JPS6048382A - Led array head - Google Patents

Abstract

PURPOSE:To obtain heat dissipating effect from cooling fins even in the outlet side of cooling air and to enhance image quality by uniformizing heat dissipation of an LED, by increasing the height of each cooling fin while tilting said fins along the air sending direction of cooling air. CONSTITUTION:A heat dissipating plate 19 is fixed to the back surface of a base board 18 having a large number of LEDs 17 linearly arranged thereto to constitute a part of an exposure apparatus 5. A plurality of cooling fins 55 are provided to the back surface of a heat dissipating plate 54 and the heights of these fins 55 are increased while tilted along the air sending direction (the arrow B-B') of cooling air due to a fan motor. Therefore, cooling due to cooling air having a low temp. can be performed even in the outlet side of cooling air separated from the fan motor and heat dissipation from the fins 55 is performed uniformly and sufficiently in the inlet and outlet sides of cooling air. As a result, the light emitting output and wavelength of LED17 are kept well over the whole.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an LED array head in an LED printer using an electrophotographic method.

Prior Art First, FIG. 1 schematically shows an LED printer. A photoreceptor belt 3 is stretched between a driving roller 1 and a driven roller 2, which are driven in the direction of the arrow. A charging charger 4 uniformly charges the surface of the photoreceptor belt 3, and a charger 4 uniformly charges the surface of the photoreceptor belt 3.
-3, an exposure device 5 for forming an electrostatic latent image and a developing device 6 for making the latent image visible are provided. Further, a paper feed roller 8 is provided which takes out the transfer paper 7 at a predetermined timing, and the transfer paper 7 taken out by the paper feed roller 8 is provided.
is transferred to the transfer device 1 via the separation roller 9 and the registration roller 10.
1, and in this transfer device 11, the photoreceptor bell 1-
The developed image on 3 is transferred to transfer paper 7. After transfer, transfer paper 7
is sent to a fixing device 12 where it is fixed, and then ejected by a paper ejection roller 13. On the other hand, the photoreceptor belt 3 is connected to the static eliminator 14.
, the surface is processed by the cleaning device 15 in preparation for the next image formation. 16 is a backup roller that prevents the photoreceptor belt 3 from being dented or the like.

Here, the exposure device 5 is based on an LED array head, and as shown in FIGS. 2 to 4, a large number of L
a substrate 18 made of ceramic or the like on which EDs 17 are arranged in a linear manner;
A heat sink 19 to which this substrate 18 is attached, an imaging element held by a holding member 20, for example a selfoc lens 21
Consists of etc.

One end of a connecting wire 22 is bonded to the electrode (for example, the anode side) of each LE[) 17 arranged on the substrate 18, and the other end of this wire 22 is connected to a matrix-structured wiring pattern (not shown) on the substrate 18. A lead wire 23 connected to the outside is soldered to this wiring pattern. Further, another electrode (for example, the cathode side) of the LED' 17 contacts a wiring pattern (not shown) in another layer on the substrate 18, and this wiring pattern connects to a lead wire (not shown) at the end of the substrate 18. connected to the outside. Pins 24 having threaded portions are attached to both ends of the holding member 20, and a brush assembly 26 having brushes 25 whose tips come into contact with the photoreceptor belt 3 is attached to the lower part over the entire circumference. These brushes 25 prevent foreign matter such as toner used in the developing device 6 and paper waste from adhering to the SELFOC lens 21 . The holding member 20 and the heat sink 19 have the LED 17 between them.
1 to the light emitting part (not shown) and the SELFOC lens 21.
- Seal member 27 to prevent adhesion of glue, paper waste, etc.
After intervening and fitting compression springs 28 to the pins 24, these pins 24 are fitted into holes 29 of the heat sink 19, and nuts 30 are screwed together to connect them. Note that depending on the degree to which this nut 30 is tightened, the above-mentioned LE
The optimum distance between the light emitting part of the D17 and the SELFOC lens 21 is adjusted, and the sealing member 27 is maintained in a compressed state even when the two 17.21 are adjusted to the maximum distance. The thickness and material of 27 are taken into consideration, and the materials used include various deformable rubbers and foamed urethane. Further, an opening 31 is formed in the center of the sealing member 27, and this opening 31 does not interfere with the optical path of the LED 17 even when the sealing member 27 is deformed due to compression, and does not touch the wire 22. There is no large enough opening to be 1X.

Therefore, deformation or disconnection of the wire 22 does not occur. Pins 32 having threaded portions are provided at both ends of the heat dissipation plate 19, and after fitting compression springs 33, these pins 32 are fitted into holes 36 of blocks 34 and 35, and nuts 37 are screwed together. A pair of blocks 34 and 35 fixed to both ends of the heat sink 19 are connected by a plate 38 located above the heat sink 19. Note that this plate 38 is fixedly attached to a rail to be described later, and the self-off lens 2
1 and the photoreceptor belt 3 can be adjusted.

The exposure device 5 configured in this way has a rail 4 fixed between the side plates 39 and 40 of the printer body shown in FIG.
1 by engaging the bent portion 42 of the plate 38 with the edge 43 of the rail 41. This support is
This is done by pushing in the bent part 42 from the direction of the arrow while engaging the edge 43, inserting a pin 44 equivalent to one of the blocks 34 into the hole 45 of the side plate 39, and inserting the pin 44 into the hole 46 of the other block 35. The exposure apparatus 5 is fixed by aligning with the screw hole 47 of the side plate 40 and tightening a screw (not shown). Note that the distance adjustment using the nuts 30 and 37 may be performed after the exposure device 5 is fixed, or may be performed in advance before attachment.

Here, when the temperature of the LED 17 rises, the light emission output decreases and the light emission wavelength shifts to the longer wavelength side. Generally, the sensitivity of a photoreceptor is low to long wavelength light. Therefore, when the temperature of the LED 17 increases, the image quality deteriorates due to a decrease in the light emission output and a decrease in photoreceptor sensitivity due to a shift in the emission wavelength. Therefore, a cooling fan motor 48 is attached to the outside of the side plate 39, and the air blown from the fan motor 48 passes through the duct portion 50 formed in the exposure device 5 through the hole 49 of the side plate 39. The liquid passes through the hole 51 of the side plate 40 and is discharged outside the printer body. This duct portion 50 is connected to the heat sink 1
9 and the plate 38 and a pair of heat dissipating fins 52 having a long height dimension formed on the back surface of the heat dissipating plate 1.
9 is further provided with a plurality of short rectangular fins 53 located between the fins 52.

Then, the air from the fan motor 48 is transmitted to each fin 52.5.
3 to prevent the temperature from rising due to the light emission of the LED 17, and to prevent the emission wavelength of the LED 17 from changing due to temperature changes.

In this way, the temperature of the LED 17 is prevented by providing the fins 52, 53 and blowing air by the fan motor 48, but the temperature of the cooling air that cools the fins 52, 53 is It rises as it moves away from the fan motor 48 due to heat radiation. Therefore, on the cooling air inlet side near the fan motor 48, the fins 52.5
3 is sufficiently cooled and the light emitting output and light emission wavelength of L E D L 7 are maintained in a good state.
53 becomes insufficient, the light emission output gradually decreases, and the light emission wavelength shifts to the longer wavelength side.

As a result, the printed image is uneven and image quality is degraded.

the purpose The present invention was made in view of these points.

The object of the present invention is to obtain an LED array head that can improve the heat dissipation effect of the fins and improve the image quality.

Construction A first embodiment of the present invention will be described based on FIG. 6. Note that the heat dissipation plate described in this embodiment and the second embodiment described later has a substrate 18 on which LEDs 17 are arranged, similar to the heat dissipation plate 19 explained in FIGS. 2 to 4. This constitutes a part of the exposure device 5. This example is.

A plurality of cooling fins 55 are provided on the back surface of the heat sink 54,
The height of these fins 55 is increased while being inclined along the direction of cooling air blown by the fan motor 48 (arrow B-B'). Therefore, fan motor 4
Cooling is also performed on the outlet side of the cooling air, which is remote from the fins 8, and heat is uniformly and sufficiently radiated from the fins 55 on the inlet and outlet sides of the cooling air. Therefore, the light emission output and light emission wavelength of the LED 17 are maintained in a good state throughout, and image quality is improved. Note that the inclination of the fins 55 depends on the amount of air blown by the fan motor 48, the surface area of the fins 55, the temperature resistance of the fins 55, and the LE
The amount of heat generated by the light emission of D17 is determined based on the following.

Next, a second embodiment of the present invention will be described based on FIG. In this embodiment, the fins 56 are provided in a direction perpendicular to the arrangement direction of the LEDs 17, and the air blowing direction (arrow C-C') by the fan motor 4 is also set in a direction perpendicular to the arrangement direction of the LEDs 17. There is. And fin 5
The height of the fins 6 is increased while being inclined along the air blowing direction, and the image quality can be improved by improving the heat dissipation effect from the fins 56.

Effects The present invention has the above-mentioned effects by increasing the height of the cooling fins while tilting them along the cooling air blowing direction.
A sufficient heat dissipation effect from the fins can be obtained even on the exit side of the cooling air, and the heat generated by LED light emission can be evenly dissipated. It is possible to prevent the image from shifting to the side, thereby improving the image quality.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of the LED printer, Fig. 2 is an enlarged vertical cross-sectional side view of the exposure device, Fig. 3 is an exploded perspective view of the exposure device, and Fig. 4 is a vertical cross-sectional front view showing a part of the exposure device. , FIG. 5 is a perspective view of the support device and fan motor that support the exposure device, and FIG. 6 is a perspective view showing the first embodiment of the present invention.
FIG. 7 is a perspective view showing a second embodiment of the present invention. 17...LED, 18...board, 54...heat sink, 55
~56...Fin Applicant Rico Co., Ltd. -

Claims (1)

[Claims] A heat sink is fixed to the back of a board on which a large number of LEDs are linearly arranged, and a plurality of heat sink fins are formed on the heat sink, which are tilted to become higher in sequence from the inlet direction to the outlet direction of the cooling air. An LED array head featuring: