JPH1144858A - Deflecting scanner and image forming device capable of mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent temperature from getting high at the inner part of an optical box by the generated heat of a driving IC. SOLUTION: The motor 3a of a rotary polygon mirror 3 is driven by a driving current supplied from the driving IC 3c on a motor base plate 3b. The periphery of the IC 3c is surrounded by an IC cap 21, and the upper end of the cap 21 is directly opened to the outer part of the optical box 10 from the aperture part 20b of a cover member 20. By directly discharging the heat generated from the IC 3c to the outside of the optical box 10, the temperature is prevented from getting high at the inner part of the optical box 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection scanning device used for an image forming apparatus such as a laser beam printer and a laser facsimile and an image forming apparatus equipped with the same.

[0002]

2. Description of the Related Art A deflection scanning device used in an image forming apparatus such as a laser beam printer or a laser facsimile reflects a light beam such as a laser beam (laser beam) by a rotating polygon mirror rotating at a high speed, and deflects and scans the beam. Then, the obtained scanning light is imaged on a photoreceptor on a rotating drum to form an electrostatic latent image. Next, the electrostatic latent image on the photoreceptor is visualized into a toner image by a developing device, transferred to a recording medium such as recording paper, sent to a fixing device, and printed by heating and fixing the toner on the recording medium ( Print) is performed.

[0003] Figure 6 shows a deflection scanning apparatus used in an image forming apparatus such as a laser beam printer or a laser facsimile according to one conventional example, the laser beam L ₀ is a light beam generated from the semiconductor laser S ₀ collimator The light is collimated by the lens, condensed into a linear light beam by the cylindrical lens C ₀ , and is incident on the reflection surface of the rotary polygon mirror 103. The reflected light is deflected and scanned by the rotation of the rotary polygon mirror 103 to become scanning light, and is formed into an imaging lens system F _0.
It focused on the photosensitive member on the rotary drum D ₀ through. The light beam forms an image on the photosensitive member forms a main scanning by rotation of the rotary polygon mirror 103, an electrostatic latent image is accompanied in the sub scanning by rotation of the rotary drum D _0.

A charging device for uniformly charging the surface of the photoconductor is provided around the photoconductor, a visualization device for visualizing an electrostatic latent image formed on the surface of the photoconductor into a toner image, the toner image is disposed such as a transfer device that transfers a recording medium such as recording paper is a by these works, the recording information corresponding to the light beam semiconductor laser S ₀ occurs is printed on the recording paper.

The scanning light of the rotary polygon mirror 103 reaches one end of its scanning surface, is reflected by a BD mirror M ₀ , is introduced into a BD sensor B ₀ through a condenser lens, and starts scanning in a processing circuit (not shown). It is converted into a signal being transmitted to the semiconductor laser S _0. The semiconductor laser S ₀ is after having received the scanning start signal, starts writing modulated based on image information transmitted from the host computer.

The semiconductor laser S ₀ , the cylindrical lens C ₀ , the rotary polygon mirror 103, the imaging lens system F ₀ , the BD mirror M ₀ , the BD sensor B _0, etc. are made of an optical box 110 made of synthetic resin.
Installed inside. The rotating drum D ₀ is an optical box 11
0 is disposed on the outside, a window for taking out toward the rotary drum D ₀ the scanning light from the optical box 110 is provided at one end of the optical box 110.

The imaging lens system F ₀ is composed of a spherical lens R ₀ and a toric lens T ₀ , and scans light scanned at a constant angular speed by the rotary polygon mirror 103 on the rotary drum D _{0 at} a constant speed. So-called fθ function.

The upward opening of the optical box 110 is
10, a rotating polygon mirror 103, an imaging lens system F ₀ , a BD mirror M _{0, and the} like are assembled.
Blocked by 20. The lid member 120 is a plate-shaped body whose outer peripheral edge is in contact with the upper end of the side wall of the optical box 110, and is assembled to the optical box 110 by screws (not shown).

A motor 1 for driving the rotary polygon mirror 103 to rotate.
03a is a driving IC mounted on the motor board 103b
Stator 103 excited by the driving current of 103c
d and a magnetic circuit composed of the rotor 103e and the like opposed thereto.

[0010]

However, according to the above prior art, when the operation of the image forming apparatus is started,
The temperature of the atmosphere outside the optical box rises to about 30 to 40 ° C, and the temperature inside the optical box rises to about 40 to 50 ° C. In addition, the surface of the driving IC instantaneously reaches 70 to
It will be in a high temperature state of 90 ° C.

During operation, the temperature inside the optical box gradually rises due to the heat generated by the driving IC, and when the heat radiation is insufficient, the atmosphere inside the optical box rises by about 10 ° C. When the temperature inside the optical box becomes high, the optical performance of the optical components such as the imaging lens system deteriorates, and the image quality of the image forming apparatus deteriorates.

In recent years, a resin-made scanning lens or the like is often used for an imaging lens system. However, a resin-made lens tends to have a remarkable change in refractive index due to a temperature change.
The effect on image performance is extremely large.

In order to avoid such troubles,
Measures such as reducing the amount of heat generated by the driving IC by suppressing the power consumption of the motor, or increasing the space around the driving IC to promote air flow, etc. are being studied. A technology that enhances heat dissipation by using sheet metal with good conductivity is also adopted.

However, in recent years, higher definition and higher speed have been promoted, and accordingly, the number of rotations of the motor has increased, and in addition, the size of the entire apparatus has been reduced. Therefore, it is difficult to reduce the power consumption of the motor or to increase the space for accommodating the driving IC. In addition, although a method using a sheet metal lid member is useful for reducing parts costs and the like, it is not sufficient. There is an unsolved problem that a heat dissipation effect cannot be expected.

The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and the temperature inside the optical box becomes high due to heat generated by a driving IC of a motor for rotatingly driving a rotary polygon mirror. It is an object of the present invention to provide an inexpensive and high-performance deflection scanning device capable of largely improving image performance and the like by avoiding the above, and an image forming apparatus equipped with the same.

[0016]

In order to achieve the above object, a deflection scanning apparatus according to the present invention comprises a rotary polygon mirror for deflecting and scanning a light beam, a motor for driving the rotary polygon mirror, and controlling the motor. Driving means having circuit components, imaging means for forming an image of the light beam on the photoreceptor via the rotating polygon mirror, an optical box containing the imaging means, the rotating polygon mirror and the driving means, A lid member for closing an opening of the optical box,
The drive unit includes a resin cover surrounding the circuit component, and the cover is opened from the opening provided in the lid member to the outside of the optical box.

It is preferable that the lid member is made of sheet metal.

The cover may be connected to the lid member by a patching stop.

[0019]

When the temperature inside the optical box becomes high due to the heat generated by the circuit components such as the driving IC of the driving means, the optical performance of the scanning lens constituting the imaging means may be significantly impaired. Therefore, by surrounding the circuit components with a cylindrical cover and opening one end of the cover from the opening provided in the lid member to the outside of the optical box, heat generated from the circuit components is directly Releases out of the box to prevent the atmosphere inside the optical box from rising.

Since the cover is made of resin, the temperature does not rise significantly due to the heat generated from the circuit components, and if the lid member is made of sheet metal, the heat radiation effect of the lid member can be expected.

If the cover is connected to the lid member by patching, it is possible to prevent the structure of the lid member from becoming complicated and the assembly process from becoming complicated.

It is possible to prevent the optical performance of the scanning lens and the like from being impaired by the rise in temperature inside the optical box, and to realize an image forming apparatus having good image performance and the like.

[0023]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a deflection scanning device according to an embodiment. A laser beam, which is a light beam generated from a semiconductor laser 1, is collimated by a collimator lens.
The light is condensed into a linear light beam by the cylindrical lens 2 and is incident on the reflection surface of the rotary polygon mirror 3. The reflected light is
The scanning light is deflected by the rotation of the rotary polygon mirror 3 to become scanning light in the Y-axis direction (main scanning direction), and forms an image on a photosensitive member on a rotating drum 5 via a scanning lens 4 as imaging means. The light beam that forms an image on the photoreceptor forms an electrostatic latent image with the main scanning in the Y-axis direction by the rotation of the rotating polygon mirror 3 and the sub-scanning in the Z-axis direction by the rotation of the rotating drum 5.

In the periphery of the photoreceptor, a charging device for uniformly charging the surface of the photoreceptor, a visualization device for visualizing an electrostatic latent image formed on the surface of the photoreceptor into a toner image, A transfer device or the like for transferring the toner image to a recording medium such as recording paper is provided, and by these operations, recording information corresponding to the light beam generated by the semiconductor laser 1 is printed on recording paper or the like.

The scanning light of the rotary polygon mirror 3 reaches one end of the scanning surface, and passes through the condenser lens 6a to the BD sensor 6.
b, is converted into a scanning start signal by a processing circuit (not shown), and is transmitted to the semiconductor laser 1. After receiving the scan start signal, the semiconductor laser 1 starts write modulation based on image information transmitted from the host computer.

The semiconductor laser 1, the cylindrical lens 2, the rotary polygon mirror 3, the scanning lens 4, the BD sensor 6b, etc. are mounted inside an optical box 10 made of resin. The rotating drum 5 is disposed outside the optical box 10,
Is provided with a window 11 for taking out scanning light from the optical box 10 toward the rotating drum 5.

The scanning lens 4 comprises a spherical lens portion and a toric lens portion, and converts scanning light scanned at a constant angular speed by the rotary polygon mirror 3 into scanning light scanning at a constant speed in the Y-axis direction on the rotating drum 5. So-called fθ function.

On the bottom wall of the optical box 10, a semiconductor laser 1, a cylindrical lens 2, a rotary polygon mirror 3, a scanning lens 4, and the like united with a collimator lens are assembled.

A motor 3a for rotating the polygon mirror 3
Is a driving means together with a driving IC 3c which is a circuit component mounted on the motor board 3b shown in FIG. 2, and includes a stator 3d which is excited by a driving current controlled by the driving IC 3c, and a stator 3d opposed thereto. The motor 3a is configured by a magnetic circuit including the rotor 3e and the like.

The upward opening of the optical box 10 is closed by a lid member 20 after the rotary polygon mirror 3 and the scanning lens 4 are assembled in the optical box 10.

As shown in FIG. 3, the lid member 20 is a plate-like body whose outer peripheral edge is in contact with the upper end of the side wall of the optical box 10, and is assembled to the optical box 10 with screws 20a. The lid member 20 is made of sheet metal that is inexpensive and has good thermal conductivity, and has an opening 20b that opens toward the driving IC 3c on the motor substrate 3b.

An IC cap 21 which is a tubular cover having a rectangular cross section is mounted on the opening 20b of the lid member 20, and a lower end of the IC cap 21 is provided with a driving IC 3c.
And is close to the surface of the motor board 3b.
The IC cap 21 is made of a resin having a low thermal conductivity, and a pair of patch claws 21 a is integrally formed at an upper end thereof. The IC cap 21 is attached to the lid member 20 by an opening 20 b of the lid member 20. To IC cap 21
When the IC cap 21 is lowered until the lower end of the IC cap 21 comes close to the surface of the motor substrate 3b as described above, the patching is performed by so-called patching that each patching claw 21a is engaged with the surface of the lid member 20.

The driving IC 3c on the motor board 3b becomes hot when the motor 3a is started.
1 through the opening 20b of the lid member 20 through the driving IC
Since the portion 3c is directly exposed to the atmosphere outside the optical box 10, there is no possibility that the atmosphere inside the optical box 10 is significantly heated by the heat generated by the driving IC 3c. In this way, it is possible to effectively prevent the optical performance of the optical components such as the scanning lens 4 from being impaired due to the heat generated by the driving IC 3c.

In recent years, a relatively inexpensive sheet metal lid member has been often used to reduce material costs. The sheet metal lid member also has a heat radiation effect due to its heat conduction, but is less effective than the heat radiation from the opening of the lid member. On the other hand, if the temperature of the lid member is too high, the temperature inside the optical box will increase.

Since the IC cap 21 is made of a resin, it is easy to integrally form the patch claws 21a. Further, the lid member 20 need only be formed with a simple opening 20b by a known drilling process or the like. . Therefore, there is an advantage that component costs can be reduced.

Further, since the resin IC cap 21 has low thermal conductivity as described above, there is also a problem that the heat of the driving IC 3c is absorbed by the IC cap 21 and the temperature inside the optical box 10 rises. Absent.

As described above, the heat generated from the driving IC can be very effectively released to the outside of the optical box only by providing the opening in the sheet metal lid member and assembling a simple resin IC cap into the opening. In addition, the temperature of the internal optical components can be prevented from rising. In addition, since the process of attaching the inexpensive resin IC cap is simple without complicating the processing of the sheet metal lid member, the material cost and the assembly cost do not increase.

FIG. 4 shows a modification. In this case, a gap formed between the motor substrate 3b and the lower end of the IC cap 21 is sealed with a dustproof member 22 such as foamed polyurethane. If there is a gap between the IC cap 21 and the motor board 3b, outside air may enter the optical box 10 from there, and the rotating polygon mirror 3 and the scanning lens 4 may be contaminated by floating dust and the like. Then, the gap is sealed by the dustproof member 22 to prevent the invasion of outside air. As a result, it is possible to realize a deflection scanning device capable of maintaining good image quality without maintenance for a long time.

[0040]

Since the present invention is configured as described above, it has the following effects.

It is possible to prevent the inside of the optical box from becoming high temperature due to heat generated by the motor driving IC and the like, thereby realizing a high-performance and inexpensive image forming apparatus having good image performance and the like.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a deflection scanning device according to an embodiment.

FIG. 2 is a sectional view showing the device of FIG. 1 with a lid member attached.

FIG. 3 is a plan view of the apparatus of FIG. 2;

FIG. 4 is a sectional view showing a modification.

FIG. 5 is a sectional view showing a deflection scanning device according to a conventional example.

FIG. 6 is a diagram for explaining the entire device of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Cylindrical lens 3 Rotating polygon mirror 3a Motor 3b Motor board 3c Driving IC 4 Scanning lens 10 Optical box 20 Lid member 21 IC cap 22 Dustproof member

Claims (5)

[Claims] A rotary polygon mirror for deflecting and scanning a light beam;
A motor that rotationally drives the rotating polygon mirror and a driving unit including a circuit component that controls the motor; an imaging unit that forms an image of the light beam on a photoconductor via the rotating polygon mirror; An optical box housing the rotating polygon mirror and the driving means,
A lid member for closing the opening of the optical box; and a resin cover surrounding the circuit component of the driving means, wherein the cover is moved out of the optical box from an opening provided in the lid member. A deflection scanning device having an opening. 2. The deflection scanning device according to claim 1, wherein the lid member is made of sheet metal. 3. The cover according to claim 1, wherein the cover is connected to the lid by a patch stop.
The deflection scanning device according to claim 1. 4. The deflection scanning device according to claim 1, wherein the circuit component includes a driving IC. 5. An image forming apparatus comprising: the deflection scanning device according to claim 1; and a main body frame on which the deflection scanning device is mounted.