JP3057252B2 - Display device - Google Patents

Description

The present invention relates to a phosphor-excited display device having a large screen of, for example, 60 inches or more.

[Summary of the Invention]

The present invention relates to a phosphor-excited display device having a large screen of, for example, 60 inches or more, a laser light source device that generates an ultraviolet laser beam, an optical modulator that modulates the ultraviolet laser beam, and a device that transmits visible light. A screen formed by attaching a phosphor on a substrate; and an optical deflector that two-dimensionally scans the modulated ultraviolet laser beam on the phosphor attachment surface of the screen. In a display device that sequentially excites the body with the modulated ultraviolet laser beam to obtain visible light, the laser light source device generates a neodymium laser and the harmonics of the laser beam from the neodymium laser by a nonlinear optical effect. And a back plate that transmits ultraviolet light and reflects visible light on the phosphor-coated surface of the screen. , The input power for exciting the phosphor with the same laser power need be lower than conventionally,
When the phosphor is excited with the same laser power,
The screen is about twice as bright.

[Conventional technology]

2. Description of the Related Art In a television receiver or the like, a display device having a larger screen is required in order to provide a realistic and powerful video with a large screen to a viewer.

In this case, in the method of increasing the size of the color cathode ray tube, the resolution is degraded when trying to increase the brightness due to the repulsion effect between electrons, and it is difficult to manufacture a large vacuum tube. Is the limit.

Further, a direct scanning type laser display device has been proposed in which a large-screen color image is obtained by directly scanning three laser beams of red, green and blue synchronously on a screen. In such a direct scan type laser display device, the so-called speckle noise is observed on the screen due to the coherent laser beam and the screen flickers, and the screen has no afterglow characteristic. The big disadvantage is that the screen is dark.

On the other hand, a laser beam in the ultraviolet region is two-dimensionally scanned on a screen on which a phosphor is applied, and the phosphor is sequentially excited, and visible light emitted from the phosphor is transmitted to a viewer. 2. Description of the Related Art A phosphor-excited display device that emits light is known.

Figure 2 shows a conventional phosphor excitation type display apparatus disclosed in JP-A-53-21944 for example, in the FIG. 2, (1) A _r of oscillation wavelength 351nm
(Argon) UV laser generator such as laser oscillator,
(2) is a power supply, and the ultraviolet laser beam (3) generated by the laser generator (1) is incident on the optical modulator (4). (5) shows a signal device for transmitting a modulated electric signal to the optical modulator (4), and an ultraviolet laser beam (3) intensity-modulated in the optical modulator (4) according to the modulated electric signal.
Is, for example, 2 in the horizontal and vertical directions by an optical deflector (6).
Scanned dimensionally. The scanned ultraviolet laser beam (3) sequentially and two-dimensionally scans the phosphor surface of the screen (9) on which the phosphor (10) is finally applied via two mirrors (7) and (8). Therefore, visible light (11a) and (11b) are emitted from the phosphor (10) forward and backward, respectively. Then, the visible light (11a) emitted forward reaches the viewer (12).

According to the phosphor-excited display device shown in FIG. 2, the ultraviolet laser beam (3), which is coherent light, is converted into visible light (11a), which is incoherent light, and the phosphor (10) Because of the persistence characteristics, the above-mentioned drawbacks and drawbacks of direct scan laser display devices are overcome.

[Problems to be solved by the invention]

However, in the conventional phosphor-excited display device shown in FIG. 2, the screen (9) is enlarged to obtain a large screen of about 60 inches (a diagonal length of about 1.5 m and an area of about 1 m ² ). However, since the energy conversion efficiency is extremely poor, there is a disadvantage that the screen is extremely dark with the input power that is usually allowable.

Considering this quantitatively, the luminance of a screen that can be clearly seen in a bright room is generally 100 fL (foot Lambert), but a luminance of 50 fL, which is a luminance that can be seen, is obtained on the screen (9). Shall be. in this case,
Since the brightness of 1 fL is defined as the brightness obtained when a 1 m (lumen) light beam enters a 1 ft ² (square foot) perfect diffusion surface, the light flux on the screen (9) is P, and the brightness is B And the area is S [ft ² ], then B = P / S (1). Since it is assumed that S 画面 1 m ² = 10.75 ft ² on a 60-inch screen, and B = 50 fL, the light flux P = 538 [lm] (2) from equation (1). Furthermore, the lamp efficiency (output luminous flux / input power, that is, lm / l) of the phosphor (10) applied to the screen (9)
Assuming that W) is 124 lm / W, the value of the input laser power L is 538/124 ≒ 4.3 [W] (3) in order to obtain the light flux expressed by the equation (2). . Although A _r laser oscillator of the ultraviolet laser oscillator (1) for example an oscillation wavelength 351nm in the second illustrated example is used, the oscillation efficiency of the wavelength 351nm for the input power of the A _r laser oscillator substantially 0.01 Only%. Therefore, the input power IN supplied to the _Ar laser oscillator to obtain the laser power L of the equation (3) is as follows: input power IN = 4.3 / 0.0001 [W] = 43 [kW] (4) This 43 kW input power IN is 430 times the input power (about 100 W) of a normal home television receiver,
It is not enough power for ordinary households. Conversely, if the value of the input power IN is set to, for example, 1 kW, which can be covered by ordinary households, the brightness B of the screen (9) becomes about 1/40, and there is a problem that the screen becomes extremely dark.

In view of the above, the present invention requires less input power to excite the phosphor with the same laser power than before, and provides a brighter screen than before when the phosphor is excited with the same laser power. An object is to propose a more practical display device.

[Means for solving the problem]

As shown in FIG. 1, for example, a display device according to the present invention includes a laser light source device for generating an ultraviolet laser beam (20), an optical modulator (21) for modulating the ultraviolet laser beam (20), and a visible light (26). Screen (25) with phosphors (29R), (29G), and (29B) deposited on a substrate (27) that transmits light, and a modulated ultraviolet laser beam (20)
And a light deflector (32) for two-dimensionally scanning the phosphor-coated surface of the screen (25).
The phosphors (29R), (29G), and (29B) of (5) are sequentially excited by the modulated ultraviolet laser beam (20) to emit visible light (26).
In the display device, the laser light source device is composed of a neodymium laser (13) and an optical element (15) that generates a harmonic of a laser beam (14) from the neodymium laser (13) by a nonlinear optical effect. , (1
8) and (19), with a back plate (32) that transmits ultraviolet light (20) and reflects visible light (26) on the phosphor-coated surface of the screen (25). It is.

[Action]

According to the present invention, the phosphors (29R), (29G),
(29B) From the visible light emitted by the excitation by the ultraviolet laser beam (20), the visible light emitted in the direction of the back plate (32) is directed from the back plate (32) to the substrate (27). The light is reflected, transmitted through the substrate (27), and emitted to the outside. Therefore, even if the laser power of the ultraviolet laser beam (20) is the same as that of the related art, the brightness of the screen on the screen (25) is twice that of the related art.

Also, harmonics of the laser beam (14) from the neodymium laser (13) are generated by the optical elements (15), (18), and (19) due to the nonlinear optical effect, and the harmonics are used as an ultraviolet laser beam. As a result, the oscillation efficiency, which is the ratio of the laser power of the ultraviolet laser beam to the input power, is improved as compared with the case where an Ar laser oscillator is used as in the related art. Therefore, the input power for exciting the phosphor with the same laser power can be lower than in the conventional case.

〔Example〕

Hereinafter, an embodiment of a display device according to the present invention will be described with reference to FIG. In this example, the present invention is applied to a television receiver having a large screen of 60 inches.

FIG. 1 shows a television receiver of the present embodiment.
In the figure, reference numeral 13 denotes a mode-locked Nd: YAG (neodymium: YAG) laser oscillator of a flash lamp excitation type or a laser diode excitation type, and the mode-locked Nd: YAG laser oscillator (13) has a wavelength λ of 1.064. μm (angular frequency is ω) infrared laser beam (14)
Generated by pulse lighting of 200MHz or more. This laser beam (14) is input to a first nonlinear optical crystal (15) made of, for example, KTP (potassium titanophosphate KTiOPO ₄ ), and an angular frequency of 2
A second harmonic (16) of ω and a fundamental (17) of angular frequency ω are generated. Then, the second wave is provided by a half-wave plate (18).
After rotating the polarization plane of the harmonic (16) by 90 ° and mixing the second harmonic (16) with the fundamental (17), the mixed second harmonic (16) and fundamental (17) are mixed. For example, β-BBO (B
And input to a second nonlinear optical crystal (19) made of barium borate (BaB ₂ O ₄ ) to generate a third harmonic (20) having an angular frequency of 3ω by generating a sum frequency signal. Since the wavelength λ ₃ of the third harmonic (20) is λ ₃ = λ / 3 = 355 [nm] (5), the third harmonic (20) is used as the ultraviolet laser beam of this example. . In this case, experimentally _{L o / L i ≒ 0.05 =} 5 [%] is the ratio of the laser power L _o of the laser power L _i and ultraviolet laser beam generated (20) of the laser beam in the infrared region (14) … (6) The oscillation efficiency, which is the ratio of the laser power of the laser beam (14) having an oscillation wavelength of 1.064 μm to the input power IN of the Nd: YAG laser oscillator (13), is about 2% for the flash lamp excitation type and the laser diode excitation type. About 40%. Therefore, from the equation (6), the laser power L of the ultraviolet laser beam (20) with respect to the input power IN is
When a flash lamp pumped Nd: YAG laser (13) is used, the ratio L / IN becomes L / IN ≒ 0.02 × 0.05 = 0.1 [%] (7), and the laser diode pumped Nd: YAG laser (13)
When L is used, L / IN ≒ 0.4 × 0.05 = 2 [%] (8) Therefore, the oscillation efficiency of the conventional _Ar laser oscillator
It can be seen that one to two orders of magnitude are improved with respect to 0.01%.

In FIG. 1, the ultraviolet laser beam (20) is input to an optical modulator (21). A modulation circuit (22) synchronizes a red signal R, a green signal G, and a blue signal B separated from a composite video signal of a television signal with a synchronization signal obtained from a light-receiving element (not shown). Then, the light is supplied to the optical modulator (21) while performing time division. The optical modulator (21) deflects the ultraviolet laser beam (20) time-divisionally modulated with the red signal R, the green signal G, and the blue signal B by, for example, a plurality of galvanometer mirrors or a plurality of polygon mirrors. Input to the optical deflector (23), and the optical deflector (23) two-dimensionally scans by synchronizing the ultraviolet laser beam (20) with the horizontal synchronization signal and the vertical synchronization signal extracted from the composite video signal. Form a beam (24). The optical modulator (2
1) can be constituted by, for example, an acousto-optic effect element or an electro-optic effect element.

(25) shows a so-called beam index type screen of 60 inches (1.5 m in diagonal length, approximately 1 m ² in area). This screen (25) is basically a front glass (27) with a red phosphor (29R). , Green phosphor (29G) and blue phosphor (29G)
B) are applied alternately in a stripe shape at a predetermined pitch in a direction perpendicular to the paper surface of FIG. 1, and then a back glass (32) is formed on the phosphor application surface. Then, a coating film (28) that reflects ultraviolet light and transmits visible light is formed on the front glass (27) on the phosphor application surface side by, for example, dichroic coating, and the three types of phosphors are formed. A black stripe (30) is formed at the intermediate part of each of (29R), (29G) and (29B). On the other hand, a coating film (3) that transmits ultraviolet light and reflects visible light by, for example, dichroic coating is applied to the surface of the back glass (32) to be attached to the front glass (27).
Form 1).

As the front glass (27), ordinary blue plate glass or the like can be used, and as the rear glass (32), white plate glass or the like can be used. The rear glass (32) must be formed of a material that transmits ultraviolet light. Generally, the transmission of ultraviolet light having a wavelength of 300 nm or less is limited to expensive quartz glass or the like, whereas the wavelength of 300 nm is used. Inexpensive white plate glass or the like can be used as a material that transmits ultraviolet light exceeding. Therefore, when ultraviolet light having a wavelength of 300 nm or more is used as in this example, there is an advantage that the back glass (32) can be manufactured at low cost.

In FIG. 1, an optical deflector (23) synchronizes a scanning beam (2) with a horizontal synchronizing signal separated from a composite video signal.
4) is scanned with respect to the screen (25) in a direction parallel to the plane of the paper of FIG. 1, and the scanning beam (24) is scanned with respect to the screen (25) in synchronization with the vertical synchronizing signal separated from the composite video signal. Scanning in a direction perpendicular to the plane of FIG.
In this case, since the scanning beam (24) is point-sequentially modulated by the light modulator (21) in accordance with the red signal R, the green signal G and the blue signal B, the scanning beam (24) is applied to the front glass (27). The viewer (12) can view a color image by the visible light (26) emitted from the phosphors (29R), (29G), and (29B). In particular, in this example, the back glass (32)
Since a coating film (31) that transmits ultraviolet light and reflects visible light is formed on the side, the phosphor (29R), (29
G), the visible light emitted from (29B) is the back glass (32)
Since it is transmitted as visible light (26) in the direction of the viewer (12) without being transmitted to the side, there is an advantage that the screen is at least twice as bright as before.

Next, in the television receiver of this example, in order to achieve a luminance of 50 fL (foot Lambert), which is a luminance that can be managed on the screen (25), that is, a light flux of 538 lm (see equation (2)). Required mode lock type N
d: Estimate the input power IN to the YAG laser. The premise is that the red phosphor (29R) applied to the front glass (27),
Green phosphor (29G), and blue phosphors respectively as the material of (29B) Y (P, V ) O 4; E u 3+ (B i 3+), Y 2 S i O 5: C e 3+, Tb ³⁺ and
B _a Mg ₂ Al ₁₆ O ₂₇ : Select _Eu ²⁺ . The red phosphor (29
The _{R) 3.5MgO0.5MgF 2 G e O 2} : M n 4+ or the like can be used.
Table 1 shows the quantum efficiency (conversion efficiency) and lamp efficiency (output light flux / input power, ie, lm / W) of these phosphors. In the example shown in Table 1, the screen gain was set to 1 because there is no gain in the screen (25).

First, a red phosphor (29R), a green phosphor, for example, excited (29G), and blue phosphors (29B), the laser power, respectively Table 1 required to obtain the luminous flux 538lm of CIE D ₆₅ standard daylight As shown, they are 12.5W, 4.3W and 17.2W. Also,
Laser light source device of this example (13), (15), (18), (19)
As described above, the oscillation efficiency, which is the ratio of the laser power L of the ultraviolet laser beam (20) to the input power IN, is about 0.1% (see equation (7)) for the flash lamp excitation type, and It is approximately 2% (Equation (8)
reference). Therefore, the input power IN to the mode-locked Nd: YAG laser (13) is as shown in Table 1. In the column of input power in Table 1, the upper row shows the case of the flash lamp excitation type, and the lower row shows the case of the laser diode excitation type.

According to Table 1, when a flashlamp-pumped Nd: YAG laser (13) is used, the green phosphor (29G) is more conventional than the conventional 43 kW represented by equation (14). Of the input power is only one tenth of the input power. Further, when the coating film (31) that reflects visible light is taken into consideration, the input power is 1/20 of the conventional one. On the other hand, when the laser diode pumped Nd: YAG laser (13) is used, it can be seen that the input power on the order of 1/100 of that of the conventional case is sufficient.

However, in Table 1, the value of the laser power of the ultraviolet laser beam for exciting the phosphor is 4 W to 17 W, but this value is not a value easily obtained by an inexpensive laser light source device at present. In order to further reduce the laser power, it is conceivable that the screen (25) in FIG. 1 has a so-called lenticular structure. By using the lenticular structure, the brightness of the screen of the screen (25) can be made about five times. That is, since the screen gain becomes five times, if the luminance of 10 fL is achieved on the screen (25), the substantial luminance of the screen will be 50 fL. Table 2 shows the laser power and input power in this case.

According to Table 2, when the screen gain is increased by a factor of 5, the input power of the laser diode pumped Nd: YAG laser (13) can be as low as about 300 W. But it can be used easily.

In addition, the mode-locked Nd: YAG laser currently available at low cost is of the flashlamp-pumped type, and an ultraviolet laser beam stably obtained when using the flashlamp-pumped mode-locked Nd: YAG laser. Although the laser power of (20) is only about 1 W, it can be seen from Table 2 that at a laser power of 1 W, sufficient luminance can be obtained with the green phosphor (29).
G) only. Therefore, in order to obtain a bright screen on a screen of 60 inches or more with an inexpensive structure, a flashlamp-excited mode-locked Nd: YAG laser, a lenticular structure with a screen gain of 5 times and a green phosphor are combined. It can be said that the structure is good.

In the above-described embodiment, the laser light source device is configured by combining the mode-locked Nd: YAG laser (13) and the nonlinear optical crystals (15) and (19). A laser oscillator may be used.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

According to the present invention, since the back plate that transmits ultraviolet light and reflects visible light is disposed on the phosphor-coated surface of the screen, the laser power of the laser beam from the laser light source device is provided. However, there is an advantage that a screen which is about twice as bright as the conventional one can be obtained even if it is the same as the conventional one.

In addition, since the laser light source device that generates an ultraviolet laser beam is composed of a neodymium laser and an optical element that generates harmonics of the laser beam from the neodymium laser by a non-linear optical effect, the phosphor has the same laser power. Has the advantage that the input power for exciting is lower than before.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a display device according to the present invention, and FIG. 2 is a block diagram showing a conventional display device. (13) is a mode-locked Nd: YAG laser, (15) is a first nonlinear optical crystal, (18) is a half-wave plate, (19) is a second nonlinear optical crystal, and (20) is a third nonlinear optical crystal. (21) an optical modulator, (23) an optical deflector, (25) a screen, (27) a front glass, (29R), (29G),
(29B) are red phosphor, green phosphor, blue phosphor,
(31) is a coating film, and (32) is a back glass.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Kikuchi 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-63-15221 (JP, A) JP-A Sho 53-21944 (JP, A) JP-A-48-95735 (JP, A) JP-B-53-6812 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09F 9/00 H04N 5/66-5/74 G03B 21/56-21/64

Claims (1)

(57) [Claims] 1. A laser light source device for generating an ultraviolet laser beam, an optical modulator for modulating the ultraviolet laser beam, a screen comprising a substrate on which a visible light is transmitted and a phosphor adhered thereto; And a light deflector that two-dimensionally scans the ultraviolet laser beam on the phosphor-coated surface of the screen, and sequentially excites the phosphor of the screen with the modulated ultraviolet laser beam to generate visible light. In the display device, the laser light source device includes a neodymium laser and an optical element that generates a harmonic of a laser beam from the neodymium laser by a non-linear optical effect, and a phosphor-coated surface of the screen. A display device, comprising a back plate for transmitting ultraviolet light and reflecting visible light thereon.