JPS61212076A - Light-emitting diode array device - Google Patents

Abstract

PURPOSE:To extend the width of illuminance peak and to enlarge the range of precisions allowable for mounting light-emitting diode (LED) chips, by arranging each LED chip having a rectangular planar shape such that one of the diagonals is approximately perpendicular to the central axis of the chip array. CONSTITUTION:LED chips 2... are mounted in an array on an electrically insulating stem 1. A cylindrical condenser lens is fixed on a reflecting plate 3 for efficiently distributing light emitted by the LED chips 2. Each LED chip 2 is mounted in such an orientation that one of the diagonals is approximately perpendicular to the central axis of the array, so that the illuminance peak width (a') in the direction of width of the chip is substantially enlarged in comparison with the illuminance peak width (a) of a conventional LED array device. Any deviation in position of the illuminance peak, which would be caused by deviation in mounting position of the LED chips 2, can be remarkably remedied. Thus, the allowable range of precisions required for mounting an LED array device can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a light emitting diode array device used as a light source for an object reading sensor.

[Technical background of the invention]

For example, a light emitting diode array device (hereinafter referred to as an LED array device) in which a plurality of light emitting diodes (LEDs) are arranged is used as a light source for a facsimile copying machine.

FIG. 2(A) is a front view showing the external appearance of the conventional LED array device, and FIG. 2(B) is a side view. Further, FIG. 2C is a plan view showing the arrangement state of the LED chips in this array device.

In these figures, 1 is an insulating or insulated stem. On the stem 1, as shown in FIG. 2(C), a large number of LED chips 2 are mounted in a negative row. Bonding pads (not shown) are formed on the surfaces of these LED chips 2, and are connected to terminals (not shown) provided on the stem via bonding wires (not shown). The stem 1 includes a reflector plate 3 for efficiently distributing light from the LED chips 2...
is provided, and a condenser lens 4 is fixed thereon.

Note that the LED chips 2... all have a rectangular planar shape (for example, 0.3 #I x O, 3m). Moreover, as shown in the figure, each LED chip 2... is installed with its opposing sides parallel to the array center line.

FIG. 3 shows the light intensity distribution in the width direction of the conventional LED array device. Due to the action of the condensing lens 4,
As shown in the figure, a light distribution characteristic with a narrow peak width is obtained.

[Problems with background technology]

In the above LED array device, the LED chip 2...
When a mount misalignment occurs, the peak illuminance position will be shifted approximately four times as much as the mount misalignment. For example, if a deviation of ±0.15111111 occurs due to manual mounting work, a deviation of -Q,5+n will occur in the peak illuminance position.

In addition, if a mount deviation of ±0.05fllffl occurs with automatic mounting, the peak illuminance position will be 0.2111
A deviation of 1 occurs. For this reason, the peak line of the light condensed by the lens 4 winds along the center line of the array, causing the following problem.

That is, when using the above LED array, the LED array shown in FIG.
), light is irradiated at an angle of incidence oblique to the irradiation surface X, and the reflected light is detected by the light receiving element 5. In this case, it is used in such a manner that 80% to 90% of the peak illuminance hits the irradiated surface ), the part with even lower illuminance hits the irradiation surface X,
The illuminance decreases and it becomes unusable. Therefore, there is a problem in that not only is the mounting of the LED array and the light receiving element 5 required to be delicate and highly accurate, but also that if a peak shift occurs, the current must be increased to increase the illuminance.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and the width of the illuminance peak can be expanded simply by changing the mounting form of the light emitting diode chip, and even if the mount is misaligned, the mounting accuracy of the light emitting diode array device can be improved. The purpose is to obtain a wide tolerance range.

[Summary of the invention]

The light emitting diode array device according to the present invention mounts a plurality of light emitting diode chips having a rectangular planar shape in a line on an insulating or insulating stem, and wire bonding each chip in parallel. In the assembled light emitting diode array device, the individual light emitting diode chips are arranged so that one diagonal line thereof is substantially perpendicular to the center line of the seven rays.

Since the diagonal line of an LED chip having a rectangular planar shape is longer than one side thereof, the width of the illuminance peak is expanded by making the diagonal line of the chip perpendicular to the array center line as described above.

[Embodiments of the invention]

FIG. 1 is a plan view showing the arrangement of LED chips in an LED array device according to an embodiment of the present invention. In this figure, the same parts as in FIGS. 2(A) to 2(C) are given the same reference numerals. That is, 1 is an insulating stem;
2... is an LED chip, and 3 is a reflector. Each LED
A bonding pad (not shown) is formed on the surface of each chip 2, and is connected to a terminal (not shown) provided on the stem via a bonding wire (not shown).

Also, as shown in FIG. 2 (A>(B)), a cylindrical condensing lens is mounted and fixed on the reflection plate 3. These structures are almost the same as in the conventional example shown in FIG. Exactly the same, LE
The planar shape of the D chip 2... is also a square of 0.3 aw x 13 mm. However, the mounting state of the LED chips 2 is different from the conventional one, and as shown in the figure, each LED 2 is mounted with one diagonal line substantially perpendicular to the array center line.

In the LED array device of the above embodiment, the individual LED chips 2... are mounted in an orientation rotated by 45 degrees from the conventional orientation, so the length in the direction perpendicular to the array center line is doubled. ing.

That is, conventionally, as shown in FIG. 5(A), the LED chip 2
In contrast, in the above embodiment, a length of 0.311LI equal to one side of
A length of 2u+ can be obtained. Therefore, as shown in FIG. 6, the illuminance peak width a' (FIG. 6(B)) in the width direction of the LED array device of the above embodiment is different from that of the conventional L
Illuminance peak width a in the ED array device ((A) in the same figure)
is significantly expanded compared to

As a result of expanding the illuminance peak width in this way, the displacement of the illuminance peak due to the mounting displacement of the LED chip 2 in the above embodiment is significantly improved, and the tolerance range of precision required for mounting the LED array device can be expanded. .

Incidentally, in the above embodiment, even if a deviation of ±0.15 mm occurs due to manual mounting work, the illuminance beak deviation is only ±0.121. Moreover, for a deviation of ±0°05 during automatic mounting, the deviation of the illuminance peak can be almost ignored.

Note that, without relying on the present invention, an LED chip 2' having a rectangular (0,3a+m xO06go++ ) planar shape as shown in FIG. 7(A) is used, and its long side is perpendicular to the array center line. It is also possible to obtain the same effects as in the above embodiment by arranging them. However, even in this case, greater effects can be obtained if the present invention is applied. FIG. 6(B) is a plan view showing the mounting direction of the chip in another embodiment using this LED chip 72'. As shown, this embodiment also provides the same effect as when the chip width is increased by 0.071 m compared to the conventional example shown in FIG. 6(A).

(Effects of the Invention) As described in detail above, according to the present invention, the illuminance peak width of the light emitting diode array device can be expanded simply by changing the mounting form of the light emitting diode chip, and even if the mount is misaligned, the light emission can be continued. The mounting of the diode array device has remarkable effects such as being able to obtain a wide tolerance range for accuracy.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the arrangement of chips in an LED array device which is an example of the present invention, Fig. 2 (A) is a front view of a conventional LED array device, and Fig. 2 (B) is a side view thereof. FIG. 3 is a plan view showing the arrangement state of the chips, and FIG. 3 is a line showing the light intensity distribution in the width direction in the conventional LED array device shown in FIGS. 2(A) to (C). Figure, 4th
Figures 5(A) and 6(B) are explanatory diagrams showing the usage status of the conventional LED array device and its problems. It is an explanatory view showing the effect in an example. DESCRIPTION OF SYMBOLS 1... Insulating stem, 2, 2'... LE[) chip, 3... Reflection plate, 4... Condensing lens, 5... Light receiving element. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (A) (B) Figure 3 Figure 4 (A) (B) Figure 6 Figure 7 (A) (B) 2'

Claims (1)

[Claims] A light emitting diode array assembled by mounting a plurality of light emitting diode chips having a rectangular planar shape in a line on an insulating or insulating stem, and wire bonding each chip in parallel or series. 1. A light emitting diode array device, characterized in that the individual light emitting diode chips are arranged so that one diagonal line thereof is substantially perpendicular to the array center line.