JP3320171B2 - Ejection optical device for adjustment and focus adjustment method for scanning optical device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission optical device for adjusting light emitted from a light source into collimated light by a collimator lens and condensing the light by a focus lens, and a method of adjusting the focus of a scanning optical device using the device. Things.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram of a scanning optical device using an emission optical device 1. As shown in FIG. A beam L from the semiconductor laser light source 2 is emitted through a collimator lens 3 and a focus lens 4. A cylindrical lens 5 and a polygon mirror 6 are arranged in the traveling direction of the beam L. An fθ lens 7 and a folding mirror 8 are arranged in the traveling direction of the beam L deflected by the polygon mirror 6, and a photosensitive drum 9 is arranged in the traveling direction of the beam L folded by the folding mirror 8. The polygon mirror 6
Are driven to rotate by a drive motor 10.

[0003] The emission optical device 1 shown in FIG. 10 is configured to adjust the focus by rotating a focus lens 4. That is, a circuit board 11 provided with the semiconductor laser light source 2 is attached to the rear end of the base 12, and a collimator lens barrel 13 having the collimator lens 3 built therein is fitted to the front end of the base 12. Further, a focus lens barrel 14 having a built-in focus lens 4 is screwed to the front end of the collimator lens barrel 13 so as to be movable back and forth by rotation.

When adjusting the focus of such a product emission optical device 1, the focus lens 4 is rotated and moved in the optical axis direction so that the diameter of the beam emitted from the focus lens 4 is minimized.

[0005]

However, at the time of assembling the above-described emission optical device 1, the processing accuracy of the focus lens 4 itself, the assembly accuracy of the focus lens 4 with respect to the focus lens barrel 14, and the focus lens barrel 14
When the precision of screwing into the collimator lens barrel 13 is poor, the focus lens 4 is decentered when the focus lens 4 is rotated, which makes it difficult to adjust the focus. Further, since the focus lens 4 is manually rotated, there is a problem that the working efficiency is poor. Furthermore,
If an automatic focus adjustment device is added to the emission optical device 1, there is also a problem that the cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, to make it possible to move a focus lens straight, and to automatically adjust the focus, and to provide a method of adjusting a focus of a scanning optical device using the same. Is to provide.

[0007]

According to a first aspect of the present invention, there is provided an adjustment optical system for adjusting a light source for emitting a light beam, and an adjusting focus for condensing the light beam emitted from the light source. The adjusting focus lens is attached to a rectilinear body that moves in the optical axis direction, and the rectilinear body is attached to a rotary driving body via a movement direction conversion unit.

According to a second aspect of the present invention, there is provided a method of adjusting the focus of a scanning optical device using an adjusting emission optical device, comprising a light source for emitting a light beam and a product focus lens which moves in the optical axis direction by rotation. When adjusting the focus of the scanning optical device to which the emission optical device is attached, the light source includes a light source that emits a light beam, and an adjustment focus lens that condenses the light beam emitted from the light source. A linearly-moving body that moves in a direction, and the linearly-moving body is attached to the emission optical apparatus with an adjusting emission optical device mounted on a rotary driving body via a movement direction conversion unit.
And a second step of rotating the rotary driver so as to minimize the light beam diameter while positioning the adjustment focus lens while measuring the light beam diameter transmitted through the adjustment focus lens by the light beam diameter measurement unit. A third step of setting the position of the product focus lens by rotating the product focus lens based on the position of the adjustment focus lens, and a fourth step of removing the adjustment emission optical device from the emission optical device. And a fifth step of attaching the product emission optical device, in which the position of the product focus lens is set, to the scanning optical device.

[0009]

In the adjusting emission optical device according to the first aspect of the present invention, when the rotating body rotates, the rectilinear body moves in the optical axis direction via the movement direction converting means, and the focus lens moves in the optical axis direction. Move in the direction.

In the method of adjusting a scanning optical device using the adjusting emission optical device according to the second invention, the adjusting emission optical device is mounted on the scanning optical device, and the diameter of the light beam emitted from the adjusting focus lens is adjusted. The rotating body is rotated while measuring with the light beam diameter measuring device, and the adjustment focus lens is moved in the optical axis direction to fix the adjustment focus lens at a position where the light beam diameter is minimized. Then, the product focus lens of the product emission optical device is rotated to fix the product focus lens at the same position as the adjustment focus lens, and then the focus adjusted product emission optical device is attached to the scanning optical device. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a side view in which a part of the emission optical device 21 of the first adjustment example is sectioned. Base 22
The semiconductor laser light source 2 is provided on the rear surface of the flange portion 22a.
3 is mounted. A collimator lens barrel 26 having a built-in collimator lens 25 is fitted and fixed to the cylindrical hole 22 b of the base 22.
The collimator lens barrel 26 has a focus lens 27
Is externally movably fitted in the optical axis direction indicated by the arrow A.

A fixed plate 29 is provided at a predetermined interval behind the circuit board 24, and a stepping motor 30 is attached to a rear end of the fixed plate 29. 32 is fixed. Further, a straight body 33 is externally fitted to the screw portion 31a in front of the rotary shaft 31 via a ball screw (not shown) so as to be movable in the axial direction indicated by the arrow B.

Near the upper and lower edges of the linear body 33, the base 22,
Driving rods 34 and 35 slidably penetrating the circuit board 24 and the fixing plate 29 are respectively fixed therethrough. Drive rod 3
The tips of 4 and 35 are connected to the flange 28a of the focus lens barrel 28. Here, between the rear surface of the flange portion 28 a of the focus lens barrel 28 and the front surface of the cylindrical portion 22 c of the base 22, bias springs 36, 37 are fitted to the drive rods 34, 35, respectively. The focus lens barrel 28 is constantly biased forward by the biasing springs 36 and 37.

An origin detecting sensor 38 for detecting the position of a slit provided in the slit plate 32 is disposed near the outer peripheral edge of the slit plate 32.
8 is fixed to a fixing plate 29. A near origin detection sensor 39 for detecting the position of the rectilinear body 33 is disposed near the outer peripheral edge of the rectilinear body 33.
9 is also fixed to the fixing plate 29. At the rear end of the rotation shaft 31 of the stepping motor 30, a knob 40 for manually rotating the rotation shaft 31 is provided.

With this configuration, when the stepping motor 30 operates and the rotating shaft 31 rotates, the rotation is transmitted to the linear body 33 via the ball screw, and the linear body 3 is rotated.
3 moves in the direction of arrow B. The movement of the rectilinear body 33 is transmitted to the focus lens barrel 28 via the drive rods 34 and 35, and the focus lens 27 moves in the arrow A direction together with the focus lens barrel 28. At this time, the movement of the rectilinear body 33 is detected by the near origin sensor 39, and at the same time, the slit position of the slit plate 32 is detected by the origin detection sensor 38.

FIG. 2 shows an emission optical device 21 'of the second embodiment.
FIG. 3 is a side view in which a part of FIG. Here, an ultrasonic motor is used instead of the stepping motor 30. The structure in front of the circuit board 24 is the same as that of the first embodiment, and a fixed plate 41 is attached to the rear surface of the circuit board 24 via a support frame 41a. A first housing 42 of the ultrasonic motor is fixed to the fixed plate 41, and a second housing 43 is fixed to the first housing 42 by screws 44. A rotating body 45 is rotatably supported on the inner peripheral surface of the second housing 43 via a bearing 46. The screw portion 47a of the fixed shaft 47 is fitted to the center of the rotating body 45 by a ball screw, and the front end of the fixed shaft 47 slidably penetrates the first housing 42 and the fixed plate 41 to the linear body 48. Are combined. Driving rods 49 and 50 having the same operation as the driving rods 34 and 35 of the first embodiment are connected to the linear body 48.

A rotor 51 is fixed via a pressure spring 52 near the peripheral edge of the rotating body 45 of the ultrasonic motor. A stator 53 cooperating with the rotor 51 is fixed to the first housing 42 so as to face the rotor 51.
A friction material 54 is interposed between the motor and the stator 53.
An encoder pulse plate 55 is fixed to a rear surface of the rotating body 45, and a peripheral edge of the encoder pulse plate 55 is disposed in a sensor 56 attached to an inner peripheral surface of the second housing 43. At the center of the rear surface of the encoder pulse plate 55, a detent 57 projecting from the rear surface of the second housing 43 to the outside is provided.

With such a configuration, when an oscillating vibration is generated in the stator 53, the vibration is transmitted to the rotor 51 via the friction material 54, and the rotating body 45 rotates together with the rotor 51. The rotation of the rotating body 45 is transmitted to the fixed shaft 47 via a ball screw, and the fixed shaft 47 moves in the axial direction, so that the rectilinear body 48 moves in the arrow B direction. The movement of the rectilinear body 48 is transmitted to the focus lens barrel 28 via the drive rods 49 and 50, and the focus lens 27 moves in the arrow A direction together with the focus lens barrel 28.

FIG. 3 is a block diagram for explaining a focus adjusting method of the scanning optical device 51 for adjustment. Note that the same reference numerals as those in FIG. 9 indicate the same members. Here, an enlargement optical system 61 for measuring a beam diameter is disposed at a position corresponding to the photosensitive drum 9. The magnifying optical system 61 includes a light receiving unit 62 that receives the beam L emitted from the semiconductor laser light source 23 and a camera 63 that captures the beam L.

The output of the camera 63 is connected via an image processing device 64 to a data processing device 66 having a display 65. The output of the light receiving section 62 is connected to a data processing device 66 via a delay circuit 67, a pulse generator 68, and a laser drive circuit 69. The outputs of the origin detection sensor 38 and the near origin detection sensor 39 are connected to a data processing device 66 via a digital input / output circuit 70, and the output of the data processing device 66 is connected to the stepping motor 30 via a controller 71. . The output of the laser drive circuit 69 is connected to the semiconductor laser light source 23.

When adjusting the focus of the adjusting scanning optical device 21 having such a configuration, first, the focus lens 2
7. Perform origin search. The stepping motor 30 is rotated by the data processing device 66 through the controller 71, and the rectilinear body 33 of the adjusting ejection optical device 21 is moved to the stepping motor 30 side. When the motor 30 rotates and the screw portion 41a of the rotating shaft 31 rotates, the linear body 33 moves toward the stepping motor 30 via the ball screw,
The near origin detection sensor 39 is turned on. Further, the screw portion 41
When a rotates, the origin detection sensor 38 turns the slit plate 32
The slit of is detected. At this time, the stepping motor 30 is stopped, whereby the origin search of the focus lens 27 is completed.

Next, a power meter (not shown) is arranged in front of the focus lens 27. In this state, the laser driving circuit 69 is operated by the data processing device 66 to emit a beam L from the light source 23, and the power of the beam L is adjusted to a predetermined value while being measured by a power meter.
When the polygon mirror 6 is rotated at a constant speed after adjusting the power, the beam L enters the light receiving unit 62 while being deflected and scanned by the polygon mirror 6. At this time, as shown in FIG. 4, the light source 23 is turned off after the time t1 from the time when the beam L enters the light receiving unit 62, turned on for the time t3 after the time t2, and turned off for the time t4. Where time t
1, t2 are determined by the rotation speed of the polygon mirror 6.
That is, the rotational speed of the polygon mirror 6 is determined so that the light is emitted for the time t3 within the field of view of the display 66 after the beam L enters the light receiving unit 62. At this time, the time t3 is set to a sufficiently short time so that a beam diameter equivalent to that at rest can be obtained. Thus, the beam diameter can be measured with the polygon mirror 6 rotated.

In such a state, the focus of the beam L in the main scanning direction is adjusted. Stepping motor 3
0 and rotate the focus lens 2 by half the moving range.
7 is moved to the stepping motor 30 side. At this position, the stepping motor 30 is rotated in the reverse direction, and the focus lens 27 is moved to the opposite side of the stepping motor 30 for a movement range. During this time, the rotation amount of the stepping motor 30 and the beam diameter in the main scanning direction are taken into the data processing device 66 via the controller 71 and the image processing device 64, respectively.

The measurement of the beam diameter is performed according to the flow shown in the flowchart of FIG. That is, an image is captured (A1), a histogram is output (A2), a peak value is detected (A3), a slice level is determined (A4), and a beam diameter is calculated (A5). In detail, it may be performed according to the following flow.

A histogram is taken from the image captured by the camera 63 as shown in the graph of FIG.
Find s. The slice level is determined by this peak value Vps.
SLs is calculated from the following equation. SLs = Vps / e ² (where e is the base of natural logarithm)

The diameter of the beam B is calculated from the coordinates of the intersection of the thus calculated slice level SLs and the histogram.

As shown in FIG. 7, the stepping motor 3
Assuming that the movement amount t of the focus lens 27 converted from the rotation amount of 0 is the horizontal axis and the beam diameter R in the main scanning direction is the vertical axis, the coordinates of the intersection are (t1, R1), (t2, R2),. (ti, Ri), ... (t _n-1 , R
_n-1), a (t _n, R _n).

Here, when moving average is performed to remove the noise component, the moving amount t and the beam diameter R become [ti, {(R _i-1 )
+ (Ri) + (R _{i + 1} )} / 3].

If the slice level SLs is SLs = 1.1 · RO with respect to the minimum beam diameter RO, and the moving positions of the intersections between the slice level SLs and the histogram of the beam diameter R are t _a and t _b , the optimum focus is obtained. The position is (t _a + t _b ) / 2.

Here, the moving positions t _a , t _b are given by the following equations by complementary calculation. t _a = t _m + (1.1 · RO−R _m ) · (t _{m + 1} + t _m ) / (R _{m + 1} -R _m )

The stepping motor 30 may be rotated based on the calculation result to move the focus lens 27 to the optimum focus position. On the other hand, in order to adjust the focus in the sub-scanning direction, the cylindrical lens 5 may be moved in the optical axis direction by an eccentric pin (not shown) and fixed at the optimum focus position.

Finally, based on the calculation result of the position of the focus lens 27 adjusted by the adjusting emission optical device 21, the conventional product emission optical device 1 as shown in FIG.
The position of the focus lens 7 is adjusted. Then, the ejection optical device for adjustment 21 is detached from the scanning optical device,
The product injection optical device 1 is attached. This completes the scanning optical device.

FIG. 8 is an explanatory diagram of another focus adjusting method of the scanning optical device. Here, the magnifying optical system 61 in FIG.
Is mounted on a slide 73 that slides horizontally on the base 72. The slide table 73 is connected to a computer 66 via a motor controller 74.

At the time of focus adjustment, the computer 66 first passes through the motor controller 74 through the magnifying optical system 6.
In a state in which the lens 1 is located at the position A, the focus lens 27 of the adjustment emission optical device 11 is moved to the optimum focus position in the main scanning direction in the same manner as in FIG. Position and record their adjustment positions. Next, the magnifying optical system 61 is moved to the position B by moving the slide table 73, and the focus is adjusted based on a method similar to the method performed at the position A. Further, the focus adjustment is performed by moving the magnifying optical system 61 to the position C.

The optimum focus positions of the focus lens 27 and the cylindrical lens 5 at each of the positions A, B, and C are calculated by a predetermined formula, and the focus lens 27 and the cylindrical lens 5 are set at positions based on the calculation results.
Is fixed. After that, the adjustment emission optical device 21 is removed, and the product emission optical device 1 is attached.

[0036]

As described above, the adjusting emission optical device according to the first aspect of the present invention can move the focus lens straight in the optical axis direction, thereby preventing the optical axis from shifting.
Further, the focus adjustment of the focus lens can be automated, the accuracy of the focus adjustment can be improved, and the time of the focus adjustment can be reduced.

In the focus adjusting method of the scanning optical device using the adjusting emission optical device according to the second invention, the optical axis shift can be prevented by moving the focus lens straight in the optical axis direction. The focus adjustment can be automated by the optical device, so that the focus adjustment can be performed with higher precision and the focus adjustment time can be shortened, and the required number of components can be reduced, thereby reducing the cost.

[Brief description of the drawings]

FIG. 1 is a side view showing a part of the first embodiment in cross section.

FIG. 2 is a side view showing a part of the second embodiment in cross section.

FIG. 3 is a block diagram for explaining a focus adjustment method of the scanning optical device.

FIG. 4 is a timing chart of the output of the light receiving unit and the output of the light source.

FIG. 5 is a flowchart of a beam diameter calculation.

FIG. 6 is a graph for calculating a beam diameter.

FIG. 7 is a graph showing a movement amount and a beam diameter;

FIG. 8 is a block circuit diagram for explaining another focus adjusting method of the scanning optical device.

FIG. 9 is a configuration diagram of a scanning optical device.

FIG. 10 is a sectional view of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnifying optical system 2 light receiving unit 3 slide 21, 21 ′ emission optical device 23 semiconductor laser light source 25 collimator lens 27 focus lens 30 stepping motor 31 rotation axis 31 a screw part 32 slit plate 33 linear body 34, 35, 49, 50 Drive rod 38 Origin detection sensor 39 Near origin detection sensor 74 Motor controller

Claims (3)

(57) [Claims] 1. A light source for emitting a light beam, and an adjusting focus lens for condensing the light beam emitted from the light source, wherein the adjusting focus lens is attached to a linear body that moves in the optical axis direction. An adjusting optical output device mounted on a rotary drive via a motion direction converting means. 2. The adjustment optical apparatus according to claim 1, wherein the movement direction converting means is a ball screw. 3. A light source that emits a light beam when adjusting the focus of a scanning optical device to which a product emission optical device having a light source that emits a light beam and a product focus lens that moves in the optical axis direction by rotation is attached. An adjusting focus lens for condensing a light beam emitted from the light source, the adjusting focus lens being attached to a rectilinear body moving in the optical axis direction, and the rectilinear body being a rotational driving body via a motion direction converting means. A first step of attaching the adjustment emission optical device attached to the lens to the emission optical device, and the rotation driving so that the light beam diameter is minimized while measuring the light beam diameter transmitted through the adjustment focus lens by the light beam diameter measuring means. A second step of rotating the body to position the adjustment focus lens; and focusing on the product focus based on the position of the adjustment focus lens. A third step of setting the position of the product focus lens by rotating a lens, a fourth step of removing the adjusting emission optical device from the emission optical device, and the product setting the position of the product focus lens And a fifth step of attaching the emission optical device for scanning to the scanning optical device. A method of adjusting the focus of the scanning optical device using the emission optical device for adjustment.