JP2010271592A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device in which sufficient uniformity over an entire irradiation region can be achieved even when an irradiation object is exposed from a short distance utilizing an effective irradiation range in the length direction of a low voltage discharge lamp to the vicinity of limit. <P>SOLUTION: Respective low voltage discharge lamps 15 are arranged so that the end part of relatively low luminance side and the end part of a high luminance side are alternately arranged. Further, relation between the arrangement interval P of each low voltage discharge lamp 15 and an irradiation distance (d) to a liquid crystal panel 100 from each low voltage discharge lamp 15 is set to the absolute minimum irradiation distance (d) where irradiation light from the end part of the low luminance side to a liquid crystal panel 100 can be complemented by irradiation light from the end part of the adjacent high luminance side, and light emitted to the outside of an irradiation region A from the low voltage discharge lamp 15 is reflected by a reflection frame 20 surrounding the irradiation region A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source device in which a plurality of low-pressure discharge lamps are arranged in parallel.

  2. Description of the Related Art Conventionally, various light source devices for irradiating (exposing) ultraviolet rays to a liquid crystal panel or the like have been used in a liquid crystal panel manufacturing process or the like. As one of this type of light source device, for example, a plurality of low pressure discharge lamps such as ultraviolet radiation type hot cathode low pressure mercury lamps arranged in parallel as a light source is known.

  By the way, this type of low-pressure discharge lamp generally has a smaller output than a high-pressure discharge lamp or the like. Therefore, in a light source device using a low-pressure discharge lamp as a light source, in order to ensure a sufficient irradiation intensity, the low-pressure discharge lamps are arranged in a sufficiently dense manner, and each low-pressure discharge lamp is sufficiently placed on an irradiation target. Must be placed close to

  On the other hand, in the exposure process for a liquid crystal panel or the like, it is required to irradiate ultraviolet rays with a high degree of uniformity. However, when each low-pressure discharge lamp is brought close to the irradiation target, the emission characteristics of the low-pressure discharge lamp itself Will affect the exposure. In particular, in a light source such as a low-pressure discharge lamp, generally, a phosphor layer is formed by pouring a phosphor solution from one end into a bulb. The thickness and composition of the phosphor layer thus formed are Since it has a predetermined gradient in the length direction, a difference in the length direction occurs in the luminance characteristics of the low-pressure discharge lamp according to the gradient of the film thickness and composition, and it becomes more difficult to equalize.

  In response to this, for example, as in the technique disclosed in Patent Document 1, when the low-pressure discharge lamps are arranged, the end portion on the side where the thickness of the phosphor layer is small and the end portion on the large side are staggered. Thus, it is conceivable to arrange the low-pressure discharge lamps so as to equalize the illuminance.

JP-A-8-94945

  By the way, in recent years, liquid crystal panels and the like tend to increase in size, and accordingly, the light source apparatus is also required to perform exposure using the effective irradiation range in the length direction of each low-pressure discharge lamp to the limit. There is a case.

  However, when the effective irradiation range in the length direction of the low-pressure discharge lamp is used up to the limit in this way, even if the technique disclosed in the above-mentioned Patent Document 1 is adopted, the entire irradiation range is required. It may be difficult to obtain sufficient uniformity. In this case, in particular, in the corner portion on the irradiation area where the low-luminance end of the low-pressure discharge lamp located at the end of the array is opposed, a dark portion is likely to occur, and further improvement for improving the uniformity is required. It was.

  The present invention can achieve a sufficient degree of uniformity over the entire irradiation region even when the irradiation target is exposed from a short distance by using the effective irradiation range in the length direction of the low-pressure discharge lamp to near the limit. An object is to provide a light source device.

  In the present invention, a plurality of straight tube-type low-pressure discharge lamps having a gradient in luminance distribution in the length direction at one end side and the other end side are arranged in parallel as a light source, and an irradiation target is exposed by the plurality of low-pressure discharge lamps. A light source device, wherein the low-pressure discharge lamps are arranged so that relatively low-luminance side ends and high-luminance side ends are alternately arranged, and the arrangement intervals of the low-pressure discharge lamps and the respective Irradiation that can complement the relationship with the irradiation distance from the low-pressure discharge lamp to the irradiation object by irradiation light from the end on the high luminance side adjacent to the irradiation light from the end on the low luminance side to the irradiation object A side surface that reflects the light emitted from the low-pressure discharge lamp toward the outside of the irradiation region at both ends of the irradiation region corresponding to both ends in the length direction of the low-pressure discharge lamp, at a distance. A reflection plate is provided.

  According to the light source device of the present invention, even when the irradiation target is exposed from a short distance by using the effective irradiation range in the length direction of the low-pressure discharge lamp to near the limit, sufficient uniformity is obtained over the entire irradiation region. Can be realized.

Exploded perspective view showing schematic configuration of ultraviolet irradiation device Cross-sectional view of the main part showing the ultraviolet irradiation device along the direction of arrangement of the low-pressure discharge lamps Cross-sectional view of the main part showing the ultraviolet irradiation device along the length direction of the low-pressure discharge lamp Plan view of the main part of the light source unit viewed from below Chart showing the relative luminance distribution along the length direction of the low-pressure discharge lamp (A) is a chart showing the illuminance distribution in the irradiation region, and (b) is a chart showing an ultraviolet illuminance curve along the arrangement direction and the length direction of the low-pressure discharge lamp. The principal part sectional view showing the ultraviolet irradiation device concerning the comparative example of this embodiment along the arrangement direction of a low-pressure discharge lamp (A) is a chart showing the illuminance distribution in the irradiation area, and (b) is a chart showing the ultraviolet illuminance curve along the arrangement direction and the length direction of the low-pressure discharge lamps. The principal part sectional view showing the ultraviolet irradiation device concerning the comparative example of this embodiment along the arrangement direction of a low-pressure discharge lamp (A) is a chart showing the illuminance distribution in the irradiation area, and (b) is a chart showing the ultraviolet illuminance curve along the arrangement direction and the length direction of the low-pressure discharge lamps.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an ultraviolet irradiation device as an example of a light source device, and this ultraviolet irradiation device 1 is suitably used, for example, in an alignment film forming process of a liquid crystal panel 100 for a large screen television device. It is. Here, for example, as shown in FIGS. 1 to 3, the ultraviolet irradiation device 1 of the present embodiment applies ultraviolet rays simultaneously to 2 × 2 relatively large liquid crystal panels 100 placed on a stage 101. For irradiating. Therefore, a wide area is set as the irradiation area A set on the stage 101 of the ultraviolet irradiation apparatus 1, and in this embodiment, specifically, the length of one side (X direction) is set. A rectangular area of x0 = 2500 [mm] and the other side (Y direction) side length y0 = 2200 [mm] is set.

  The ultraviolet irradiation device 1 has a light source unit 10. For example, the light source unit 10 includes a plurality of (for example, 44) low-pressure discharge lamps 15 provided as light sources on the lower surface side of a frame 11 having a substantially rectangular shape in plan view, and the main part is configured.

  Specifically, in the present embodiment, the low-pressure discharge lamp 15 is constituted by, for example, a 110 [W] ultraviolet radiation type hot cathode low-pressure mercury lamp. The low-pressure discharge lamp 15 is composed of, for example, a long straight tube type discharge lamp having a total length of 2367 [mm] and an effective light emission length of 2320 [mm], and has caps 16 at both ends. Further, the lamp bulb 17 formed between the pair of caps 16 is constituted by a glass tube having an outer diameter of 38 [mm] and a thickness of 0.85 [mm], for example. On the inner periphery of the lamp bulb 17, for example, a phosphor layer 18 that emits ultraviolet light by electron beam excitation is formed. The phosphor layer 18 is formed by, for example, drying and baking the phosphor applied by pouring a phosphor solution into the lamp bulb 17. Therefore, the phosphor layer 18 has a predetermined gradient with respect to its film thickness and composition from one end side to the other end side. Due to the gradient such as the film thickness, for example, as shown in FIG. 5, the low-pressure discharge lamp 15 has a gradient in the relative luminance in the length direction, and the luminance on one end side is relative to the luminance on the other end side. Is getting higher. Here, in the low-pressure discharge lamp 15 having such a luminance gradient, in order to easily distinguish the high-luminance side and the low-luminance side, the low-pressure discharge lamp 15 of the present embodiment has, for example, an end on the high-luminance side. The mark 19 for identification is attached | subjected to the part.

  The frame 11 is configured by a substantially flat member having a rectangular opening at the center. In the frame 11, a pair of sides facing each other is configured as a wiring board 12, and a plurality of pairs (for example, 44 pairs) of sockets 13 facing each other are provided at equal pitches P on the lower surface of the wiring board 12. Has been placed. Here, the arrangement interval (pitch) P of the sockets 13 is set to 58 [mm], for example.

  Then, each pair of caps 16 is fitted into each pair of sockets 13, and each low-pressure discharge lamp 15 is arranged in parallel at every equal pitch P (for example, P = 58 [mm]) on the lower surface side of the frame 11. Thus, the light source unit 10 is configured. In this case, in order to prevent illuminance unevenness due to the luminance gradient in the length direction of the low-pressure discharge lamp 15 itself, for example, as shown in FIG. 4, each low-pressure discharge lamp 15 has an end portion on the low-luminance side. It is attached to the socket 13 so that the high luminance side ends are alternately arranged.

  The light source unit 10 configured as described above is disposed opposite to the liquid crystal panel 100 placed on the stage 101 as an irradiation target at the time of exposure.

  The irradiation distance (distance from the lower end of the low-pressure discharge lamp 15 to the liquid crystal panel 100 (irradiation target)) d in this case is defined based on, for example, the relationship with the arrangement interval (pitch) P of the low-pressure discharge lamps 15. Yes. That is, the irradiation distance d is related to, for example, the illuminance ripple caused by the irradiation light from the low-luminance end of the low-pressure discharge lamp 15 to the liquid crystal panel 100 in relation to the arrangement interval of the low-pressure discharge lamps 15. The low-pressure discharge lamp 15 is set to a distance that can be reduced by complementation with irradiation light from the end portion on the high luminance side. More specifically, it is desirable that the irradiation distance d is set within a range of 1.5 to 3 times the arrangement interval P of the low-pressure discharge lamps 15. In this embodiment in which P is set to 58 [mm], the irradiation distance d is set to 110 [mm], for example.

  Here, in the light source unit 10 described above, about two to four low-pressure discharge lamps 15 positioned at both ends in the arrangement direction are offset relative to the liquid crystal panel 100 side relative to the other low-pressure discharge lamps 15. It is also possible. This offset is preferably performed within a range that maintains a predetermined relationship between the arrangement interval P of the low-pressure discharge lamps 15 and the irradiation distance d described above. In this embodiment, for example, as shown in FIG. The two low-pressure discharge lamps 15 located at both ends in the arrangement direction are offset by an offset amount Δd = 5 [mm].

  Moreover, the ultraviolet irradiation device 1 has a reflection frame 20 on the exposure side of the light source unit 10. The reflection frame 20 includes a first side reflector 21 disposed at both ends (both ends in the X direction in FIG. 1) of the irradiation region A corresponding to both ends in the length direction of the low-pressure discharge lamp 15, and a low pressure. And second side reflectors 22 disposed at both ends of the irradiation region A (both ends in the Y direction in FIG. 1) corresponding to both ends in the arrangement direction of the discharge lamps 15, and these are connected together. Thus, the main part is configured. For example, the reflection frame 20 is configured to move up and down integrally with the light source unit 10 with respect to the stage 101. When the reflection frame 20 is lowered onto the stage 101 during exposure, in the gap between each low-pressure discharge lamp 15 and the stage 101, The irradiation area A is surrounded.

  Further, the ultraviolet irradiation device 1 has a reflection plate 25 on the non-exposure side of the light source unit 10. The reflection plate 25 is made of, for example, an aluminum plate having a substantially rectangular shape in a plan view and having a reflectance of about 85%, and is disposed on the upper side of the light source unit 10 at a position that closes the opening of the frame body 11. . For example, the reflector 25 is configured to move up and down integrally with the light source unit 10 with respect to the stage 101, and reflects light emitted from each low-pressure discharge lamp 15 to the non-exposure side at the time of exposure. Lead to 100 side.

  According to such an embodiment, by arranging the low-pressure discharge lamps 15 so that the relatively low-luminance side ends and the high-luminance side ends are alternately arranged, The uniformity of the irradiation area A can be improved by reducing the influence of the luminance gradient. Then, the relationship between the arrangement interval P of the low-pressure discharge lamps 15 and the irradiation distance d from the low-pressure discharge lamps 15 to the liquid crystal panel 100 is adjacent to the irradiation light to the liquid crystal panel 100 from the end on the low luminance side. The minimum required irradiation distance d that can be complemented by the irradiation light from the end portion on the high luminance side is set, and radiation from the low-pressure discharge lamp 15 toward the outside of the irradiation area A is performed by the reflection frame 20 surrounding the irradiation area A. Even when the liquid crystal panel 100 is exposed from a short distance by using the effective irradiation range in the length direction of the low-pressure discharge lamp 15 to near the limit by reflecting the generated light, the low-pressure discharge lamp 15 is made as much as possible. While making it approach the liquid crystal panel 100 side, the reflected light from the reflection frame 20 can be effectively contributed to the uniformity of the illuminance, and a sufficient uniformity can be realized over the entire irradiation area A.

  At that time, the low-pressure discharge lamps 15 located at both ends in the arrangement direction on the light source unit 10 are offset to the liquid crystal panel 100 side relative to the other low-pressure discharge lamps 15, particularly in the irradiation region A. The uniformity in the corner portion can be improved more efficiently.

  Further, a reflection plate 25 is disposed on the anti-exposure side of the light source unit 10, and the reflected light from each low-pressure discharge lamp 15 is reflected by the reflection plate 25 toward the liquid crystal panel 100, so that it is counteracted from each low-pressure discharge lamp 15. The average illuminance at the time of exposure with respect to the liquid crystal panel 100 can be improved by effectively using the light emitted to the exposure side (upper side).

  As a result, as shown in FIGS. 6A and 6B, sufficient uniformity can be realized over the entire irradiation area A without generating a dark part even in a corner portion or the like of the irradiation area A. .

Here, in the above-described configuration, the minimum illuminance obtained on the irradiation area A is 6.9633e ⁻⁶ [W / mm ² ], and the maximum illuminance is 8.7160e ⁻⁶ [W / mm ² ]. And the uniformity calculated | required from the following (1) Formula using these becomes 11.2%.

Uniformity = ((maximum illuminance−minimum illuminance) / (maximum illuminance + minimum illuminance)) × 100 (1)
In this way, it can be confirmed that the numerical value is sufficiently good.

  Here, as a comparative example, for example, a light source device 1A having a configuration in which the reflection frame 20 is omitted from the light source device 1 of the present embodiment and the offset of the low-pressure discharge lamp 15 at both ends in the arrangement direction is eliminated is illustrated in FIG. . Further, FIG. 9 shows a light source device 1B in which the reflection plate 25 is further omitted from the light source device 1A in FIG.

As shown in FIGS. 8A and 8B, the exposure using the light source device 1A of FIG. 7 is performed along the edge of the irradiation area A as compared with the exposure using the light source device 1 according to the present embodiment. A noticeable dark area appears. In this case, the minimum illuminance obtained on the irradiation area A is 6.3023e ⁻⁶ [W / mm ² ], and the maximum illuminance is 9.4355e ⁻⁶ [W / mm ² ]. And using these, the uniformity obtained from the equation (1) is 19.9%, which is significantly worse than the light source device 1 of the present embodiment.

On the other hand, as shown in FIGS. 10A and 10B, in the exposure using the light source device 1B of FIG. 9, the dark part at the edge of the irradiation area A is relatively reduced, and the minimum illuminance obtained thereby. Is 5.8567e ⁻⁶ [W / mm ² ], and the maximum illuminance is 8.3627e ⁻⁶ [W / mm ² ]. And using these, the uniformity obtained from the equation (1) is 17.6%, and the uniformity is slightly improved as compared with the light source device 1A. However, this uniformity does not reach the light source device 1 according to the present embodiment, and the average illuminance is reduced by about 3% due to the omission of the reflector 25.

  In the light source device 1 described in the above embodiment, in particular, the irradiation area A corresponding to the both ends in the longitudinal direction of the low-pressure discharge lamp 15 is defined after defining the irradiation distance d based on the relationship with the arrangement interval P. It has been confirmed by experiments, simulations, and the like by the present inventors that the side reflectors (first side reflectors 21) provided at both ends of each of these plates contribute most effectively to improving the uniformity. Therefore, depending on the degree of uniformity required for the light source device 1, the second side reflector 22 can be omitted as appropriate from the viewpoint of simplification of the structure and the like. It is also possible to abolish the offset of the lamp 15 as appropriate.

  On the other hand, in the above-described embodiment, in order to more efficiently realize the improvement of the uniformity in the corner portion of the irradiation area A, the arrangement interval of the low-pressure discharge lamps 15 arranged at both ends in the arrangement direction is changed to another arrangement. It may be smaller than the interval P.

  DESCRIPTION OF SYMBOLS 1 ... Ultraviolet irradiation apparatus, 10 ... Light source unit, 11 ... Frame, 12 ... Wiring board, 13 ... Socket, 15 ... Low pressure discharge lamp, 16 ... Base, 17 ... Lamp bulb, 18 ... Phosphor layer, 19 ... For identification Mark: 20 ... Reflection frame, 21 ... First side reflector, 22 ... Second side reflector, 25 ... Reflector, 100 ... Liquid crystal panel, 101 ... Stage, A ... Irradiation area, d ... Irradiation distance, P ... array interval, Δd ... offset amount

Claims (5)

A light source device in which a plurality of straight-line low-pressure discharge lamps having a gradient in luminance distribution in the longitudinal direction at one end side and the other end side are arranged in parallel as a light source, and an irradiation target is exposed by the plurality of low-pressure discharge lamps. And
Arranging each of the low-pressure discharge lamps so that relatively low-luminance side ends and high-luminance side ends are alternately arranged,
The relationship between the arrangement interval of the low-pressure discharge lamps and the irradiation distance from the low-pressure discharge lamps to the irradiation target, the irradiation light to the irradiation target from the end on the low-luminance side is adjacent to the high-luminance side While setting the irradiation distance that can be complemented by the irradiation light from the end,
Side reflectors for reflecting light emitted from the low-pressure discharge lamp toward the outside of the irradiation region are provided at least at both ends of the irradiation region corresponding to both ends in the length direction of the low-pressure discharge lamp. A light source device characterized by the above.   The irradiation distance from each low-pressure discharge lamp to the irradiation target is set in a range of 1.5 to 3 times the arrangement interval of the low-pressure discharge lamps. Light source device.   Side reflectors for reflecting light emitted from the low-pressure discharge lamp toward the outside of the irradiation region are provided at both ends of the irradiation region corresponding to both ends in the arrangement direction of the plurality of low-pressure discharge lamps. The light source device according to claim 1, wherein the light source device is a light source device.   4. The light source device according to claim 1, further comprising a reflector that reflects light emitted from the low-pressure discharge lamp toward the counter-exposure side. 5.   The said low-pressure discharge lamp located in the edge part of the said array was offset to the said irradiation object side relatively rather than the other said low-pressure discharge lamp, The any one of the Claims 1 thru | or 4 characterized by the above-mentioned. The light source device according to 1.