JPS63175822A - Light beam scanning recorder - Google Patents

Abstract

PURPOSE:To improve the image quality by forming the spot of the light beam projected on a recording medium into an ellipse longer in the subscanning direction and allowing spots to overlap between adjacent scanning lines. CONSTITUTION:A beam shaping optical system 44 includes a collimator lens 56 which converts a laser light L as the diffused light outputted from a laser diode 40 to a luminous flux of parallel rays, an aperture 58 which shapes the beam section of the laser light L to an ellipse, and two condenser lenses 60 and 62 constituting a beam expander which expands the beam diameter of the laser light L. In this case, the aperture 58 has an elliptic aperture part 58a whose major axis is set in the main scanning direction of the laser light L to a film 18. The length of the major axis is so set that edge parts of spots 66 of the laser light L projected on adjacent scanning lines 64 overlap. Thus, an image of good quality where shading is inconspicuous is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light beam scanning recording device, and more particularly, to a light beam scanning recording device.
In an apparatus that scans a light beam onto a record carrier and records text information, image information, etc. as binary information, the spot shape of the light beam irradiated onto the record carrier is elongated in the sub-scanning direction. The present invention relates to a light beam scanning recording device that can further improve the quality of recorded images by forming an elliptical shape.

For example, in the field of printing plate making, streamlining of work processes,
2. Description of the Related Art Image scanning recording and reproducing systems that electrically process image information carried on a document to create a film master are widely used for the purpose of improving image quality.

This image scanning recording/reproducing system basically consists of an image reading device and an image recording device. That is, in an image reading device, image information of a document that is conveyed in a sub-scan direction in an image reading section is main-scanned by a laser beam, and converted into an electrical signal by a photoelectric conversion element. Next, the image information photoelectrically converted by the image reading device is subjected to arithmetic processing such as gradation correction and edge enhancement according to the plate-making conditions in the image recording device, and then converted to an optical signal of a laser beam, which is then used to film the film. Recording and reproduction are performed on a record carrier made of a photosensitive material such as. Note that this recording carrier is developed by a predetermined developing device and used as a film original for printing or the like.

Incidentally, in the image recording apparatus, image information is recorded by main-scanning an intensity-modulated laser beam onto a record carrier that is conveyed in a sub-scanning direction, as in the case of an image reading apparatus. In this case, the laser light is generally irradiated onto the record carrier as a circular spot having a Gaussian intensity distribution. Therefore, for example, if the diameter of the spot is set small, there will always be a portion between the scanning lines on the record carrier that is not irradiated with the laser beam until the density reaches a sufficient density as a recorded image. This causes the inconvenience that a white unexposed area remains and a high quality image cannot be obtained. In addition, in this case, if there is uneven feeding of the record carrier in the sub-scanning direction, this uneven feeding will appear as a change in the spacing of the unexposed area between the scanning lines, making the sliver-like unevenness noticeable and causing the image to become uneven. It has been pointed out that this method has the disadvantage of further deteriorating quality.

On the other hand, when the diameter of the spot is set large, no unexposed portions occur between scanning lines, and deterioration in image quality due to uneven feeding of the recording carrier or the like is effectively suppressed. However, since the convergence of the laser beam deteriorates, the sharpness of the image in the main scanning direction deteriorates, resulting in disadvantages such as a decrease in resolution and unstable gradation.

The present invention has been made in order to overcome the above-mentioned disadvantages, and provides an apparatus for recording image information etc. as binary information by scanning a light beam on a record carrier. To provide a light beam scanning recording device that achieves low visibility of unevenness in recorded image information, etc. and improves image quality by making the beam spot shape elongated in the sub-scanning direction. With the goal.

In order to achieve the above object, the present invention provides a light beam scanning recording device that scans a light beam onto a record carrier and records text information, image information, etc. as binary information. The spot shape of the light beam irradiated along the line is adjusted in the sub-scanning direction using a light source of the light beam or a beam shaping optical system so that the edge portions of the spots of the light beam on the adjacent main scanning line overlap. It is characterized by being constructed in a long shape.

Next, preferred embodiments of the light beam scanning recording apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a main body of an image scanning recording and reproducing system including a light beam scanning recording device according to the present invention, and this main body 10 is a document 1 for printing and duplicating.
an input unit 14 on which the device 2 is placed and the initial conditions thereof are set;
Basically, it consists of a reading section 16 that scans and reads the image information carried on the original document 12, a recording section 20 that records the image information on the sheet-like film 18, and a light beam scanning recording device 22 according to the present invention. configured. In this case, the light beam scanning recording device 22 reads the image information carried on the document 12 and records the image information on the film 18.

Note that various operations within the main body section 10 and electrical processing of image information are processed in the control section 24.

The input unit 14 is provided with a digitizer 26 for placing the original 12 and determining initial conditions such as the plate-making range, and an endless cane conveyor belt 28 for transporting the original 12 to the next stage reading unit 16. On the other hand, the reading unit 16 is provided with conveyance rollers 30a to 30e constituting a conveyance system.
is conveyed in the sub-scanning direction by these rollers 30a to 30e.

The recording section 20 is provided with a drum 32 for transporting the film and a pair of pinch rollers 34a and 34b that are pressed against the drum 32 with the film 18 interposed therebetween. In this case, the film 18 is supplied from a supply magazine 36 and stored in a storage magazine 38 disposed below the recording section 20.

On the other hand, the light beam scanning recording device 22 according to the present invention includes a laser diode 40 that outputs laser light, and a beam shaping optical system 44 that shapes the beam cross-sectional shape of the laser light.
and galvanometer mirror 4 that swings at high speed in the direction of the arrow.
6, a scanning lens 48 consisting of an fθ lens, and a half mirror 50. In this case, the half mirror 50 directs the laser beam to the reading section 16 side and the recording section 2 side.
It has a function of dividing and deriving each to the 0 side. The reading unit 16 is provided with a photomultiplier 54 that collects the laser light reflected by the surface of the original 12 using a light guide 52 such as an optical fiber and then detects the light.

Here, the beam shaping optical system 44 is constructed as shown in FIG. That is, this beam shaping optical system 4
Reference numeral 4 denotes a collimator lens 56 that converts the laser light as a diffused light outputted from the laser diode 40 into a parallel light beam, an aperture 58 that shapes the beam cross-sectional shape of the laser light into an ellipse, and a beam that expands the beam diameter of the laser light. It includes two condensing lenses 60 and 62 that constitute an expander. In this case, the aperture 58 has an elliptical opening 58a with a long sleeve in the main scanning direction of the laser beam on the film 18, as shown in FIG.

The light beam scanning recording device of this embodiment is basically constructed as described above, and its operation and effects will be explained next.

First, the original 12 to be printed and reproduced is placed on the digitizer 26 of the input unit 14, and the reading range of its image information is set using a cursor or the like (not shown). Next, manuscript 12
are the conveyor belt 28 and the conveyor rollers 30a to 30e.
is conveyed to the next stage reading section 16.

The surface of the document 12 conveyed to the reading section 16 is irradiated with laser light from the light beam scanning recording device 22 . That is, the laser light output from the laser diode 40 passes through the collimator lens 5 that constitutes the beam shaping optical system 44.
6 into a parallel light beam, the cross-sectional shape of the light beam is shaped into an ellipse by the opening 58a of the aperture 58.

Next, the condenser lens 60 that constitutes the beam expander
．． After being expanded to a predetermined beam diameter by 62, the beam enters the galvanometer mirror 4G. Galvanometer mirror 46 deflects the laser beam and irradiates it onto document 12 via scanning lens 48 and half mirror 50 . in this case,
The galvanometer mirror 46 is rocking at high speed,
This swinging operation causes the laser beam to scan the original 12 in the main scanning direction (direction perpendicular to FIG. 1). On the other hand, manuscript 1
2 is conveyed in the sub-scanning direction shown by the arrow by the rotation of the feeding rollers 30a to 30e. In this way,
The original 12 is two-dimensionally scanned by laser light.

Next, reflected laser light from the image information carried on the document 12 is collected by a light guide 52 and converted into an electrical signal by a photomultiplier 54. Note that the original 12 whose image information has been read is returned to the input section 14 by driving of the transport rollers 30a to 30e.

On the other hand, the original 1 that has been subjected to predetermined processing in the control unit 24
Image information No. 2 is again recorded on the film 18 by laser light. In this case, the film 18 is sequentially fed out from the supply magazine 36, and the film 18 is fed out from the drum 32 and the pinch roller 34.
a and 34b, and is conveyed in the sub-scanning direction shown by the arrow. Therefore, the laser diode 40
The laser light outputted from the laser beam enters the galvanometer mirror 46 via the beam shaping optical system 44, and then enters the scanning lens 4.
8, the light passes through the half mirror 50 and is irradiated onto the film 18. The laser beam scans the film 18, which is conveyed in the sub-scanning direction, in the main scanning direction (direction orthogonal to FIG. 1) by the swinging operation of the galvanometer mirror 46, as in the case of reading image information. As a result, film 18
is exposed to laser light, and predetermined image information is reproduced on its surface. After the film 18 on which image information has been recorded is stored in the storage magazine 38, it is developed by a predetermined developing device to complete a film original.

Here, the laser beam output from the laser diode 40 is irradiated onto the film 18 with the beam cross-sectional shape shaped into a predetermined shape by the beam shaping optical system 44. That is, the laser beam output from the laser diode 40 is made into a parallel beam by the collimator lens 56, and then passes through an elliptical opening 58a formed in the aperture 58, so that the cross-sectional shape of the beam is shaped into an ellipse. Ru. Then, the beam diameter is expanded to a predetermined size by the condensing lenses 60 and 62 constituting the beam expander, and the beam enters the galvanometer mirror 46, is condensed by the scanning lens 48, and is focused on the film 1.
8.

In this case, since the elliptical opening 58a formed in the aperture 58 is configured such that its long axis is parallel to the main scanning direction of the film 18, as shown in FIG. The side edge i of is cut off. Therefore, on the film 18 after being focused by the scanning lens 48 via the galvanometer mirror 46, an elliptical spot 66 with a long sleeve perpendicular to each scanning line 64 is formed, as shown in FIG. will be formed. It is assumed that the length of the long sleeve is set so that the edges of the laser beam spots 66 irradiated onto adjacent scanning lines 64 overlap each other. Here, the distance between the scanning lines 64 is do, and the short axis length and long axis length of the spot 66 are d, respectively.
, d, then d, = (1,0 to 1.4) x
d o ... (1) d, = (1,5 to 1.7)
It is preferable to set the shape of the spot 66 so that x d o (2).

When image information is recorded on the film 18 using laser light shaped in this way, an extremely high quality image can be obtained. That is, the intensity distribution on the spot 66 of the laser beam irradiated onto the film 18 has a shape including minute side lobes 68, as shown in FIG. The extent in the direction is determined by the shape of the opening 58a formed in the aperture 58.

Therefore, when the shape of the opening 58a is optimally set based on equations (1) and (2), the rise of the spot 66 in the main scanning direction, that is, the density change on the film 18 exposed by the laser beam is Become sharp (6th
(see figure a). Furthermore, by shortening the interval of the synchronization signal for the laser beam and overlapping the edge of the spot 66 in the main scanning direction, it is possible to similarly sharpen the rise in the sub-scanning direction (see Figure 6). ).

Therefore, it is possible to form an image with high sharpness in both the main scanning direction and the sub-scanning direction. As a result, for example, when a gradation image formed by halftone dots is reproduced, a high resolution image can be obtained without the highlights or shadows being distorted.

Furthermore, since no unexposed areas occur between the scanning lines 64, even if, for example, there is unevenness in the conveying speed of the film 18 during sub-scanning forwarding, the image quality will deteriorate due to the unexposed areas. It is possible to provide high quality images.

Note that the laser beam spot 66 includes a side rope 68 formed by the beam shaping optical system 44, as shown in FIG. In this case, if the strength k of the side rope 68 is 10% or less of the maximum intensity of the laser beam, the film 1
The side rope 6 for image information recorded on 8
8 can be ignored.

On the other hand, the beam shaping optical system 44 can also be configured as shown in FIG. That is, the beam shaping optical system 74 can be constructed using two prisms 70 and 72 instead of the aperture 58 shown in FIG. In this case, prisms 70 and 72 are collimator lenses 5
By deflecting the laser beam, which has been made into a parallel beam by 6, in the main scanning direction, the cross-sectional shape of the beam is expanded only in the main scanning direction.

Furthermore, as shown in FIG. 8, a beam shaping optical system 80 can be constructed using two cylindrical lenses 76 and 78 instead of the aperture 58. In this case, the cylindrical lenses 76 and 78, like the prisms 70 and 72, have the effect of enlarging the beam diameter in the main scanning direction by refracting the laser beam only in the main scanning direction.

In the embodiment described above, an example was shown in which the spot shape formed on the film 18 was an ellipse, but if the spot is long in the sub-scanning direction, for example, the spot shape may be close to a rectangle. It can also be formatted into

As described above, according to the present invention, in an apparatus for recording character information, image information, etc. by scanning a light beam onto a record carrier, the spot shape of the light beam irradiated onto the record carrier is adjusted in the sub-scanning direction. In addition to making it a long shape,
The spots are configured to overlap each other between adjacent scanning lines. Therefore, a portion not irradiated with the light beam does not always occur between the scanning lines, and it is possible to obtain a high-quality image with inconspicuous unevenness.

In addition, it is possible to improve the rise characteristics of the light beam intensity in the main scanning direction and the sub-scanning direction, making it possible to make highlights or shadows clearer, improve sharpness, and form images with high resolution. becomes.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
For example, if a light source with an elliptical beam cross section is used, there is no need to use a beam shaping optical system such as an aperture, and various improvements and design changes can be made without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the main body of an image scanning recording and reproducing system including a light beam scanning recording device according to the present invention, and FIG. 2 is a diagram illustrating the configuration of a beam shaping optical system in the light beam scanning recording device according to the present invention. , FIG. 3 is a front view of the aperture shown in FIG. 2, FIG. 4 is an explanatory diagram of a light beam spot formed by the light beam scanning recording device according to the present invention, and FIG. 5 is a diagram of intensity distribution characteristics of the light beam. , FIGS. 6a and 6b are density characteristic diagrams of an image recorded on a record carrier by a light beam formed by a light beam scanning recording device according to the present invention, and FIGS. FIG. 7 is a configuration explanatory diagram showing another embodiment of the beam shaping optical system in the beam scanning recording device. 10...Main unit 12...Manuscript 14...
- Input section 16... Reading section 18... Film 22... Light beam scanning recording device 24... Control section 40... Laser diode 44... Beam shaping optical system 46... Galvanometer mirror 48 ...Scanning lens 50...Half mirror
56...Collimator lens 58...Averture 5
8a...Aperture 60.62...Condenser lens 70.72...Prism 76.78...Cylindrical lens 58a Main scanning direction

Claims (5)

[Claims] (1) In a light beam scanning recording device that scans a light beam onto a record carrier and records text information, image information, etc. as binary information, the light beam is irradiated along the main scanning line on the record carrier. The spot shape is configured to be elongated in the sub-scanning direction using the light source of the light beam or the beam shaping optical system so that the edge portions of the spots of the light beam on the adjacent main scanning lines overlap. A light beam scanning recording device characterized by: (2) In the apparatus according to claim 1, the spot shape of the light beam scanning on the record carrier is such that the short axis length is about 1.0 to 1.4 times the main scanning line interval, and the long axis length is about 1.0 to 1.4 times the main scanning line interval. A light beam scanning recording device configured in an elliptical shape with a distance of about 1.5 to 1.7 times the main scanning line interval. (3) In the apparatus according to claim 1, the beam shaping optical system passes the light beam through an aperture having an elliptical opening, thereby shaping the light beam into an elliptical spot on the record carrier. Beam scanning recording device. (4) A light beam scanning recording device according to claim 1, wherein the beam shaping optical system refracts the light beam using a prism to shape the light beam into an elliptical spot on the record carrier. (5) A light beam scanning recording device according to claim 1, wherein the beam shaping optical system shapes the light beam into an elliptical spot on the record carrier by passing the light beam through a cylindrical lens.