JPS60230628A - Led lighting device - Google Patents

Abstract

PURPOSE:To reduce illuminance irregularity, and to manufacture the LED lighting device which has a condenser lens held over an LED chip at low cost and high yield by using a long-sized LED chip for the LED lighting device. CONSTITUTION:The long-sized LED chips 2 is provided on the substrate 1 in this invention. Then, the condenser lens 3 is supported by a support 4 provided at both side parts of the substrate 1. This device has a uniform illuminance distribution at the center part of length l1 and obtains sufficient illuminance. Namely, this long-sized LED chip 2 is made of one crystal wafer; and (l2+2l2) is about 19mm. and l1 is about 4mm., so chips of this size can be manufactured sufficiently. Further, a long-sized, fixed shape is employed, so illuminance irregularity never increases during manufacture and low cost, high yield, and less illuminance irregularity are realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an LED lighting device, and more particularly to an LED lighting device used for illuminating the surface of a document in an image reading device.

[Prior art]

In recent years, there has been an increasing demand for miniaturization of image reading devices such as facsimile machines and copying machines, and as a result, new LEDs have been introduced to illuminate the document surface in place of conventional fluorescent lights. LED arrays consisting of a large number of Tezzos are now being used.

FIG. 4 shows a schematic configuration of a conventional LED play. FIG. 4(a) is a front view, and FIG. 4(bl is a side view). A columnar condensing lens 3 is disposed, and the condensing lens 3 is supported by supports 4 provided on both sides of the substrate 1.In this LED array, the light emitted from the LED chips 2 The light is focused by a condenser lens 3 and illuminates the document surface 10.

Incidentally, in the image reading apparatus described above, conventionally, in view of the reading speed, an LED array is provided over the entire width of the document surface (for example, 210 mm for an A4 size document) to read one line at a time. For this reason, L.E.
If the D array is short or long, use L.
The number of ED Chinno 2 will also increase. Therefore, if the characteristics of each chip vary or if the arrangement of each chip deviates from a straight line, uneven illumination is likely to occur.

FIGS. 4(al) and (b) also show an example of the illuminance distribution on the document surface 10 in the conventional LED illumination device as described above. That is, the LED chips 2 are arranged at intervals, and the arrangement thereof is If there is a variation in the pitch, an illuminance distribution as shown by the dotted line in FIG. As shown, a decrease in illuminance occurs at the desired position.
In the illuminance distribution of (bl), the solid line indicates the desired illuminance distribution.

However, although a large number of LED chips 2 are manufactured from one crystal wafer, the variation in brightness among the obtained chips is approximately 50%. For this reason, conventional LE
When fabricating the D array, in order to reduce variations in brightness between chips, it is recommended to select and fabricate the chips at adjacent positions on the wafer (marked with circles in the figure) as much as possible, as shown in Figure 5. It is done.

As described above, when manufacturing a conventional LED lighting device, in order to obtain uniform illuminance on the document surface, LEDs with uniform brightness are used.
It is necessary to select and position and arrange D chips with high precision, and therefore there are disadvantages in that many steps are required for each step and the yield is low.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide an LED lighting device that has less uneven illumination and can be manufactured at low cost and high yield.

[Summary of the invention]

According to the present invention, the above objects are achieved by using elongated LED chips as LED chips in an LED lighting device.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic configuration diagram showing a first embodiment of the LED lighting device of the present invention, and is a diagram similar to FIGS. A long LED chip 2 is provided.Furthermore, a cylindrical condensing lens 3 is arranged above the substrate 1, and the condensing lens 3 is attached to supports provided on both sides of the substrate 1. It is supported by 4.

FIGS. 1(al and (bl) show the illuminance distribution on the document surface 10 similarly to FIGS. 4(al and (bl). In the apparatus of this embodiment, as shown in FIG. 1(al),
The illuminance distribution is uniform in the central portion of the length tl, and as shown in FIG. 1(b), sufficient illuminance can be obtained in the desired portion. 2 is a schematic configuration diagram showing a second embodiment of the LED lighting device, FIG. 2(a) shows a front view, and FIG. 2(b) shows a side view.In the figure, FIG. Similar members are given the same reference numerals.

In this embodiment, a bellows-shaped lens is used as the condensing lens 3. Therefore, a uniform illuminance distribution can be obtained on the document surface 10 over a length that is almost the same as the length tl of the LED chip 2, and It becomes possible to use a large LED chip.

The LED lighting device of the above embodiment is mounted together with a reading device on a carriage that reciprocates in a direction perpendicular to the longitudinal direction (i.e., the direction of arrow A in FIG. 1(b) and FIG. 2 (in the direction of arrow A in BL)). It is used effectively when reading the width.Generally, the width of the document surface 10 that is read as the carriage moves is about 41a, and in this case, (t1+2t2) in FIG. 1 is about 19m. Also, tl in Fig. 2 is about 4 fins.Such a long LE
The D-chip 2 is manufactured from a single crystal wafer as shown in FIG. 3, and can be manufactured sufficiently as long as it has the above-mentioned length.

In the above embodiments, a case has been described in which the illumination device is mounted on a carriage together with a reading device, but it goes without saying that the illumination device of the present invention may be used in a fixed position together with a fixedly placed reading device. .

〔Effect of the invention〕

According to the present invention as described above, since the LED chip has an elongated fixed shape, brightness unevenness does not become large during manufacturing, and there is no need to take the trouble of selecting and arranging LED chips with high precision. Therefore, an LED lighting device with less uneven illumination can be obtained at low cost and high yield.

[Brief explanation of drawings]

Figures 1 fA) and (b) and Figures 2 (a) and (b) are configuration diagrams of the LED lighting device of the present invention. Figures 3 and 5
The figure is a plan view of a crystal wafer. FIG. 4 (al and (bl) are block diagrams of a conventional LED lighting device. 1... Substrate, 2... LED chip, 3... Condenser lens, 4... Support body, 10... ...Manuscript surface. @ Figure 1 (a) (b) Figure II2 (G)

Claims (2)

[Claims] (1) If an LED chip is provided on the board, the LED
An LED lighting device in which a condensing lens is held above a D-chip, characterized in that the LED chip is a long LED chip. (2) The length of the LED chip is 3.5 to 20 cm.
Item 1. LED lighting device.