JP2009258345A - Projector and method for controlling ventilation volume of projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technique to effectively exhaust heat inside a housing by absorbing variation of illuminance of a lamp of a projector. <P>SOLUTION: When a light source 2 is turned on, a control part 16 acquires an internal temperature detection value V1 (S11), acquires an external temperature detection value V2 (S12), reads out a threshold table from a threshold storage part 13 (S13), and sets first to fourth thresholds Th1 to Th4 based on the threshold table (S14). Furthermore, the control part 16 reads out lamp voltage VL (S15), corrects the first to fourth thresholds Th1 to Th4 based on the lamp voltage VL (S16), and calculates a difference ΔV between the internal temperature detection value and the external temperature detection value (S17). Then, the control part 16 compares the difference ΔV between the internal temperature detection value and the external temperature detection value with the first threshold Th1 to the fourth threshold Th4 (S18, S20, S22 and S24), and performs control to stop a fan 10 (S19) or set it to low-speed rotation (S21), to middle-speed rotation (S23), to high-speed rotation (S25), or turn off the light source (S26). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projector and a method for controlling the air flow rate of the projector, and in particular, detects a temperature inside and outside the housing that houses the light source, and controls the air flow according to the temperature difference between inside and outside the housing. And a method for controlling the air flow.

  In a projector, a problem to be overcome is a thermal problem. In general, a projector stores a lamp light source in a housing having a predetermined shape, and discharges heat generated in the housing with a fan in order to protect internal components from heat emitted from the lamp light source or the like. . In addition, an upper limit temperature when the exhaust port portion is heated by exhaust heat is defined from the viewpoint of safety. Due to this background, countermeasures against heat have become very important in the development of projectors. Naturally, increasing the number of revolutions of the fan can increase the amount of air flow and enhance the exhaust heat effect, but the noise increases with the number of revolutions and may exceed the user's tolerance. .

  Therefore, several techniques for effectively exhausting heat by balancing the rotational speed of the fan and noise have been proposed. For example, there is a technique for downsizing a projector and efficiently cooling the inside of the apparatus (for example, see Patent Document 1). In this technology, in a projection display device including an optical unit, a power supply unit, and an exterior case that houses the optical unit and the power supply unit, an intake opening is formed at one end of the power supply unit, and the other An exhaust opening is formed at the end, the intake opening is disposed in the vicinity of the air intake of the exterior case, and the exhaust opening is disposed in the vicinity of the exhaust opening of the exterior case. Since the intake opening and the exhaust opening are provided, the inside of the power supply unit can be independently and efficiently cooled, and the optical unit and the power supply unit can be closely arranged.

  In addition, there is a technique for suppressing deterioration of a fan and preventing deterioration of a light source, an optical element, and the like (see, for example, Patent Document 2). In this technique, a projection display device includes a light source lamp unit, an optical system unit including a modulation device, a projection lens that enlarges and projects an image formed by the optical system, and a power supply unit that supplies power for driving the device. A power supply intake fan, a modulator intake fan, and an exhaust fan. By driving only the power supply intake fan for a certain period after the power is turned on, the noise of the fan can be suppressed. Further, the other fans can prevent deterioration of the light source lamp, the optical element, and the like by controlling the rotation speed based on the temperature detected by the temperature sensor.

However, in the technologies disclosed in Patent Documents 1 and 2, it has been a problem that the noise of the fan is suppressed and the electronic components and the light source are prevented from being deteriorated by heat, and the addition of the temperature detecting means is unnecessary. . That is, when the light amount of the light source decreases with time, the amount of heat given to the DMD (Digital Micromirror Device) by light irradiation decreases. On the other hand, the amount of heat conducted from the light source to the surroundings does not change. Accordingly, as the cumulative lighting time of the light source is longer, the temperature of the DMD becomes lower than that of other electronic components, and the temperature sensor is disposed in the vicinity of the DMD, so that the fan does not rotate despite the high temperature of the electronic components. In addition, the light source may not be turned off. That is, although the ambient temperature of the light source has risen to a temperature that causes deterioration of the electronic component, the temperature of the DMD remains low, so the fan speed does not increase and the electronic component and the light source deteriorate. There was a problem. A technique for realizing the problem solution has also been proposed (see, for example, Patent Document 3). In this technology, a light source housed in a housing having a vent hole, a DMD that modulates light from the light source, and an internal temperature detection unit that detects the temperature inside the housing, and an internal temperature detection Threshold table in which the lighting time of the light source and the threshold value are associated with the projector that controls the number of rotations of the fan according to the temperature difference detected by the external unit and the external temperature detection unit and projects the modulated light modulated by the DMD. And, a timing unit that measures the lighting time of the light source, a specifying unit that specifies a threshold based on the lighting time and threshold table timed by the timing unit, and compares the threshold value specified by the specifying unit and the temperature difference, Means for controlling the rotational speed of the fan in accordance with the comparison result. With such a configuration, efficient exhaust heat reflecting the influence of the amount of light that changes with time without adding temperature detection means is achieved.
Japanese Patent Laid-Open No. 10-186513 JP 2000-35613 A JP 2007-279365 A

By the way, in the technique disclosed in Patent Document 3, the setting value for switching the rotational speed of the fan and turning off the power source is changed according to the cumulative lighting time of the lamp. In this technique, an average value measured in advance as the dimming characteristic of the lamp is used. FIG. 6 shows a general relationship between the lamp voltage VL and the illuminance with respect to the cumulative lighting time of the light source (lamp). Here, the central lamp voltage VL (A2) corresponds to the central illuminance (A1), and the upper lamp voltage VL (C2).
Corresponds to the lower illuminance (C1), and the lower illuminance (B1) corresponds to the lower lamp voltage Vl (B2). As illustrated, as the cumulative lighting time increases, the illuminance gradually decreases but the lamp voltage VL increases. Further, the dimming characteristics vary depending on the individual, and there is a problem that optimal control cannot be performed for a lamp having an extremely short lifetime or an extremely long lifetime. Although it is technically possible to additionally install a temperature sensor not only in the vicinity of the DMD but also in the vicinity of the light source, another technique has been demanded from the viewpoint of an increase in cost.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique that absorbs variations in illuminance of lamps of a projector and effectively realizes exhaust heat inside the housing.

One embodiment of the present invention relates to a projector. The projector includes a light source housed in a housing having a vent, an internal temperature detection unit that detects a temperature inside the housing, an external temperature detection unit that detects a temperature outside the housing, A ventilation means for venting the inside of the housing, controlling the ventilation means in accordance with a difference in temperature detected by the internal temperature detection section and the external temperature detection section, and allowing light from the light source to be emitted by a light modulation element. In a projector configured to project modulated light that has been modulated, a light source voltage detection unit that acquires a voltage applied to the light source, a voltage acquired by the light source voltage detection unit, the internal temperature detection unit, and the external temperature A ventilation control unit that controls the ventilation rate of the ventilation unit according to the temperature difference detected by the detection unit.
The ventilation amount controlled by the ventilation control unit may be variably set in a plurality of stages according to the temperature difference detected by the internal temperature detection unit and the external temperature detection unit.
The air flow control unit may correct the air flow amount variably set in the plurality of stages according to the voltage acquired by the light source voltage detection unit.
Further, the ventilation control unit may refer to a table in which a threshold value is stored according to the voltage acquired by the light source voltage detection unit as the ventilation amount variably set in the plurality of stages.
Further, the ventilation means may include a fan, and the ventilation control unit may control the ventilation amount by controlling the rotation amount of the fan.
In addition, the ventilation unit may include a ventilation direction changing unit that changes a direction of the ventilation, and the ventilation control unit may control the ventilation amount by controlling the direction of the ventilation.
The internal temperature detection unit may be provided in the vicinity of the light modulation element.
Another aspect of the present invention relates to a method for controlling an air flow rate in a projector. The method includes: a light source housed in a housing having a vent; an internal temperature detection unit that detects a temperature inside the housing; an external temperature detection unit that detects a temperature outside the housing; A ventilation means for venting the inside of the housing, controlling the ventilation means in accordance with a difference in temperature detected by the internal temperature detection unit and the external temperature detection unit, and using a light modulation element A method of controlling an air flow rate in a projector that modulates and projects modulated light, the light source voltage detecting step for obtaining a voltage applied to the light source, the temperature outside the housing, and the housing A temperature difference detecting step of acquiring a temperature inside the body and detecting a temperature difference between the outside and the inside of the housing; and a control amount of the ventilation amount of the ventilation means based on the voltage and the temperature difference And a control amount determination step for determining.
In addition, the control amount determination step may include a table reference step in which a control amount of the ventilation amount of the ventilation unit refers to a table in which a plurality of threshold values are set according to the temperature difference.
Further, the control amount determination step may determine the number of rotations of a ventilation fan provided in the projector, using the ventilation amount of the ventilation means as a control amount.
Further, the control amount determination step may correct a threshold value for determining a rotation speed of the fan in accordance with the voltage applied to the light source.

ADVANTAGE OF THE INVENTION According to this invention, the technique which absorbs the variation in the illumination intensity of the lamp | ramp of a projector, and implement | achieves the waste heat inside a housing | casing effectively can be provided.

  Hereinafter, the best mode for carrying out the invention (hereinafter, simply referred to as “embodiment”) will be described in detail with reference to the drawings. In the following description, in order to optimize the exhaust heat in the projector, the temperature difference between the inside and outside of the housing is calculated, and the rotation speed of the exhaust fan is determined by comparing the temperature difference with a predetermined threshold value. Further, in order to reflect the dimming characteristic due to the change with time as shown in FIG. 6 in the control of the rotational speed of the exhaust fan, the threshold value is changed according to the lamp voltage.

  FIG. 1 is a schematic cross-sectional view of the structure of a DLP (Digital Light Processing: registered trademark) type projector 100 according to the embodiment, and FIG. 2 is a functional block mainly for realizing the operation of the projector 100. FIG. As shown in FIG. 1, the projector 100 accommodates a light source 2 such as an ultra-high pressure mercury lamp or a metal halide lamp in a hollow substantially rectangular parallelepiped casing 1.

  The housing 1 includes a rectangular bottom plate portion 1a. Front walls 1b, side walls 1c and 1d, and a back wall 1e are formed substantially perpendicular to the bottom plate portion 1a on four sides of the bottom plate portion 1a. . A top plate portion (not shown) is formed at the upper ends of the front wall 1b, the side walls 1c and 1d, and the back wall 1e. The side walls 1c, 1d and the back wall 1e are respectively formed with vent holes 1f, 1g, 1h comprising a plurality of slits.

  The light source 2 is disposed at a corner on the back side inside the housing 1, and a lighting circuit 20 that supplies power to light the light source 2 is connected to the light source 2. A lamp voltage detector 23 is connected to the lighting circuit 20 and detects the lamp voltage VL of the light source 2. Note that the circuit of the lighting circuit 20 and the lamp voltage detection unit 23 can be realized with a general configuration, and thus description thereof is omitted. The white light emitted from the light source 2 is reflected by the rotary parabolic reflecting mirror 3, passes through the color wheel 4, and enters the rod integrator 6.

  The color wheel 4 has fan-shaped color filters that transmit red, green, and blue light in the circumferential direction. The color wheel 4 is arranged such that the light projecting area of the light source 2 is located in the rotation pass area of the color filter. Yes.

  An output shaft of a motor 5 that is rotationally driven by a motor drive unit 22 is connected to the center of the color wheel 4, and the motor drive unit 22 rotates the motor 5 at a constant speed. The rotation of the motor 5 is controlled by a control unit 16 comprising a microcomputer.

  When the color wheel 4 rotates at a constant speed, the white light sequentially enters the red, green, and blue color filters, and is time-divided into red, green, and blue light in a time series. The color-time-divided light enters the entrance of the substantially rectangular rod integrator 6, and the incident light repeats reflection on the inner surface of the rod integrator 6 to become uniform light and enters the illumination lens group 7 from the exit. To do.

  The illumination lens group 7 includes a condenser lens and a relay lens, and makes white light enter a light modulation element, for example, the DMD 8. The DMD 8 includes a plurality of minute movable mirrors associated with each dot of the image related to the image data, and is arranged so as to be separated from the light source 2 in the lateral direction of the housing 1. A DMD driving unit 21 is connected to the DMD 8, and the DMD driving unit 21 receives red, green, and blue light that has been color-time-divided based on the image data supplied from the control unit 16 to the projection lens 9. Alternatively, each minute movable mirror is selectively tilted ± 10 degrees so as to be selectively reflected out of the projection lens 9. The light that has entered the DMD 8 is optically modulated by the minute movable mirror of the DMD 8, and the modulated light that has undergone optical modulation enters the projection lens 9.

  The projection lens 9 is provided at one side of the front wall 1b in the lateral direction, at a position diagonal to the light source 2, and projects modulated light, that is, light for enlarging and displaying an image on the screen. As a result, the image related to the image data is displayed on the screen in color time division.

  In the vicinity of the light source 2 on the back wall 1e, an exhaust fan 10 for ventilating the inside of the housing 1 and air-cooling the light source 2, the control unit 16, the DMD 8, and the like is disposed. An output shaft of a motor (not shown) that rotates the fan 10 is connected to the rotation center of the fan 10, and the fan 10 is rotationally driven by the fan driving unit 17.

  The DMD 8 is provided with an internal temperature detection unit 11 that detects the temperatures of the DMD 8 and the control unit 16 disposed inside the housing 1.

  For example, the internal temperature detection unit 11 outputs the temperature inside the housing 1 to the first ADC 15 as a potential signal. The first ADC 15 outputs the input potential signal to a digital detection value V1 (hereinafter referred to as “internal temperature detection value V1”). The internal temperature detection value V1 after AD conversion is supplied to the control unit 16. The internal temperature detection unit 11 is a general temperature sensor composed of a thermistor and a plurality of resistors. Here, the internal temperature detection value V1 output increases as the temperature decreases. However, the internal temperature detection unit 11 of a type in which the internal temperature detection value V1 output as the temperature decreases may be used.

  An external temperature detector 12 for detecting the temperature outside the housing 1 is arranged in parallel in the ventilation hole 1g formed in the side wall 1d. Since the temperature of the air sucked into the housing 1 from the ventilation hole 1g is approximately the same as the temperature outside the housing 1, the external temperature detection unit 12 detects the temperature of the sucked air, thereby 1 External temperature can be detected. The external temperature detection unit 12 outputs the detected temperature to the second ADC 18 as a potential signal by the same operation and function as the internal temperature detection unit 11. Then, the second ADC 18 AD converts the potential signal input from the external temperature detection unit 12 into a digital detection value V2 (hereinafter referred to as “external temperature detection value V2”), and the AD converted external temperature detection value V2 is a control unit. 16 As with the internal temperature detection unit 11, the external temperature detection unit 12 outputs an external temperature detection value V2 that is output as the temperature decreases.

  The control unit 16 includes, for example, a microcomputer, and includes a CPU, a ROM, a RAM, and the like connected to the CPU via a bus. The ROM stores a control program for controlling the lighting of the light source 2, the rotation speed of the fan 10, the light modulation by the DMD 8, and the like. The CPU reads the control program from the ROM into the RAM and executes various programs. Control hardware operation.

  The control unit 16 is connected to a timer unit 14 for measuring the cumulative lighting time of the light source 2. When the light source 2 is turned on, the control unit 16 gives a timing start control signal to the timing unit 14, and when the light source 2 is turned off, the control unit 16 gives a timing stop control signal to the timing unit 14. When receiving a control signal for starting timing from the control unit 16, the timer unit 14 starts timing, and when receiving a control signal for stopping timing, stops the timing and retains the timing result, so that the light source 2 Count the cumulative lighting time.

  The control unit 16 is connected to a threshold storage unit 13 that stores a threshold table. The threshold value table is a table in which the first to fourth threshold values Th1 to Th4 for controlling the temperature difference between the inside and outside of the housing 1 and switching of the rotation speed of the fan 10 and lighting of the light source 2 are associated with each other. FIG. 3 shows a difference ΔV (= V1−V2; hereinafter referred to as “internal / external temperature detection value difference ΔV”) between the external temperature detection value V2 and the internal temperature detection value V1, the rotation speed of the fan 10, and the first to fourth threshold values Th1. The relationship with ~ Th4 is shown. In the drawing, a graph indicated by a bold line indicates the rotational speed of the fan 10 at the initial setting, and a broken line indicates the rotational speed of the fan 10 after being corrected by the lamp voltage VL.

  Specifically, the first threshold value Th1 is a threshold value for determining whether the fan 10 is rotated at a low speed L or stopped, and the control unit 16 determines the difference between the detected internal and external temperature ΔV and the first threshold value Th1. By comparing, it is determined whether the fan 10 is rotated at a low speed L or stopped. Specifically, if the detected internal / external temperature difference ΔV is less than the first threshold Th1, the controller 16 has a small temperature difference between the inside and outside of the housing 1 and the inside of the housing 1 is not so hot, and the fan rotates. It is determined that it is not necessary to stop the fan 10, and the fan 10 is stopped.

  The second threshold Th2 is a threshold for determining whether or not to rotate the fan 10 at a low speed L, and is a value larger than the first threshold Th1. The control unit 16 determines whether or not to rotate the fan 10 at a low speed L by comparing the internal / external temperature detection value difference ΔV and the second threshold Th2. When the internal / external temperature detection value difference ΔV is equal to or greater than the first threshold Th1 and less than the second threshold Th2, the control unit 16 rotates the fan 10 at low speed L.

  The third threshold value Th3 is a threshold value for determining whether or not the fan 10 is to be rotated at the medium speed M, and is larger than the second threshold value Th2. The control unit 16 determines whether or not the fan 10 is to be rotated at a medium speed M by comparing the difference between the detected internal and external temperature ΔV and the third threshold Th3. When the detected internal / external temperature difference ΔV is equal to or greater than the second threshold Th2 and less than the third threshold Th3, the controller 16 rotates the fan 10 at medium speed.

  The fourth threshold Th4 is a threshold for determining whether to rotate the fan 10 at high speed H, and is a value larger than the third threshold Th3. The controller 16 determines whether or not the fan 10 is to be rotated at high speed H by comparing the internal / external temperature detection value difference ΔV with the fourth threshold Th4. When the internal / external temperature detection value difference ΔV is not less than the third threshold Th3 and less than the fourth threshold Th4, the fan 10 is rotated at a high speed. When the internal / external temperature detection value difference ΔV is equal to or greater than the fourth threshold Th4, the light source 2 is turned off (indicated as “lamp off” in the figure), and the rotation of the fan 10 is stopped after a predetermined time has elapsed.

The first to fourth threshold values Th1 to Th4 are shifted from the initial setting values indicated by the thick lines in the figure to the corrected values (Th1 ′ to Th4 ′) indicated by the broken lines in accordance with the lamp voltage VL. To do. FIG. 4 is a graph illustrating an example of a correspondence relationship between the lamp voltage VL of the light source 2 and the first threshold Th1 in the threshold table of the threshold storage unit 13. The horizontal axis represents the lamp voltage VL of the light source 2, and the vertical axis represents the first threshold Th1. The first threshold Th1 is, for example, a linear decreasing function with respect to the lamp voltage VL, and the relationship between the lamp voltage VL and the first threshold Th1 is expressed by the following formula (1).
Th1 = −α × VL + C0 (1)
However, (alpha) is inclination and C0 is a constant, and is equivalent to 1st threshold value Th1 in case lamp voltage VL = 0. In addition, the slope α is separately determined experimentally.

  As described above, as the cumulative lighting time increases, the illuminance of the light source 2 decreases while the lamp voltage VL increases. As a result, the temperature of the DMD 8 that is irradiated with light decreases, and the internal temperature detection value V1 of the internal temperature detection unit 11 provided in parallel with the DMD 8 increases. Therefore, the value of the detected internal / external temperature difference ΔV (= V2−V1) becomes smaller as the cumulative lighting time becomes longer, that is, as the lamp voltage VL increases, even if the temperature difference between the inside and outside of the housing 1 is constant. Become. For this reason, the first threshold value Th1 is set to be lower in accordance with the change in the detected internal / external temperature difference ΔV due to the temporal change of the light source 2. The second threshold value Th2 to the fourth threshold value Th4 are also set to a linear decrease function similar to the first threshold value Th1.

  FIG. 5 is a flowchart showing a processing procedure of the control unit 16 related to the rotation speed of the fan 10 and lighting of the light source 2.

  When the power is turned on and the light source 2 is turned on, the control unit 16 acquires the internal temperature detection value V1 of the internal temperature detection unit 11 from the first ADC 15 (S11). And the external temperature detection value V2 of the external temperature detection part 12 is acquired from 2nd ADC18 (S12).

  Next, the control unit 16 reads the threshold value table from the threshold value storage unit 13 (S13), and sets the first to fourth threshold values Th1 to Th4 based on the read threshold value table (S14).

  Next, the control unit 16 reads the lamp voltage VL from the lamp voltage detection unit 23 (S15), and on the basis of the read lamp voltage VL, as shown in FIG. The correction of Th4 is executed (S16).

  Then, the control unit 16 calculates the internal / external temperature detection value difference ΔV from the external temperature detection value V2 and the internal temperature detection value V1 (S17). Next, the control unit 16 determines whether or not the detected internal / external temperature difference ΔV is less than the first threshold Th1 (S18). When it is determined that the detected internal / external temperature difference ΔV is less than the first threshold Th1 (Y in S18), the control unit 16 controls the fan driving unit 17 to stop the fan 10 (S19).

  When it is determined that the internal / external temperature detection value difference ΔV is equal to or greater than the first threshold Th1 (N in S18), the control unit 16 determines whether the internal / external temperature detection value difference ΔV is less than the second threshold Th2 ( S20). When it is determined that the internal / external temperature detection value difference ΔV is less than the second threshold Th2 (Y in S20), the control unit 16 controls the fan driving unit 17 to rotate the fan 10 at a low speed L (S21).

  When it is determined that the internal / external temperature detection value difference ΔV is equal to or greater than the second threshold Th2 (N in S20), the control unit 16 determines whether the internal / external temperature detection value difference ΔV is less than the third threshold Th3 ( S22). When it is determined that the internal / external temperature detection value difference ΔV is less than the third threshold Th3 (Y in S22), the control unit 16 controls the fan driving unit 17 to rotate the fan 10 at medium speed M (S23).

  When it is determined that the internal / external temperature detection value difference ΔV is equal to or greater than the third threshold Th3 (N in S22), the control unit 16 determines whether the internal / external temperature detection value difference ΔV is less than the fourth threshold Th4 ( S24). When it is determined that the internal / external temperature detection value difference ΔV is less than the fourth threshold Th4 (Y in S24), the control unit 16 controls the fan driving unit 17 to rotate the fan 10 at high speed H (S25).

  When it is determined that the internal / external temperature detection value difference ΔV is equal to or greater than the fourth threshold Th4 (N in S24), the control unit 16 controls the lighting circuit 20 to turn off the light source 2 (S26), and after a predetermined time has passed. The fan drive unit 17 is controlled to stop the rotation of the fan 10 (S27). When the stop of the fan 10 (S19, S27) or the setting of the rotation speed (S21, S23, S25) is completed, the processing relating to the rotation speed of the fan 10 and the lighting of the light source 2 is completed. Note that the control unit 16 may stop the fan 10 when the internal / external temperature detection value difference ΔV reaches a predetermined value in the process of S27.

  According to the projector 100 that performs the above-described configuration and operation, the rotation speed of the fan 10 and the lighting control of the light source 2 can be controlled in accordance with the lamp voltage VL of the light source 2, in other words, in accordance with changes over time. By specifying the fourth threshold value Th1 to Th4 and controlling the rotation speed of the fan 10 and the lighting of the light source 2, even if the light source 2 changes with time, the noise of the fan 10 is suppressed and the electronic component and the light source 2 can be prevented from being deteriorated by heat.

  Further, since it is not necessary to add a temperature detection unit to detect the temperature inside the casing 1 other than the internal temperature detection unit 11 provided in the vicinity of the DMD 8, the projector 100 having the above-described effects can be realized at low cost. Furthermore, even if the illuminance of the light source 2 included in the projector 100 varies in the manufacturing process, the rotation speed of the fan 10 is controlled according to the lamp voltage VL reflecting the illuminance, so the noise of the fan 10 is reduced. It can suppress and it can prevent that an electronic component and the light source 2 deteriorate with heat.

  In addition, in the configuration in which the illuminance is estimated from the elapsed time as in the technology disclosed in Patent Document 3 of the background art, inappropriate control is performed when the user forgets to reset the lamp (reset elapsed time) after replacing the lamp. There is a risk of becoming. However, the projector 100 according to the present embodiment uses the lamp voltage VL to perform optimal fan control even when such lamp reset is forgotten. Therefore, fan noise is not generated more than necessary, or heat stress is not applied to parts more than necessary.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  The projector 100 described above includes the DMD 8 as a light modulation element, but may include another light modulation element such as a liquid crystal panel. Furthermore, although the external temperature detection unit 12 that detects the temperature outside the housing 1 is disposed near the ventilation hole 1g inside the housing 1, it may be disposed outside the housing 1.

  In the projector 100 described above, the air flow rate is controlled by the rotational speed of the exhaust fan 10, but the present invention is not limited to this. For example, if the projector 100 includes an intake fan, the air flow may be controlled by controlling the rotational speed of the intake fan. Naturally, the rotational speeds of both the exhaust fan 10 and the intake fan may be controlled. Further, if the projector 100 includes a movable blade (louver) or the like in the ventilation hole 1h of the back wall 1e, the ventilation amount may be controlled by controlling the direction of the louver. .

1 is a schematic cross-sectional view of a structure of a DLP projector according to an embodiment. It is a block diagram which shows the structure of the projector based on Embodiment. It is a graph which shows the relationship between internal / external temperature detection value difference (DELTA) V, the rotation speed of a fan, and the 1st-4th threshold value based on Embodiment. It is a graph which shows the example of the correspondence of the lamp voltage VL of the light source and 1st threshold value in the threshold value table of the threshold value memory | storage part based on embodiment. It is a flowchart which shows the process sequence of the control part concerning the rotation speed of the fan in a projector, and lighting of a light source based on Embodiment. It is a graph which shows the general relationship of the lamp voltage VL with respect to the cumulative lighting time of a light source, and illumination intensity based on a prior art.

Explanation of symbols

1 Housing 2 Light source 8 DMD
10 Fan 11 Internal Temperature Detection Unit 12 External Temperature Detection Unit 13 Threshold Storage Unit 15 First ADC
16 Control part 17 Fan drive part 18 2nd ADC
23 Lamp voltage detector

Claims (11)

A light source housed in a housing having a vent hole, an internal temperature detecting unit for detecting the temperature inside the housing, an external temperature detecting unit for detecting a temperature outside the housing, and the inside of the housing. A modulated light obtained by modulating the light of the light source with a light modulation element by controlling the ventilation means according to a difference in temperature detected by the internal temperature detection unit and the external temperature detection unit. In a projector that projects
A light source voltage detector for acquiring a voltage applied to the light source;
A ventilation control unit that controls a ventilation amount of the ventilation unit according to a voltage acquired by the light source voltage detection unit and a difference between temperatures detected by the internal temperature detection unit and the external temperature detection unit;
A projector comprising:   The ventilation amount controlled by the ventilation control unit is variably set in a plurality of stages according to a difference in temperature detected by the internal temperature detection unit and the external temperature detection unit. The projector according to claim 1.   The projector according to claim 2, wherein the air flow control unit corrects the air flow amount variably set in the plurality of stages according to a voltage acquired by the light source voltage detection unit.   The air flow control unit refers to a table in which a threshold value is stored according to the voltage acquired by the light source voltage detection unit as the air flow amount variably set in the plurality of stages. 2. The projector according to 2. The ventilation means includes a fan,
The projector according to claim 1, wherein the ventilation control unit controls the ventilation amount by controlling a rotation amount of the fan. The ventilation means includes ventilation direction changing means for changing the direction of the ventilation,
The projector according to claim 1, wherein the ventilation control unit controls the ventilation amount by controlling a direction of the ventilation.   The projector according to claim 1, wherein the internal temperature detection unit is provided in the vicinity of the light modulation element. A light source housed in a housing having a vent hole, an internal temperature detecting unit for detecting the temperature inside the housing, an external temperature detecting unit for detecting a temperature outside the housing, and the inside of the housing. A ventilation means for ventilating, controlling the ventilation means according to a difference in temperature detected by the internal temperature detection section and the external temperature detection section, and modulating the light of the light source by a light modulation element. A method for controlling an air flow rate in a projector that projects light,
A light source voltage detection step of acquiring a voltage applied to the light source;
A temperature difference detecting step of acquiring a temperature outside the housing and a temperature inside the housing and detecting a temperature difference between the outside and the inside of the housing;
A control amount determination step of determining a control amount of the ventilation amount of the ventilation means based on the voltage and the temperature difference;
A method for controlling an air flow rate, comprising:   The control amount determination step includes a table reference step of referring to a table in which the control amount of the ventilation amount of the ventilation means refers to a table in which a plurality of threshold values are set according to the temperature difference. Control method of air flow.   The method of controlling a ventilation amount according to claim 8 or 9, wherein, in the control amount determination step, the number of rotations of a ventilation fan included in the projector is determined using the ventilation amount of the ventilation means as a control amount. .   The ventilation amount control method according to claim 10, wherein the control amount determination step corrects a threshold value for determining a rotation speed of the fan according to the voltage applied to the light source.

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