JP3209810B2 - Optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used for optical scanning and writing in a laser printer, a digital copying machine, and the like.

[0002]

2. Description of the Related Art Heretofore, there is an optical scanning apparatus of this type using a semiconductor laser as a light source, in which a semiconductor laser having a plurality of light emitting sources is used. In this case, as shown in Japanese Patent Publication No. 60-33019 and the like, a semiconductor laser having a plurality of light emitting sources disposed on a straight line is disposed obliquely around the optical axis to thereby provide these light emitting sources. There is one that is set at a different position in the sub-scanning direction to correspond to the writing density. According to this, optical writing for a plurality of lines can be performed at the same time, which is advantageous for speeding up.

In this case, a spot position shifts in the main scanning direction. However, it is difficult to separately detect each spot and obtain a synchronization detection signal separately. For this reason, as a synchronization detection method, as disclosed in Japanese Patent Application Laid-Open No. 57-64718, the scanning light of a specific light emitting source is detected and received, and the other light emitting sources are shifted by a predetermined delay time. In some cases, a write start time (position) is determined.

[0004]

[Problems to be solved by the invention]
In the case of the -33019 system, the writing density in the main scanning direction can be changed by changing the pixel clock, but the writing density in the sub-scanning direction cannot be changed. Therefore, since the writing density cannot be changed according to the purpose of use, the following inconvenience occurs. For example, in the facsimile mode, when priority is given to saving the image memory capacity, shortening the processing time, shortening the communication time, and the like, rather than the image quality, it is preferable to set the writing density to a relatively low writing density, but this is not possible. In addition, it is necessary to make differently according to each writing density even in the manufacturing stage, and the production efficiency is low.

That is, in the case of a semiconductor laser having a single light emitting source, it is possible to easily cope with a change in writing density by switching the scanning frequency of the rotary polygon mirror from the outside. In the case of a semiconductor laser, there is a problem in changing the scanning interval and correcting the write start position as described above, and therefore, the response to the change in the write density is insufficient.

[0006]

According to the present invention, there is provided a semiconductor laser having a plurality of light emitting sources arranged in a straight line, and a collimator lens for converting a divergent light beam from the semiconductor laser into a substantially parallel light beam. An optical scanning device in which the light source device provided with the light source device is tilted around the optical axis to determine the writing interval in the sub-scanning direction on the surface to be scanned. a locking means for stepwise restricting the inclination angle of the optical axis of the apparatus, the initial setting
Set the writing interval in the sub-scanning direction to Po, and actually write
Pn, the number of light emitting sources in the sub-scanning direction
N, writing in the sub-scanning direction, where v is the linear velocity of the surface to be scanned
And delay means for delaying only the start time by {(N-1) / 2} × (Po-Pn) / v .

At this time, in the invention according to claim 2, the first
Of scanning light between the light source of any one and any N-th light source
A light receiving element is provided, and scanning light detected by the light receiving element is provided.
Is obtained by a delay time Δt obtained by dividing the time difference T of
In the main scanning direction from the illuminant
A delay means for sequentially delaying the writing start time of each light emitting source is provided.

[0008]

According to the first aspect of the present invention, the inclination angle around the optical axis of the light source device including the semiconductor laser having the plurality of light emitting sources is regulated in a stepwise manner by the locking means. Can be changed as appropriate, and the writing density can be easily changed. Further, the write start time of the sub-run <br/>査direction, initialization sub-scanning direction of the write interval Po by actually writing interval in the sub-scanning direction of writing Pn, the number of light emitting sources of N, the surface to be scanned Since the delay means for delaying by a predetermined delay time based on the linear velocity v is provided, when the writing interval in the sub-scanning direction is changed, the optical writing can be performed at an appropriate writing start time without resetting this time. Thus, an optical scanning device with high versatility and variable writing density can be obtained.

Further, in the second aspect of the present invention, 1
The delay time between the light emitting sources is determined based on the time difference between the scanning light beams of the Nth and Nth light emitting sources, and the writing start time in the main scanning direction is controlled by the delay means. It is not necessary to individually set the writing start time for each, and even if there is an individual difference in the light emitting source interval between the semiconductor lasers, there is no need to individually correct the delay time, and a highly versatile writing density variable. It can be an optical scanning device.

[0010]

An embodiment of the present invention will be described with reference to the drawings. First, the basic configuration and operation of an optical scanning device to which the present invention is applied will be described with reference to FIGS. The optical system of this optical scanning device deflects and scans a light beam emitted from the light source device 1 by a polygon mirror 2 that is rotated at a high speed. While forming an image on the spot like
The main scanning is performed in the direction of the arrow. here,
As a synchronizing means for setting a writing timing in the main scanning direction, a synchronizing reflection mirror 7 for reflecting a light beam transmitted through an end portion of the fθ lens 3 in the main scanning direction and a light beam reflected by the synchronizing reflection mirror 7 are received. A synchronization detection device 8 is provided. The synchronization detecting device 8 includes a cylindrical lens 9 for optical path correction and an optical fiber 10 for guiding the received light to a predetermined detection control system.

The light source device 1 comprises a semiconductor laser 11, a collimator lens 12 for converting a divergent light beam emitted from the semiconductor laser 11 into a substantially parallel light beam, and a drive circuit board 13 for driving the semiconductor laser 11. It is constructed and assembled as shown in FIG. First, a holding member 14 for holding the semiconductor laser 11 by fitting it into the stepped through hole 14a is provided. The holding member 14 is mounted and integrated on the drive circuit board 13 by fitting two guide pins 14b on diagonal lines into the guide holes 13a. On the other hand, the collimator lens 12 is integrated with the lens barrel 15, and is provided with a flange 16 that fits and holds the outer peripheral portion of the lens barrel 15 with the cylindrical portion 16a. Here, after adjusting the position of the lens barrel 15 fitted in the cylindrical part 16a in the optical axis direction, the adhesive is poured through the cutout part 16b, so that the collimator lens 12 is fixed to the flange 16. Such a flange 16 screwes a screw 17 into a screw hole 14c through a mounting hole 16c with respect to a holding member 14 integrated with the drive circuit board 13, so that the semiconductor laser 11
The light source device 1 is completed so that the light source device 1 is positioned on the optical axis.

Thus, the semiconductor laser 11 used in the present embodiment is not one having a single light emitting source, but has a plurality (N) of light emitting sources. FIG. 1 shows a light source device 1 including such a semiconductor laser 11 with respect to a light source mounting portion 19 formed in a part of an optical box 18 for arranging optical components constituting an optical scanning device at predetermined positions. Installed and fixed as shown. First, the light source mounting portion 19 has the flange 16
A fitting hole 19a into which the cylindrical portion 16a is fitted is formed,
Around the fitting hole 19a, two arc-shaped long holes 19b centering on the optical axis 20 are formed. Light source mounting part 1
On the side opposite to 9, there is provided a support plate 22 having a screw hole 22 a into which the light source device 1 is screwed with a screw 21. The support plate 22 also has a fitting hole 22b into which the tubular portion 16a is fitted, and a concave portion 2 around which the wavy washer 23 is inserted around the screw hole 22a.
2c is formed. The long hole 19b is for allowing the screw 21 to pass therethrough.

Therefore, the light source device 1 is provided with the screw 21 and the support plate 2.
2, the light source mounting portion 19 is fixed so as to sandwich the light source mounting portion 19. At this time, by adjusting the penetrating position with respect to the elongated hole 19b, the arrangement direction of the light emitting sources in the semiconductor laser 11 is changed to the optical axis. It can be fixed in a state of being appropriately inclined around 20 turns. Thus, a locking means 24 for regulating such an inclined state stepwise is provided. The locking means 24 includes a plurality of gear-shaped locking portions 19 formed on the upper edge of the light source mounting portion 19 in an arc around the optical axis 20.
c, and a bent portion 22d which is formed by bending a portion of the upper edge side of the support plate 22 so as to have leaf spring-like elasticity and selectively lock to any of the gear-shaped locking portions 19c. Have been. Here, the gear-shaped locking portion 19c is set so that a plurality of desired scanning line intervals (writing density in the sub-scanning direction) can be obtained.

Therefore, according to such a mounting structure of the light source device 1, the bent portion 22d with respect to the gear-shaped locking portion 19c is provided.
, The inclination angle of the light source device 1 around the optical axis 20, that is, the inclination angle in the arrangement direction of the light emitting sources of the semiconductor laser 11, can be changed in a plurality of stages, for example, three stages. I understand. If the inclination angle in the arrangement direction of the light emitting sources of the semiconductor laser 11 changes, the interval between the light emitting sources in the sub-scanning direction also changes, and the writing interval (writing density) in the sub-scanning direction can be changed.

By the way, as described above, the optical axis 2 of the light source device 1
When the tilt angle around 0 is varied, the writing position (writing start time = vertical registration) in the sub-scanning direction differs depending on the changed writing density. For example, when the number N = 4 of the light emitting sources of the semiconductor laser 11, as shown in FIG. 4, four of these light emission sources beam spot B ₁ ~
B ₄ inclination angle is 0 ° in the initial setting, that is, as had been arranged in the state that are arranged in a line in the main scanning direction, such that the inclination angle as shown in the drawing by writing density change θ Consider the case of tilting. In this case, the scanning line interval (writing interval) of each beam spot B _{1 to} B ₄ is Pn (= 2).
In order to incline so as to be 5.4 / dpi) mm, as a resist error Dn, Dn = {(N−1) / 2} ×
(Po-Pn) occurs. In FIG. 4, since the initial setting values Po = 0 and N = 4, Dn = − (3/2)
× Pn.

Therefore, in this embodiment, when the linear velocity of the surface 6 to be scanned is v, the writing start time of each light emitting source in the sub-scanning direction is delayed by Dn / v (or relatively advanced). As described above, delay means (not shown) for setting in advance for each writing density or delaying the initial setting value
Is provided.

On the other hand, considering the writing start time in the main scanning direction, the synchronization detecting device 8 for the _first light emitting source L1 is used.
The timing is determined on the basis of synchronization detection by the light source, but the intervals of the second and subsequent light emitting sources L _{2 to} L _{N in the} main scanning direction are also changed due to the change in the inclination angle of the light source device 1. at the time variable density must change the write start time of the second and subsequent emission source L ₂ ~L _N.

Therefore, a countermeasure as shown in FIG. 5 is taken. First, in the synchronization detecting device 8, the first light emitting source L
Made to emit light and ₁ and N-th light emitting source L _N, when turned off the light emitting source L ₁ upon detecting the scanning light by the light emitting source L ₁ reaching the synchronous detector 8 above prior to the main scanning direction The scanning light of the N-th light source _LN is detected by the light that arrives next. Therefore, by inputting these detection signals to the counter 25 and counting the number of pulses of the reference clock, the time difference T between them is calculated. By multiplying the time difference T by 1 / (N-1) by the multiplier 26,
(N-1) The delay means 2 for determining the divided delay time Δt and controlling the delay time of the second and subsequent light emitting sources L _{2 to} L _N
7 given. That is, with respect to the main scanning direction, as shown in FIG. 6, when the writing start time (time from the synchronization detection) of the _first light emitting source L ₁ is tn, the second light emitting source L ₂
Write start time is the tn + Δt, 3-th write start time of the light emitting source L ₃ is a tn + 2? T, write start time of the N-th light emitting source L _N is set to tn + (N-1) Δt . In this case, the higher the reference clock, the smaller the error.

Note that the time tn from the synchronization detection of the _first light emitting source L1 to the start of writing changes the speed of the polygon mirror 2, so that the writing position (horizontal registration) in the main scanning direction.
Is the initial set writing density (dpi) and the initial set value t
₀ , tn = t ₀ · (initial setting writing density) /
(Write density for actually writing).

According to such a method, if the scanning light of the _first light source L ₁ and an arbitrary N-th light source L _N are synchronously detected and used for calculating the delay time, the scanning of all the light sources is performed. Although a high quality image can be obtained without detecting light, the scanning light may not be completely separated and detected between adjacent light emitting sources, and a detection error is likely to occur. Therefore, as described above, it is preferable that the N-th light source L _N be the last light source farthest from the _first light source L ₁ .

In this embodiment, the locking means 24 for controlling the inclination angle in a stepwise manner has been described as being adapted to a plurality of writing densities. However, the locking means 24, specifically, the gear-shaped locking portion 19c Is formed at a smaller pitch, it can also be applied as an adjusting means for finely adjusting the interval between scanning lines in the sub-scanning direction. In addition, a plurality of light emitting sources are not used all at the same time, but, for example, by alternately using every other light source, the writing density can be further halved (roughened), and the writing density can be made multi-step by using the variable writing density. It becomes possible.

[0022]

According to the first aspect of the present invention, the inclination angle around the optical axis of the light source device including the semiconductor laser having the plurality of light emitting sources is regulated stepwise by the locking means. The writing interval in the sub-scanning direction can be appropriately changed, and the writing density can be easily changed. Also,
The writing start time in the sub-scanning direction is determined by the writing interval Po in the sub-scanning direction by initial setting, the writing interval Pn in the sub-scanning direction for actually writing, the number N of light emitting sources, and the linear velocity v of the surface to be scanned.
The delay means for delaying by a predetermined delay time based on the above is provided, so that when the writing interval in the sub-scanning direction is changed, the optical writing can be performed at an appropriate writing start time without resetting this time. Thus, a highly versatile optical scanning device with variable writing density can be obtained.

Further, according to the second aspect of the invention, the first and N-th main scanning direction write start by the delay means to determine the delay time between each light-emitting source based on the time difference of the scanning light by the light emitting source Since the time is controlled, it is not necessary to individually set the write start time for each of the second and subsequent light emitting sources, and even if there is an individual difference in the light emitting source interval between the semiconductor lasers, the delay time is reduced. There is no need for individual correction, and a highly versatile optical scanning device with variable writing density can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention.

FIG. 2 is a perspective view illustrating a basic optical system configuration of the optical scanning device.

FIG. 3 is an exploded perspective view of the light source device.

FIG. 4 is a schematic diagram for explaining a vertical resist.

FIG. 5 is a block diagram showing a control system for starting writing in the main scanning direction.

FIG. 6 is a timing chart showing the operation.

[Explanation of symbols]

 Reference Signs List 1 light source device 6 scanned surface 11 semiconductor laser 12 collimator lens 18 optical box 20 optical axis 24 locking means 27 delay means L light emitting source

Claims (2)

(57) [Claims] 1. A light source device comprising: a semiconductor laser having a plurality of light emitting sources arranged in a straight line; and a collimator lens for converting a divergent light beam from the semiconductor laser into a substantially parallel light beam. In the optical scanning device, which determines the writing interval in the sub-scanning direction on the surface to be scanned, the inclination angle around the optical axis of the light source device is set stepwise on a part of the optical box in which the light source device is mounted. Locking means to regulate
And the writing interval in the sub-scanning direction by the initial setting is Po.
The writing interval in the sub-scanning direction for writing is Pn,
When the number is N and the linear velocity of the surface to be scanned is v, the sub-scanning direction
A delay means for delaying the writing start time of {(N-1) / 2} × (Po-Pn) / v by a factor of 1 . 2. A first light source and an arbitrary N-th light source
A light receiving element for detecting the scanning light with
The time difference T of the scanning light detected from the above is divided into (N-1).
The last light emission from the first light source by the delay time Δt
A delay means for sequentially delaying a writing start time of each light emitting source in a main scanning direction up to the light source is provided.
The optical scanning device according to claim 1.