JP2009053452A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a lamp current at every segment with a simple configuration in an image projection apparatus which variably controlling the lamp current at every segment of a rotating color filter. <P>SOLUTION: The image projection apparatus which performs color separation of light of a high-pressure discharge lamp 2 with the rotating color filter 4, modulates the color-separated light with an image display element 6 and projects the modulated light on a screen with a projection lens 7 is provided with a synchronizing signal generation device 10 of detecting a rotation state of the rotating color filter 4 and generating a synchronizing signal Sync, wherein the synchronizing signal Sync inputs an ON signal to a high-pressure discharge lamp lighting device 1 in synchronization with a time width of one segment among a plurality of color segments in the rotating color filter 4, sets time widths of remaining color segments in accordance with the time width of the ON signal and controls the lamp current I<SB>L</SB>of the high-pressure discharge lamp 2 so as to become a current value set every color segment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image projection apparatus using an image display element such as a rotating color filter and a fine movable mirror integrated element.

  Conventionally, as an image projection device used for projectors, projection televisions, etc., a light beam from a high pressure discharge lamp lit by a high pressure discharge lamp lighting device is irradiated on a rotating color filter and divided into three primary colors of light such as RGB. An apparatus for creating an image using a reflective image display element called DMD (digital micromirror device) and projecting a color image on a screen via a projection lens is known.

  The projector market is rapidly expanding not only for business use but also for home use, and further market expansion is expected in the future. However, the TV market is shifting to larger screens as represented by LCD TVs and plasma TVs. Until now, large-screen liquid crystal televisions and plasma televisions were expensive, and with the advancement of technologies such as improving the image quality of projectors, the demand for inexpensive rear-projection televisions that made use of this technology was increasing, particularly in North America. However, in recent years, the price of liquid crystal televisions and plasma televisions has been reduced, and the difference from inexpensive rear projection televisions tends to be reduced. Therefore, in order to maintain and expand the projection television market, further improvements in image quality and price reduction are important factors.

Therefore, an improvement in color reproducibility can be mentioned to improve the image quality. In this regard, Japanese Patent Publication No. 8-505031 (Patent Document 1) discloses that a rotary color wheel has three color segments of R (red), G (green), and B (blue) in a system in which a high-pressure discharge lamp is turned on by alternating current. In an image projection apparatus constituted by types, it has been proposed to change the current level for each color segment. Also, in Japanese Patent Application Laid-Open No. 2007-79330 (Patent Document 2), in the method of direct-current lighting of a high pressure discharge lamp, the color segments of the rotating color filter are R (red), G (green), B (blue), Y ( It has been proposed to improve image quality by changing the current level for each color segment in an image projection apparatus configured with six types of yellow, M (magenta), and C (cyan).
Japanese National Patent Publication No. 8-505031 JP 2007-79330 A

  However, in Patent Document 1, the ON / OFF signal of the synchronization signal frequency is determined according to the number of segments of the rotating color filter used by each user (projector manufacturer), the angle of each segment, the number of rotations of the rotating color filter, that is, the synchronization signal frequency, and the like. The timing must be changed. Also, the on-time of the synchronization signal must consider the minimum time of each segment used by the user. Further, in Patent Document 2, a synchronization signal is generated for each segment of the rotating color filter, and there is a problem that generation of the synchronization signal and processing thereof are complicated.

  An object of the present invention is to enable control of a lamp current for each segment with a simple configuration in an image projection apparatus that variably controls the lamp current for each segment of a rotating color filter.

According to invention of Claim 1, in order to solve said subject, as shown in FIG. 1, the high-pressure discharge lamp lighting device 1, the high-pressure discharge lamp 2 lit by the high-pressure discharge lamp lighting device 1, A rotating color filter 4 that separates the luminous flux of the high-pressure discharge lamp 2 into at least three colors, an image display element 6 that is irradiated with a luminous flux that has passed through the rotating color filter 4, and the image display element 6 modulates the luminous flux. An image projection apparatus comprising: a projection lens 7 that projects a reflected light beam on a screen; and a synchronization signal generator 10 that detects a rotation state of the rotary color filter 4 and generates a synchronization signal. As shown in FIG. 2, the synchronization signal Sync output from is synchronized with the time width Ty of one segment Y among the plurality of color segments in the rotating color filter 4. An ON signal is input to the pressure discharge lamp lighting device 1, and the time widths Tg, Tc, Tw, Tb, Tr of the remaining color segments are set according to the time width Ty of the ON signal, and the high pressure discharge lamp 1 is set. The flowing lamp current I _L is controlled so as to become current values Iy, Ig, Ic, Iw, Ib, Ir set for each color segment.

According to the invention of claim 2, in the invention of claim 1, the high-pressure discharge lamp lighting device 1 is a lighting device that causes the high-pressure discharge lamp 2 to be AC-lit, and the polarity of the lamp current I _L flowing through the high-pressure discharge lamp 2 is changed. As shown in FIG. 3, the inversion timing is synchronized with the timing when the synchronization signal Sync is turned on or turned off.

  According to the present invention, in the image projection apparatus that variably controls the lamp current for each segment of the rotating color filter, an ON signal that is synchronized with the time width of one of the plurality of color segments in the rotating color filter is input. The time width of the remaining color segments is set according to the time width of the ON signal, and the lamp current flowing through the high-pressure discharge lamp is controlled to be a current value set for each color segment. Therefore, it is possible to realize a control that makes the output light of the high-pressure discharge lamp variable for each color segment with a simple configuration, and various color reproducibility that meets the user's requirements regardless of the number of rotations of the rotating color filter. There is an effect that can be realized.

(Embodiment 1)
FIG. 1 is a block diagram showing a system configuration of an image projection apparatus according to Embodiment 1 of the present invention, and FIG. 2 shows a selected state of a rotating color filter segment used in this embodiment, a waveform of a synchronization signal Sync, and a direct current. the relationship between the lamp current I _L of the high pressure discharge lamp lighting method which is depicted in the same time axis. In addition, although the part which reduces the influence between the segments called SPOKE between each color segment is set, since it is also a part which shows a transient operation, description is abbreviate | omitted this time.

  As shown in FIG. 1, the high-pressure discharge lamp 2 is turned on by the high-pressure discharge lamp lighting device 1, and the white light beam output from the high-pressure discharge lamp 2 is collected by the lens 3 and transmitted through the rotating color filter 4. Is irradiated onto the DMD element 6 which is a reflection type image display element through the lens 5, and the reflected light is projected onto a screen (not shown) through the projection lens 7. Here, the DMD (digital micromirror device) element 6 is an element in which hundreds of thousands to millions of mirrors that move independently on a CMOS semiconductor are spread, and by controlling individual mirrors A gray image can be displayed.

  The rotating color filter driving device 9 rotates the rotating color filter 4 according to the synchronizing signal of the video signal displayed on the DMD element 6. As the rotary color filter 4 rotates at a high speed by the drive signal from the rotary color filter drive device 9, the light radiated to the DMD element 6 is R (red), Y (yellow), G (green), C (cyan). , W (white), B (blue). By detecting the rotation of the rotating color filter 4, a synchronizing signal Sync is input from the synchronizing signal generator 10 to the high pressure discharge lamp lighting device 1, and a signal for driving the DMD element 6 is transmitted to the optical element driving device 8. Then, a color image can be projected onto the screen by providing the DMD element 6 with a luminous flux for each color segment and a luminance image signal from the optical element driving device 8.

  Here, as shown in FIG. 2, the angles of the color segments R (red), Y (yellow), G (green), C (cyan), W (white), and B (blue) are set to θr, θy, θg, θc, θw, and θb are set, and the times during which light passes through each color segment are set to Tr, Ty, Tg, Tc, Tw, and Tb, respectively. The sum of the angles θr, θy, θg, θc, θw, and θb is 360 ° because it is one rotation of the rotating color filter, and the total time for light to pass through each color segment is one rotation of the rotating color filter 4. It corresponds to time. The timing at which the synchronization signal Sync is turned on is set in any one of the color segments. In the present embodiment, the synchronization signal Sync is synchronized with the color segment Y (yellow).

  Since there is often only one type of rotating color filter that is set and used in the image projection apparatus, the angle of each segment is known in advance, and the rest other than the color segment Y (yellow) for which the sync signal Sync is turned on The time of each color segment G (green), C (cyan), W (white), B (blue), and R (red) is Tg = Ty × θg ÷ θy, Tc = Ty × θc ÷ θy, Tw = By setting in the high pressure discharge lamp lighting device such as Ty × θw ÷ θy, Tb = Ty × θb ÷ θy, Tr = Ty × θr ÷ θy, each of the remaining items excluding the color segment Y (yellow) Color segment time can be set. Although the time Tr of the color segment R (red) is calculated by an arithmetic expression (Tr = Ty × θr ÷ θy), the synchronization signal synchronized with the color segment Y (yellow) without using the arithmetic expression. The time Tr may be ended at the timing when the Sync is turned on.

Next, the lamp current I _L of the high-pressure discharge lamp when light passes through each color segment R (red), Y (yellow), G (green), C (cyan), W (white), and B (blue). Is set to be Ir, Iy, Ig, Ic, Iw, and Ib, respectively, it is possible to realize color reproducibility according to the user's request.

  Even if the frequency of the synchronization signal Sync changes, the angle θy of the color segment Y (yellow) is the same, so the ratio of the time Ty to the whole (time of one rotation of the rotating color filter) remains the same. Therefore, although it depends on the accuracy of the arithmetic expression, the ratio of the remaining color segments to the whole (the time for one rotation of the rotating color filter) is hardly changed, and the brightness and color of the color image output from the image projection apparatus There is almost no change in reproducibility.

(Embodiment 2)
FIG. 3 is an operation explanatory diagram of Embodiment 2 of the present invention. The system configuration of the image projection apparatus may be the same as in FIG. 1, but the high pressure discharge lamp is an AC lighting type, and the high pressure discharge lamp lighting apparatus is a lighting apparatus capable of AC lighting. Figure 3 is a selected state of the segments of the rotary color filter used in this embodiment, in which the waveform of the synchronizing signal Sync, showing the relationship of the lamp current I _L of the high pressure discharge lamp of the alternating current lighting system in the same time axis. Note that the SPOKE interposed between the color segments is omitted as in the first embodiment.

As shown in FIG. 3, in the case of using a high-pressure discharge lamp of the AC lighting system, when the lamp current I polarity synchronizing signal Sync timing for inversion of _L of the high pressure discharge lamp is set to a timing that is off, the synchronization signal Even if the Sync frequency changes, the lamp current of the high-pressure discharge lamp and the color segment switching timing of the rotating color filter are synchronized in accordance with the frequency of the synchronization signal.

  In FIG. 3, the current polarity of the high-pressure discharge lamp is inverted at the timing when the synchronization signal Sync is turned off. However, the same effect can be obtained by inverting the current polarity of the high-pressure discharge lamp at the timing when the synchronization signal Sync is turned on. can get.

In the description of each of the above embodiments, the circuit configuration of the high-pressure discharge lamp lighting device 1 is well known, and thus is not illustrated. For example, a rectifier circuit that rectifies a commercial AC voltage and an output voltage of the rectifier circuit are boosted. A step-up chopper circuit that converts to a DC voltage, a step-down chopper circuit that steps down the output voltage of the step-up chopper circuit and adjusts the current supplied to the discharge lamp (and thus the lamp power), and the output voltage of the step-down chopper circuit are inverted. A full bridge circuit that supplies the discharge lamp, an igniter circuit that is inserted between the output of the full bridge circuit and the discharge lamp and applies a high voltage at the start, and a control circuit that controls them. The control circuit of the frequency and duty of the switching element of the step-down chopper circuit by variably controlling, controls so that the lamp current I _L flowing through the discharge lamp becomes a predetermined value. It also controls the timing for switching the output polarity of the full bridge circuit. The control circuit is composed of a microcomputer (hereinafter referred to as “microcomputer”).

  The sensor connected to the synchronization signal generator 10 detects the rotation of the rotating color filter 4 and outputs a synchronization signal Sync that becomes High level at a timing when the selected color is Y (yellow). This signal is input to the binary input port of the microcomputer constituting the control circuit and monitored. For example, an interrupt operation is performed every minute using the timer interrupt function of the microcomputer, and when the synchronization signal Sync changes from Low level to High level, the timer count variable Ty is reset and counting starts from the initial value 0 As long as the synchronization signal Sync is at a high level, the variable Ty is incremented by one each time a timer interrupt occurs. During this time, the target value of the lamp current is set to Iy, and a signal for controlling the lamp current to Iy is output from the output port of the microcomputer. In response to this signal, the switching element of the step-down chopper circuit is controlled, so that the lamp current is controlled to be Iy. When the synchronization signal Sync changes from the High level to the Low level, the counting of the variable Ty is stopped, and the count value is set as the count value of the time Ty during which the color of Y (yellow) is selected.

  Next, the timer count variable Tg is reset from the timing when the synchronization signal Sync becomes the Low level, the count is started from the initial value 0, and each time the timer interrupt occurs, the variable Tg is incremented by one. Go. The calculation value of the variable Tg is calculated as (Ty × θg ÷ θy) by the calculation function of the microcomputer, and the count ends when the count value of the variable Tg reaches the target value. During this time, the target value of the lamp current is set to Ig, and a signal for controlling the lamp current to Ig is output from the output port of the microcomputer. By receiving this signal and controlling the switching element of the step-down chopper circuit, the lamp current is controlled to be Ig.

  Next, when the counting of the variable Tg is completed, the timer count variable Tc starts counting from that timing, and the target value of the lamp current is set to Ic. Similarly, while counting the variables Tw, Tb, Tr from the initial value 0 to the target values Ty × θw ÷ θy, Ty × θb ÷ θy, Ty × θr ÷ θy, the target values of the lamp current are respectively set. Set to Iw, Ib, Ir.

Note that the last period in place of the count of the timer variable Tr, also constitute a target value of the lamp current I _L to the timing of the synchronization signal Sync is changed from the Low level to the High level so is set to Ir good.

  At the timing when the synchronization signal Sync changes from the Low level to the High level (or when the synchronization signal Sync changes from the High level to the Low level), the full-bridge circuit is switched and the output polarity is inverted. Thereby, it is possible to prevent only one electrode of the discharge lamp from being consumed and to improve the life of the discharge lamp.

  In the above description, the synchronization signal Sync is high level when it is on, and positive logic that is low level when it is off. However, it is low level when it is on and high level when it is off. It may be negative logic.

  In addition, the period during which the synchronization signal Sync is turned on is the period in which Y (yellow) of the color segment is selected. However, the present invention is not limited to this and is replaced with a period in which any other color is selected. May be.

  As a means for turning on the synchronization signal Sync during a period when a specific color of the rotating color filter is selected, for example, using a photo interrupter or the like, light transmitted through a transmission window provided at a specific position of the rotating color filter or Light reflected by a reflector provided at a specific location of the rotating color filter may be detected, or other means may be used. For example, a sensor that detects only light of a specific color is arranged around the lens 5, and a portion where light condensed by the lens 3 on the light source side is irradiated on the rotating color filter 4 is observed from the lens 5 side, A configuration in which the synchronization signal Sync is turned on while light of a specific color is being output may be used.

  In the illustrated embodiment, the configuration using a reflective image display element such as the DMD element 6 is exemplified, but the present invention is not limited to this, and light passing through a color filter is not limited to a monochrome liquid crystal display element. The present invention can also be applied to a configuration in which a transmissive image display element modulates a grayscale image of each color and projects it onto a screen via the projection lens 7.

It is a block diagram which shows the system configuration | structure of the image projector of Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the synchronizing signal of Embodiment 1 of this invention, and the lamp current of the high pressure discharge lamp of a DC lighting system. It is explanatory drawing which shows the relationship between the synchronizing signal of Embodiment 2 of this invention, and the lamp current of the high voltage | pressure discharge lamp of an alternating current lighting system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure discharge lamp lighting device 2 High pressure discharge lamp 3 Lens 4 Rotation color filter 5 Lens 6 DMD element 7 Projection lens 8 Optical element drive device 9 Rotation color filter drive device 10 Synchronous signal generator

Claims (2)

A high pressure discharge lamp lighting device, a high pressure discharge lamp that is lit by the high pressure discharge lamp lighting device, a rotating color filter that separates the luminous flux of the high pressure discharge lamp into at least three colors, and the rotating color filter An image display element that is irradiated with a light beam, a projection lens that projects a light beam modulated by the image display element on a screen, and a synchronization signal generator that detects a rotation state of the rotating color filter and generates a synchronization signal The synchronization signal output from the synchronization signal generator is synchronized with the time width of one of the plurality of color segments in the rotating color filter and is supplied to the high pressure discharge lamp lighting device. An ON signal is input, the time width of the remaining color segments is set according to the time width of the ON signal, and the high pressure discharge lamp is Image projection apparatus characterized by a lamp current is controlled to be a current value set for each color segment. 2. The high pressure discharge lamp lighting device according to claim 1, wherein the high pressure discharge lamp is turned on in an alternating current, and the timing for reversing the polarity of the lamp current flowing through the high pressure discharge lamp is the timing when the synchronization signal is turned on or turned off. An image projection apparatus characterized by being synchronized with the above.

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