JPH05221013A - Multibeam laser printer - Google Patents

Abstract

PURPOSE: To provide a multiple beam laser printer capable of having a quicker operating speed than that of the conventional laser thermal printer and using structurally a less complex optical system than that of the conventional printer. CONSTITUTION: Each of laser diodes 52 is directed by individual optical fibers 54, and output ends of the optical fibers 54 are closely and accurately spaced in a grooved array support 56. All output beams from the optial fibers 54 are simultaneously scanned across a receiver 68 after each of the beams is individually modulated in accordance with image information data. An image is formed with a plurality of image lines being generated simultaneously.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to printers, and more particularly to printers in which images are generated on a line-by-line correspondence basis.

[0002]

BACKGROUND OF THE INVENTION Many printers use a modulated beam to produce an image on a receiver or print medium. In some printers, known as laser thermal printers, a die (dye) transfer paper is sandwiched between a laser energy source and a receiver. The modulated laser beam scans the die transfer paper to transfer the dye from the die transfer paper to the corresponding location on the receiver, producing an image on the receiver. An example of such a printer is disclosed in US patent application Ser. No. 457,593 (filed Dec. 27, 1990, inventor S Sarah) filed by the same applicant as the present patent application entitled "Thermal Printer". ..

Prior art printers typically used a single laser to produce the image. In this scheme, the printer had to produce an image in a series of single line scans. When these single laser printers are used to produce high resolution images (e.g., 2000 dots per inch or more), their scanning speed is extremely slow, and it takes several minutes to produce one image.

Further, in a laser printer operating as a thermal printer, it is necessary to apply a sufficient amount of concentrated energy to a limited minute spot on the donor paper. This would require extremely high power lasers and complex optical systems to focus the laser output beam to the desired location.

FIG. 1 shows a conventional thermal printer 20.
A perspective view (hereinafter referred to as printer 20) is shown.
The printer 20 includes a diode laser 22 (hereinafter, laser 2
2), a first collimating lens 24, a cylindrical lens 26, a second collimating lens 28,
A fixed mirror 30, a beam deflection grabberometer 32,
It comprises an F theta (θ) lens 34 and a translation table 36. The printer 20 produces an image on a receiver (recording medium) 38 carried on the parallel movement table 36. Figure 1
In the case of, the receiver is a 35 mm slide.

In operation, printer 20 includes a stack of dye donor papers (not shown for clarity).
A desired image is generated on the receiver 38 by dot-transferring a die (dye) onto the receiver (recording medium). Die dot transfer to the receiver 38 occurs when a portion of the dye donor paper is heated by the focused beam 40 of laser light. This localized heating causes the sublimation of the corresponding die on the donor paper to be transferred onto the receiver 38 in a manner as disclosed in the above-referenced U.S. Patent Application No. 457,593.

Beam 40 is produced by laser 22. The output light level of the laser 22 is modulated in a known manner according to the image data sent to the printer 20 from an image source (not shown).

The modulated light from the laser 22 is received by the receiver 38.
Moving to the desired spot above requires a complex combination of optical and scanning devices. The first collimating lens 24 is a divergent output beam 42 from the laser 22.
Collimate in parallel. This first collimating lens 2
The cross section of the beam 44 collimated at 4 is elliptical. A beam with an elliptical cross section is not suitable for producing high resolution images. There, the beam 44 is converted into a beam 46 having a circular cross section by passing through the cylindrical lens 26. However, passing through the cylindrical lens 26 causes the beam 46 to diverge again. Therefore, the second
It needs to be passed through the collimating lens 28 into a collimated beam 48 having a circular cross section.

The collimated beam 48 is reflected by the fixed mirror 30 and scanned by the beam deflecting granometer 32 through an F theta (θ) lens 34. The F theta (θ) lens 34 focuses the beam 48 along a focal plane that coincides with the Didonor paper. This focused beam is shown as beam 40.

[0010]

In general office equipment, the use of laser thermal printers to produce high resolution images is preferred, and such devices are suitable for desktop printing of slides or other display media. Each is connected to a small personal computer. In this case, in the conventional printer, due to the delay in the operation speed as described above and the high cost due to the complicated optical system,
It was inconvenient to use in the business office.

Therefore, an object of the present invention is to provide a high resolution laser thermal printer which has a high operation speed and a low cost.

[0012]

The present invention comprises, in part,
It relates to a printer that uses a modulated laser beam to form a progressive image on a receiver on a line-by-line basis. This printer comprises a plurality of individually operable lasers and a plurality of optical fibers having input and output ends. Each input end of the optical fiber is connected to a corresponding laser. On the other hand, each output end of the optical fiber is located on an array in which the optical fibers are arranged at a predetermined distance from each other. Also provided is output beam deflecting means for simultaneously scanning the output beam from all optical fibers onto the receiver surface, thereby producing multiple lines simultaneously in one image.

Another aspect of the invention relates to a printer which uses a modulated laser beam to progressively form an image on a recording sheet on a multiline basis. The printer has a plurality of individually operable lasers. The lasers are spaced so that they are not thermally influenced by each other. Optical fibers having input and output ends are optically connected to the lasers at their input ends. Each output end of the optical fiber is located on an array in which the optical fibers are spaced apart from each other. Further, output beam deflecting means for scanning the output beams from all the optical fibers onto the surface of the recording paper at the same time is also provided, whereby a plurality of lines are simultaneously generated in one image.

The invention will be better understood by the following detailed description with reference to the drawings.

[0015]

The printer according to the present invention is a thermal printer in which a plurality of lasers are used to produce an image on a receiver (recording medium) in a multiline operating mode. Each laser has an output light beam guided by a separate optical fiber. The output ends of the optical fibers are closely spaced and precisely spaced on the grooved array support. All output beams from the optical fibers are individually modulated according to the imaging data and scanned simultaneously on the receiver. Then, one image is formed by a plurality of image lines generated at substantially the same time.

[0016]

2 shows a multi-beam laser printer 50 (hereinafter referred to as printer 50) according to the present invention. The printer 50 includes a plurality of laser diodes 52.
(Hereinafter referred to as laser 52) and a plurality of optical fibers 54
And a single optical fiber support array unit 56 with a cover plate 57 (hereinafter referred to as array support unit 56)
, Collimating lens 58, fixed mirror 60
, Beam scanning grabometer 62, T theta (θ)
It comprises a lens 64 and a translation table 66 for carrying a receiver (print medium) 68. Array support unit 56
Includes a pivot portion 76, a fixed base 78, and a clamp 80, which are shown in more detail in FIG.

Each laser 52 is connected to an individual optical fiber 54 at each input end of the optical fiber 54.
The output ends of the optical fibers 54 are carried on the array support portion 56 at a predetermined distance from each other. The output ray 72 (shown in dashed lines) from each optical fiber 54 passes through the collimating lens 58 and exits the lens as a collimated, collimated beam 74. The collimated beam 74 is reflected by the fixed mirror 60, and the beam scanning grabometer 6
2 is scanned so as to pass through the F theta (θ) lens 64. The F-theta (θ) lens 64 is used by the receiver 6
Focus the beam 74 along a focal plane that coincides with the dye donor paper (not shown for clarity) surface that is overlaid with 8. These focused beams are shown as beams 70.

The operation of the printer 50 is performed by the receiver 6
The desired image is produced on the receiver 68 by transferring the dies (dye) in dots from the dye donor paper overlaid on the 8 to the receiver. The transfer of the die with this dot is
In the manner disclosed in the above-mentioned U.S. Patent Application No. 457,593,
A focused beam 70 of the laser is made by heating a limited spot of dye donor paper to sublimate the dye in that area.

The output beam level of each of the lasers 52 is modulated according to the image data sent to the printer 50 from a conventional image source (not shown). Known modulation systems can be used for this modulation. In an embodiment of the invention, a modulation system (not shown) assigns image data to various channels. Laser 52 on each channel
Related to each of. In this manner, respective portions of the image are produced by each of the lasers 52. For more information on this type of modulation system, see U.S. Pat.
No. 655 (inventor: H. Baeck and several others).

The printer 50 has significant advantages over the printer 20 of FIG. Especially the printer 50 operates quickly,
The structure is simple. The printer 50 can simultaneously generate a plurality of lines in one image, and
Since the number of optical components is smaller than that of the printer 20 of FIG. 1,
The cost is also low.

FIG. 3 shows the cover plate 5 shown in FIG.
It is an enlarged view of the array support part 56 with 7. The cover plate 57 has been removed in FIG. 3 for clarity. This enlarged end view clearly shows the means by which the printer 50 (as compared to the printer 20 of FIG. 1 operating in single line mode) produces images in multi-line mode. The optical fiber 54 is inclined by the angle A, because the array support part 56 is supported by the pivot part 76. The pivot part 76 is the fixed base 7.
8 and is supported at a desired angle by a clamp 80. The angular position of the pivot part 76 is set by the micrometer adjusting part 82.

As the angle A changes, the horizontal distance d between the centers of the optical fibers 54 also changes.
As the angle A becomes smaller, the distance d also becomes smaller. For example, when it is desired to generate a high resolution image of 2000 dots / inch or more, it is important to keep the distance d small.

Returning again to FIG. 2, a plurality of beams 70 are scanned longitudinally side by side on receiver 68. The distance between the beams 70 is the distance d in FIG. 3, that is, the distance between the output ends of the optical fibers 54 in the horizontal direction. In this way, each of the beams 70 is vertically aligned and scanned by the receiver 68, thus creating a plurality of parallel image lines simultaneously.

Each of the beams 70 has a different point in the longitudinal direction with respect to the receiver at any instant. Such vertical variations in beam 70 are corrected by the channel direction-determining modulation disclosed in U.S. Patent Application No. 451,655. The modulation data for each laser 52 is sent with a different predetermined delay time. The delay time for each beam 70 corresponds to the time required for that beam to reach the reference spot on receiver 68. Thus, the beam 70
Each produce the desired image portion at the desired vertical location on the receiver 68.

The image is produced on receiver 68 as a collection of pixels. In an embodiment of the invention, the receiver is 35
mm slide. The pixels that form the image on the slide are also not necessarily square, because the height and width of the slide are not always equal. Basically, 35
For mm slides, the pixels have the same aspect ratio of 1: 1.25.

Printer 50 is designed to produce an image with a nominal resolution of 4000 dots / inch. The modulators individually change the light level in the vertical direction at a rate of 4000 modulations per inch. The horizontal spacing d between the beams 70 is 4000 / 1.25 beams per inch, or 3200
It must be the spacing that produces the beam. In other words, in order to achieve a nominal resolution of 4000 dots / inch, the distance d between the centerlines of the optical fibers 54 of FIG. 3 should be less than 10 microns.

In an embodiment of the invention, array support 56 and optical fiber 54 are on an array of the type disclosed in US Pat. No. 4,911,526 (Sue et al.) Owned by the same applicant as the present patent application. It is located in. In this example, the optical fibers are located in grooves spaced 20 microns apart. The array support 56 is tilted by the angle A so that the distance between the optical fibers is 10 microns.

In one embodiment of printer 50, some amount of dot overlap was created in the image. This was easily accomplished by changing the angle A to produce the desired overlap.

In FIGS. 2 and 3, the printer 50 is depicted as having only four lasers 52 and optical fibers 54, but a printer according to an embodiment of the present invention may have up to 35 lasers 52 and the same number. Optical fiber 54 of. Further, the collimating lens used in the embodiments of the present invention is an Olympus AV8414 having a focal length of 8.42 mm, a numerical aperture of 0.14, and a fan-shaped field of view of a focal plane of 700 μm.
It has been found that collimating lenses such as

By combining the optical fiber 54 and the collimating lens 58 as described above, it becomes possible to collimate 35 beams 72 shown in FIG. 2 at the same time. Similarly, it becomes possible to scan all of these 35 parallel beams 74 at the same time. This significantly improves the operating speed of the print 50. The printer 50
35 of printer 20 operating in single line mode of FIG.
Has twice the speed. This is because 35 lines are generated at one time in one image by scanning in the vertical direction.

Each of the lasers 52 is an independent unit that is individually modulated. This independent placement provides an image of the same quality as that obtained with a single laser printer. This is not necessarily limited to conventional printers that use multiple laser diode arrays as light sources to generate images in multi-line mode. When laser diode arrays are used in printers, thermal crosstalk occurs between the lasers. In other words, lasers placed in close proximity on the array are affected by the heat emitted by adjacent lasers. This heat crosstalk leads to deterioration in image quality.

Some laser diode array printers use complex cancellation systems to reduce the adverse effects of thermal crosstalk. In the printer 50, the lasers 52 are arranged at a sufficient distance from each other so that they are not thermally affected. That is, the printer 50 does not require the complicated cancellation device found in laser diode printers.

Of course, it is possible to finish the printer 50 with different numbers of lasers 52 in accordance with the principles of the present invention. Printer 5 with a reduced number of lasers 52
0 is made at a very low cost, but operates slowly. Conversely, increasing the number of lasers 52 increases manufacturing costs but operates at high speed. According to the present invention, the number of laser diodes can be adjusted to meet the desired design at the cost of operating speed. This is a preferred design quality for printers for office equipment.

It should also be noted that the output ray 72 exiting the output end of the optical fiber 54 is circular in cross section. This is because the optical fibers 54 are optically connected to the corresponding lasers 52. With this arrangement,
The rays from laser 52 do not have an elliptical cross section as seen in printer 20 of FIG. Since the output light beam 72 has a circular cross section, the cylindrical lens 26 and the second collimating lens 2 required in the conventional printer 20 are used.
It eliminates the need for eight.

Further, the printer 50 is particularly effective when using a donor paper containing a die that requires a high energy level to transfer the die (dye). When using such a dye donor paper, the optical fiber must be a multimode fiber in order to transfer a sufficient amount of energy from the laser 52 to the dye donor paper. Although the multimode fiber diffuses the beam 72 somewhat, a single collimating lens 58 alone is sufficient to provide the collimation function required by the printer 50 because the output ends of the optical fibers 54 are closely spaced. be able to.

That is, the printer 50 of the present invention is structurally simpler than the conventional printer 20 and an optical system with less complexity can be used. In the printer applied to the desktop, the reduction of the number of lenses leads to a great improvement in both cost and size. Considering that the resulting printer operates at up to 35 times the speed of conventional printers, the complexity reduction described above becomes even more pronounced.

In addition to being simpler in construction and faster in operation speed than the conventional single laser thermal printer, the printer 50 is more widely applied than the printer 20 of FIG.
For example, the printer 50 is a silver halide system (Si
It is also used for image generation using lver halide systems. This is because a laser connected to an optical fiber having a small diameter (such as coupling of the laser 52 and the optical fiber 54) is used, and a filtering phenomenon related to spontaneous emission occurs. This filtering effect causes the laser beam 70 to have a particularly high contrast ratio. In conventional printers, such as printer 20 of FIG. 1, the contrast ratio of focused beam 40 of FIG. 1 is typically limited to 30: 1. That is, the maximum light level of the concentrated beam 40 is 30 times or less the minimum light level. A contrast ratio of 30: 1 is sufficient for thermal printing with donor paper containing dies that sublime at a limited energy level. However, with a contrast ratio of 30: 1 or higher, a silver halide system cannot produce high quality images. Silver halide systems generally require a contrast ratio of 100: 1 or higher.

The printer 50 has a contrast ratio of 300: 1.
It is possible to generate a beam 70 of That is, the printer 50 can easily generate an image even with the silver halide system.

The embodiments described herein are merely an example of the general principles of the invention, and it should be understood by those skilled in the art that various modifications in accordance with the above principles are possible. For example, the printer of the present invention can be applied to an opaque large size receiver (print medium). It is also possible to operate the printer with rotating prisms and other forms of scanning devices instead of the beam scanning galvanometer described above.

[0040]

According to the marui beam laser printer of the present invention, a plurality of image lines can be simultaneously formed in one image with high density, so that the operation speed can be improved and a high resolution image can be obtained. .. Also,
The optical fiber array support allows the cross-sectional shape of the output beam to be circular and eliminates thermal crosstalk, thus allowing a simple optical system to be used and further thermal effects between lasers. Therefore, it is not necessary to provide a canceling device for canceling the problem, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional thermal printer.

FIG. 2 is a perspective view of a thermal printer according to the present invention.

3 is a front view of the array support part of the thermal printer of FIG. 2, as seen from line 3-3 of FIG.

[Explanation of symbols]

 50 multi-beam laser printer 52 laser diode 54 optical fiber 56 optical fiber support array section 58 collimating lens 60 fixed mirror 62 beam scanning galvanometer 64 F theta lens 68 receiver (recording medium)

Claims (15)

[Claims] 1. A multi-beam laser printer for progressively generating line-to-line correspondence on a receiver (recording medium) using a modulated laser beam, having a plurality of individually modulated lasers and an input / output terminal. A plurality of optical fibers, each input end of the optical fibers is optically connected to a respective laser, each output end is an optical fiber located on an array in which the optical fibers are respectively arranged at a predetermined interval, A multi-beam laser printer comprising: an output beam deflecting unit that simultaneously scans the output beams from all the optical fibers onto a receiver to generate a plurality of lines in one image at a time. 2. The multi-beam laser printer according to claim 1, further comprising a collimating lens located between the output end of the optical fiber and the output beam deflecting means. 3. The multi-beam laser printer according to claim 1, wherein the lasers are arranged at equal intervals, and basically, thermal crosstalk between the lasers does not occur. 4. The multi-beam laser printer according to claim 1, wherein the output beam has a contrast ratio of about 100: 1 or more. 5. The multi-beam laser printer according to claim 1, further comprising means for adjusting an interval between output beams. 6. The multi-beam laser printer according to claim 5, wherein the output beam interval adjusting means includes an array support part for holding the output ends of the optical fibers on the linear array at a predetermined interval, and a linear support for the receiver. A multi-beam laser printer comprising: means for changing the direction angle of the array; 7. The multi-beam laser printer according to claim 6, wherein the positions of the output beams are adjusted so as to overlap each other by a desired amount. 8. The multi-beam laser printer according to claim 2, wherein the collimating lens is a single lens, and has a field of view wide enough to collimate all output beams. A multi-beam laser printer. 9. The multi-beam laser printer according to claim 8, wherein the number of lasers is 30 or more. 10. The multi-beam laser printer according to claim 8, wherein the optical fibers are arranged with a center-to-center distance of about 20 microns or less. 11. A multi-beam laser printer, which uses a modulated laser beam to progressively generate an image on a receiver (recording medium) on a multi-line basis, is arranged at equal intervals so as not to be thermally influenced by each other. In addition, there are multiple individually operable lasers and multiple optical fibers with input and output ends.Each input end of this optical fiber is optically connected to each laser, and each output end has an optical fiber. Optical fibers located on the array at a predetermined distance from each other, and an output beam polarization means for scanning the output beams from all the optical fibers onto the receiver at the same time and generating multiple lines in one image at a time. A multi-beam laser printer comprising: 12. The multi-beam laser printer according to claim 11, further comprising a collimating lens located between the output end of the optical fiber and the output beam deflecting means. 13. The multi-beam laser printer according to claim 12, wherein the collimating lens is a single lens, and has a field of view wide enough to collimate all output beams. A multi-beam laser printer. 14. The multi-beam laser printer according to claim 12, wherein the number of lasers is 30 or more. 15. The multi-beam laser printer according to claim 12, wherein the optical fibers are arranged with a center-to-center distance of about 20 microns or less.