JP3323282B2 - Laser recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser recording apparatus for recording an image using a laser beam, and more particularly to a laser recording apparatus suitable for applications requiring high resolution (for example, a film plotter).

[0002]

2. Description of the Related Art In a conventional laser recording apparatus, a laser beam output from a single laser diode (hereinafter referred to as an LD) is converted into a parallel beam by a collimator lens, and this is converted into a parallel beam by an objective lens. To form a recording laser beam spot, scan the recording medium with the laser beam spot, and control the output of the LD according to the image signal to record on the recording medium. Had gone.

[0003]

However, such a configuration has a problem in that when recording an image at a high resolution, the number of pixels increases and the time required for recording increases.

In order to shorten the recording time, it is necessary to increase the scanning speed. However, when the scanning speed is increased, the exposure time of each pixel is shortened, so that the image quality is reduced. In order to avoid this, it is necessary to increase the output of the laser. For that purpose, a large multi-mode laser must be used, and a large cooling device is required because the multi-mode laser generates much heat. There is a problem that the size of the device increases and the cost increases. Further, when the scanning speed is increased, there is also a problem that a load on a scanning mechanism such as a scanning motor increases.

The present invention has been made in view of the above-mentioned problems, and enables high-resolution image recording without increasing the laser output and without increasing the scanning speed. It is an object to provide a laser recording device.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present application uses a plurality of laser light irradiation means, and uses a plurality of laser light irradiation means from the plurality of laser light irradiation means.
Intermediate lens and objective as common lens optical system for laser light
Using a plurality of laser light irradiating hands
Step, the laser beam is incident approximately at the center of its intermediate lens
The intermediate lens has a plurality of laser beams
With its optical axis passing near the center of the objective lens.
And each of the laser beams is directed to the objective lens.
Equipped with a function to expand so as to pass through a large area of
It is provided with a configuration of causing the

[0007]

According to a second aspect of the present invention, the plurality of laser beam irradiation means and the intermediate lens are mounted on a common movable stage, and an adjusting mechanism for moving the movable stage in the optical axis direction of the objective lens is provided. It has a configuration.

[0009]

[0010]

[0011]

According to the first aspect of the present invention, a plurality of laser light
Set the irradiation means so that the laser light enters almost the center of the intermediate lens.
The intermediate lens and objective
Many laser light sources without increasing the lens diameter
Means can be arranged, and many laser light
Higher-speed recording is possible by using a pot.
You. Further, the intermediate lens is provided with a plurality of incoming laser beams.
So that its optical axis passes near the center of the objective lens.
Each of the laser beams is directed to the objective lens
By passing through a large area of
Equalize the shape of each laser beam spot shape applied to the recording medium.
And high quality image recording becomes possible.

[0012]

According to the second aspect of the present invention, since a plurality of laser beam irradiation means and an intermediate lens are mounted on a moving table, and the moving table is moved in the optical axis direction of the objective lens by an adjusting mechanism, The laser beam irradiating means and the intermediate lens can be integrally moved with respect to the objective lens in the optical axis direction, and the diameter and interval (pitch) of the laser beam spot can be easily adjusted by the movement. Further, a zoom lens is not required for a change in spot diameter.

[0014]

[0015]

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

FIG. 1 is a schematic perspective view showing main parts of a laser recording apparatus according to a first embodiment of the present invention, and FIG. 2 is a schematic sectional view thereof. 1 and 2, reference numeral 1 denotes a recording medium such as a film, which is indicated by an arrow A (hereinafter referred to as a main scanning direction).
It is held to travel. Although shown in a flat plate shape in the drawings, this is for explanation purposes and is usually mounted on the surface of a rotating drum, and travels in the main scanning direction A by rotation of the rotating drum. 2 is a recording medium 1
A recording head for recording with a plurality of laser beams
Is a linear motor for moving the recording head 2 in the direction of arrow B parallel to the recording medium 1 (hereinafter referred to as the sub-scanning direction).

Reference numeral 5 denotes a base, 6 denotes an objective lens disposed at the front end of the base 5 so as to face the recording medium 1, and 7 denotes an arrow C- parallel to the optical axis of the objective lens 6 with respect to the base 5.
A movable table 8 movably held in the C direction, 8 is an intermediate lens attached to the tip of the movable table 7 so as to be positioned on the optical axis of the objective lens 6, and 9 is a rear end of the movable table 7. The attached spherical support 10 is a plurality of LDs (laser diodes) attached to the support 9, and 11 is an LD arranged before each LD 10 so as to collect laser light from each LD 10. Lens. This LD10 and L
The D lens 11 constitutes a laser beam irradiation unit. In the present embodiment, six laser beam irradiation units are provided. The six laser beam irradiating units are arranged so that their optical axes pass near the center of the intermediate lens 8 and at substantially the same position from the intermediate lens 8. Further, the six laser light irradiators are arranged such that the six laser lights 12 radiated from each of them have a constant interval in the sub-scanning direction B in the DD plane as shown in FIG. Are located.
The LD 10 used here is a small single-mode laser (short-wavelength laser).

In FIG. 2, the intermediate lens 8 directs the six incident laser beams so that their optical axes pass near the center of the objective lens 6, and each of the laser beams increases the wide area of the objective lens. It has a function to enlarge it so that it passes. Therefore, the laser beam 13 that has exited the intermediate lens 8 is in the EE plane immediately before the objective lens 6,
As shown in FIG. 6, most are in an overlapping state, and the respective optical axes 14 are in a close state. The objective lens 6 functions to form an image of the six incident laser beams 13 on the recording medium 1 so as to form laser beam spots of a desired size and at a desired interval, that is, a pitch between the laser beam spots. It has. Thus,
As shown in FIG. 4, on the recording medium 1, six laser light spots 14 arranged at a constant pitch in the sub-scanning direction B are provided.
Are formed. The intermediate lens 8 and the objective lens 6 convert a plurality of laser beams from a plurality of laser beam irradiation units into a multi-spot consisting of a plurality of laser beam spots of a predetermined size arranged at predetermined intervals on a recording medium. Thus, a common lens optical system for forming an image is formed.

In FIGS. 1 and 2, reference numeral 16 denotes a screw shaft rotatably held by the base 5, reference numeral 17 denotes a connecting member which is attached to the moving table 7 and incorporates a nut which meshes with the screw shaft 16, and reference numeral 18 denotes a screw shaft 16. Is a motor that rotationally drives the motor. By rotating the screw shaft 16 with the motor 18, the movable table 7 can be moved in the direction of arrow CC. The screw shaft 16, the connecting member 17, the motor 18 and the like constitute an adjusting mechanism for moving the movable table in the optical axis direction of the objective lens. This adjustment mechanism is for adjusting the diameter, interval, and the like of each laser light spot 14 of the multi-spot.
That is, when the moving table 7 is at the position shown in FIG.
As shown in (a), when the pitch of the six spots 14 in the sub-scanning direction is p and the spot diameter is d, the movable table 7 is moved in the direction approaching the objective lens 6 as shown in FIG. When moved, the laser beam spot 14 at that time is
As shown in (b), both the pitch in the sub-scanning direction and the spot diameter increase. Therefore, by adjusting the position of the movable table 7 by the adjusting mechanism, it is possible to obtain a pitch in the sub-scanning direction and a spot diameter corresponding to a desired pixel density.

Although not shown in FIGS. 1 and 2, a control means for driving each LD 10 in accordance with an image signal to be recorded is connected to each LD 10.

Next, a recording operation by the laser recording apparatus having the above configuration will be described. While the recording medium 1 travels in the main scanning direction A, the recording head 2 irradiates the recording medium 1 with a multi-spot consisting of six laser light spots 14 (see FIG. 4), and image recording is performed by the multi-spot. Do. Accordingly, recording of six scanning lines is simultaneously performed in the main scanning direction by the six laser light spots 14 at the same time. On the other hand, while the recording medium 1 performs one scan in the main scanning direction A, the linear motor 3 moves the optical head 2 in the sub scanning direction B.
It is moved by an amount corresponding to six scanning lines. Thus, the recording surface of the recording medium 1 is scanned by the multi-spot in both the main scanning direction and the sub-scanning direction, and image recording is performed.

As described above, since the image recording is performed by the six laser light spots, the recording is performed at a speed six times as fast as the case where the image recording is performed by the single laser light spot. Therefore, even when high-resolution image recording is performed, it is not necessary to increase the scanning speed so much, so that it is not necessary to increase the laser output, and a small single-mode laser can be used. Further, it is not necessary to apply a high-speed driving load to the scanning mechanism, and the scanning mechanism is not complicated and large.

In the above embodiment, a plurality of laser light irradiating means are arranged so as to be directed to the center of the intermediate lens 8 so that the optical axis of the laser light passes through the center of the intermediate lens 8. With this configuration, there is an advantage that the apertures of the intermediate lens 8 and the objective lens 6 can be reduced irrespective of the mounting area of the plurality of laser light irradiation units. In other words, many laser light irradiation means can be used without being limited by the apertures of the intermediate laser 8 and the objective lens 6. Further, in the above embodiment, as shown in FIG. 6, the laser beam 13 is enlarged by the intermediate lens 8, and the six laser beams 13 pass through the objective lens 6 in a state where a considerable portion thereof overlaps. I have. With this configuration, the six laser beams 13 pass through substantially the same area of the objective lens 6, and the advantage that the shapes of the six laser light spots 14 formed by the objective lens 6 become uniform is obtained. Can be

FIG. 8 is a schematic sectional view showing main parts of a laser recording apparatus according to a second embodiment of the present invention, and the same or similar parts as those of the embodiment shown in FIGS. Is shown. In this embodiment, an objective lens 6 having a large aperture is provided opposite to the recording medium 1, an intermediate lens is not used for the moving table 7, and the LD 10 and the collimator lens 1 are not used.
A plurality (three) of laser light irradiating means of 1A are provided substantially in parallel (strictly speaking, the central laser light irradiating means is arranged on the optical axis of the objective lens 6, and the upper and lower laser light irradiating means are light The laser beam 21 converted into parallel light by the collimator lens 11 is slightly incident on the objective lens 6 (slightly and symmetrically inclined with respect to the axis). The objective lens 6 narrows the laser beam 21 incident substantially parallel to a laser beam spot of a predetermined size and also reduces the pitch thereof. Thus, on the recording medium, as shown in FIG.
A multi-spot consisting of two is formed. Therefore, in this embodiment, the objective lens 6 uses the plurality of laser beams from the plurality of laser beam irradiating means to form a multi-spot consisting of a plurality of laser beam spots of a predetermined size arranged at predetermined intervals on a recording medium. A common lens optical system for forming an image is formed as follows. Other configurations are the same as those of the first embodiment.

Also in this embodiment, an image is recorded by a multi-spot consisting of three laser beam spots 22 scanning on a recording medium, and a high-resolution image can be formed without increasing the scanning speed. Becomes The pitch of the laser beam spot 22 in the sub-scanning direction can be adjusted by rotating the screw shaft 16 by the motor 18 and moving the movable table 7 in the C direction. That is, the objective lens 6
The upper and lower two of the laser beams incident on the objective lens 6
Since the position of the laser light irradiating means is changed in the direction of the optical axis of the objective lens 6, the incident position of the laser light on the objective lens 6 changes, and the laser light The interval between the spots 22 can be adjusted.

In this embodiment, the intermediate lens is omitted, and the laser beam 21 from the laser beam irradiating means is directly applied to the objective lens 6.
, The optical diameter of the lens can be simplified as compared with the first embodiment shown in FIGS. However, since a plurality of laser light irradiating means are provided substantially in parallel and a plurality of laser lights are incident on the objective lens 6 almost in parallel, the aperture of the objective lens 6 is set to be smaller than the position of the plurality of laser light irradiating means. Has to be increased, and a disadvantage arises in that a large-diameter objective lens must be used. The plurality of laser beams 21 pass through different regions of the objective lens 6 (the central laser beam 21 passes only through the center of the objective lens 6, and the other laser beams 21 pass only through the peripheral portion of the objective lens 6). Therefore, the shape of the laser beam spot becomes non-uniform, and the image quality may be degraded. Therefore, when high image quality is required, the first embodiment is more preferable.

FIG. 10 is a schematic sectional view showing main parts of a laser recording apparatus according to a third embodiment of the present invention.
Components that are the same as or similar to the embodiment shown in FIG. 9 are denoted by the same reference numerals. In this embodiment, a large LD10A
Is provided at a place different from the moving table 7, an optical fiber 23 is connected to each LD 10A, its tip 23a is attached substantially parallel to the moving table 7, and a collimator lens 11A for converting laser light into parallel light is disposed in front of the optical fiber 23. ing. This LD10
A, the optical fiber 23, the collimator lens 11A, and the like constitute a laser beam irradiation unit. In this embodiment, two laser beam irradiation units are used. These two laser beam irradiation means are arranged so that the laser beam 21 having exited from each collimator lens 11A is incident on the objective lens 6 almost in parallel (strictly, slightly and symmetrically with respect to the optical axis of the objective lens 6). (In such a manner as to be incident at an angle). Thus, the laser beams 21 from the two laser beam irradiation means enter the objective lens 6 almost in parallel, and form an image on the recording surface of the recording medium 1, as shown in FIG. Two laser light spots 22 having a constant pitch are formed in the sub-scanning direction B. Other configurations are the same as those of the second embodiment in FIG.

In this embodiment, two spots 2
The image recording is performed by scanning the multi-spot consisting of two on the recording medium, and the recording can be performed at twice the speed as compared with the recording using the single spot. FIG.
Similarly to the second embodiment, the pitch of the laser beam spot 22 in the sub-scanning direction can be adjusted by rotating the screw shaft 16 by the motor 18 and moving the movable table 7 in the C direction.

In this embodiment, since the number of spots is smaller than in the other embodiments, it is necessary to increase the laser output and increase the scanning speed to secure the same recording speed. Therefore, it is necessary to use a large-sized laser. However, by arranging the LD 10A in a place different from the moving table 7 as shown in FIG.
3a and the collimator lens 11A can be arranged in a relatively narrow area, and there is an advantage that the aperture of the objective lens 6 can be reduced. However, there is a disadvantage that transmission loss occurs due to the use of the optical fiber 23.

Although the three embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be variously modified. For example, the number of laser irradiation means used in each embodiment can be appropriately increased or decreased. In addition, although a screw shaft and a motor are used as a device for adjusting the interval between laser light spots,
The present invention is not limited to this, and the moving table may be manually moved. Further, in the embodiment of FIG.
Instead of providing 10, as in the embodiment shown in FIG.
The LD 10 may be installed in a place different from the support 9 on the moving table 7, an optical fiber may be connected to the LD 10, and only the tip of the optical fiber may be attached to the support 9.

[0032]

As is clear from the above description, the first aspect of the present invention provides an intermediate lens and an objective lens as a laser optical system.
Using a plurality of laser light irradiating means
The laser beam is incident on almost the center of the intermediate lens.
The intermediate lens is provided with a plurality of laser beams,
So that its optical axis passes near the center of the objective lens
Each of the laser beams is directed to the objective lens
With a function to enlarge so that it passes through a large area of
The intermediate lens and objective lens
Laser light irradiation without increasing the diameter of the lens
Means can be arranged, and many laser light
By using the unit, high-speed recording becomes possible,
Further, the intermediate lens converts a plurality of incoming laser beams into
Orient the optical axis so that it passes near the center of the objective lens.
And each of the laser beams is spread by the objective lens.
By expanding the area so that it passes through
This has the effect that the shape of the light spot can be made uniform and high-quality recording can be performed .

[0033]

Further, the invention according to a second aspect of the present invention provides an adjusting mechanism for mounting the plurality of laser beam irradiation means and the intermediate lens on a common movable base, and moving the movable base in the optical axis direction of the objective lens. With this arrangement, the diameter and pitch of the laser light spot can be adjusted by moving the plurality of laser light irradiation means and the intermediate lens integrally with each other in the optical axis direction with respect to the objective lens. Has an effect that the adjustment of is easy.

[0035]

[0036]

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing main parts of a laser recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view thereof.

FIG. 3 is a schematic cross-sectional view of the same portion as FIG. 2 showing a state in which a movable table is moved in order to adjust the diameter and pitch of a laser beam spot in the embodiment.

FIG. 4 is a front view showing a multi-spot irradiated on a recording medium in the embodiment.

FIG. 5 is a front view showing a laser beam on a DD plane of FIG. 2;

FIG. 6 is a front view showing a laser beam on an EE plane in FIG. 2;

7A is a front view showing a multi-spot irradiated on the recording medium in FIG. 2; FIG. 7B is a front view showing a multi-spot irradiated on the recording medium in FIG. 3;

FIG. 8 is a partial sectional view showing main components of a laser recording apparatus according to a second embodiment of the present invention.

FIG. 9 is a front view showing a multi-spot irradiated on a recording medium in the embodiment of FIG. 8;

FIG. 10 is a partial sectional view showing main components of a laser recording apparatus according to a third embodiment of the present invention.

11 is a front view showing a multi-spot irradiated on a recording medium in the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording medium 2 Recording head 3 Linear motor 5 Base 6 Objective lens 7 Moving stand 8 Intermediate lens 9 Support 10 LD 11 LD lens 12, 13 Laser light 14 Laser light spot

Claims (2)

(57) [Claims] 1. A plurality of laser light irradiating means and a plurality of laser light spots of a predetermined size arranged at predetermined intervals on a recording medium on a recording medium. A common lens optical system that forms an image so as to form a multi-spot, and a control unit that drives the plurality of laser light irradiation units according to an image signal to be recorded,
Scanning means for scanning the recording medium with the multi-spot , wherein the lens optical system includes an intermediate lens and an objective lens.
A plurality of laser beam irradiating means.
So that the laser light is incident almost at the center of the intermediate lens.
The intermediate lens is provided with a plurality of laser beams.
With its optical axis passing near the center of the objective lens.
And each of the laser beams is directed to the objective lens.
Equipped with a function to expand so as to pass through a large area of
A laser recording device, comprising: 2. The method according to claim 1, wherein the plurality of laser light irradiation means and the intermediate lens are provided.
The moving table and the moving table in the optical axis direction of the objective lens
And an adjusting mechanism for moving.
2. The laser recording device according to 1 .