JP2007279366A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector for suppressing power consumption and also achieving a power saving mode along with the improvement of color reproducibility. <P>SOLUTION: By switching the polarity of a superposed pulse current from positive to negative and changing the level of the pulse current, only light quantity when white light is generated is reduced, a supply current to a light source is decreased and also the light quantity of the white light is relatively made smaller than that of other chromatic color. Thus, the power consumption is suppressed while the power saving mode along with the improvement of the color reproducibility is achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projector that generates a plurality of colors of light from white light emitted from a light source in a time-sharing manner and projects an image by projecting the generated light, and particularly suppresses power consumption while improving color reproducibility. It is related with the projector which can do.

  Projectors used in presentations or video projections form an image on an image device such as a liquid crystal panel or DMD (Digital Micromirror Device: registered trademark of TI), and reflect the projection light from the light source with the image device. The image is projected to the outside depending on whether it is transmitted through the image device, and the image on the image device is projected onto an external screen or wall. In such a projector, a color image is projected by projecting chromatic images such as R (red), G (green), and B (blue) in a time-sharing manner.

  A projector that projects a color image in a time-sharing manner includes a disk-shaped color wheel divided into RGB color filters around a rotation axis between a light source and an image device, and rotates white light projected from the light source. By passing through the color wheel, the white light passes through the filters of each color by rotation, and time division of the RGB images is realized. The projection light time-divided into RGB colors is irradiated on the image device. The image device forms an image for each color in synchronization with the rotation of the color wheel, and the formed image of each color is projected onto an external screen or wall in a time-division manner.

  The configuration of the color wheel of the projector is determined according to the specifications of the projector so that the brightness, color reproducibility, and white balance of the image projected by the projector are in an optimal state. In a projector that projects on a screen or a wall or the like, the projection light needs to be bright because the projection area is large. Therefore, by adding a transparent (W) filter that transmits white light projected from the light source to the color wheel, it is possible to insert a high-luminance image and increase the brightness of the projected image.

  In addition, the amount of light of a specific color is increased by superimposing a pulse current on the current supplied to the light source in synchronization with the projection light passing through one specific filter among the filters of each color of the color wheel. A technique for improving color reproducibility is disclosed (Patent Document 1).

  In addition to adding a W filter to the color wheel, it is possible to further increase the brightness by superimposing a pulse current in synchronization with the passage of light through the W filter. In view of this, a projector that places importance on lightness has a configuration in which a color filter is provided with a W filter and a pulse current synchronized with the W filter is supplied to the light source. However, in order to increase the brightness, the W filter is provided as described above, and the amount of light passing through the W filter is increased by a pulse current, so that an image created by another chromatic color filter is white light with a large amount of light. It becomes whitish under the influence of, and the color reproducibility deteriorates.

Further, if the amount of current to the light source is increased to increase the brightness of the projected image, the projector consumes a large amount of power. In order to suppress power consumption, a technology for realizing power saving by controlling the light amount of a light source according to the average luminance of an image to be displayed is disclosed (Patent Document 2). Also disclosed is a technique that achieves power saving by switching a light source to a small light source in conjunction with an operation of an optical system that projects an image, for example, having a large and small light source and lowering the projection magnification (Patent Document). 3). In these technologies, the amount of current supplied to the light source is reduced overall in the power saving mode for realizing power saving. FIG. 3 is an exemplary diagram illustrating an example of control of a current supplied to a light source in a power saving mode in a conventional projector. In the figure, the horizontal axis represents time, and the vertical axis represents the amount of current. FIG. 3A shows the color of light at each time point in RGBW. FIG. 3B is an example of the current supplied to the light source in the power saving mode of the conventional projector. In the figure, the broken line indicates the supply current to the light source in the normal mode, and the solid line indicates the supply current to the light source in the power saving mode. In the power saving mode, the amount of supplied current is reduced as a whole from the normal mode, and power saving is realized by lowering the average value.
JP 2004-212890 A Japanese Patent Laid-Open No. 2005-274883 JP 2003-29341 A

  However, in the conventional power saving mode, since the amount of supply current is reduced as a whole, the pulse current superimposed on the direct current from the power supply makes the light amount passing through the W filter larger than the light amount passing through other filters. The pulse shape was kept. Therefore, in the power saving mode, the brightness of the projected image is lowered and the color reproducibility is still deteriorated.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a projector capable of suppressing power consumption and enabling a power saving mode with improved color reproducibility.

  Another object of the present invention is to provide a projector capable of reducing power consumption and switching to a power saving mode with improved color reproducibility in a plurality of stages.

  Another object of the present invention is to provide a projector capable of further reducing power consumption by reducing the amount of current from the power source.

  Another object of the present invention is to provide a projector capable of suppressing power consumption and allowing the user to select a power saving mode with improved color reproducibility.

  Another object of the present invention is to provide a projector capable of suppressing the number of rotations of the light source cooling fan in synchronization with increase / decrease in the amount of current supplied to the light source, further reducing power consumption and noise. It is in.

  The projector according to the present invention includes a light source that generates white light according to the amount of current supplied, a color wheel that includes a chromatic color and a transparent filter, and white light from the light source as a filter for each color of the color wheel. Means for sequentially generating light of each color by passing in sequence, means for sequentially projecting the light of each color generated, means for generating pulse current, and superimposing means for superimposing said pulse current on a direct current supplied from a power source And means for supplying the superimposed current to the light source, wherein the superimposing means superimposes the pulse current in synchronization with a period during which white light from the light source passes through the transparent filter of the color wheel. A projector is characterized by comprising control means for controlling the amount of current to the light source by switching the polarity and / or changing the magnitude of the pulse current. .

  In the present invention, when the pulse current synchronized with the white light from the light source passing through the transparent color filter is supplied to the light source superimposed on the direct current from the power source, the polarity of the pulse current is switched. And / or it is set as the structure which can change the magnitude | size of a pulse current. As a result, when the polarity of the pulse current is switched from positive to negative, or when the pulse current polarity is switched from positive to negative by changing the magnitude of the pulse current, the white light from the light source is switched to the transparent color filter. The amount of current supplied to the light source at the transmission timing decreases. At the same time, the amount of light passing through the transparent color filter is reduced, while the amount of current supplied to the light source at the timing when white light from the light source passes through the chromatic filter does not change. The amount of light passing through does not change. In addition, when the polarity of the pulse current remains positive and the magnitude of the pulse current is increased, the amount of current supplied to the light source increases while the white light from the light source passes through the transparent color filter. Is reduced, the amount of current supplied to the light source decreases while white light from the light source passes through the transparent color filter.

  The projector according to the present invention is characterized in that the control means changes the magnitude of the pulse current stepwise.

  In this invention, it is set as the structure which can change the magnitude | size of the pulse current superimposed on the electric current to a light source in steps. By preparing a value for changing the magnitude of the pulse current at a plurality of stages and switching to one of the prepared values, it becomes possible to switch the amount of white light passing through the transparent color filter. .

  In the projector according to the aspect of the invention, the control unit includes a unit that controls a DC current amount from the power source, and the DC power from the power source is changed when the polarity of the pulse current is switched and / or the magnitude is changed. It is characterized by changing the flow rate.

  In the present invention, when the polarity of the pulse current is switched and / or the magnitude is changed, the DC current amount from the power source can be changed. When the polarity of the pulse current is switched from positive to negative and / or when the magnitude of the pulse current is changed, the amount of current supplied to the light source is reduced overall by reducing the amount of direct current from the power source.

  The projector according to the present invention includes means for receiving a control instruction from the outside, and the control means switches the polarity and / or changes the magnitude of the pulse current when the control instruction is received from the outside. It is characterized by being.

  In the present invention, there is provided a means for receiving a control instruction from the outside, and the pulse current is controlled when the control instruction is received from the outside. Thus, when a control instruction is received from the outside, the polarity of the pulse current is switched and / or the magnitude is changed, and the amount of current supplied to the light source is increased or decreased.

  The projector according to the present invention includes a light source cooling fan, and switches the number of rotations of the light source cooling fan in conjunction with a change in polarity and / or a change in the magnitude of the pulse current by the control means. It is characterized by that.

  In the present invention, the rotation speed of the light source cooling fan is switched in conjunction with switching the polarity and / or changing the magnitude of the pulse current. As a result, when the polarity of the pulse current is switched from positive to negative and / or when the magnitude of the pulse current is changed, the rotational speed of the light source cooling fan decreases.

  In the case of the present invention, the polarity of the pulse current superimposed on the direct current from the power supply is switched to negative, and the amount of current to the light source is reduced by changing the magnitude of the pulse current, thereby saving power consumption. Switch to mode. Furthermore, switching the polarity of the pulse current synchronized with the W filter to negative simultaneously reduces only the amount of white light without reducing the amount of chromatic color, and relative to the amount of chromatic color compared to white light. Can be increased. Accordingly, color reproducibility can be improved without changing the configuration of the color wheel to which the W filter is added with emphasis on brightness. As a result, it is possible to reduce the power consumption and to achieve a power saving mode with improved color reproducibility.

  In the case of the present invention, the magnitude of the pulse current to be superimposed on the direct current from the power source is switched in stages, and the amount of current to the light source is increased or decreased in multiple stages, so that the degree of suppression of power consumption can be changed to multiple levels. Switching between power saving modes divided into stages is possible.

  According to the present invention, when reducing the amount of current to the light source by switching the polarity and / or changing the magnitude of the pulse current superimposed on the direct current from the power source, also reduce the amount of DC current from the power source. As a result, not only the amount of white light but also the amount of chromatic light can be reduced overall, further reducing power consumption.

  According to the present invention, the user of the projector can perform step-by-step switching operation of the power saving mode in addition to the operation of whether or not to reduce the power consumption, and saves according to the brightness of the place where the projector is used. A power mode can be selected.

  According to the present invention, when the projector is used in the power saving mode, the number of rotations of the light source cooling fan can be decreased in conjunction with a decrease in the amount of current supplied to the light source. Thus, the present invention has excellent effects such as further reducing power consumption and suppressing noise.

  Hereinafter, a projector according to the present invention will be specifically described with reference to the drawings illustrating an embodiment thereof. FIG. 1 is a block diagram showing a configuration of a projector according to the present invention. The projector includes a light source 11 that uses a DC lamp that emits white light, such as a halogen lamp, a metal halide lamp, or an ultra-high pressure mercury lamp, a color wheel 12 that transmits white light from the light source 11, and an image device that forms an image. 13, a projection optical system 14 that has a projection lens or the like and projects light from the image device 13 to the outside, and a fan 15 that cools the light source 11 by sucking air from outside the projector and / or exhausting it outside the projector. Prepare. A white arrow in FIG. 1 indicates light emitted from the light source 11, passing through the color wheel 12, reflected by the image device 13, or passed through the image device 13 and projected by the projection optical system 14.

  The projector further includes a control unit 21 that controls the entire projector, a power supply circuit 22 that supplies a direct current, a direct current ballast control circuit 23 that controls a supply current to the light source 11, and a pulse current generation circuit 24 that generates a pulse current. A color wheel sensor 25 that detects the rotational position of the color wheel 12, an image device control circuit 26 that controls the operation of the image device 13, a fan control circuit 27 that controls the rotation of the fan 15, and an image data signal. Receiving unit 28, and an operation unit 29 that receives a user's operation.

  The color wheel 12 is formed of a four-color filter obtained by adding a W (transparent) filter that transmits white light from the light source 11 as it is to an R (red) G (green) B (blue) filter. When white light from the light source 11 passes through each filter, four colors of light are generated by adding white light to each RGB color. Each of the RGBW filters is arranged so as to divide the disk-shaped color wheel 12 into four parts at a predetermined ratio in the circumferential direction. The color wheel 12 is installed so that the rotation axis is parallel to the optical axis of white light from the light source 11 and the rotation axis is deviated from the optical axis. White light from the light source 11 is collected at a point that intersects the color wheel 12 by an optical system (not shown), and when the color wheel 12 is rotated, light of each RGBW color is generated in the order of arrangement of the filters.

  The image device 13 is composed of a liquid crystal panel or DMD (Digital Mirror Device: registered trademark of TI), and the like, and the control unit 21 generates an image for each RGB color based on image data received from the outside via the receiving unit 28. Form by dividing. Light of each color of RGBW that is time-divided through the color wheel 12 is irradiated to the image device 13 by an optical system (not shown). The image device 13 forms an image for each color of RGB in synchronization with the light of each color that arrives, and transmits or reflects an image for each color, and transmits or reflects white light as it is. A color image is projected onto a screen or the like by projecting an image for each color and white light through the projection optical system 14.

  The control unit 21 includes a processor that performs calculation, a ROM that stores information such as a program necessary for the calculation, and a RAM that stores information generated temporarily by the calculation, and controls the entire projector. The control unit 21 receives an image data signal from an external device such as a PC (Personal Computer) or a video reproduction device via the receiving unit 28, and inputs the image data signal to the image device control circuit 26. Further, the control unit 21 receives an operation from a projector user via the operation unit 29 and inputs a switching signal to the DC ballast control circuit 23 and the fan control circuit 27 according to various operations.

  The control unit 21 rotates the color wheel 12 via a drive unit (not shown). Each time the color wheel 12 makes a round, the color wheel sensor 25 sends to the control unit 21 a position detection signal that detects a passing start point at which white light from the light source 11 starts to pass through the W filter in the color wheel 12. The control unit 21 sends a synchronization signal synchronized with the position detection signal to the pulse current generation circuit 24 and the image device control circuit 26.

  The pulse current generation circuit 24 generates a pulse current having a preset period, pulse width, base current, and peak current in synchronization with the timing at which the synchronization signal sent from the control unit 21 is detected. Input to the control circuit 23. The base current value of the pulse current is 0 (A), and the current value of the peak current is 0.35I (A). The period of the pulse current is controlled to synchronize with one rotation of the color wheel 12, and the pulse width of the pulse current is set to synchronize with the time when the white light from the light source 11 passes through the W filter of the color wheel 12. Is done. Also, the pulse current is supplied by the DC ballast control circuit 23 in which the pulse current is superimposed on the light source 11, and the time taken for the white light from the light source 11 to reach the W filter is calculated backward to advance the time phase. It is compatible. The image device control circuit 26 forms an image for each color of RGB on the image device 13 in synchronization with the synchronization signal input from the control unit 21.

  The operation unit 29 includes a switching button for switching the projector operation mode. A plurality of stages are prepared for the operation mode, and each time the switching button is pressed, the operation mode is switched in the order of the normal mode, the power saving mode A, the power saving mode B, and the power saving mode C. The control unit 21 detects that the switching button has been pressed via the operation unit 29, and sends a switching signal to the DC ballast control circuit 23 and the fan control circuit 27 each time the detection is made.

  The fan control circuit 27 is supplied with current from the power supply circuit 22 and rotates the fan 15 to control the rotation speed. The fan control circuit 27 switches the rotational speed of the fan 15 when detecting the switching signal sent out by the control unit 21. The rotation speed of the fan 15 is set in advance as F in the normal mode, 0.9F in the power saving mode A, 0.8F in the power saving mode B, and 0.7F in the power saving mode C, and a switching signal is detected. In this case, the rotation speed of the fan 15 is switched to a preset value.

  The direct current ballast control circuit 23 superimposes the direct current supplied from the power supply circuit 22 on the direct current by changing the polarity and magnitude of the pulse current input from the pulse current generation circuit 24 and supplies the superimposed current to the light source 11. The DC ballast control circuit 23 sets the polarity and magnitude of the pulse current to + (positive) 1 in the normal mode, − (negative) 0.6 in the power saving mode A, −1.2 in the power saving mode B, and power saving. In mode C, -1.8 is set in advance. When the switching signal sent by the control unit 21 is detected, the polarity of the pulse current is switched from positive to negative and the magnitude of the pulse current is switched as set.

  In the normal mode, the direct current ballast control circuit 23 superimposes the input pulse current on the direct current and supplies it to the light source 11. In the power saving mode A, the peak current value 0.35I (A) of the input pulse current is multiplied by 0.6, and the peak current value of the pulse current is changed to 0.21I (A). Further, since the polarity is inverted, the changed pulse current has a base current value of 0 (A) and a peak current value of -0.21I (A). In the power saving mode B, the input pulse current is changed from the peak current value 0.35I (A) to 1.2 times, and the polarity is inverted. Accordingly, the changed pulse current has a base current value of 0 (A) and a peak current value of -0.42I (A). In the power saving mode C, the input pulse current is changed from the peak current value 0.35I (A) to 1.8 times, and the polarity is inverted. Therefore, the changed pulse current has a base current value of 0 (A) and a peak current value of -0.63I (A). The DC ballast control circuit 23 switches so that the pulse current is changed as described above in each operation mode, and supplies the pulse current after the change to the DC light supplied from the power supply circuit 22 to the light source 11. .

  The direct current ballast control circuit 23 controls the amount of direct current supplied from the power supply circuit 22. In the normal mode and the power saving modes A and B, the DC ballast control circuit 23 sets the amount of DC current supplied from the power supply circuit 22 to I (A). In the power saving mode C, the amount of direct current supplied from the power supply circuit 22 is reduced to 90% to 0.9I (A).

  FIG. 2 is a timing chart showing an example of control of the current supplied to the light source 11 of the projector according to the present invention. In the figure, the horizontal axis represents time, and the vertical axis represents the amount of current. FIG. 2A shows in RGBW which color light is generated when the white light from the light source 11 passes through the RGBW filters in the color wheel 12 at each time point. The time width in which light of each color of RGBW is generated is a width corresponding to the ratio of the configuration of each filter of RGBW of the color wheel 12. In the present embodiment, the W filter of the color wheel 12 is arranged so that the occupied angle is 80 °. When the period of the pulse current synchronized with one rotation of the color wheel 12 is 1 t (seconds), the pulse width synchronized with the W filter is 80 ° / 360 ° = 0.22 t (seconds).

  FIG. 2B shows a direct current supplied from the power supply circuit 22. The vertical axis represents the amount of current. The direct current shown in FIG. 2B is a direct current before the pulse current is superimposed, and the current value is I (A). FIG. 2C shows the pulse current input from the pulse current generation circuit 24. Similarly, the vertical axis represents the amount of current. The time phase of the pulse current shown in FIG. 2 (c) is advanced as described above. As described above, the pulse current has a base current value of 0 (A) and a peak current value of 0.35 I (A). The solid line in FIG. 2D shows the supply current to the light source 11 in which the DC ballast control circuit 23 superimposes the pulse current in FIG. 2C on the DC current shown in FIG. The vertical axis represents the amount of current. The base current value of the supply current is I (A), and the peak current value is 1.35I (A). When the projector is in the normal mode, the current shown in FIG. 2D is supplied to the light source 11 and the fan 15 is rotating at the rotation speed F.

  Thus, in the normal mode, a current of 1.35 I (A) is supplied while white light from the light source 11 passes through the W filter of the color wheel 12 (0.22 tsec), and each of the other RGB filters The current of I (A) is supplied while passing through (0.78 tsec). Since white light is emitted from the light source 11 in accordance with the amount of current, the amount of light passing through the W filter is greater than the amount of light passing through the RGB filters, and the brightness of the projected image from the projector is improved.

  When the projector is operated in the normal mode and the switch button is pressed by the user of the projector, the operation mode of the projector is switched to the power saving mode A. When the DC ballast control circuit 23 detects the switching signal sent from the control unit 21 while operating in the normal mode, the magnitude of the pulse current shown in FIG. Then, the polarity is switched so that the polarity is inverted, and the changed pulse current is superimposed on the direct current from the power supply circuit 22. At the same time, when the fan control circuit 27 detects a switching signal while operating in the normal mode, the fan control circuit 27 reduces the rotational speed of the fan 15 to 0.9F. A solid line in FIG. 2E indicates a current supplied to the light source 11 by the DC ballast control circuit 23 when the projector is in the power saving mode A. The vertical axis represents the amount of current. The base current value of the supply current in the power saving mode A after superimposing the pulse current is I + 0 = I (A), and the peak current value is I−0.21I = 0.79I (A). A broken line in FIG. 2E indicates a supply current to the light source 11 in the normal mode for comparison.

  Thereby, in the power saving mode A, while the white light from the light source 11 passes through the W filter of the color wheel 12, a current having a current value of 0.79I (A) is supplied and passes through the other RGB filters. During this period, a current having a current value I (A) is supplied. In the power saving mode A, the total amount of supply current is reduced compared to the normal mode. In the power saving mode A, the amount of white light while passing through the RGB filters does not change at the same time, but the amount of white light while passing through the W filters is white light while passing through the RGB filters. Relatively less than the amount of light.

  When the projector is operating in the power saving mode A and the switch button is pressed by the user of the projector, the projector operating mode is switched to the power saving mode B. When the DC ballast control circuit 23 detects the switching signal sent from the control unit 21 when operating in the power saving mode A, the magnitude of the pulse current shown in FIG. The polarity is inverted so that the polarity is inverted, and the pulse current after the change is superimposed on the direct current from the power supply circuit 22. At the same time, when the fan control circuit 27 detects a switching signal when operating in the power saving mode A, the fan control circuit 27 reduces the rotational speed of the fan 15 to 0.8F. The solid line in FIG. 2 (f) indicates the current that the DC ballast control circuit 23 supplies to the light source 11 when the projector is in the power saving mode B. The vertical axis represents the amount of current. The base current value of the supply current in the power saving mode B after superimposing the pulse current is I + 0 = I (A), and the peak current value is I−0.42I = 0.58I (A). The broken line in FIG. 2 (f) shows the supply current to the light source 11 in the normal mode for comparison.

  As a result, in the power saving mode B, while the white light from the light source 11 passes through the W filter of the color wheel 12, a current of 0.58I (A) is supplied and passes through the other RGB filters. During this period, a current having a current value I (A) is supplied. In the power saving mode B, the total amount of supply current is reduced compared to the normal mode and the power saving mode A. In the power saving mode B, the amount of white light while passing through the RGB filters does not change at the same time. However, compared with the power saving mode A, the amount of white light passing through the W filter is RGB. Relatively less than the amount of white light passing through each filter.

  When the projector is operating in the power saving mode B and the switching button is pressed by the user of the projector, the projector operating mode is switched to the power saving mode C. When the DC ballast control circuit 23 detects a switching signal sent from the control unit 21 while operating in the power saving mode B, the DC ballast control circuit 23 sends a control signal to the power supply circuit 22 and receives the DC signal inputted from the power supply circuit 22. Reduce current to 90% current. Further, the direct current ballast control circuit 23 switches so that the magnitude of the pulse current shown in FIG. 2C is changed to 1.8 times and the polarity is inverted, and the changed pulse current is supplied from the power supply circuit 22. Superimpose on the direct current. At the same time, when the fan control circuit 27 detects a switching signal when operating in the power saving mode B, the fan control circuit 27 decreases the rotational speed of the fan 15 to 0.7F. The solid line in FIG. 2G indicates the current that the DC ballast control circuit 23 supplies to the light source 11 when the projector is in the power saving mode C. The vertical axis represents the amount of current. The base current value of the supply current in the power saving mode C after superimposing the pulse current is 0.9I + 0 = 0.9I (A), and the peak current value is 0.9I−0.63I = 0.27I (A). Become. A broken line in FIG. 2G indicates a supply current to the light source 11 in the normal mode for comparison.

  As a result, in the power saving mode C, while the white light from the light source 11 passes through the W filter of the color wheel 12, a current having a current value of 0.27I (A) is supplied and passes through the other RGB filters. During this period, a current having a current value of 0.9I (A) is supplied. In the power saving mode C, the total amount of supply current is further reduced as compared with the normal mode and the power saving modes A and B. In the power saving mode C, the amount of white light while passing through the RGB filters is also reduced, but the amount of white light passing through the W filter as compared with the normal mode and the power saving modes A and B is also reduced. Is relatively less than the amount of white light while passing through the RGB filters.

  When the projector is operating in the power saving mode C, when the switching button is pressed by the user of the projector, the projector returns to the normal mode. When the DC ballast control circuit 23 detects a switching signal sent from the control unit 21 when operating in the power saving mode C, the DC ballast control circuit 23 sends a control signal to the power supply circuit 22 and receives the DC signal inputted from the power supply circuit 22. The current is returned to the current value I (A). Further, the polarity and magnitude of the pulse current are returned so that the base current value is 0 (A) and the peak current value is 0.35 I (A), and the supply current to the light source 11 is shown in FIG. Thus, the base current value is I (A) and the peak current value is 1.35I (A). At the same time, when the fan control circuit 27 detects a switching signal while operating in the power saving mode C, the fan control circuit 27 returns the rotational speed of the fan 15 to F.

  With the above configuration, it is possible to switch to the power saving mode step by step with the effect of improving the color reproducibility.

The power consumption that can be suppressed by the projector according to the present invention will be described below. In the present embodiment, the time width during which the W filter is irradiated with white light from the light source 11 is 0.22 t (seconds) out of the period 1 t (second) of each RGBW color depending on the ratio of the W filter to the color wheel 12. It is. In addition, the supply current to the light source 11 in the normal mode has a base current value of I (A) and a peak current value of 1.35I (A) as shown in FIG. The current consumption Pw of the pulse part is
Pw = 0.22t × 1.35I = 0.297t · I
The total current consumption P is
P = (1−0.22) t × I + Pw = 1.077 t · I
It is. Therefore, the current consumption of the pulse portion synchronized with the W filter is
Pw / P = 0.297 / 1.077 = 0.276
This will account for 27.6% of the total. Thereby, in the power saving mode of the projector according to the present invention, the power consumption can be effectively suppressed by reducing the current amount Pw synchronized with the W filter.

As shown in FIG. 2E, the supply current to the light source 11 in the power saving mode A of the projector according to the present invention has a base current value of I (A) and a peak current value of 0.79I (A ). The current consumption PwA of the pulse part is
PwA = 0.22t × 0.79I = 0.174t · I
The total current consumption PA is
PA = (1−0.22) t × I + PwA = 0.904t · I
It is. Therefore, the power consumption ratio PrA compared with the normal mode is
PrA = 0.954 / 1.077 = 0.886
Thus, power consumption can be suppressed to about 89%. In addition, since the number of rotations of the light source cooling fan 15 is reduced from F to 0.9F, power consumption can be further suppressed.

As shown in FIG. 2F, the supply current to the light source 11 in the power saving mode B of the projector according to the present invention is that the base current value is I (A) and the peak current value is 0.58I (A). It is. The current consumption PwB of the pulse part is
PwB = 0.22t × 0.58I = 0.128t · I
The total current consumption PB is
PB = (1−0.22) t × I + PwB = 0.908 t · I
It is. Therefore, the power consumption ratio PrB compared with the normal mode is
PrB = 0.908 / 1.077 = 0.843
Thus, power consumption can be suppressed to about 84%. In addition, since the number of revolutions of the light source cooling fan 15 is further reduced to 0.8 F, the power consumption can be further suppressed.

As shown in FIG. 2G, the current supplied to the light source 11 in the power saving mode C of the projector according to the present invention has a base current value of 0.9I (A) and a peak current value of 0.27I ( A). The current consumption PwC of the pulse part is
PwC = 0.22t × 0.27I = 0.0594t · I
The total amount of current consumption PC is
PC = (1−0.22) t × 0.9I + PwC = 0.7614t · I
It is. Therefore, the power consumption ratio PrC compared with the normal mode is
PrC = 0.761 / 1.077 = 0.707
Thus, power consumption can be suppressed to about 71%. In addition, since the number of revolutions of the light source cooling fan 15 is further reduced to 0.7 F, power consumption can be further suppressed.

  As described above, in the present invention, the amount of current supplied to the light source 11 can be reduced by operating in the power saving modes A and B, and at the same time, the light passes through the W filter without changing the light amount of each RGB color. It is possible to make the amount of white light during the period relatively smaller than the amount of white light while passing through the RGB filters. In addition, by operating in the power saving mode C, the amount of current supplied to the light source 11 can be further reduced, and at the same time, the amount of light passing through the W filter is greater than the amount of white light while passing through the RGB filters. It becomes possible to reduce relatively. As a result, the projector according to the present invention reduces power consumption, and at the same time, reduces the amount of white light relative to the amount of light of each RGB color while maintaining the configuration of the color wheel 12 composed of RGBW filters that emphasize lightness. Thus, the influence of white light inserted between the images of the respective colors can be reduced. In other words, the projector according to the present invention can realize a power saving mode with reduced power consumption and improved color reproducibility. Furthermore, in the power saving modes A, B, and C, the number of rotations of the fan can be reduced, and power consumption and noise can be suppressed.

  In the present invention, the supply current to the light source 11 in each power saving mode is switched by the DC ballast control circuit 23 by switching the polarity and magnitude of the pulse current superimposed on the DC current supplied from the power supply circuit 22. Therefore, the pulse current generation circuit 24 does not need to generate a plurality of types of pulse currents.

  In the present embodiment, the color wheel 12 is composed of four color filters in which a W filter is added to each of the RGB filters, but is not limited to this, and C (cyan), Y (yellow), and M (magenta). It is good also as a structure provided with the filter of other colors, such as these complementary colors. The W filter is arranged so that the occupation angle is 80 °. However, the present invention is not limited to this, and the W filter may be arranged at an angle larger or smaller than 80 °.

  In the present embodiment, the light source cooling fan 15 is provided. However, the fan 15 may be omitted. In the present embodiment, the power saving mode has three stages of A, B, and C. However, it is needless to say that a configuration with fewer or more stages may be prepared. Further, the switching to the normal mode and the power saving modes A, B, and C is performed by switching only the switching button, but the present invention is not limited to this, and the button is set for each of the normal mode, the power saving modes A, B, and C. It is good also as a structure which is provided and switches to each mode directly.

  In the present embodiment, the polarity and magnitude of the pulse current to be superimposed are set in advance as -0.6, -1.2, and -1.8 in the power saving modes A, B, and C, respectively. In the mode C, the amount of direct current from the power supply circuit 22 is reduced to 90%. However, the value for changing the magnitude of the pulse current and the magnitude of the direct current from the power supply circuit 22 is not limited to these. It is. In addition, the rotation speed of the light source cooling fan 15 in the power saving modes A, B, and C is set to 0.9 F, 0.8 F, and 0.7 F, respectively, with respect to the rotation speed F in the normal mode. Of course, it is not limited to these.

It is a block diagram which shows the structure of the projector which concerns on this invention. It is a timing chart which shows the example of control of the electric current supplied to the light source of the projector which concerns on this invention. It is an illustration figure which shows the example of control of the electric current supplied to the light source in the power saving mode in the conventional projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Color wheel 13 Image device 14 Projection optical system 15 Fan 21 Control part 23 DC ballast control circuit 24 Pulse current generation circuit 25 Color wheel sensor 26 Image device control circuit 27 Fan control circuit 29 Operation part

Claims (5)

A light source that generates white light according to the amount of current supplied, a color wheel that includes chromatic and transparent filters, and light of each color by sequentially passing the white light from the light source through the filters of each color of the color wheel. , Means for sequentially projecting the generated light of each color, means for generating a pulse current, superposition means for superimposing the pulse current on a direct current supplied from a power source, and the superimposed current as a light source In the projector, wherein the superimposing means superimposes the pulse current in synchronization with a period during which white light from the light source passes through the transparent filter of the color wheel.
A projector comprising: control means for controlling the amount of current to the light source by switching the polarity and / or changing the magnitude of the pulse current. The control means includes
The projector according to claim 1, wherein the magnitude of the pulse current is changed stepwise. The control means includes
Means for controlling the amount of direct current from the power source;
3. The projector according to claim 1, wherein the direct current amount from the power source is changed when the polarity of the pulse current is switched and / or the magnitude is changed. Means for receiving control instructions from the outside,
The control means includes
The projector according to any one of claims 1 to 3, wherein when a control instruction is received from outside, the polarity of the pulse current is switched and / or the magnitude is changed. It has a fan for cooling the light source,
5. The rotation speed of the light source cooling fan is switched in conjunction with a change in polarity and / or a change in the magnitude of the pulse current by the control means. 6. Projector described in 1.

Images