TECHNICAL FIELD
[0001] The present invention relates to an imaging apparatus, and specifically the present invention relates to an imaging apparatus having an exhaust section which exhausts air used by a cooling section for cooling a projection section to the outside of an exterior cabinet.
BACKGROUND ART
[0002] A cooling device for a conventional projection-type imaging apparatus will now be described with reference to the drawings.
[0003] In reference to Figures
21 and
22, a projection-type imaging apparatus
2100 includes a projection section
2202 for projecting an image onto a screen, a cooling section
2203 for cooling the projection section
2202 using air, and an exterior cabinet
1 for housing the projection section
2202 and the cooling section
2203. The projection section
2202 includes a light source lamp unit
7, a mirror box
31, an emission optical unit
9, an imaging element unit
10, a projection lens unit
2201, a circuit unit
13, a power supply unit
14, and a light source lamp power supply unit
15. The cooling section
2203 includes a lamp cooling fan
19, a mirror cooling fan
20, a first cooling fan
16, a second cooling fan
17, and a third cooling fan
18.
[0004] The light source lamp unit
7 includes a light source lamp
5 and an oval reflection mirror
6. The projection lens unit
2201 includes a projection lens
12 and a lens moving device
11. The mirror box
31 includes a reflection mirror
8.
[0005] The exterior cabinet
1 has a front cabinet
21, a first side cabinet
22, a second side cabinet
23, a rear cabinet
24, an upper cabinet
25 and a lower cabinet
26. The front cabinet
21 has a first air intake
2, the first side cabinet
22 has a second air intake
3, the second side cabinet
23 has a third air intake
27, and the upper cabinet
25 has an exhaust port
4. The rear cabinet
24 has a first exhaust port
28, a second exhaust port
29, and a third exhaust port
30.
[0006] The exterior cabinet
1 is formed of metal or resin, and has a six-faceted structure. The first intake
2 and the second intake
3 take in air, with which the cooling section
2203 cools down the projection section
2202, from outside the cabinet
1. The exhaust port
4 and the first to third exhaust ports
28 to
30 exhaust air which the cooling section
2203 has used for cooling, to the outside of the cabinet
1. As shown by arrows
2101 to
2105, the noise caused by the cooling section
2203 leaks to the outside of the cabinet
1, from the first air intake
2, the second air intake
3, the exhaust port
4,and the exhaust ports
28 to
30.
[0007] As the light source lamp
5, a xenon lamp or the like is used for a large output. The light emitted from the light source lamp
5 is reflected against the oval reflection mirror
6, and is optically reflected by the reflection mirror
8, thereby guided to the emission optical unit
9. The emission optical unit
9 is comprised of a condenser lens (not shown) and the like, for guiding light effectively to the imaging element unit
10. The imaging element unit
10 is a light valve for optically modulating image signals, and is a transmission type element such as liquid crystal or a reflection type element comprised of micro mirrors, etc., so as to generate optical picture information using light from the emission optical unit
9.
[0008] The optical picture information from the imaging element unit
10 is enlarged and projected through the projection lens
12. The projection lens
12 is capable of moving upward, downward, rightward, and leftward, by means of the lens moving device
11, for focus adjustments and angle of view adjustments.
[0009] The circuit unit
13 controls the imaging element unit
10. The power supply unit
14 drives the circuit unit
13 and the like. The light source lamp power supply unit
15 starts the light source lamp
5. The first cooling fan
16, the second cooling fan
17, and the third cooling fan
18 cool down the circuit unit
13, the power supply unit
14, and the light source lamp power supply unit
15, respectively.
[0010] The large-size lamp cooling fan
19 cools down the light source lamp
5. The mirror cooling fan
20 cools down the emission optical unit
9.
[0011] The first air intake
2 provided on the front cabinet
21, the second air intake
3 provided on the first side cabinet
22, and the third air intake
27 provided on the second side cabinet
23 take in exterior air as indicated by arrows
2204,
2205, and
2206. The first exhaust port
28 provided on the rear cabinet
24 exhausts air used for the cooling of the light source lamp power supply unit
15 as indicated by an arrow
2207. The second exhaust port
29 exhausts air used for the cooling of the light source lamp box
7 as indicated by an arrow
2208. The third exhaust port
30 exhausts air used for the cooling of the emission optical unit
9, from the mirror box
31, as indicated by an arrow
2209.
[0012] In order to obtain an image with a higher luminance, it is necessary to employ a light source lamp unit
7 and a light source lamp power supply unit
15 having a greater output. With such a structure, the quantity of the generated heat increases as the output increases, and therefore it is necessary to employ a large cooling fan so as to improve the cooling performance. Using a large cooling fan, however, results in a problem of increasing the cooling noise.
[0013] Furthermore, the use of projection-type imaging apparatuses is not only for presentations in conference rooms and the like but also includes viewing of images in halls, and therefore the market expects viewing of high quality images in quieter environments. With the structure described with reference to Figures
21 and
22, in which the air intakes
2,
3, and
27 are provided on the cabinet
1 so as to take in air, the noise of the cooling fans
16,
17,
18,
19, and
20 cutting the air is naturally radiated from the air intakes
2,
3, and
27, which results in a problem of increasing the noise from the imaging apparatus
2100.
[0014] In addition, the light emitted from the light source lamp
5 leaks outside the cabinet
1 from the air intakes
2,
3, and
27. This particularly poses a problem of not being able to obtain a high quality image when the image is projected in a dark environment such as in a movie theater, since the leaked light illuminates places other than the screen, which leads to not only worsening of the image viewing atmosphere but also deterioration of the image quality.
[0015] One object of the present invention is to provide an imaging apparatus which is capable of controlling emission of the noise caused by the cooling section so as to suppress the noise leaving the device, even in the case where a large cooling section is used for cooling a projection section with a high output needed for obtaining images with higher luminance.
[0016] Another object of the present invention is to provide an imaging apparatus which is capable of preventing light emitted from the light source lamp unit from illuminating places other than the screen.
DISCLOSURE OF THE INVENTION
[0017] According to one aspect of the invention, an imaging apparatus includes: a projection section for projecting an image onto a screen; a cooling section for cooling the projection section by means of air; an exterior cabinet for housing the projection section and the cooling section; and an exhaust section for exhausting air used for the cooling of the projection section by the cooling section, from the exterior cabinet wherein the exhaust section has a function for attenuating a noise caused by the cooling section.
[0018] The exhaust section may include an exhaust duct having a ventilation path for guiding the noise and air from the projection section to the exterior of the exterior cabinet; and the ventilation path is formed so that the noise strikes an interior surface of the ventilation path and changes its direction of movement.
[0019] The ventilation path may be formed so that the moving path of the noise contains at least one L shape.
[0020] The exhaust duct may include a sound absorption material which is provided on the interior surface of the ventilation path for absorbing the noise.
[0021] The exterior cabinet may have a rear face which is formed on a side opposite to the screen; the exhaust duct may be provided on the location corresponding to the rear face; and the exhaust duct may exhaust air in a direction which is opposite to the direction in which the projection section projects the image onto the screen.
[0022] The exhaust duct may exhaust the air in a direction which is substantially the same as the direction in which the projection section projects the image onto the screen.
[0023] The exhaust duct may include at least one active muffling device provided in the ventilation path.
[0024] The projection section may include a light source lamp unit, an emission optical unit for collecting light from the light source lamp unit, an imaging element unit for generating optical picture information using light collected by the emission optical unit, and a projection lens unit for enlarging and projecting the optical picture information; and the cooling section may include a lamp cooling fan for cooling the light source lamp cooling unit, and a mirror cooling fan for cooling the emission optical unit.
[0025] The projection section may further include a circuit unit for controlling the imaging element unit, a power supply unit for driving the circuit unit; and a light source lamp power supply unit for driving the light source lamp unit; and the cooling section may further include a first cooling fan for cooling the circuit unit, a second cooling fan for cooling the power supply unit, and a third cooling fan for cooling the light source lamp power supply unit.
[0026] The cooling section may include a cooling fan.
[0027] The imaging apparatus may further include an air intake section for taking in air from outside the exterior cabinet and providing air to the cooling section.
[0028] The air intake section may include an air intake duct for guiding air from the exterior of the exterior cabinet to the cooling section and for guiding the noise from the projection section to the exterior of the exterior cabinet; and the ventilation path may be formed so that the noise strikes an interior surface of the ventilation path and changes its direction of movement.
[0029] The ventilation path may be formed so that the moving path of the noise has at least one L shape.
[0030] The air intake duct may include a sound absorption material which is provided on the interior surface of the ventilation path for absorbing the noise.
[0031] The air intake duct may be provided at a position corresponding to the lower face of the exterior cabinet.
[0032] The air intake duct may include at least one active muffling device provided in the ventilation path.
[0033] The exterior cabinet may include a sound absorption material which is provided on at least one of interior surfaces of the exterior cabinet for absorbing the noise.
[0034] The projection section may include a light source lamp unit, an emission optical unit for collecting light from the light source lamp unit, an imaging element unit for generating optical picture information using light collected by the emission optical unit, and a projection lens unit for enlarging and projecting the optical picture information; the projection lens unit may include a projection lens and a projection lens moving device for moving the projection lens; and the exterior cabinet may have a front face which is formed at the side of the screen, the exterior cabinet further including a dust-proofing section which is provided between the front face and the projection lens moving device, for preventing outside dust from entering the apparatus; wherein the dust-proofing section includes at least two pieces of cloth, and a sound absorbing material inserted between the two pieces of cloth.
[0035] The imaging apparatus may be a projection-type imaging apparatus.
[0036] The imaging apparatus may be a liquid crystal projector.
[0037] The imaging apparatus may be a rear-projection television.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038]
Figure 1 is a profile view of a projection-type imaging apparatus according to Example 1;
Figure 2 is a cross-sectional plan view of the projection-type imaging apparatus according to Example 1;
Figure 3 is a diagram illustrating an exhaust duct of the projection-type imaging apparatus according to Example 1;
Figure 4 is a cross-sectional side view of the projection-type imaging apparatus according to Example 1;
Figure 5 is a diagram illustrating an exhaust duct of the projection-type imaging apparatus according to Example 2:
Figure 6 is a cross-sectional side view of the projection-type imaging apparatus according to Example 2;
Figure 7 is a cross-sectional view of the exhaust duct of the projection-type imaging apparatus according to Example 2;
Figure 8 is another cross-sectional view of the exhaust duct of the projection-type imaging apparatus according to Example 2;
Figure 9 is still another cross-sectional view of the exhaust duct of the projection-type imaging apparatus according to Example 2:
Figure 10 is a diagram illustrating an active muffling device of the projection-type imaging apparatus according to Example 2;
Figure 11 is a cross-sectional side view of the projection-type imaging apparatus according to Example 3;
Figure 12 is a profile view of the air intake duct of the projection-type imaging apparatus according to Example 3;
Figure 13 is a diagram illustrating a dust-proofing cloth of a projection-type imaging apparatus according to Example 4;
Figure 14 is a graph illustrating the noise reduction effects of the projection-type imaging apparatus according to the examples;
Figure 15 is a diagram illustrating the noise level values of the projection-type imaging apparatuses according to Examples 1 to 4;
Figure 16 is a graph analyzing the noise frequency of the projection-type imaging apparatuses according to Examples 1 to 4;
Figure 17 is a graph illustrating the relationship between the luminance and the noise level of the projection-type imaging apparatuses according to Example 1 to 4;
Figure 18 is a cross-sectional plan view of a projection-type imaging apparatus according to Example 5;
Figure 19 is a cross-sectional plan view of a liquid crystal projector according to Example 6;
Figure 20 is a cross-sectional side view of a rear-projection television according to Example 7;
Figure 21 is a profile view of a conventional imaging apparatus; and
Figure 22 is a cross-sectional plan view of a conventional imaging apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
[0039] A projection-type imaging apparatus according to Example 1 will be described with reference to Figures
1 to
4. Figure
1 is a profile view of the projection-type imaging apparatus
100 according to Example 1, Figure
2 is a cross-sectional plan view of the imaging apparatus
100, Figure
3 is a diagram illustrating an exhaust duct
336 of the imaging apparatus
100, and Figure
4 is a cross-sectional side view of the imaging apparatus
100. Components similar to those of the imaging apparatus
2100 described with reference to Figures
21 and
22 will be denoted by the same reference numerals, and detailed explanation thereof will be omitted.
[0040] The projection-type imaging apparatus
100 includes a projection section
2202 for projecting an image onto a screen, a cooling section
2203 for cooling the projection section
2203 by means of air, and an exterior cabinet
1A for housing the projection-section
2202 and the cooling section
2203.
[0041] The projection section
2202 includes a light source lamp unit
7, a mirror box
31, an emission optical unit
9, an imaging element unit
10, a projection lens unit
2201, a circuit unit
13, a power supply unit
14, and a light source lamp power supply unit
15. The cooling section
2203 includes a lamp cooling fan
19, a mirror cooling fan
20, a first cooling fan
16, a second cooling fan
17 and a third cooling fan
18.
[0042] The light source lamp unit
7 includes a light source lamp
5 and an oval reflection mirror
6. The projection lens unit
2201 includes a projection lens
12 and a lens moving device
11. The mirror box
31 includes a reflection mirror
8.
[0043] The light emitted from the light source lamp
5 is reflected against the oval reflection mirror
6, and is optically reflected by the reflection mirror
8, thereby being guided to the emission optical unit
9. The emission optical unit
9 is comprised of a condenser lens (not shown) and the like, for guiding light effectively to the imaging element unit
10. The imaging element unit
10 is a light valve for optically modulating image signals, which is a transmission type elements such as liquid crystals or a reflection type element comprised of micro mirrors, etc., so as to generate optical picture information using light from the emission optical unit
9.
[0044] The optical picture information from the imaging element unit
10 is enlarged and projected through the projection lens
12. The projection lens
12 is capable of moving upward, downward, rightward, and leftward, by means of the lens moving device
11, for focus adjustments and angle of view adjustments.
[0045] The circuit unit
13 controls the imaging element unit
10. The power supply unit
14 drives the circuit unit
13 and the like. The light source lamp power supply unit
15 starts the light source lamp
5. The first cooling fan
16, the second cooling fan
17, and the third cooling fan
18 cool down the circuit unit
13, the power supply unit
14, and the light source lamp power supply unit
15, respectively.
[0046] The large-size lamp cooling fan
19 cools down the light source lamp
5. The mirror cooling fan
20 cools down the emission optical unit
9.
[0047] The exterior cabinet
1A has a front cabinet
21A, a first side cabinet
22A, a second side cabinet
23A, a rear cabinet
24A, an upper cabinet
25A and a lower cabinet
26A. The lower cabinet
26A has an air intake
39.
[0048] The difference from the conventional imaging apparatus illustrated in Figure
21 is that no air intake is provided on cabinets other than the lower cabinet
26A. Furthermore, a porous first sound absorbing material
32, second sound absorbing material
33, third sound absorbing material
34, and fourth sound absorbing material (not shown) may be adhered by an adhesive or the like on interior sides of the front cabinet
21A, the first side cabinet
22A, the second side cabinet
23A, and the upper cabinet
25A (Figure
1). Naturally, portions where the cabinets are fitted together are coupled so as not to leak sounds.
[0049] The porous sound absorbing material may be, for example, rubber foaming material (product code: EE710) with a thickness of 5 to 10 mm of EPDM (ethylene, propylene, diene, and methylene gauge) material manufactured by Nitto Denko Corporation.
[0050] The imaging apparatus
100 further includes an exhaust duct
336 for exhausting air used by the cooling section
2203 for cooling the projection section
2202, from the exterior cabinet
1A. The exhaust duct
336 is provided on the side of the rear cabinet
24A. The rear cabinet
24A has a first exhaust port
328, a second exhaust port
329, and a third exhaust port
330. The exhaust duct
336 includes a main body
341, and a behind-the-duct cabinet
340. The main body
341 is covered by the behind-the-duct cabinet
340 so as to have a box-like shape. The behind-the-duct cabinet
340 has exhaust ports
347 and
350.
[0051] The exhaustion from the first cooling fan
16, the second cooling fan
17, and the third cooling fan
18 (Figure
2) proceeds from the first exhaust port
328 as indicated by an arrow
354, and then advances as indicated by an arrow
355 or
356 so as to be exhausted from the exhaust port
347 or
350. The noise caused by the first cooling fan
16, the second cooling fan
17, and the third cooling fan
18 proceeds from the first exhaust port
328 as indicated by an arrow
360, and strikes the interior face
353 of the behind-the-duct cabinet
340, thereby being attenuated, and then changes its direction of movement to the direction indicated by an arrow
361. The noise then strikes the interior face
362, thereby being further attenuated, and then changes its direction of movement as indicated by an arrow
363 or
364, so as to leak outside the exhaust duct
336 from the exhaust port
347 or
350.
[0052] Similarly, the exhaustion from the lamp cooling fan
19 (Figure
2) proceeds from the second exhaust port
329 as indicated by an arrow
357 as illustrated in Figure
3, and then advances as indicated by an arrow
355 or
356 so as to be exhausted from the exhaust port
347 or
350. The noise caused by the lamp cooling fan
19 proceeds from the second exhaust port
329 as indicated by an arrow
365, and strikes the interior face
352, thereby being attenuated, and then changes its direction of movement and advances as indicated by an arrow
366. The noise then strikes the interior face
362, thereby being further attenuated, and changes its direction of movement and advances as indicated by an arrow
363 or
364 so as to leak outside the exhaust duct
336 from the exhaust port
347 or
350.
[0053] Similarly, the exhaustion from the mirror cooling fan
20 (Figure
2) proceeds from the third exhaust port
330 as indicated by an arrow
358 or
359 as illustrated in Figure
3, and then is exhausted from the exhaust port
347 or
350. The noise caused by the mirror cooling fan
20 proceeds as indicated by an arrow
367, and strikes the interior face
351, thereby being attenuated, and then changes its direction of movement as indicated by an arrow
363 or
364, so as to leak outside the exhaust duct
336 from the exhaust port
347 or
350.
[0054] As described above, the exhaust duct
336 has a ventilation path for guiding the noise and the exhaustion from the first cooling fan
16, the second cooling fan
17, the third cooling fan
18, the lamp cooling fan
19, and the mirror cooling fan
20, to outside the imaging apparatus
100. The ventilation path is formed so that the path contains at least one L shape, whereby the noise strikes the interior walls
353,
352,
351,
362 of the ventilation path, thereby being attenuated, and changes its direction of movement. Therefore, the noise exits from the imaging apparatus
100 to outside after being attenuated. This suppresses the radiation of the noise caused by the cooling section
2203. As illustrated in Figure
2, a porous duct sound absorbing material
337 may be adhered by an adhesive or the like. The material for the porous duct sound absorbing material
337 is similar to that for the aforementioned porous sound absorbing material (the first sound absorbing material
32, the second sound absorbing material
33, the third sound absorbing material
34, and the fourth sound absorbing material). By using porous sound absorbing material and duct sound absorbing material, the radiation of the noise caused by the cooling section
2203 to outside is further suppressed.
[0055] As illustrated in Figure
2, an air intake
39 is provided on the lower cabinet
26A so as to be able to lead fresh air into the imaging apparatus
100.
[0056] External air led through the air intake
39 provided on the lower cabinet
26A is used by the first cooling fan
16, the second cooling fan
17, the third cooling fan
18 for cooling the circuit unit
13, the power supply unit
14 and the light source power supply unit
15, respectively, and then flows from the first exhaust port
328 to the exhaust duct
336.
[0057] The air led through the air intake
39 also flows to the light source lamp box
7 by action of the cooling fan
19. The air, after cooling down the light source lamp
5 and the oval reflection mirror
6, flows to the exhaust duct
336 from the second exhaust port
329.
[0058] The air led through the air intake
39 is also used by the mirror cooling fan
20 for cooling the emission optical unit
9. The air then flows to the mirror box
31 for cooling the reflection mirror
8 and flows from the third exhaust port
330 to the exhaust duct
336.
[0059] According to the imaging apparatus
100, the lower cabinet
26A is provided with only one air intake
39 as an opening for taking in the air. As openings for exhaustion, only the exhaust ports
347,
350 are formed, which are provided on the exhaust duct
336. The radiation of the internal noise occurs mainly through openings, and therefore according to the imaging apparatus
100, which has fewer openings than a conventional apparatus, the quantity of the radiation of the internal noise to outside the apparatus is markedly reduced in comparison with the conventional apparatus.
[0060] As illustrated in Figure
4, the air intake
39 is formed on the lower cabinet
26A. The imaging apparatus
100 is usually placed on the floor
401. The radiating sound from the air intake
39, which is due to the noise of the cooling section
2203, does not directly leak outside the apparatus but becomes radiating sound after it has reflected against the floor. Therefore, the noise to the outside can be reduced.
(Example 2)
[0061] A projection-type imaging apparatus
200 will be described with reference to Figures
5 to
10. Figure
5 is a diagram illustrating an exhaust duct of the projection-type imaging apparatus
200. Figure
6 is a cross-sectional side view of the projection-type imaging apparatus
200. Components similar to those of the imaging apparatus
100 will be denoted by the same reference numerals, and detailed explanation thereof will be omitted.
[0062] With reference to Figures
5 and
6, the imaging apparatus
200 according to Example 2 is different from the imaging apparatus
100 according to Example 1 in that the imaging apparatus
200 has an exhaust duct
536 having a three-stage structure instead of the exhaust duct
336.
[0063] The exhaust duct
536 includes an upper exhaust duct
541, a middle exhaust duct
542, a lower exhaust duct
543, and a behind-the-duct cabinet
540. The exhaust duct
536 is formed so as to be covered by the behind-the-duct cabinet
540. The exhaust duct
536 is provided on the side of a rear cabinet
24B. The rear cabinet
24B has a first exhaust port
528, a second exhaust port
329, and a third exhaust port
330. The first exhaust port
528 corresponds to the upper exhaust duct
541. Furthermore, a first speaker box
544 is placed on the other side, and a speaker
546A (described later with reference to Figure
7) is placed in a speaker installation hole
545.
[0064] The exhaustion of air from the first exhaust port
528 is exhausted from the upper exhaust port
547 provided on the behind-the-duct cabinet
540 as indicated by an arrow
551.
[0065] A second speaker box
548 is placed on the middle stage exhaust duct
542, which is separated from the lower exhaust duct
543 by a partition board
549. It is possible to guide the exhaustions of air from the light source lamp box
7 and the mirror box
31 through the second exhaust port
329 and the third exhaust port
330.
[0066] These exhaustions of air merge together inside the middle exhaust duct
542 as indicated by an arrow
552, and then flow into the lower exhaust duct
543 since the partition board
549 is only formed partway. The air flown to the lower exhaust duct
543 is exhausted outside from the lower exhaust port
550 as indicated by an arrow
553. Similar to the exhaust duct
336 described in Example 1, the exhaust duct
543 has at least one L shape. The direct noise form the first exhaust port
528, the second exhaust port
329 and the third exhaust port
330 strikes the behind-the-duct cabinet
540, and because of the absorption by the duct sound absorbing material and the attenuation inside the exhaust duct
536, the exhausted noise from the exhaust port
547 and the exhausted port
550 is significantly reduced in comparison with the conventional apparatus.
[0067] Figure
7 illustrates a cross-sectional view of the upper stage exhaust duct
541 seen from the above, Figure
8 illustrates a cross-sectional view of the middle stage exhaust duct
542 seen from the above, and Figure
9 illustrates a cross-sectional view of the lower exhaust duct
543 seen from the above. Arrows
551,
552, and
553 indicate ventilation paths.
[0068] In addition, a porous duct sound absorbing material
537 is adhered inside the upper stage exhaust duct
541, the middle stage exhaust duct
542, and the lower stage exhaust duct
543 by an adhesive or the like, so as to increase sound absorbing effect.
[0069] Figure
10 illustrates a structure in which the speaker
546A is used in order to actively muffle the noise inside the exhaust duct
536.
[0070] As illustrated in Figure
10, the exhaust duct
536 further includes a noise detection microphone
551A provided in the vicinity of the first exhaust port
528 of the upper exhaust duct
541 for detecting the ventilation noise, an error detection microphone
552A provided in the vicinity of the upper exhaust port
547 for detecting the noise at the upper exhaust port
547, a speaker
546A provided in the vicinity of the error detection microphone
552A, for generating a sound which has a sound pressure substantially the same as and the phase opposite to those of the noise in the duct detected by the error detection microphone
552A, and an ANC computation circuit
553A for performing computations based on signals from the noise detection microphone
551A and the error detection microphone
552A, so as to make the signal from the error detection microphone
552A smaller, and outputting control signals to speaker
546A.
[0071] The middle stage exhaust duct
542 and the lower stage exhaust duct
543 also include a noise detection microphone
551B, an error detection microphone
552B, an ANC computation circuit
553B, and a speaker
546B, which have a similar structure and function. This principle is generally called ANC (Active Noise Control) technique, and this structure not only provides a sound absorbing effects inside the exhaust duct
536 but also detects the interior noise of the exhaust duct
536 and outputs from the speaker
546A and
546B a sound which has the phase opposite to that of the detected noise at the exhaust region, thereby making it possible a further increase of the reduction of the exhaust noise from the exhaust duct
536.
[0072] In Figure
10, it is also effective to have a structure in which a plate-like flow smoother
554, which changes the ventilation condition from a turbulent condition to a smoothed condition, is provided so as to bridge the middle stage exhaust duct
542 and the lower stage exhaust duct
543, and a grille-like flow smoother
555 and a mesh-like flow smoother
556 are provided in the lower stage exhaust duct
543. As illustrated in Figure
10, it is appropriate that the plate-like flow smoother
554 is formed with a plurality of C-shaped thin plates of 1 mm or less and is placed at the location where the direction of the ventilation path is changed by 180°. The grille-like flow smoother
555 is, for example, an object formed of an extremely thin aluminum with a honeycomb-shape cross section. An ordinary wire netting is effective enough for the mesh-like flow smoother
556.
(Example 3)
[0073] Figure
11 is a cross-sectional side view of an imaging apparatus
300 according to Example
3. The imaging apparatus
300 is similar to the imaging apparatus
200 of Example 2 in Figure
6 in terms of the basic structure.
[0074] Components similar to those of the imaging apparatus
200 will be denoted by the same reference numerals, and detailed explanation thereof will be omitted. The imaging apparatus
300 is different from the imaging apparatus
200 according to Example 2 in terms that the imaging apparatus
300 includes an air intake duct
1158. The air intake duct
1158 guides the air from the air intake
39 which is formed on the lower cabinet
26B to the inside of the imaging apparatus
300, as designated by an arrow
1160.
[0075] Similar to the exhaust duct
536, a sound absorbing material
59 may be adhered inside the air intake duct
1158 so as to increase the sound absorbing effect. Figure
12 is a profile view of the air intake duct
1158, in which an arrow
1160 indicates the ventilation path during the air inhalation. By adopting such a structure, the noise caused by the cooling section inside the imaging apparatus
300 is not directly radiated to the outside from the air intake
39. Similar to the exhaust ducts
336,
536 in Examples 1 and 2, the air intake duct
1158 has an L shape structure, and therefore the noise strikes an interior wall of the air intake duct
1158 and is attenuated. This reduces the quantity of radiating noise from the air intake
39 to the outside of the apparatus.
[0076] Furthermore, similar to Example 2, it is possible to attach an active muffling device, which is described in detail with reference to Figure
10. By placing an error detection microphone (not shown), a speaker box
60 and a speaker
61 on the air intake side of the air intake duct
1158, and by placing a noise detection microphone and an ANC computation circuit (not shown) on the air flow side of the air intake duct
1158, i.e., on the inner side of the apparatus, a further reduction of the noise for an imaging apparatus is possible since the quantity of noise radiation from the air intake
39 is reduced.
(Example 4)
[0077] Figure
13 illustrates Example 4 of the present application. It is common that the lens moving device
11 has a structure capable of triaxial motion, i.e., forward-backward, upward-downward, and rightward-leftward, so as to perform the focus adjustments and angle of view adjustments. This requires that the front cabinet
21 should be composed to have an opening larger than the diameter of the projection lens. An imaging apparatus is an apparatus requiring an optical accuracy, and leaving a large opening may result in the dust in the air sticking to the imaging element unit
10, and decreasing the quality of the pictures.
[0078] The countermeasure against dust is generally provided by connecting the front cabinet
21A and the lens moving device
11 with an elastic cylindrical cloth. Although cloth has air permeability and is effective for the countermeasure against the dust, it has a disadvantage that the inside noise is radiated to the outside through the cloth, which results in increasing the noise of the imaging apparatus.
[0079] The dust-proofing cloth
62 illustrated in Figure
13 has a double layered structure. Furthermore, it has a structure in which a sound absorbing material
63 is inserted between the dust-proofing cloth
62A and the dust-proofing cloth
62B, peripheries of which are then sewed together. Both ends of the dust-proofing cloths are secured on the front cabinet
21A and the lens moving device
11 by a first fastening metal
64 and a second fastening metal
65. This structure provides a feature in that dust-proofing quality is maintained as well as sound absorbing function, thereby reducing the radiation of the inside noise. Furthermore, if the dust-proofing cloth
62A and the dust-proofing. cloth
62B are formed of a material having a conductivity, such as metal fibers, the electromagnetic wave noise from the circuit unit
13, etc., is absorbed, whereby the electromagnetic wave noise from the imaging apparatus can be reduced.
[0080] The effects of the imaging apparatus according to the examples will now be described. Figure
14 shows the noise reduction effect by the exhaust duct and the air intake duct according to the example, and the noise reduction effect by the active muffling device according to the examples.
[0081] It is understood that there is a noise reduction effect in the high frequency band at about 1 KHz or higher by means of the structure of the air intake duct and the sound absorbing function of the sound absorbing material. It is understood that there is a noise reduction effect in the low frequency band at about 1 KHz or lower by means of the sound absorbing function by the active muffling device. Accordingly, by combining the passive noise reduction by means of the structure of the exhaust duct and the active noise reduction, it is possible to reduce the noise in the entire noise band.
[0082] Figure
15 shows specific effects according to Examples 1 to 3 of the present invention. Figure
15 shows the results of the noise measurement before and after the implementation of the present invention at the position which is 1 m away to the front, rear, left, right and above, respectively, from the imaging apparatus. It is confirmed from Figure
15 that there is a noise reduction effect specifically at the rear of the imaging apparatus by means of the exhaust duct and that a maximum effect of 7 dBA is achieved. In addition, it is confirmed that a noise reduction of 9 to 17 dBA is achieved by means of the exterior cabinet which has an exhaust port only on the backside. Furthermore, the noise level at the rear shows at least 4 dBA of noise reduction effected by means of the active muffling device.
[0083] Figure
16 shows an analysis result of the noise frequency before and after the implementation of the present invention. According to Figure
16, it is confirmed that an average noise reduction effect of 6 dBA (maximum 15 dBA) is achieved by the active muffling device at a frequency of 1 KHz or lower, and that a significant noise reduction is achieved by the sealed cabinet structure, exhaust duct attached structure and the adhesion of the sound absorbing material at a frequency of 1 KHz or higher.
[0084] Figure
17 shows the relationship between luminance and noise level in a variety of imaging apparatuses. Conventionally, there is a general tendency that the noise level increases as the luminance increases since the cooling section is required to be more powerful. As shown in Figure
17, although the luminance is increased the noise level according to the present invention is similar to that of the low-luminance model. This confirms that an excellent silence characteristic is achieved.
(Example 5)
[0085] Figure
18 is a cross-sectional plan view of a projection-type imaging apparatus
500 according to Example 5. Components similar to those of the imaging apparatus
100 will be denoted by the same reference numerals, and detailed explanation thereof will be omitted. Examples 1 to 4, to which the subject invention is not limited, show examples in which the exhaust duct exhausts the air in the direction opposite to the direction in which the projection lens projects an image onto the screen (backward). As shown in Figure
18, the exhaust duct
1836 may exhaust the air from the exhaust port
1847 in a direction
1848 which is substantially the same as the direction
1849 in which the projection lens
12 projects an image onto the screen. The exhaust duct
1836 is provided so as to extend along the second side cabinet
23A.
(Example 6)
[0086] Figure
19 is a cross-sectional plan view of a liquid crystal projector
600 according to Example 6. Aforementioned Examples 1 to 5, to which the subject invention is not limited, show examples in which the present invention is implemented in a projection-type imaging apparatus. As illustrated in Figure
19, the present invention is also implemented in a liquid crystal projector.
[0087] The liquid crystal projector
600 includes an exterior cabinet
1906, a lamp
1901, a mirror
1903, a dichroic mirror
1904, a liquid crystal panel
1910, a projection lens
1905, a cooling fan
1909, and a power supply
1902.
[0088] The exterior cabinet
1906 is provided with an exhaust duct
1908 which has an L shape so as to guide the noise caused by the cooling fan
1909 and the air taken in from the air intake
1907, to the outside of the exterior cabinet
1906.
[0089] The noise strikes an interior face of the exhaust duct
1908 and is attenuated, and then changes its direction of movement as indicated by an arrow
1911 and is guided outside the exterior cabinet
1906.
(Example 7)
[0090] Figure
20 is a cross-sectional side view of a rear-projection television
700 according to Example
7. Aforementioned Examples 1 to 5 show examples in which the present invention is implemented in a projection-type imaging apparatus, and Example 6 shows an example in which the present invention is implemented in a liquid crystal projector. The present invention is not limited to these examples. As illustrated in Figure
20, the present invention can also be implemented in a rear-projection television.
[0091] The rear-projection television
700 includes an exterior cabinet
2004, an imaging tube
2001, a mirror
2002, a screen
2003, a drive circuit
2005, and a cooling fan
2007.
[0092] The exterior cabinet
2004 is provided with an exhaust duct
2008 for guiding the noise caused by the cooling fan
2007 and the air taken in from the air intake
2006, to the outside of the exterior cabinet
2004. The noise strikes an interior face of the exhaust duct
2008 and is attenuated, and then changes its direction of movement as indicated by an arrow
2010 and is guided outside the exterior cabinet
2004.
INDUSTRIAL APPLICABILITY
[0093] As described above, according to the present invention; it is possible to provide an imaging apparatus which is capable of controlling emission of the noise caused by the cooling section so as to suppress the noise coming from the device, even in the case where a large cooling section is used for cooling a projection section with a high output needed for obtaining images with higher luminance.
[0094] Moreover, according to the present invention, it is possible to provide an imaging apparatus which is capable of preventing light emitted from the light source lamp unit from illuminating places other than the screen.