JPH02253276A - Attaching/detaching device for optical scanning device such as laser printer - Google Patents

Abstract

PURPOSE:To minimize scanning with deviation and to obtain an excellent picture without unevenness by arranging a stud and a fit-in member on a side fixed by a fitting screw so that they are positioned on a perpendicular passing a fixed point on which a lazer beam from a scanning device is made incident. CONSTITUTION:The front stud 3 and the front fit-in groove 8 on the side of the fitting screw 10 are arranged to be positioned on the perpendicular 13 passing the fixed point 12 on which the laser beam 6 from the laser beam emitting diode 5 is made incident. Thus, even when there is small space between a back stud and a back fit-in groove, the scanning width deviation on a photosensitive drum due to the vibration of a motor, etc., can be in an acceptable range, and therefore, the excellent picture can be obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an attachment/detachment device for an optical scanning device such as a laser printer, and in particular, a fixing member on a main body side for positioning, and an optical scanning device for attachment and detachment. The present invention relates to an attachment/detachment device in which the arrangement with a fitting member on the device side is precise and there is no deviation in the scanning position of a laser beam.

(Prior Art) When making an optical scanning device such as a laser printer into a module and making it replaceable, the space required for attaching and detaching the optical scanning device is not increased, and other replaceable units (photoreceptors, @ image, cleaning, etc.), and mechanical positional accuracy with respect to the photoreceptor is particularly important.

Therefore, the present inventor guided the sliding rib provided on the optical scanning device (optical box) by the main body guide rail, and the lateral direction was
He also invented an invention in which the optical scanning device is positioned three-dimensionally in the height and longitudinal directions by fitting the front and rear sides of the optical scanning device, and the optical scanning device is fixed to the main body using two mounting screws in the front (patent application). (See No. 116810, 1983).

(Problem to be solved by the invention) The above invention is from the lateral direction of the laser printer main body.

That is, the optical scanning device can be easily attached and detached by horizontal movement that occupies a small area, but the fitting grooves in the front and rear of the optical scanning device,
In terms of fitting accuracy with the front and rear studs of the main body, a problem arises due to a gap between the groove width of the fitting groove and the shaft diameter of the stud, that is, a deviation in the scanning position of the laser beam on the surface of the photoreceptor caused by so-called backlash.

This will be explained using FIGS. 1 to 3.

FIG. 1 shows a side sectional view of the laser printer main body 1 and the optical scanning device 2, showing a state in which the laser printer main body 1 and the optical scanning device 2 are attached.
Position the optical scanning device 2 (optical box).

The studs 3 and the rear studs 4 are installed on the inner wall of the main body casing (only one side is shown in the drawing).
Further, a photoreceptor drum 7 is disposed directly below the laser beam 6 emitted from the laser light emitting diode 5 of the optical scanning device 2 .

On the other hand, on the side wall of the optical scanning device 2 is the front side of the main body.

It has a front fitting groove 8 and a rear fitting groove 9 that fit with the rear studs 3 and 4, respectively (only one side is shown in the drawing).

The optical scanning device 2 is finally fixed to the main body 1 using two front mounting screws 10 (one screw on one side is shown in the drawing).

Normally, the fitting grooves 8 and 9 and the studs 3 and 4 require a certain amount of clearance in order to allow the optical scanning device 2 to be attached and detached. When the laser beam is scanning the surface of the photoreceptor drum 7 due to this gap, that is, when the laser printer is in operation, the optical scanning device vibrates up and down.

That is, as in the illustrated example, the side where the fitting groove and stud are fixed by the mounting screw 10 (in this case, the front 8 and 3)
does not vibrate substantially due to the holding force of the mounting screw, but
The looseness caused by the gap between the fitting groove on the opposite side of the mounting screw and the fitting part of the stud (in this case, rear 9 and 4) is due to the lack of fixing mounting screws etc. that regulate the vertical direction. It vibrates using the fitting portion on the (front) side of the mounting screw 10 as a fulcrum.

FIG. 2 is a diagram showing the deviation in the scanning width of the laser beam due to the vibration of the optical scanning bag @2. As shown in Fig. 1, with the front stud 3 and the front fitting groove 8 on the mounting screw 10 side as the fulcrum,
A gap (backlash) between the shaft diameter φx3 of the rear stud 4 on the opposite side and the groove width x2 of the rear fitting groove 9.

X, -φx2 causes the optical scanning device 2 to vibrate vertically at an angle θ
, only the amplitude movement.

As a result, the scanning position - of the laser beam 6 on the surface of the photoreceptor drum 7 is shifted by Δy (angle θj). Due to this shift, the image on the recording paper 11 is distorted from the original scanning width y (angle θj) as shown in FIG. There was a problem in that the pitch) was y±Δy, making it impossible to obtain a good image.

The present invention minimizes the deviation ±Δy of the scanning width y on the photoreceptor drum surface due to the gap between the stud on the main body side and the fitting groove on the optical scanning device side, thereby producing a good image without image unevenness. Aimed at scales.

(Structure and operation) In order to achieve the above object, the present invention includes a fixing member for positioning in a three-dimensional direction on the main body side of a laser printer, etc., and a fitting member that fits with the fixing member for positioning to an optical scanning device. In preparation for this, there is provided an attachment/detachment device configured so that the optical scanning device can be attached to and detached from the main body by coupling and detaching the fixing member and the fitting member.

The position of the fixing member and the fitting member on the side where the optical scanning device is fixed to the main body with a mounting screw is on a perpendicular line whose passing point is a fixed point where the laser beam from the optical scanning device enters the photoreceptor surface in the main body. It is characterized by being placed in.

In the present invention, the positions of one of the fixing members (studs) and the fitting member (fitting groove) that are fixed with the mounting screws are set at a fixed point where the laser beam from the optical scanning device enters the photoconductor surface as a passing point. Due to the arrangement on the perpendicular line, the deviation of the scanning width y caused by the gap between the other fixed member and the fitting member is ±
Δy can be minimized.

゛(Embodiment) As shown in FIG. The light 6 is arranged on a perpendicular line 13 whose passing point is a fixed point 12 where the light 6 is incident on the surface of the photoreceptor drum 7.

By the way, as described in FIG. 2, the laser beam 6 is generated by the gap between the rear stud 4 and the rear fitting groove 9 with the position A (fixed point) as a fulcrum due to the vibration of the motor inside the main body or the optical scanning device. The laser beam is irradiated with a deviation of rotation angle θ□ and Δ
The scanning width y of the laser beam 6 is shifted by y.

When the front stud 3 and the fitting groove 8 are arranged at the position (A) on the perpendicular line 13 as shown in FIG. Even when the laser beam 6' is incident on the surface, the laser beam 6' is incident on a fixed point 12 on the scanning line of the photosensitive drum 7, and there is no deviation in the scanning position without being affected by backlash due to gaps between the rear stud and the fitting groove.

Now, let's assume that the front stud and the fitting groove are 13', 13" above the perpendicular to the laser beam 6! (A)', (A)
'', the laser beam 6 crosses the intersection 14.15 of the perpendicular lines 13' and 13'' like 6''6'' even if the rotation angle θ2 is the same as in (A). is incident on the surface of the photoreceptor drum 7, and as it moves away from the fixed point 12, the scanning position shifts by Δyz when it crosses the intersection 14 and Δy when it crosses the intersection 15. It can be seen that the influence of backlash gradually increases depending on the gap.

A specific example of this will be explained with reference to FIG.

Comparison between the case where the front stud and the fitting groove are arranged at the position (A) on the perpendicular line 13 and the case where the front stud and the fitting groove are arranged at the position (A)' on the perpendicular line 13' in this embodiment. Spread.

When vibration causes a rotation angle θ (the illustration is shown in an enlarged scale for clarity) of the optical scanning device.

The incidence deviation on the surface of the photosensitive drum 7 at position (A) on the perpendicular line 13 (which serves as the fulcrum of vibration) is Δy4, position r! 1
In (A)', it becomes Δy, and Δy4×Δy.

Here, each distance A between the position (A) of the front stud and the front fitting groove, the fixed point 121 position (A)'', and the intersection 14 is 200.
Cabinet, length of fixed point 12 and intersection 14 (between perpendiculars 13 and 13')
When B=25 m, the diameter φG of the photosensitive drum 7 is 60, and the rotation angle θ=1'', the following calculation is obtained by substituting Δy1.Δy into equation (4), which will be described later.

That is, yx=25m, Qm,y, = 200mm
X sin 1 'Q1= 200m, then y1=
When 25 m = 0.471 When y8 = 01, x = 0.031. Here, x, = 0.03■ is ΔY** jca=
0.47m corresponds to Δy.

In other words, it becomes Δy4/Δyi''F15, so it can be seen that the scanning width is extremely different from 15=1 due to the difference in the fulcrum positions [(A) and (A)''.

As mentioned above, the front stud and the fitting groove are located on the perpendicular line 13! It is ideal to arrange (A). However, in reality, due to the structure of the device, such a position ff1i(A
) is difficult to set. In such cases,
By arranging a fixed point (fulcrum) that approximates the position (A) that satisfies the following equation, it is possible to suppress the deviation of the scanning position as much as possible.

FIG. 6 is an explanatory drawing for deriving the following formula.

In the figure, Q8 is the distance Ω between the position (A) (the fitting part of the front stud and the front fitting groove and the fixing point of the mounting screw) and the laser beam 6, and the distance Ω is the distance between the position (A) and the other rear stud. The distance θ between the position (B) (movable point) of the rear fitting groove is between the incident point 12 (fixed point) on the surface of the photoreceptor drum 7, and
The angle y between the line 16 connecting the position (A) (fixed point) and the perpendicular 13 is the distance y between the perpendicular 13 and the position [(A) (fixed point) is the distance y between the position (B) (movable point) ) The gap (backlash) between the rear stud and the rear fitting groove y is the distance Xtt x2.) of y*XQt/Qz when one rotation angle θ2. x3 indicates the change in the incident position on the surface of the photoreceptor drum, and when x3 is y2, however, Q
t+Qzeyx+yztyatXieXz+X, is per cabinet, 01. θ2 is assumed to be approximately m degrees.

First, the change distance y in the vertical direction on the beam of laser beam 6 due to m3'z generation is y, m y, X''' 6... (1) The change distance x1 in the X direction due to y8 generation is , 8, ;
JLT Coffy ... River (2) Similarly, the change distance yaxx in the X direction due to the occurrence of y3 is therefore X, is x, -xl
O at this time is ta mouth 0 = 5 ・Song・ (
5) X y is the amount of movement on the perpendicular line 13 caused by the distance w between position (B) (movable point), which is 1 m, a! Compared to,
ax is>ys. Therefore, 57 bow 7 press g
□ ...Approximate to song (6).

From the above formulas (4) and (6), 1 is (1*) V a, so if the phrase o is 5,
,,=J−Lxy,+Xs 4 lx xy.

Q, Q, Q, °------- (
8) Also, from the above formulas (5) and (8), xs = -51Xya = tanQXya = tanOXy
zX I+++++ (9) On the other hand, x is usually desirably less than the scanning line width of 171o, so it is expressed using one pixel density a.

25.4 1 x3≦□x~ ・・・・・・(lO)a
10 However, since a is DPI dots/inch, it becomes from the above equation (9) and (IQ).

By the way, for the gap between the rear stand and the rear fitting part at position 12B (movable point), 0.05- is a reasonable value based on the current processing accuracy, and if higher accuracy is required,
It also lacks Ik mass productivity and increases costs. Therefore, as a specific example of this embodiment, when yz = 0.05■, if this is substituted into the above equation (11), as long as θ is within the range shown in the above equation (!2), the light Let us assume that the fixed point of the scanning device (tolerance part I#1 of position 11fA) is the fixed point of the scanning device.

Even if there is some gap between the rear stud and the rear fitting groove, the scanning width on the surface of the photoreceptor drum due to the vibration of the motor etc. will be within an allowable range, and a high quality image can be obtained.

In addition, the above pixel density a is for DPI, but in the case of H'J/4 density b (density -), x, from equation (10), is ' becomes.

From the above formulas (9) and (10)', if we set y = 0.05- and substitute it into formula (11)', we get θ≦tan-buy'5h→xaL.

(12)' (Effects of the Invention) As explained above, the present invention provides a device in which an optical scanning device can be attached to and detached from a laser printer main body from the horizontal direction.
Even if one of the fixing member (stud) and the fitting member (fitting groove) of the main body is fixed, and there is some play in the other due to the gap, the laser beam will locate the fixing point of the one on the surface of the photoreceptor drum. By arranging the scanning line on a vertical line passing through a fixed point incident on the scanning line, deviation in scanning line width can be minimized.

Furthermore, as shown in equations (12) and (12)' above, if the position is located at a fixed point within the dimension range that is allowable in practice, deviations in scanning line width will not be a problem, and mass production will be excellent and costs will not increase. You can move around the attachment/detachment device of the optical scanning device.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional view showing how the laser printer main body and the optical scanning device are installed, Fig. 2 is a diagram showing the shift in the scanning position of the laser beam due to vibration of the optical scanning device, and Fig. 3 is the scanning on the recording paper. FIG. 4 is a diagram showing the deviation of the width y, FIG. 4 is a diagram explaining the basic principle of the present invention, and FIGS. 5 and 6 are diagrams explaining a specific example of FIG. 4. 1... Laser printer main body, 2... Optical scanning device (optical cabinet), 3... Front stud, 4...
... Rear stud, 5 ... Laser light emitting diode, 6.6', 6", 6"" ... Laser light, 7 ... Photosensitive drum. 8 ... Front fitting groove, 9.・・Rear fitting groove, 10・
...Mounting screw, 11...Recording paper, 12...Fixed point, 13.13', 13"...Perpendicular line, 14.15
... Intersection, (A) ... Position (fixed point) between the fitting part of the front stud 3 and the front fitting groove 8 and the mounting screw lO, (B
)...Position (movable point) due to the gap between the fitting part of the rear stud 4 and the front fitting groove 9. 10 mounting screws

Claims (1)

[Claims] A fixing member for positioning in a three-dimensional direction is provided on the main body side of a laser printer, etc., and a fitting member that fits with the fixing member for positioning is provided in the optical scanning device, and the fixing member and the fitting member are provided. In the attachment/detachment device configured to allow the optical scanning device to be attached to and removed from the main body by coupling and detaching, the position of the fixing member and the fitting member on the side where the optical scanning device is fixed to the main body by a mounting screw, 1. An attachment/detachment device for an optical scanning device such as a laser printer, characterized in that the attachment/detachment device for an optical scanning device such as a laser printer is arranged on a perpendicular line whose passing point is a fixed point at which laser light from the optical scanning device is incident on the surface of a photoreceptor in a main body.