JP2007233217A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector which can reduce EMI noises with simple configuration. <P>SOLUTION: Since the projector 100 is equipped with delay circuits 25, 26 for shifting the phases of a green image signal G4 and a blue image signal B4 from a red image signal R4 as a reference signal by predetermined ratio, respectively, the respective color image signals R5, G5d, B5d input to liquid crystal light valves 28R, 28G, 28B have phases different from each other. The phases of the color image signals R5, G5d, B5d are therefore different from each other, so that peak parts of higher harmonics generated in driving the liquid crystal light valves 28R, 28G, 28B are dispersed and EMI noises can be reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projector including a plurality of liquid crystal display devices as a light modulation device.

A projector that uses a discharge lamp such as a high-pressure mercury lamp or a metal halide lamp as a light source, modulates light emitted from the light source according to an image signal by a light modulation device, and enlarges and projects an image represented by the modulated modulated light is known. It has been.
As such a light modulation device for a projector, a liquid crystal light valve, which is a transmissive liquid crystal display device capable of obtaining a vivid image with natural colors, a reflective liquid crystal display device, and the like are often used.

FIG. 5 is a schematic configuration diagram of a conventional projector.
The projector 200 separates light from a light source such as a discharge lamp (not shown) into three primary color components of red light, green light, and blue light, and a liquid crystal light for each color light as a light modulation device for each color light. This is a so-called “liquid crystal three-plate projector” that modulates according to the image signal by the valves 28R, 28G, and 28B and enlarges and projects the full-color modulated light synthesized again onto the screen SC by the projection lens 50.
The projector 200 AD-converts analog RGB signals R1, G1, and B1 input from the image signal supply device 80, which is an external device, by the image signal converter 16, and further includes an image including the scaler 17 and the image signal correction unit 20. After performing predetermined image processing in the signal processing unit 23, DA conversion is performed by the DACs 27R, 27G, and 27B, which are DA converters for the respective color image signals, so that the liquid crystal light valves 28R, 28G, and 28B are suitable for display. The analog image signals R5, G5, and B5 are generated.

The liquid crystal light valves 28R, 28G, and 28B are supplied with the generated analog image signals R5, G5, and B5 and a reference clock CLK from the timing control unit 21 that serves as a reference for writing the analog image signal. It had been.
The operation clocks of the DACs 27R, 27G, and 27B are reference clocks CLK supplied from the image signal correction unit 20, and the output image signals R5, G5, and B5 are also synchronized with the reference clocks CLK, respectively. .
Thus, when the projector 200 projects an image, the image signals R5, G5, and B5 synchronized with the reference clock CLK are synchronized with the reference clock CLK in the three liquid crystal light valves 28R, 28G, and 28B. Was written. Further, the liquid crystal light valves 28R, 28G, 28B are respectively provided on the corresponding surfaces of the cross dichroic prism 45 having a substantially cubic shape with one side of several centimeters for synthesizing each color modulated light modulated for each color light. It was provided.

In addition, in an electronic device operating with a high-speed operation clock such as the projector 200 or a personal computer, electromagnetic interference (EMI: Electro Magnetic Interference) is reduced in view of the influence on other devices and the human body. It is demanded.
For this reason, for example, Patent Document 1 proposes a technique for reducing EMI noise in an MPU (Micro Processing Unit) used in an electronic device such as a projector.
The MPU of Patent Document 1 has a dedicated configuration including a spread spectrum clock generator (SSCG) so that a problematic peak portion does not occur in the high frequency generated by the operation of the MPU. Yes.
With this configuration, the frequency spectrum is spread by intentionally changing the operation clock so that a peak portion exceeding the standard does not occur.

JP 2001-14056 A

FIG. 6 is a timing chart of each color image signal in the conventional projector. As described above, since the image signals R5, G5, and B5 are synchronized with the reference clock CLK, the cycle of rising substantially simultaneously at the timing t1 and falling substantially simultaneously at the timing t2 is repeated. Therefore, when each of the liquid crystal light valves 28R, 28G, and 28B is driven, high frequencies in substantially the same frequency range generated in the liquid crystal light valves at timing t1 and timing t2 are superimposed to form a peak portion. End up.
Further, the liquid crystal light valves 28R, 28G, and 28B provided on the corresponding surfaces of the cross dichroic prism 45 are close to each other within a few centimeters, so that the high frequency is more easily superimposed.

However, when the EMI reduction technique by SSCG of Patent Document 1 is applied to the projector 200, not only the cost is increased due to the need for expensive dedicated parts including a spread spectrum clock transmitter, but the configuration of the peripheral parts is also increased. There is a problem that the configuration becomes complicated because it is necessary to support the technology.
As described above, the conventional projector 200 has a problem that it is difficult to easily reduce the EMI noise.

  In order to solve the above problems, an object of the present invention is to provide a projector capable of reducing EMI noise with a simple configuration.

  (1) In order to achieve the above-described object, the projector according to the present invention is provided with an image signal processing unit that outputs each color image signal that is an image signal for each of a plurality of color lights, and is incident on each color image signal. A color image signal other than a reference color image signal having a reference phase among a plurality of color image signals, and a light modulation device for each color light that modulates each color light according to a corresponding color image signal And a delay circuit that shifts the phase of the reference color image signal from the phase of the reference color image signal by a predetermined ratio.

According to this configuration, the projector shifts the phase of the color image signal other than the reference color image signal having the reference phase among the plurality of color image signals by a predetermined ratio from the phase of the reference color image signal. Therefore, the color image signals input to the plurality of color light modulation devices have different phases.
Therefore, since the color image signals input to the plurality of light modulation devices are all synchronized, the high-frequency components that are generated are superimposed, unlike the conventional projector that forms the peak portion of the EMI noise. In the projector, since the phases of the plurality of image signals are shifted by a predetermined ratio, high-frequency peak portions generated by driving the plurality of light modulation devices are dispersed, and EMI noise can be reduced.
Further, the delay circuit, for example, inserts a damping resistor between the output terminal of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device, or changes the length of the transmission line. A simple circuit can be used.
Therefore, a projector capable of reducing EMI noise with a simple configuration can be provided.

  (2) According to the projector of the present invention, the delay circuit is a damping provided between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light. It is a resistor or a gate element, and is preferably weighted according to the ratio of a predetermined shift amount.

According to this configuration, the delay circuit is a damping resistor or a gate element provided between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light. Since there is, it is a simple structure.
Further, since the damping resistor and the gate element are weighted according to the ratio of the predetermined shift amount, the phase of each color image signal is set at a predetermined ratio with the reference color image signal as a reference with a simple configuration. Can be shifted.
Therefore, a projector capable of reducing EMI noise with a simple configuration can be provided.

  (3) According to the projector of the present invention, the delay circuit has a wiring pattern length between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light. It is preferable that the height is adjusted according to the ratio of the predetermined shift amount.

According to this configuration, the delay circuit determines the length of the wiring pattern between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light, by the predetermined circuit. Since the adjustment is made according to the ratio of the shift amount, no special parts are required and the configuration is simple.
In addition, since the length of the wiring pattern is adjusted according to the ratio of the predetermined shift amount, the phase of each color image signal is shifted by a predetermined ratio with reference to the reference color image signal with a simple configuration. Can be made.
Therefore, a projector capable of reducing EMI noise with a simple configuration can be provided.

  (4) According to the projector of the present invention, the phase of the color image signal having the largest phase difference among the color image signals having phases shifted by a predetermined ratio with respect to the phase of the reference color image signal is It is preferable to be within ± 10% in a half cycle of the color image signal.

In a general projector, an input image signal is synchronized with a high-speed operation clock such as 75 MHz or 135 MHz in an image signal processing unit including an image processor that performs image processing such as scaling and γ correction. Have been processed.
According to this configuration, the phase of the color image signal having the largest phase difference among the color image signals having phases shifted by a predetermined ratio is within ± 10% in the ½ period of the reference color image signal. Here, the phase of the color image signal having the maximum phase difference is shifted by 10% in a ½ cycle of the reference color image signal. However, the phase difference is very small in terms of the frequency of the high-speed operation clock. Therefore, the image can be handled without affecting the image within the range of the operation margin of the light modulation device operating with the operation clock.
As described above, each color image signal other than the reference color image signal including the color image signal having the maximum phase difference is an image signal that can be handled without any problem in each light modulation device, and is based on the phase of the reference color image signal. Since the phase is shifted by a predetermined ratio, it is possible to disperse high-frequency peak portions generated by driving the light modulation device and reduce EMI noise.
Therefore, a projector capable of reducing EMI noise with a simple configuration can be provided.

  (5) According to the projector of the present invention, the plurality of color lights are red, green, and blue light, and a red image signal, a green image signal, and a blue image signal are output from the image signal processing unit. The red light modulation device, the green light modulation device, and the blue light modulation device corresponding to each color image signal have a substantially cubic shape for synthesizing each color modulated light that is light-modulated for each color light modulation device. It is preferably provided on the corresponding surface of the synthesized optical system.

As described above, the cross dichroic prism used in the synthesis optical system generally has a substantially cubic shape with a side of several centimeters.
According to this configuration, the light modulation devices for each color are close to each other, and the high frequency generated by driving the light modulation device for each color is easily superimposed. However, according to the projector of the present invention, even if the three light modulation devices are arranged close to each other, the three color image signals that are input have different phases, so that the three light modulation devices can be driven. The accompanying high frequency peak portion is dispersed, and EMI noise can be reduced.
Further, the delay circuit is provided corresponding to two color image signals excluding the reference color image signal among the three color image signals, so that the configuration is simple.
Therefore, a projector including a plurality of light modulation devices that can reduce EMI noise with a simple configuration can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
<Schematic configuration of projector>
FIG. 1 is a schematic configuration diagram mainly including a circuit block configuration of a projector according to an embodiment of the present invention. Here, an outline of a circuit block configuration of the projector 100 will be described. For comparison, the same parts as those of the conventional projector 200 will be described with the same reference numerals.
The projector 100 separates light from a discharge lamp (not shown) into three primary color components of red (R) light, green (G) light, and blue (B) light, and serves as a light modulation device for each color light. This is a so-called “liquid crystal three-plate projector” in which the liquid crystal light valves 28R, 28G, and 28B for each color light are modulated in accordance with image signals and the combined full-color modulated light is enlarged and projected.

The projector 100 includes a control unit 11, a storage unit 12, a power supply unit 13, a clock generation unit 14, an image signal converter 16, an image signal processing unit 23, delay circuits 25 and 26, DACs 27R, 27G and 27B, and liquid crystal light valves 28R and 28G. , 28B and the like.
The control unit 11 is a CPU (Central Processing Unit), exchanges signals with each unit including the image signal processing unit 23 via the bus line Bus, and controls the operation of the projector 100.
The storage unit 12 is configured by a non-volatile memory such as a mask ROM, flash memory, or FeRAM, for example. The storage unit 12 stores various programs for controlling the operation of the projector, such as an activation program that defines the order and contents for activating the projector 100, and accompanying data.
The power supply unit 13 is stabilized by introducing AC power from the external power supply 90 from the inlet, and performing processing such as transformation, rectification, and smoothing by a built-in AC / DC conversion unit (both not shown). Electric power is supplied to each part of the projector 100.

The clock generation unit 14 is, for example, an overtone oscillation circuit including a crystal oscillator, and supplies a high-speed source oscillation clock to the timing control unit 21 and the like.
The image signal converter 16 is, for example, a 3-channel AD conversion circuit (not shown) for AD-converting the analog RGB signal input from the image signal supply device 80 such as a personal computer for each of the color image signals R1, G1, and B1. ). The analog image signal is not limited to the RGB signal, and may be a component signal expressed in a format such as YUV, Y / Pb / Pr, Y / Cb / Cr, or Y / RY / BY. good.
The image signal converter 16 performs AD conversion along the sampling clock SCLK supplied from the scaler 17, and outputs the generated digital color image signals R 2, G 2, and B 2 to the scaler 17.

The image signal processing unit 23 includes a scaler 17 and an image signal correction unit 20. The scaler 17 is a scaler and has a frame memory 18 attached.
The frame memory 18 is composed of, for example, three memory planes configured by DRAM (Dynamic Random Access Memory) and storing image data based on color image signals for each color light of RGB.
The scaler 17 writes the image represented by each color image signal R2, G2, B2 into the frame memory 18 for each RGB color light at the resolution of each color image signal, and can display it on the liquid crystal light valves 28R, 28G, 28B. Image signals R3, G3, and B3 are generated by converting the data to a high resolution and reading it out. In addition, trapezoidal correction processing for bringing the shape of the effective image projected on the screen closer to a rectangle is also performed together with scaling. The scaler 17 includes a sampling clock generation circuit 19 including a PLL (Phase Locked Loop). For example, the sampling clock SCLK obtained by multiplying the horizontal synchronization frequency of the synchronization signal SYNC is generated and supplied to the image signal converter 16. Output. Note that the sampling clock generation circuit 19 may be included in the image signal converter 16.

A timing control unit 21 and an OSD memory 22 are attached to the image signal correction unit 20. The timing control unit 21 is a timing generator, and generates a plurality of timing signals such as a reference clock CLK that is an operation clock from the input source oscillation clock of the clock generation unit 14 and the synchronization signal SYNC of the sampling clock generation circuit 19. And supplied to each part including the liquid crystal light valves 28R, 28G, and 28B.
The image signal correction unit 20 includes a 1D (Dimension) -LUT and a 3D-LUT, and performs image processing on each of the color image signals R3, G3, and B3 at a timing synchronized with the reference clock CLK supplied from the timing control unit 21. Apply. Specific image processing contents include γ correction for correcting VT characteristics (characteristics of applied voltage and transmittance) for each of the liquid crystal light valves 28R, 28G, and 28B by 1D-LUT, and the liquid crystal light valve by 3D-LUT. Color unevenness correction and color gamut correction for correcting unique color unevenness of each.
The image signal correction unit 20 also performs phase expansion processing for converting the color image signal of the serial data into parallel data of a plurality of phases in order to reliably write the image signal to the high-resolution liquid crystal light valves 28R, 28G, and 28B. Done. In the projector 100, each color image signal is expanded into 12 phases.

Further, the image signal correction unit 20 controls an OSD (On Screen Display) function of reading an image adjustment setting screen or the like from the OSD memory 22 and superimposing the read setting screen on the image signal. In addition to the image adjustment setting screen, the OSD memory 22 stores various operation menu screens for operating the projector 100, status display information such as “computer” representing the name of the input image source, and the like. Has been.
The image signal correction unit 20 outputs the respective color image signals R4, G4, B4 subjected to such image processing and the reference clock CLK from the respective output units.
In the projector 100, the image signal processing unit 23 including the scaler 17 and the image signal correction unit 20 is configured as a video processor IC of one package. Further, the video processor IC may be configured to have the function of the control unit 11. According to these structures, since each part can be accommodated in one package IC, the number of parts and a mounting area can be reduced significantly.

The delay circuit 25 which is a feature of the present invention includes a damping resistor provided between the output unit of the green image signal G4 in the image signal correction unit 20 and the liquid crystal light valve 28G which is a light modulator for green light. Or it is a gate element. Similarly, the delay circuit 26 is a damping resistor or a gate element provided between the output unit of the blue image signal B4 in the image signal correction unit 20 and the liquid crystal light valve 28B which is a light modulator for blue light. is there. Further, the delay circuits 25 and 26 are configured by adjusting the length of the wiring pattern between the output portions of the color image signals G4 and B4 in the image signal correction portion 20 and the liquid crystal light valves 28G and 28B. There may be.
Further, the circuit constant weights of the delay circuit 25 and the delay circuit 26 are different, and the phase of the signal that has passed through the delay circuit is shifted in accordance with the circuit constant set in advance at a predetermined ratio. A specific delay amount will be described later.

The green image signal G4 and the reference clock CLK input to the delay circuit 25 are delayed according to the circuit constants of the delay circuit, respectively, and are output to the DAC 27G as the green image signal G4d and the clock CLd1.
The DAC 27G is a DA converter corresponding to the green image signal G4d, DA converts the digital green image signal G4d using the input clock CLd1 as an operation clock, and outputs the generated analog green image signal G5d to the liquid crystal light valve 28G.
The blue image signal B4 and the reference clock CLK input to the delay circuit 26 are delayed according to the circuit constants of the delay circuit, respectively, and are output to the DAC 27B as the blue image signal B4d and the clock CLd2.
The DAC 27B is a DA converter corresponding to the blue image signal B4d, DA-converts the digital blue image signal B4d using the input clock CLd2 as an operation clock, and outputs the generated analog blue image signal B5d to the liquid crystal light valve 28B.

In the projector 100, since the reference color image signal is the red image signal R4, a delay circuit is not provided in the output portion of the red image signal R4. For this reason, the red image signal R4 and the reference clock CLK output from the image signal correction unit 20 are input to the corresponding DAC 27R in the same phase state.
The DAC 27R is a DA converter corresponding to the red image signal R4, DA-converts the digital red image signal R4 using the input reference clock CLK as an operation clock, and outputs the generated analog red image signal R5 to the liquid crystal light valve 28R. .

The liquid crystal light valves 28R, 28G, and 28B, which are light modulation devices, include a pixel electrode and a base substrate on which switching elements such as thin film transistor elements and thin film diodes for driving the pixel electrodes are formed in a grid pattern, and a common electrode over the entire surface. This is an active matrix type liquid crystal display device having a configuration in which a TN type liquid crystal (none of which is shown) is sandwiched between a counter substrate on which is formed.
A driver circuit (not shown) including a shift register for driving the switching element is incorporated in the outer peripheral portion of the liquid crystal light valves 28R, 28G, and 28B, and each color from the DACs 27R, 27G, and 27B is incorporated. The image signals R5, G5d, and B5d are input to corresponding driver circuits. Further, the reference clock CLK is input from the timing control unit 21 to the driver circuit as an operation clock.

The liquid crystal light valve 28R writes the red image signal R5 synchronized with the reference clock CLK at a timing synchronized with the reference clock CLK from the timing control unit 21, and displays an image represented by the image signal.
The liquid crystal light valve 28G writes the green image signal G5d synchronized with the clock CLd1 at a timing synchronized with the reference clock CLK from the timing control unit 21, and displays an image represented by the image signal.
The liquid crystal light valve 28B writes the blue image signal B5d synchronized with the clock CLd2 at a timing synchronized with the reference clock CLK from the timing control unit 21, and displays an image represented by the image signal.

<Outline of optical system>
FIG. 2 is a schematic configuration diagram of an optical system in the projector of the present invention.
Here, an outline of the optical system of the projector 100 will be described with reference to FIG. For comparison, the same parts as those of the conventional projector 200 will be described with the same reference numerals. In the following description, red light is expressed as “R light”, green light as “G light”, and blue light as “B light”.
The optical system of the projector 100 includes a light source unit 5, a uniform illumination system 10, a separation optical system 34, a relay optical system 39, a combining optical system 45, and the like.

The light source unit 5 includes a discharge lamp 1 that can obtain high brightness such as a metal halide lamp and a high-pressure mercury lamp, and a reflector 3 that collects the light emitted from the discharge lamp 1 and emits the light toward the uniform illumination system 10. It is configured to include.
The uniform illumination system 10 includes two fly-eye lenses 6, a polarization conversion element 7, a condenser lens 8, a reflection mirror 9, and the like.
The fly-eye lens 6 has a configuration in which small lenses having a substantially rectangular outline when viewed from the direction of the light source unit 5 are arranged in a matrix, and two pairs form a pair. Each pair of small lenses divides the light beam emitted from the light source unit 5 into partial light beams and emits them in the optical axis direction. A plurality of light source images emitted from the respective small lenses are formed on the surfaces of the liquid crystal light valves 28R, 28G, and 28B through the condenser lens 8 and the like. Thereby, the luminance distribution on the surfaces of the liquid crystal light valves 28R, 28G, and 28B is made uniform.

The polarization conversion element 7 includes a PBS (Polarization Beam Splitter) array, a half-wave plate, and the like, and converts random polarization into specific linear polarization. Since the specific linearly polarized light is polarized light that can be incident on an incident polarizing plate (not shown) provided on the incident surface of each liquid crystal light valve, it cannot pass through the incident polarizing plate without the polarization conversion element 7. The light that has been wasted as heat can be used effectively.
The light emitted from the light source unit 5 passes through the two fly-eye lenses 6, the polarization conversion element 7, and the condenser lens 8, is reflected by the reflection mirror 9, and is emitted toward the separation optical system 34 side.

The separation optical system 34 includes a dichroic mirror 32 and a dichroic mirror 33.
The dichroic mirror 32 is an optical element formed with a dichroic film having a property of transmitting R light to a glass plate or the like and reflecting B light and G light. The dichroic mirror 32 transmits R light and transmits B light and G light to the dichroic mirror 33. Reflect to the side. The R light that has passed through the dichroic mirror 32 is reflected by the reflecting mirror 35, and then is collimated by the collimating lens 40 and enters the liquid crystal light valve 28R. The B light and G light reflected by the dichroic mirror 32 enter the dichroic mirror 33.
The dichroic mirror 33 is an optical element including a dichroic film that reflects G light and transmits B light. The dichroic mirror 33 reflects G light toward the liquid crystal light valve 28G and transmits B light. The G light reflected by the dichroic mirror 33 is collimated by the collimating lens 40 and enters the liquid crystal light valve 28G. The B light transmitted through the dichroic mirror 33 enters the relay optical system 39.

The relay optical system 39 includes two relay lenses 37, two reflection mirrors 38, and the like.
The B light that has passed through the dichroic mirror 33 is reflected by the reflecting mirror 38 via the relay lens 37, further reflected by the reflecting mirror 38 via the relay lens 37, and then collimated by the collimating lens 40. Incident on 28B. The two relay lenses 37 are provided in order to prevent attenuation of the B light passing through the longest optical path among the separated three color lights.

The synthesizing optical system 45 has a structure in which four right angle prisms are bonded to each other, and a dichroic film 42 that is a dielectric multilayer film that transmits G light and reflects B light, and transmits G light and transmits R light. This is a cross dichroic prism provided with an X-shaped dichroic film 43 that is a dielectric multilayer film that reflects.
The liquid crystal light valves 28R, 28G, and 28B are provided facing three surfaces of the combining optical system 45 having a substantially cubic shape with a side of several centimeters. In addition, an incident polarizing plate is provided on the light incident surface of each of the liquid crystal light valves 28R, 28G, and 28B, and an outgoing polarizing plate (not shown) is provided on the light emitting surface facing the synthesis optical system 45. It has been. Note that the output polarizing plate may be configured to be attached in advance to each surface of the synthetic optical system 45.
Each color light incident on the liquid crystal light valves 28R, 28G, 28B having a plurality of pixels corresponding to the resolution is modulated into each color modulated light including an optical image for each color light according to each color image signal R5, G5d, B5d. And are respectively emitted into the synthesis optical system 45.

The synthesizing optical system 45 transmits the green modulated light from the liquid crystal light valve 28G, and combines the green modulated light with the red modulated light from the liquid crystal light valve 28R and the blue modulated light from the liquid crystal light valve 28B. The modulated light that is reflected and superimposed and includes a full-color image obtained by synthesizing the modulated light of the three primary colors is emitted to the projection lens 50.
The modulated light emitted from the combining optical system 45 is enlarged and projected as a full-color image on a screen or the like by a projection lens 50 that is a wide-angle zoom lens in which a plurality of Gaussian lenses or the like are combined.

<< Driving Mode of Light Modulator >>
FIG. 3 is a diagram showing a timing chart of each color image signal in the projector of the present invention. Here, a driving mode of the liquid crystal light valves 28R, 28G, and 28B, which are light modulation devices of the projector 100, will be described with reference to FIG.
As described above, the liquid crystal light valves 28R, 28G, and 28B are driven by the reference clock CLK from the timing control unit 21 to display images included in the color image signals R5, G5d, and B5d.

Here, when the phase of the red image signal R5 synchronized with the reference clock CLK is used as a reference, the phase of the green image signal G5d synchronized with the clock CLd1 is delayed by the delay time d1. Similarly, the phase of the blue image signal B5d synchronized with the clock CLd2 is delayed by the delay time d2.
The delay time d1 corresponds to 5% in a half cycle of the reference clock CLK, and the delay time d2 is a time corresponding to 10%.
As described above, the phase of the green image signal G5d is shifted by 5% in the 1/2 cycle of the reference clock CLK as a predetermined ratio from the red image signal R5 that is the reference color image signal, and the phase of the blue image signal B5d is green. It is further shifted by 5% from the phase of the image signal G5d. That is, the phase of the green image signal G5d and the blue image signal B5d is shifted from the phase of the red image signal R5 by 5% as a predetermined ratio. The predetermined ratio is not limited to 5% in the ½ period of the reference clock CLK, and the phase of the blue image signal B5d having the largest phase difference is within 10% in the ½ period of the reference clock CLK. Any category that fits in.

The delay time d1 and the delay time d2 are determined in advance by weighting circuit constants of the delay circuit 25 and the delay circuit 26. For example, when the delay circuit is configured by a damping resistor, the damping resistance value of the delay circuit 26 is set to twice the damping resistance value of the delay circuit 25. When the delay circuit 25 is provided with one stage of gate elements, the delay circuit 26 is provided with two stages of gate elements. When the delay circuit is configured by adjusting the wiring pattern length, the wiring pattern length of the delay circuit 26 is set to twice the wiring pattern length in the delay circuit 25.
When the reference clock CLK is 75 MHz, the ½ period is about 6.67 nsec, 10% in the ½ period is 0.667 nsec, and the delay time d2 is very short. This delay time d2 is such that it can be handled without affecting the image within the range of the operation margin in the driver circuit of the liquid crystal light valve 28B operating with the high-speed reference clock CLK. The same applies to the degree of influence of the delay time d1 in the liquid crystal light valve 28G.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The projector 100 includes delay circuits 25 and 26 for shifting the phases of the green image signal G4 and the blue image signal B4 by a predetermined ratio from the phase of the red image signal R4 that is the reference color image signal. The color image signals R5, G5d, and B5d input to the liquid crystal light valves 28R, 28G, and 28B have different phases as shown in FIG.
Therefore, since the phases of the color image signals R5, G5d, and B5d are different from each other, high-frequency peak portions that are generated when the liquid crystal light valves 28R, 28G, and 28B are driven are dispersed, and EMI noise can be reduced.
Further, the delay circuits 25 and 26 can be simply configured by a damping resistor or a gate element.
Therefore, it is possible to provide projector 100 that can reduce EMI noise with a simple configuration.

(2) The delay circuit 25 is a damping resistor or a gate element provided between the output unit of the green image signal G4 in the image signal correction unit 20 and the liquid crystal light valve 28G which is a light modulator for green light. is there. Similarly, the delay circuit 26 is a damping resistor or a gate element provided between the output unit of the blue image signal B4 in the image signal correction unit 20 and the liquid crystal light valve 28B which is a light modulator for blue light. is there.
Therefore, the delay circuits 25 and 26 can be simply configured.
Further, since the damping resistor and the gate element are respectively weighted according to the ratio of a predetermined shift amount, the phases of the color image signals G4 and B4 are respectively determined with a simple configuration with the red image signal R4 as a reference. It is possible to shift by a percentage.
Therefore, it is possible to provide projector 100 that can reduce EMI noise with a simple configuration.

(3) The delay circuits 25 and 26 are configured by adjusting the length of the wiring pattern between the output units of the color image signals G4 and B4 in the image signal correction unit 20 and the liquid crystal light valves 28G and 28B. You can also.
Since the delay circuits 25 and 26 are obtained by adjusting the length of the wiring pattern in accordance with the ratio of the predetermined shift amount, the delay circuits 25 and 26 are based on the red image signal R4 with a simple configuration that does not require special parts. The phases of the color image signals G4 and B4 can be shifted by a predetermined ratio.
Therefore, it is possible to provide projector 100 that can reduce EMI noise with a simple configuration.

(4) The predetermined ratio is set so that the phase of the blue image signal B5d having the largest phase difference from the reference color image signal is within 10% in the ½ period of the reference clock CLK. For example, when the reference clock CLK is 75 MHz, the 1/2 cycle is about 6.67 nsec, 10% in the 1/2 cycle is 0.667 nsec, and the delay time d2 of the blue image signal B5d is a very short time. is there.
The blue image signal B5d is shifted in phase by the delay time d2, but has a very slight phase difference from the frequency of the high-speed reference clock CLK, so that the liquid crystal light valve 28B operating with the reference clock CLK The driver circuit can be handled without affecting the image within the range of the operation margin. The same applies to the degree of influence of the green image signal G5d whose phase is shifted by the delay time d1 in the liquid crystal light valve 28G.

Thus, the green image signal G5d and the blue image signal B5d are image signals that can be handled without affecting the image in the liquid crystal light valves 28G and 28B, and are transmitted to the liquid crystal light valves 28G and 28B in synchronization with the reference clock CLK. Written. Further, the green and blue modulated lights emitted from the liquid crystal light valves 28G and 28B are combined with the red modulated light from the liquid crystal light valve 28R synchronized with the reference clock CLK in the combining optical system 45, and thus full color modulated light. To the projection lens 50.
Therefore, the projected image represented by the modulated light, which is the combined light of the RGB color modulated lights that are synchronized, is a natural and vivid full-color projected image that is a feature of the liquid crystal three-plate type.
Further, the green image signal G5d and the blue image signal B5d are shifted in phase by a predetermined ratio with respect to the phase of the red image signal R5, respectively, so that a high-frequency peak portion generated by driving the liquid crystal light valve. EMI noise can be reduced.
Therefore, it is possible to provide a projector 100 that can project a natural and vivid image and reduce EMI noise with a simple configuration.

(5) The liquid crystal light valves 28R, 28G, and 28B provided facing three surfaces of the synthetic optical system 45 having a substantially cubic shape with a side of several centimeters are close to each other. The high frequency generated by driving is easily superimposed. However, since the phases of the color image signals R5, G5d, and B5d supplied to the liquid crystal light valve are different due to the action of the delay circuits 25 and 26 having a simple configuration, the liquid crystal light valves 28R, 28G, and 28B have different phases. High frequency peaks generated by driving are dispersed, and EMI noise can be reduced.
Therefore, it is possible to provide the projector 100 including a plurality of light modulation devices that can reduce EMI noise with a simple configuration.

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

(Modification 1)
FIG. 4 is a schematic configuration diagram of a projector having a different aspect. Here, a schematic configuration of the projector 110 in a different aspect will be described with reference to FIG. Note that the same components as those of the projector 100 in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. In the projector 110, the color liquid crystal drivers 29R, 29G, and 29B are provided in the subsequent stage of the DACs 27R, 27G, and 27B, and the reference clock CLK is input to the color liquid crystal drivers. The liquid crystal light valves 28R, Only the configuration of driving 28G and 28B is different from the projector 100.
In the embodiment, the drive timing signal including the reference clock CLK to each of the liquid crystal light valves 28R, 28G, and 28B is supplied from the timing control unit 21 to each of the liquid crystal light valves. However, the present invention is not limited to this configuration. .

For example, as shown in FIG. 4, the color liquid crystal drivers 29 </ b> R, 29 </ b> G, 29 </ b> B may be provided in the subsequent stage of the DACs 27 </ b> R, 27 </ b> G, 27 </ b> B.
In the semiconductor market, many ICs in which a DA converter and a liquid crystal driver are packaged as one package are marketed as general-purpose ICs. According to this configuration, the DACs 27R, 27G, and 27B for each color image signal and the respective color liquid crystal drivers 29R, 29G, and 29B can be configured by three package ICs, respectively. The mounting area can be reduced. Further, since the driving timing of each of the liquid crystal light valves 28R, 28G, and 28B and the phase shift mode of each of the color image signals R5, G5d, and B5d are the same as those of the projector 100, the same functions and effects as those of the above-described embodiment are achieved. be able to.
Therefore, it is possible to provide the projector 110 that can reduce EMI noise with a simple configuration.

(Modification 2)
This will be described with reference to FIG. In the embodiment, the phases of the green image signal G5d and the blue image signal B5d are respectively delayed by the delay time d1 or the delay time d2 with respect to the phase of the red image signal R5 synchronized with the reference clock CLK. However, the present invention is not limited to this.
For example, the phases of the green image signal G5d and the blue image signal B5d may be advanced by a predetermined ratio with respect to the phase of the red image signal R5. In other words, the phase of the color image signal having the largest phase difference from the reference color image signal may be within a range that is within ± 10% in the ½ period of the reference clock CLK.
Even in this configuration, each color image signal is an image signal that can be handled without any problem in each of the liquid crystal light valves 28R, 28G, and 28B, and the phase is shifted by a predetermined ratio with respect to the phase of the reference color image signal. Therefore, it is possible to disperse the high-frequency peak portion that is generated when the liquid crystal light valve is driven, and to reduce EMI noise.
Therefore, it is possible to obtain the same operational effects as in the above embodiment.

(Modification 3)
This will be described with reference to FIG. In the embodiment described above, the projector 100 includes the transmissive liquid crystal light valves 28R, 28G, and 28B as the light modulation device, but the present invention is not limited to this configuration. For example, a configuration using three reflective liquid crystal display devices for red, green, and blue light may be used.
Further, the electronic apparatus to be applied is not limited to the projection type projector, and may be, for example, a rear projector including an optical system including a plurality of light modulation devices and a screen in one individual. Also in this configuration, a transmissive liquid crystal light valve or a reflective liquid crystal display device can be used as the light modulation device.
Even with these configurations, it is possible to obtain the same effects as those of the above-described embodiment and the modified example by shifting the phase of each color image signal applied to the plurality of light modulation devices.

1 is a schematic configuration diagram mainly including a circuit block configuration of a projector according to an embodiment. 1 is a schematic configuration diagram of an optical system. The figure which shows the timing chart of each color image signal. The schematic block diagram of the projector of a different aspect. 1 is a schematic configuration diagram of a conventional projector. The figure which shows the timing chart of each color image signal in the conventional projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 17 ... Scaler of image signal processing part, 20 ... Image signal correction part of image signal processing part, 23 ... Image signal processing part, 25, 26 ... Delay circuit, 27R, 27G, 27B ... DAC, 28R, 28G, 28B ... Light Liquid crystal light valve as modulation device, 45... Synthetic optical system, 100. Projector, R1 to R3... Red image signal, R4 to R5... Red image signal as reference color image signal, G1 to G4, G4d to G5d. Signals, B1 to B4, B4d to B5d, blue image signal, CLK, reference clock, CLd1, CLd2, clock, d1, d2, delay time.

Claims (5)

An image signal processing unit for outputting each color image signal which is an image signal for each of a plurality of color lights;
A light modulation device for each color light that is provided for each color image signal and modulates each incident color light according to the corresponding color image signal,
And a delay circuit that shifts the phase of a color image signal other than the reference color image signal having a reference phase among the plurality of color image signals by a predetermined ratio from the phase of the reference color image signal. Projector.   The delay circuit is a damping resistor or a gate element provided between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light, The projector according to claim 1, wherein the projector is weighted according to a ratio of a predetermined shift amount.   The delay circuit sets the length of the wiring pattern between the output unit of each color image signal other than the reference color image signal in the image signal processing unit and the light modulation device for each color light by the predetermined shift amount. The projector according to claim 1, wherein the projector is adjusted according to a ratio.   The phase of the color image signal having the largest phase difference among the color image signals having the phase shifted by the predetermined ratio with respect to the phase of the reference color image signal is ½ period of the reference color image signal. The projector according to claim 1, wherein the projector falls within ± 10%. The plurality of color lights are red, green, and blue light,
The image signal processing unit outputs a red image signal, a green image signal, and a blue image signal. The red light modulation device, the green light modulation device, and the blue light modulation corresponding to each color image signal are output. The apparatus is provided on a corresponding surface of a substantially cubic combining optical system for combining each color modulated light that is light-modulated for each color light modulating device. 5. The projector according to any one of 4.

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