and a current is further added to the first drive waveform during normal operation. The light source is driven with a drive waveform of
According to such a light source driving method, when performing autofocus adjustment, the light source is driven with the first driving waveform. In a normal case, the light source is driven with a second drive waveform obtained by adding a current to the first drive waveform.

  Therefore, when performing autofocus adjustment, the brightness of image data obtained by capturing a projected image with an image sensor or the like can be made constant, for example, by driving the light source with the first drive waveform. In addition, it is possible to project a flicker-free projected image by driving the light source with the second drive waveform at normal times.

In order to achieve the above-described object, the present invention is a projector that projects light by modulating light from a light source with a spatial light modulation element, and the driving waveform of the light source during auto focus adjustment and during normal time. It is characterized by making it different.
According to such a projector, the light source is driven with different drive waveforms at the time of autofocus adjustment and at the normal time.

  Therefore, when performing autofocus adjustment, for example, the brightness of image data obtained by capturing a projected image with an image sensor or the like can be made constant by driving the light source with a drive waveform for autofocus adjustment. . Further, by driving the light source with a normal driving waveform at normal times, it is possible to project a flicker-free projection image, for example.

According to a preferred aspect of the present invention, the projector is a projector in which the light source is driven with the first drive waveform during autofocus adjustment, and the current is further added to the first drive waveform during normal operation. The light source is driven by a waveform.
According to such a projector, when performing autofocus adjustment, the light source is driven with the first drive waveform. In a normal case, the light source is driven with a second drive waveform obtained by adding a current to the first drive waveform.

  Therefore, when performing autofocus adjustment, the brightness of image data obtained by capturing a projected image with an image sensor or the like can be made constant, for example, by driving the light source with the first drive waveform. In addition, it is possible to project a flicker-free projected image by driving the light source with the second drive waveform at normal times.

According to a preferred aspect of the present invention, the projector is a light source driving unit that outputs a first driving waveform and a second driving waveform, and first and second driving waveforms output from the light source driving unit. And a current control instructing unit for instructing switching control.
According to such a projector, the light source drive unit outputs a first drive waveform and a second drive waveform for driving the light source. The current control instruction unit issues a control instruction for switching between the first and second drive waveforms output from the light source driving unit.

  Therefore, for example, when a projected image is captured using an imaging device, the captured image data is detected, and the autofocus adjustment of the projected image is performed based on the detection result, the current control instruction unit is A control instruction for switching the second drive waveform to the first drive waveform during autofocus adjustment can be performed. Further, when the autofocus adjustment is completed, a control instruction for switching to the second drive waveform which is a normal drive waveform can be issued. As a result, the brightness of each captured image data can be made constant during autofocus adjustment, so that a projected image can be detected accurately and accurate autofocus adjustment can be performed. Further, it is possible to project a projected image without flicker at normal times.

Further, according to a preferred aspect of the present invention, in order to perform autofocus adjustment, the projector acquires an image acquisition unit that receives reflected light of a projection image and acquires image data, and an image acquired by the image acquisition unit. And an image processing unit that performs processing based on the data.
Such a projector includes an image acquisition unit and an image processing unit in order to perform autofocus adjustment. Then, the image acquisition unit receives reflected light of the projection image and acquires it as image data, and the image processing unit processes the acquired image data.

  Therefore, when performing autofocus adjustment, the current control instruction unit switches to the first drive waveform to drive the light source. Therefore, when the image acquisition unit receives the reflected light of the projection image and acquires the image data, the brightness for each acquired image data can be made constant. As a result, the image processing unit can perform accurate autofocus adjustment by analyzing the image data.

In order to achieve the above-described object, the present invention is a light source driving device for a projector, and includes a light source driving unit, a current control instruction unit, and a control unit that controls the current control instruction unit. It is characterized by.
According to such a light source drive device, the light source drive unit outputs the first and second drive waveforms for driving the light source, and the current control instruction unit switches the drive waveform in the light source drive unit. Provide control instructions. Then, the control unit controls the current control instruction unit.

  As a result, when this light source driving device is mounted on a projector, for example, when a projected image is captured using an image sensor, the captured image data is detected, and the projected image is adjusted based on the detection result. In addition, under the control of the control unit, the current control instruction unit can issue a control instruction to switch the driving waveform output from the light source driving unit to the first driving waveform during autofocus adjustment. As a result, the brightness of each captured image data can be made constant, so that a projected image can be accurately detected and accurate autofocus adjustment can be performed. Further, at the normal time, it is possible to project a flicker-free projection image by performing a control instruction for the current control instruction unit to switch to the normal second drive waveform.

1 is a schematic configuration diagram when performing autofocus adjustment of a projector according to a first embodiment of the present invention. FIG. The figure which shows a lamp drive current and shutter opening timing. The figure showing the time change of the brightness when flickering generate | occur | produces in image data. The flowchart in the case of performing autofocus adjustment. The figure which represented the brightness difference of image data on the time axis. The schematic block diagram of the projector in the case of performing the auto zoom adjustment of the projector which concerns on 2nd Embodiment. The flowchart in the case of performing auto zoom adjustment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
(First embodiment)

  FIG. 1 is a schematic configuration diagram when performing autofocus adjustment using a lamp driving power control unit as a light source driving unit in a projector.

The configuration of the projector 1 will be described with reference to FIG.
The projector 1 includes a lamp 2 as a light source that emits light, and an optical system (not shown) that performs polarization conversion on the emitted light from the lamp 2, color-separates, modulates the light by a spatial light modulation element, and combines the light. And a projection lens 4 for enlarging and projecting the combined light. Then, an image as composite light is projected onto a screen 100 installed on a wall or the like.
The projector 1 also includes a lamp driving power control unit 3 as a light source driving unit that supplies power to the lamp 2. Further, the drive waveform control circuit 3 has a built-in lamp driving power control unit 3 that adds a current to the first driving waveform and the first driving waveform to generate a second driving waveform. A high current ON / OFF switching unit 5 is provided as a current control instruction unit for instructing switching. A CPU (Central Processing Unit) 6 is provided as a control unit that controls the entire operation of the projector 1 including these operations.

  As a configuration for performing the autofocus adjustment, the projector 1 captures an image as an image acquisition unit that captures the projected image as image data by receiving the reflected light of the image projected on the screen 100 by the autofocus adjustment unit. A unit 7, an image memory 8 for storing captured image data, and an image processing unit 9 for analyzing the image data are provided. Further, the focus lens 41 constituting the projection lens 4 that receives the signal of the analysis result in the image processing unit 9 and focuses the projected image, the focus lens drive unit 10 that drives the focus lens 41, and the drive of the focus lens 41 And a focus lens position detection unit 11 for detecting the position to be operated.

In the present embodiment, a CCD (Charge Coupled Device) camera is adopted as the imaging unit 7 and is installed on the projection side front surface of the projector body. Further, a photoelectric rotary encoder is employed as the focus lens position detection unit 11 to detect the position (movement distance) of the focus lens 41. The focus lens driving unit 10 employs a DC (direct current) motor to drive the focus lens 41. These controls are performed by the CPU 6.
The description of the autofocus adjustment based on the configuration of FIG. 1 will be described in detail with reference to FIG.

FIG. 2 is a diagram illustrating a lamp driving current waveform output from the lamp driving power control unit and a shutter opening timing of the CCD camera of the imaging unit.
The driving current of the lamp driving power control unit 3 and the shutter opening timing of the CCD camera will be described with reference to FIG.

  Regarding the current waveform which is the lamp driving current output from the lamp driving power control unit 3 in the figure, the horizontal axis indicates time and the vertical axis indicates the driving current. Moreover, the current waveform in the figure shows a second drive waveform for driving the lamp 2 in a normal state. This drive current is an alternating current, and the polarity is inverted (+/−) and repeated at a period T. Specifically, a current I1 that is a driving current according to the specification of the lamp 2 is output only for a time T1, and a current larger than the current I1 for a moment T2 immediately before the current switches from + to −. A current I2 (hereinafter referred to as a high current) is output. This output pattern is also performed on the-side, +/- is repeatedly output as one cycle T, and a current is supplied to the lamp 2. The frequency with respect to the period T in this embodiment employs 90 Hz.

  Thereby, the discharge-type lamp 2 discharges electrons between the electrodes of the arc tube (not shown) constituting the lamp 2 by applying the alternating current of the driving current I1 of the lamp driving power control unit 3. Emits light and emits light. The lamp 2 applies a current I2, which is higher than the normal current I1, for a moment T2, thereby stabilizing the electron discharge trajectory between the electrodes. This avoids the problem of flickering of the projected image that occurs when the discharge trajectory between the electrodes becomes unstable if the electron discharge is continued for a long time.

  Here, a problem in the case where autofocus adjustment is performed using the lamp drive power control unit 3 that outputs the second drive waveform that prevents flickering of the projected image will be described.

  By applying the high current I2 periodically between the electrodes of the lamp 2 for a time T2, the discharge trajectory can be stabilized and flickering of the projected image can be prevented. This means that all flickering can be prevented. However, the CCD camera as the image pickup unit 7 in the case of performing autofocus adjustment takes in a projection image as image data by applying the high current I2, which is a flicker avoidance method, for an instant T2. Thus, there is a problem that the brightness of each image data is not stable (this phenomenon is called flicker of image data).

The cause of the malfunction will be described with reference to the shutter opening timing diagram shown in FIG.
When the imaging unit 7 starts autofocus adjustment, for example, when the shutter of the CCD camera is opened until time t2 at the timing (time t1) at which the lamp driving current is first switched from − to +, The lamp driving current is I1, and the lamp driving current does not change. However, when the CCD camera captures a projected image at a predetermined period, the shutter opening timing always comes from time t _n to t _{n + 1} . The lamp driving current in this case is a driving current portion of the current I1 and the high current I2. In this case, the brightness of the image data captured at the timing from the time t _n to t _{n + 1} is extremely bright with respect to the image data captured at the timing from the first time t1 to t2. Become.
As described above, a phenomenon (flicker) in which the brightness differs for each image data occurs due to the difference in the corresponding lamp driving current at the timing of imaging.

  FIG. 3 is a diagram illustrating temporal changes in brightness when flickering occurs in image data obtained by capturing an image of a projected image by an imaging unit. A change in brightness of the image data due to the flicker of the image data described above will be described with reference to FIG.

In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the brightness of image data. Further, FIG. 3 shows a temporal (positional) change in brightness when the shutter opening timing is gradually shifted in the period T of the lamp driving current shown in FIG.
The brightness when the shutter opening time described in FIG. 2 is located within the period in which only the driving current I1 is applied to the lamp 2 (for example, within the period from time t1 to t2) is L1. In contrast, when the shutter opening time is located within a period including the high current I2 (for example, within a period from time t _n to t _{n + 1} ), the brightness of the image data is increased as in the time T3 portion. The part that becomes brighter up to L2 appears. As a result, the accuracy of autofocus adjustment using the brightness difference is affected.

  FIG. 4 is a flowchart for performing autofocus adjustment in the present embodiment. The autofocus adjustment method of this embodiment will be described with reference to FIGS.

In step S100, the user performs an input operation from an input unit (not shown) provided in the projector 1, the CPU 6 receives the operation signal, and activates the projector 1.
In step S <b> 101, the CPU 6 sends a signal for instructing the lamp driving power control unit 3 to drive the lamp 2 to emit light to the high current ON / OFF switching unit 5. In response to the signal, the high current ON / OFF switching unit 5 outputs the current of the second drive waveform including the current I1 and the high current I2 to the high current generation circuit 31 of the lamp drive power control unit 3. An “ON” signal that is a control instruction signal is sent. The high current generation circuit 31 receives the “ON” signal, and starts the output of the current of the second drive waveform composed of the current I1 and the high current I2 from the lamp drive power control unit 3 (the drive waveform shown in FIG. 2). The same). The lamp 2 starts to emit light when the output current is supplied from the lamp driving power control unit 3.

In step S102, the user performs an input operation for autofocus adjustment from the input unit provided in the projector 1, the CPU 6 receives the operation signal, and autofocus adjustment is started. Then, the CPU 6 projects a focus pattern for autofocus adjustment onto the screen 100 by the projection lens 4.
In this embodiment, as the focus pattern, an image in which a plurality of black straight lines are arranged on a plane of a white image to form a stripe pattern is used.

  In step S <b> 103, the CPU 6 sends a signal for instructing the lamp 2 to drive the lamp driving power control unit 3 in order to cause the lamp 2 to emit light for performing autofocus adjustment, to the high current ON / OFF switching unit 5. . In response to the signal, the high current ON / OFF switching unit 5 sends the second drive waveform current composed of the current I1 and the high current I2 to the high current generation circuit 31 of the lamp drive power control unit 3 from the current I1. An “OFF” signal that is a control instruction signal for outputting a current switched to the current of the first drive waveform is sent. The high current generation circuit 31 receives the “OFF” signal, and converts the current of the second drive waveform composed of the current I1 and the high current I2 from the lamp drive power control unit 3 into the current of the first drive waveform composed of the current I1. Output the switched current. Thereby, the high current I2 is switched to the current I1, and output of the current I1 is started. The period T shown in FIG. 2 does not change, and the high current I2, which is the drive current during the time T2, is switched to the current I1 and output. The lamp 2 is switched in light emission by supplying a current having a first driving waveform from the lamp driving power control unit 3.

  Next, the process proceeds to step S104. In step S104, autofocus adjustment is started. The autofocus adjustment method in this embodiment will be described in the steps after step S105.

  In step S <b> 105, the focus lens driving unit 10 starts driving the focus lens 41 from a position where the focal point is closer than the screen 100. In step S <b> 106, the focus lens position detection unit 11 detects the position of the focus lens 41. In step S107, a focus pattern, which is a projected image at the position where the position is detected, is picked up by a CCD camera as the image pickup unit 7 and acquired as image data. In step S <b> 108, the captured image data of the focus pattern is stored in the image memory 8.

  In step S <b> 109, the image processing unit 9 detects the brightness difference between adjacent pixels for all the pixels of one piece of image data based on the image data stored in the image memory 8. In step S110, the CPU 6 calculates the sum of the absolute values of the brightness differences based on the detected brightness difference. In step S111, the CPU 6 compares the calculation result with the previous image data, and determines whether or not the current total is smaller than the previous total (whether or not the previous total is maximum). . Here, when it does not become small, it transfers to step S106 again and performs from the position detection of the focus lens 41. FIG. Steps S106 to S111 are repeated until it is determined in step S111 that the sum of the absolute values of the brightness differences is smaller than the previous sum. In this way, the focus lens position where the sum of the absolute values of the brightness differences is maximized is searched for.

  In step S111, when the CPU 6 determines that the sum of the absolute values of the lightness difference this time is smaller than the previous time (the previous sum is the maximum), the focus lens position with respect to the previous image data is focused. It will be determined that the position. At that time, the focus lens driving unit 10 stops the movement of the focus lens 41 by a signal from the CPU 6. In step S112, the CPU 6 drives the focus lens driving unit 10 to move the focus lens 41 so that the previous focus lens position is in focus. As a result, the process proceeds to step S113, and the autofocus adjustment ends. Then, the process proceeds to step S114.

In step S114, the CPU 6 drives the lamp driving power control unit 3 to cause the high current ON / OFF switching unit 5 to perform normal light emission (light emission for projecting an image used by the user). Send a signal to give instructions to do. In response to the signal, the high current ON / OFF switching unit 5 supplies the high current generation circuit 31 with the current having the first drive waveform including the current I1 and the second drive including the current I1 and the high current I2 again. In order to output as a waveform current, an “ON” signal which is a control instruction signal is sent. The high current generation circuit 31 receives the “ON” signal, and again converts the current of the first drive waveform composed of the current I1 from the lamp drive power control unit 3 into the current of the second drive waveform composed of the current I1 and the high current I2. To output. Thereby, the lamp driving power control unit 3 is switched to the lamp driving current similar to that in FIG. 2, and is output as the second driving waveform. The lamp 2 is switched to light emission without flickering in the projected image by supplying the current of the second driving waveform from the lamp driving power control unit 3.
Auto focus adjustment is performed by this series of flowcharts.

  Here, during autofocus adjustment, since the driving with the high current I2 for preventing flickering of the projected image is not performed, the projected image basically has flickering. However, the autofocus adjustment is at a level where the brightness difference of the projected image is low because the focus lens 41 is out of focus for a long time and the flicker is hardly perceived. Further, in the present embodiment, the autofocus adjustment is completed within a short time of 5 seconds or less including disturbance processing. At the same time as the autofocus adjustment is completed, the drive current is switched to the second drive waveform that outputs the high current I2 in accordance with an instruction from the high current ON / OFF switching unit 5 so that the flicker of the projected image is reduced as much as possible. doing.

FIG. 5 shows the brightness difference of the image data obtained by capturing the projected image when the focus lens 41 is moved at a constant speed from the position where the focus lens 41 is in focus at a short distance from the distance to the screen 100 to the position where the focus is at a long distance. It is the figure represented with respect to the time axis. FIG. 5A is a diagram of brightness difference when the high current generation circuit 31 is “ON”. FIG. 5B is a diagram of brightness difference when the high current generation circuit 31 is “OFF”.
The case where the high current generation circuit 31 is “ON” and “OFF” will be described with reference to FIG.

  In FIG. 5A, when the high current generation circuit 31 is “ON” (in the case of the second drive waveform using the high current I2), the focus lens 41 is moved at a random position while moving. Places (time (points) represented by t11, t12, t13, t14 in the figure) and places of normal brightness appear. Therefore, when the CPU 6 determines the maximum value of the sum of the brightness differences based on the analysis result in the image processing unit 9, it cannot determine whether the position is in focus. The position t10 in the figure is the position where the focus is achieved.

On the other hand, in FIG. 5B, when the high current generation circuit 31 is “OFF” (in the case of the first drive waveform driven by dropping the high current I2 into the current I1), the focus lens 41 is moved. Even so, since the brightness of the image data is stable, the change in brightness difference is also stable. For this reason, the change in brightness difference gradually increases as the focus starts, reaches a maximum at t10 at the focused position, and gradually decreases as the focus shifts.
Thus, when performing autofocus adjustment, the high current generation circuit 31 is switched from “ON” to “OFF” to switch the high current I2 to the current I1 (the second drive waveform is the first drive waveform). 5), the uniform brightness difference changes as shown in FIG. 5B, and the autofocus adjustment can be performed accurately.

According to the first embodiment described above, the following effects can be obtained.
(1) Since the high current ON / OFF switching unit 5 is provided, during autofocus adjustment, the high current generation circuit 31 is switched from “ON” to “OFF” to switch the high current I2 to the current I1 (second The drive waveform is switched to the first drive waveform), so that the captured image data can have a stable brightness, and the autofocus adjustment can be performed accurately.

  (2) Conventionally, in order to compare and judge the maximum value of the sum of absolute values of brightness differences, a plurality of pieces of image data are required for each measurement point of the focus lens position, and the image data is analyzed. Since the brightness variation was smoothed by calculating the average value and the sum of brightness differences was calculated, it took time to adjust the autofocus. However, the high current ON / OFF switching unit 5 is provided to switch the high current generation circuit 31 from “ON” to “OFF” to drop the high current I2 to the current I1 (the second drive waveform is changed to the first drive waveform). The lamp driving power control unit 3 can be driven by switching to a waveform), so that image data with stable brightness can be taken into the image memory 8. Then, only one image data is required for each measurement location, and autofocus adjustment can be performed at high speed. In the conventional autofocus adjustment, the time required from the start to the end is about 1 minute, but in this embodiment, high-speed processing of 5 seconds or less is realized.

  (3) During autofocus adjustment, the projection image is basically flickered because it is driven with the first drive waveform that is not driven with the high current I2 for preventing flickering of the projected image. However, the autofocus adjustment is at a level where the brightness difference of the projected image is low and the user does not feel flicker because the period when the focus lens 41 is out of focus is long. Further, in this embodiment, the autofocus adjustment is completed in a short time of 5 seconds or less including disturbance processing. At the same time as the autofocus adjustment is completed, the drive current is switched to the second drive waveform that outputs the high current I2 in accordance with an instruction from the high current ON / OFF switching unit 5 so that the flicker of the projected image is reduced as much as possible. it can. As a result, the autofocus adjustment can be performed with almost no flickering of the projected image for the user.

  (4) Control for controlling the lamp driving power control unit 3 as the light source driving unit, the high current ON / OFF switching unit 5 as the current control instruction unit, and the high current ON / OFF switching unit 5 in the light source driving device. It can comprise with CPU6 as a part. Then, by using the light source driving device for the projector 1 in the present embodiment, when the autofocus adjustment is performed, the driving that the high current ON / OFF switching unit 5 outputs from the lamp driving power control unit 3 is controlled by the CPU 6. A waveform control instruction (in this case, output of the first drive waveform) can be performed. As a result, the brightness of each captured image data can be made constant, so that the projected image can be detected accurately and adjusted accurately.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 6 is a schematic configuration diagram when auto-zoom adjustment is performed using a lamp driving power control unit as a light source driving unit in the projector. The configuration of the projector 1 will be described with reference to FIG.

  In the configuration of FIG. 6, different components from the configuration of FIG. 1 will be described. In addition, regarding the same components as in FIG.

  1 are the zoom lens 42, the focus lens driving unit 10 is the zoom lens driving unit 12, and the focus lens position detecting unit 11 is the zoom lens position detecting unit 13. It is that you are. Other configurations are the same as those in FIG.

  FIG. 7 is a flowchart for performing auto-zoom adjustment. Further, in the flowchart shown in FIG. 4, step S <b> 101 and subsequent steps are the flowchart of FIG. 7. The operation will be described with reference to FIG.

  In step S200, the user performs an input operation for auto-zoom adjustment from the input unit provided in the projector 1, the CPU 6 receives the operation signal, and auto-zoom adjustment is started. Then, the CPU 6 projects a zoom pattern for auto zoom adjustment onto the screen 100 by the projection lens 4. In this case, an all-white image is projected as the zoom pattern.

  In step S201, as in step S103 of FIG. 4, the CPU 6 drives the lamp driving power control unit 3 to cause the high current ON / OFF switching unit 5 to perform light emission for performing auto zoom adjustment on the lamp 2. Send a signal to give instructions. In response to the signal, the high current ON / OFF switching unit 5 sends the second drive waveform current composed of the current I1 and the high current I2 to the high current generation circuit 31 of the lamp drive power control unit 3 from the current I1. An “OFF” signal that is a control instruction signal for outputting a current switched to the current of the first drive waveform is sent. The high current generation circuit 31 receives the “OFF” signal, and converts the current of the second drive waveform composed of the current I1 and the high current I2 from the lamp drive power control unit 3 into the current of the first drive waveform composed of the current I1. Output the switched current. Thereby, the high current I2 is switched to the current I1, and output of the current I1 is started. The lamp 2 is switched in light emission by supplying a current having a first driving waveform from the lamp driving power control unit 3.

  Next, the process proceeds to step S202. In step S202, auto zoom adjustment is started. Then, an all white screen is projected on the screen 100 as a zoom pattern. The auto-zoom adjustment method in this embodiment will be described in the steps after step S203.

  In step S <b> 203, the zoom lens driving unit 12 starts driving the zoom lens 42. In step S <b> 204, the zoom lens position detection unit 13 detects the position of the zoom lens 42. In step S205, a zoom pattern, which is a projected image at the position where the position is detected, is captured by a CCD camera, which is the imaging unit 7, and acquired as image data. In step S206, the image data of the zoom pattern captured in the image memory 8 is stored.

  In step S <b> 207, the image processing unit 9 detects the brightness for all the pixels of the image data based on the image data stored in the image memory 8. In step S208, the CPU 6 determines an all white range based on the detected brightness based on a predetermined threshold. Next, the outer shape of the screen 100 is determined by a predetermined threshold within the range of all white. Here, when the outer shape of the screen 100 cannot be determined, it is determined that the all white screen is in the outer shape of the screen 100. In this case, the process returns to step S204, and the zoom lens position detection unit 13 detects the position where the zoom lens driving unit 12 has driven the zoom lens 42 in order to increase the zoom ratio as the position of the next zoom lens. In step S205, the zoom pattern enlarged from the previous time is imaged by the CCD camera. In this manner, this series of operations is repeated until the outline range of the screen 100 can be determined in step S208.

  If the CPU 6 determines in step S208 that the outline range of the screen 100 is within the all white screen, the process proceeds to step S209. In step S209, the CPU 6 reads the outer position of the screen 100 from the detected value of brightness difference, and the outer data of the screen 100 read from the detected value of brightness difference based on the initial position data of the zoom lens 42. Compare. Then, the CPU 6 calculates the amount of movement from the current position of the zoom lens 42 to determine how far the entire white screen will enter the outer shape of the screen 100. Next, in step S <b> 210, the CPU 6 drives the zoom lens driving unit 12 and the zoom lens position detection unit 13 based on the current position and movement amount of the zoom lens 42, and moves the zoom lens 42, thereby moving the screen 100. Put a white screen in the outline. As a result, the process proceeds to step S211, and the automatic zoom adjustment ends.

  In step S208, if the CPU 6 determines that the outline range of the screen 100 is within the all-white screen, the process proceeds to step S209, and the CPU 6 changes the outline position of the screen 100 to the brightness difference. Read from the detected value. Then, based on the initial position data of the zoom lens 42, it is compared with the outline data of the screen 100 read from the detected value of brightness difference. Then, the CPU 6 calculates the amount of movement from the current position of the zoom lens 42 to determine how far the entire white screen will enter the outer shape of the screen 100. Next, in step S <b> 210, the CPU 6 drives the zoom lens driving unit 12 and the zoom lens position detection unit 13 based on the current position and the movement amount of the zoom lens 42, and moves the zoom lens 42 to make it the outer shape of the screen 100. Auto zoom adjustment is performed by putting an all-white screen.

When the above-described auto zoom adjustment is completed, the process proceeds to step S212.
In step S212, as in step S114 of FIG. 4, the CPU 6 causes the high current ON / OFF switching unit 5 to cause the lamp 2 to perform normal light emission (light emission for projecting an image used by the user). Sends a signal to issue an instruction to drive the lamp driving power control unit 3. In response to the signal, the high current ON / OFF switching unit 5 supplies the high current generation circuit 31 with the current having the first drive waveform including the current I1 and the second drive including the current I1 and the high current I2 again. In order to output as a waveform current, an “ON” signal which is a control instruction signal is sent. The high current generation circuit 31 receives the “ON” signal, and again converts the current of the first drive waveform composed of the current I1 from the lamp drive power control unit 3 into the current of the second drive waveform composed of the current I1 and the high current I2. To output. Thereby, the lamp driving power control unit 3 is switched to the lamp driving current similar to that in FIG. 2, and is output as the second driving waveform. The lamp 2 is switched to light emission without flickering in the projected image by supplying the current of the second driving waveform from the lamp driving power control unit 3.
The automatic zoom adjustment using the high current ON / OFF switching unit 5 is performed by the above-described configuration and flowchart.

According to the second embodiment described above, the following effects can be obtained.
(1) Since the high current ON / OFF switching unit 5 is provided, during auto zoom adjustment, the high current generation circuit 31 is switched from “ON” to “OFF” to switch the high current I2 to the current I1 (second The drive waveform is switched to the first drive waveform), so that the captured image data can have a stable brightness, and the auto zoom adjustment can be performed accurately.

  (2) Even in auto zoom adjustment, since there is no variation in brightness in image data obtained by imaging a zoom pattern, the number of image data to be taken may be one in one place, so that auto zoom adjustment is performed at high speed. Can do. Therefore, flickering of the projected image during auto zoom adjustment can be reduced as much as possible. As a result, the auto zoom adjustment can be performed with almost no flickering of the projected image for the user.

  The present invention is not limited to the above-described embodiment, and various changes and improvements can be added to the above-described embodiment. A modification will be described below.

  (Modification 1) In the above embodiment, the high current ON / OFF switching unit 5 switches the high current I2 from the current I1 to the high current generation circuit 31 (the second drive waveform is changed to the first drive waveform). In order to output the switched current, an “OFF” signal is output as a control instruction signal. However, the present invention is not limited to this, and the high current I2 may be switched to a preset current value and output by an “OFF” signal. Thereby, it is possible to set a current value to be switched by looking at the flicker level of the projected image. Therefore, for example, if flicker is found in the projected image during autofocus adjustment, a current value slightly higher than the current I1 can be output without reducing the high current I2 to the current I1, thereby reducing flicker in the projected image. . Thus, the current value to be switched can be set by checking the flickering of both the projected image and the image data.

  (Modification 2) According to the embodiment, since the high current ON / OFF switching unit 5 is provided and the auto focus adjustment and the auto zoom adjustment can be performed, the keystone distortion correction of the projected image can be performed. Specifically, when trapezoidal distortion occurs, the distance and angle of the projector 1 with respect to the screen 100 can be calculated by autofocus adjustment, and correction by autozoom adjustment can be added to perform trapezoidal distortion correction. . At that time, since the brightness of each image data picked up by the image pickup unit 7 is stable, the keystone distortion correction can be performed at high speed and accurately.

  (Modification 3) The projector 1 provided with the high current ON / OFF switching unit 5 in the above embodiment is a transmissive liquid crystal projector. However, the present invention is not limited to this, and the present invention can be implemented in a projector that employs a DLP (registered trademark) (Digital Light Processing) method, a LCOS (Liquid Crystal On Silicon) method that is a reflective liquid crystal method, or the like. As a result, when performing auto focus adjustment, auto zoom adjustment, or the like for a projector employing various methods, the drive waveform of the lamp 2 can be switched by the high current ON / OFF switching unit 5. It is possible to obtain a projection image without image and image data.

  (Modification 4) In the first embodiment, since the high current ON / OFF switching unit 5 is provided, the captured image data can be made stable brightness without flicker during autofocus adjustment. However, the present invention is not limited to this. For example, each color (red, green, blue, white, black, etc.) is projected onto an unspecified projection target surface such as a wall, and the original color with respect to the color of the projection target surface. The high current ON / OFF switching unit 5 can also be used when executing a color correction function for a projection target surface such as detecting a difference between the two and projecting with reverse correction. As a result, a plurality of pieces of image data are conventionally required due to variations in brightness. However, one piece of image data is sufficient, and the execution speed of the color correction function for the projection target surface can be improved.

  (Modification 5) In the first embodiment, as the autofocus adjustment method, the sum of absolute values of brightness differences adjacent to all pixels of image data is calculated. However, the present invention is not limited to this method. For example, a specific pixel is set instead of all pixels of the image data, and the sum of absolute values of adjacent brightness differences is calculated only for that pixel. Also good. As a result, it is possible to perform faster autofocus adjustment.

(Modification 6) In the first embodiment, as the autofocus adjustment method, the sum of absolute values of brightness differences adjacent to all pixels of the image data is calculated, and the focus lens for the image data having the maximum sum. A method is used in which the position 41 is in a focused position. However, the method is not limited to this method. For example, a method of simply setting the position of the focus lens 41 where the brightness of the brightest portion in the image data is maximized to the focused position may be used. Alternatively, a method may be used in which the position of the focus lens 41 where the brightness difference or ratio between the brightest part and the darkest part in the image data is maximized is the in-focus position. Alternatively, a method may be used in which the position of the focus lens 41 that maximizes the sum of the powers of the absolute values of the brightness differences between adjacent pixels of the image data is the in-focus position.
As described above, various focus adjustment methods can be used.

  (Modification 7) In the first embodiment, according to the flowchart shown in FIG. 4, when the autofocus adjustment is started in step S <b> 102, it is started by performing an input operation to the projector 1 by the user. Become. However, the present invention is not limited to this, and if the high current generation circuit 31 is turned “ON” in step S101, the CPU 6 may execute a program for issuing a signal for starting an autofocus adjustment start operation. This eliminates the need for user input operations and simplifies the autofocus adjustment operation.

  (Modification 8) The projection image used for autofocus adjustment of the first embodiment uses an image in which a stripe pattern in which a plurality of black straight lines are arranged on the plane of a white image is used as the focus pattern. ing. However, the present invention is not limited to this, and if the entire image is a still image with a non-uniform color, autofocus adjustment can be performed. Accordingly, it is possible to perform autofocus adjustment even using a still image used by the user, and the convenience in the operation for entering the user's presentation is improved.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Lamp as light source, 3 ... Lamp drive power control part as light source drive part, 4 ... Projection lens, 5 ... High current ON / OFF switching part as current control instruction | indication part, 6 ... As control part , 7 ... an imaging unit as an image acquisition unit, 8 ... an image memory, 9 ... an image processing unit, 10 ... a focus lens drive unit, 11 ... a focus lens position detection unit, 12 ... a zoom lens drive unit, 13 ... zoom Lens position detection unit 31... High current generation circuit constituting a lamp driving power control unit 41. Focus lens 42. Zoom lens

Claims (5)

A light source driving method for a projector that projects light by modulating light from a light source, which is a discharge lamp, with a spatial light modulator,
An image having a predetermined color is projected onto the projection target surface, the difference between the color of the projection target surface and the original color is detected, and the color correction function is executed based on this difference, and the normal time Different light source drive waveforms ,
When the color correction function is executed, the light source is driven with a first drive waveform, and at the normal time, the light source is driven with a second drive waveform obtained by adding a current to the first drive waveform. A light source driving method as a feature. A projector that projects light by modulating light from a light source, which is a discharge lamp, with a spatial light modulator,
An image having a predetermined color is projected onto the projection target surface, the difference between the color of the projection target surface and the original color is detected, and the color correction function is executed based on this difference, and the normal time Different light source drive waveforms ,
When the color correction function is executed, the light source is driven with a first drive waveform, and at the normal time, the light source is driven with a second drive waveform obtained by adding a current to the first drive waveform. Characteristic projector. The projector according to claim 2 ,
A light source driver that outputs the first drive waveform and the second drive waveform;
A projector comprising: a current control instruction unit that issues a control instruction for switching between the first and second drive waveforms output from the light source drive unit. The projector according to claim 2 or 3 , wherein
In order to execute the color correction function, an image acquisition unit that receives reflected light of a projection image and acquires image data;
An image processing unit that performs processing based on image data acquired by the image acquisition unit. A light source driving device for a projector according to claim 3 ,
A light source drive device comprising: the light source drive unit; the current control instruction unit; and a control unit that controls the current control instruction unit.

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