JPS62109019A - Light beam recorder - Google Patents

Abstract

PURPOSE:To make effective use of both the time and quantity of light of scanning to make effective scanning and to make design and formation easy by changing scanning width according to the width of a recording body to be recorded with image information. CONSTITUTION:The recording body 9 is attracted on an endless belt device 10, and is conveyed in an arrow D direction approximately orthogonal with the main scanning direction. The recording body 9 is two-dimensionally scanned with a light beam 2 over the entire surface by the deflection of the light beam 2 by a rotary polygon mirror body 3 and the conveyance of the recording body 9 by the device 10, by which the necessary image information is recorded over the entire surface of the body 9. The rotary polygon mirror body 3 consisting of three rotary polygon mirrors 3A-3C which are different in the number of reflective surfaces from each other is provided as a deflector to reflect and deflect the light beam 2 in the above-mentioned manner and therefore, the main scanning width by the light beam 2 can be changed according to the width of the main scanning direction of the recording body to be subjected to recording.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a light beam recording device that records an image by deflecting a light beam modulated based on image information and scanning it over a recording medium. relates to a light beam recording device that can change the scanning width depending on the recording medium.

(Technical Background and Prior Art of the Invention) Conventionally, a light beam emitted from a beam light source is modulated based on image information, and the modulated light beam is scanned two-dimensionally over a recording medium. Various light beam recording devices for recording image information have been proposed. These light beam recording devices, for example, which have been proposed by the applicant in recent years and have attracted attention, scan radiation image information photoelectrically by scanning a stimulable phosphor sheet on which radiation image information is stored and recorded with excitation light. It is connected to a radiographic image information reading device that reads the image and outputs the image A3@, and is suitably used to obtain a high-quality hard copy that is suitable for observation and interpretation based on the read image signal.

A known optical beam recording device uses a rotating polygon mirror as a deflector, and this optical beam scanning device reflects a light beam emitted from a light source in the main scanning direction using a rotating polygon mirror. The recording medium is deflected and sent relative to the light beam in a direction perpendicular to the main scanning direction (Rj constant scanning) to two-dimensionally scan the recording medium. Further, a scanning lens is provided between the rotating polygon mirror and the recording medium to pass through a light beam having a certain thickness that has been reflected and deflected by the rotating polygon mirror, and to focus it on the recording medium. , a θ lens is usually used as this scanning lens.

The scanning width of the light beam on the recording medium is expressed as L-f·θ, where θ is the deflection angle of the light beam by the rotating polygon mirror, and f is the focal length of the scanning lens. However, in the conventional optical beam recording Hfff using a rotating polygon mirror, the deflection angle of the rotating polygon mirror is constant, and the focal length of the scanning lens is also constant, so the scanning width is always constant, and therefore the recording In order to perform scanning that is compatible with recording media of various widths, it is necessary to set the scanning width to be larger than the required maximum width. Therefore, when scanning a recording medium with a relatively small width, both ends of the main scan of the light beam become unnecessary scans, and the total amount of light beam used for scanning and the scanning time decrease. There is a lot of waste;
There was a problem that scanning efficiency deteriorated.

In addition, in order to realize scanning without wasting the light beam by changing the scanning width according to the width of the recording medium, it is also possible to switch and use scanning lenses with different focal lengths depending on the recording medium. However, if the focal length of the scanning lens is changed, the optical path length to the scanning position changes each time the scanning lens is switched, making it difficult to design the device.
Furthermore, since optical elements are usually installed in the optical path of the light beam to correct the tilting and wobbling of the rotating polygon mirror, it is difficult to design an optical system that switches the scanning lens by taking these optical elements into account. There is a problem.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and it reduces the scanning time by changing the scanning width according to the width of the recording medium on which image information is recorded. , both the amount of light can be used effectively and scanning can be performed efficiently.
Another object of the present invention is to provide a light beam recording device that is relatively easy to design and manufacture.

(Structure of the Invention) In the light beam recording device of the present invention, the deflector for deflecting the light beam is a rotating polygon body formed by coaxially stacking a plurality of rotating polygon mirrors each having a different number of reflective surfaces, The rotating polygon mirror is moved such that any one of the plurality of rotating polygon mirrors is selectively positioned in the optical path of the light beam,
The feature of @1 is that the scanning width is changed according to the width of the recording medium in the main scanning direction.

That is, as mentioned above, the scanning width of the light beam is determined by the deflection angle of the deflector and the focal length of the scanning lens. By changing the number of reflection surfaces of the rotating polygon mirror on which the beam is incident and by changing the deflection angle of the deflector, it is possible to obtain a main scanning line with a width that corresponds to the recording medium. The deflection angle of a rotating polygon mirror decreases as the number of reflective surfaces increases (for example, 120° for 6 surfaces, 90° for 8 surfaces, 1
In the case of 0 surface, it is 72@), and when scanning a recording medium with a small width in the main scanning direction, a rotating polygon mirror with a relatively large number of surfaces may be used.

By the way, when the rotating polygon mirror that reflects and deflects the light beam is switched according to the width of the recording medium in the main scanning direction as described above, the rotational speed of the rotating polygon mirror (main scanning speed) and the width of the recording medium are When the relative conveyance speed (sub-scanning speed) is kept constant, the interval between scanning lines formed on the recording medium changes depending on the number of reflecting surfaces of the rotating polygon mirror used. That is, during one rotation of the rotating polygon mirror, for example, a six-sided rotating polygon mirror forms six scanning lines, and an eight-sided rotating polygon mirror forms eight scanning lines. Therefore, in a narrow recording medium on which recording is performed using a rotating polygon mirror with a relatively large number of reflective surfaces, the spacing between scanning lines becomes close. Therefore, if the rotating polygon mirror is switched depending on the width of the recording medium and the main scanning speed and sub-scanning speed are kept constant, the image quality of the recorded image will be uneven between relatively large and small recording bodies. A problem will arise. Therefore, in the apparatus of the present invention, the sub-scanning speed and/or The second feature is that the rotational speed of the rotating polygon iA is varied so that the interval between the scanning lines is constant regardless of the size of the recording medium.

(Actual IM Mode) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an outline of a light beam recording device according to an embodiment of the present invention.

The light beam 2 emitted from the laser beam lK11 enters the modulator 5, which is modulated by the modulator drive circuit 6 based on the signal emitted from the image signal output circuit 7 that outputs the image signal, and the modulated invasion signal is , the first rotating polygon mirror 3Δ having 9 reflective surfaces, the second rotating polygon ff13B having 12 reflective surfaces, and the third rotating polygon 1 having 15 reflective surfaces.
3C are stacked coaxially, and are incident on a rotating polygon mirror 3 rotated by a motor 4 in the direction of the arrow claw, and are reflected and deflected. The light beam 2 reflected and deflected by the rotating polygon mirror 3 passes through an fθ lens 8, which is a scanning lens, provided on the optical path. Main scanning V is performed on the recording medium 9 in the direction of arrow B. The recording medium 9 is attracted onto the endless belt device 10 and conveyed in the direction indicated by the arrow, which is substantially perpendicular to the main scanning direction, and the recording medium 9 is deflected by the rotating polygon mirror 3 and recorded by the endless belt device 10. As the body 9 is transported, the light beam 2 scans the entire surface of the recording body 9 two-dimensionally, and necessary image information is recorded on the entire surface of the recording body 9.

By the way, as described above, the apparatus of the present embodiment i11 uses three rotating polygon mirrors 3A having different numbers of reflection surfaces as deflectors for reflecting and deflecting the light beam 2.

By providing the rotating polygon mirror 3 made up of 3B and 3C, the main scanning width of the light beam 2 can be changed in accordance with the width of the recording medium on which recording is performed in the main scanning direction. That is, since the deflection angle of the light beam by the zero-transfer mirror and the main scanning width of the light beam are inversely proportional to the number of reflective surfaces of the rotating polygon mirror, in the above device, the rotating polygon mirror 3 is
As shown in FIG. 1 and FIG. 2, which is a side view of the rotating polygon mirror body 3, each of the rotating polygons is movable in the direction of arrow C! Any one of 13A, 3B, and 3C is selectively positioned in the optical path of the light beam 2. In addition,
The movement of this rotating polygonal mirror 3 in the C direction is carried out by the edict motor 4.
This may be done by a known moving mechanism using a motor, solenoid, etc., integrally with the motor. As shown in FIG. 3, the deflection angle θ1 is 80° when the first rotating polygon mirror 3A is used, and the deflection angle θ2 is 60° when the second rotating polygon mirror 3B is used.
°, deflection angle θ when using the third rotating polygon M3C,
is 48°, and since the focal length of the θ lens 8 is always constant, a scanning line of quality proportional to the deflection angle is formed. Therefore, when scanning a relatively wide recording medium, The light beam 2 is deflected using the first rotating polygon mirror 3A, and as the width of the recording medium becomes smaller, the light beam 2 is deflected using the second rotating polygon mirror 3B and the third rotating polygon 13c. The rotating polygon mirror 3 may be moved as shown in FIG. Needless to say, it can be arbitrarily determined depending on the situation.

By the way, when the rotating polygonal boundary is switched and used as described above, and assuming that the rotational speed of the rotating polygonal boundary 3 and the conveyance speed of the recording medium 9 are constant, the interval between the scanning lines is determined by the rotating polygonal boundary with a large number of reflective surfaces. When polygon mirrors are used, recording media with a small width in the main scanning direction will be dense, and recording media with a large width will be coarse, resulting in uneven image quality depending on the size of the recording media. There is a problem. In order to always form scanning lines with a constant interval regardless of the change in the number of surfaces of the rotating polygon mirror depending on the size of the recording medium, it is necessary to maintain a sub-scanning speed corresponding to the distance M (interval) between the scanning lines. The product of the time required for the light beam 2 to form one scanning line (main scanning time) may be made constant. Note that it is better to keep the rotational speed of the rotating polygon mirror 3 constant (main scanning speed constant) and change only the sub-scanning speed, if the speed of the recording body 9 is the same regardless of the size, the laser There is no need to change the intensity of the light beam 2 from the light source 1 (also, a small recording medium is desirable because the recording time is shortened. Therefore, in the apparatus of this embodiment, the rotational speed of the rotating polygonal chain 3 is constant (the main scanning time is inversely proportional to the number of surfaces of the rotating polygon surface used), and the recording medium 9
By changing the conveyance speed in proportion to the surface of the rotating polygon mirror used, scanning lines are always formed at approximately constant intervals. In order to change the conveyance speed of the recording medium 9 as described above, in the real fM position, the driven roller 11 [3
A motor 1 that drives a rotating roller IIA provided therewith.
A control section 13 is provided which sends an i'J till signal to the recording medium 2, controls the drive of the motor 12, and transports the recording medium 9 at a conveyance speed corresponding to the size of the recording medium (X).

Hereinafter, specific examples of the number of surfaces of the rotating polygon mirror and the conveyance speed (sub-scanning speed) of the recording body, which are determined according to the size of the recording body, will be shown.

(Example 1) Rotating polygon mirrors with the above number of surfaces are used for recording medium A, recording medium B, and recording medium C of the above-mentioned sizes, and an fθ lens (scanning lens) is used for recording medium under the above conditions. Recording body A has a focal length where the recording body width/scanning line length for C is 1.

For both recording bodies B and C, the value of recording body width/scanning line length is close to 1, and efficient scanning can be performed without wasting the light beam. In addition, when the rotational speed of the rotating polygonal boundary (body) is constant, the time per main scan is expressed as 1 for the recording medium C, and the above values are obtained for the other recording bodies. scan speed,
If the sub-scanning speed for the recording medium A is set to the above value expressed as 1, the intervals between the scanning lines formed on each recording medium will be approximately equal, and the image quality of all reproduced images will be approximately the same. .

Example 2) Using recording bodies A, recording B, and recording body C as in Example 1, changing the number of surfaces of the rotating polygon mirror for each recording body as above, and under the above conditions, It has a focal length where the width of the recording body/length of the scanning line is 1 [If scanning is performed using a θ lens, the value of the width of the recording body/length of the scanning line for any recording body is is close to 1.

Note that Example 2 is preferable in terms of smaller variations in the values of each recording medium and more efficient use of the light beam, but because it uses an 11-sided rotating polygon mirror that is difficult to manufacture,
The device is easier to manufacture in Example 1.

In addition, when the rotational speed of the rotating polygon mirror (body) is constant, the time per main scan is expressed as 1 for recording body C, and the above values for other recording bodies are 0.
If the 1 scanning speed is set to the above value, where the n1 scanning speed to the recording medium is 1, the intervals between the scanning lines formed on each recording medium will be approximately equal, and the image quality of any reproduced image will be improved. They will be almost equal.

In this way, the apparatus of this embodiment can perform efficient scanning without wasting the light beam by switching between rotating polygon mirrors with different numbers of surfaces depending on the size of the recording medium. In addition, by changing the sub-scanning speed in proportion to the number of surfaces of the rotating polygon mirror used, the interval between the scanning lines can always be kept substantially constant regardless of the size of the recording medium. To make the interval between the scanning lines constant, in addition to changing the sub-scanning speed, it is also necessary to keep the sub-scanning speed constant and change the rotational speed of the rotating polygon mirror in inverse proportion to the number of surfaces of the rotating polygon mirror ( The main scanning time may be kept constant. Further, as described above, both the conveyance speed of the recording medium and the rotational speed of the rotating polygon mirror may be changed so that the product of the sub-scanning speed and the main-scanning time is constant.

(Effects of the Invention) As described in detail above, according to the light beam recording device of the present invention, a light beam is recorded using a rotating polygon body including a plurality of rotating polygon mirrors each having a different number of reflecting surfaces. By performing deflection and switching the rotating polygon mirror used according to the width of the recording medium in the main scanning direction, the main scanning width can be changed according to the width of the recording medium, making it efficient without wasting the light beam. It is possible to perform a typical scan. Furthermore, in the apparatus of the present invention, the rotational speed of the rotating polygon mirror and/or the relative conveyance speed (1illll scanning speed) of the recording medium are changed, so that scanning can be performed regardless of the number of surfaces of the rotating polygon mirror used. By making the intervals at which the lines are formed substantially constant, a reproduced image of uniform quality can be obtained for any size of recording medium.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an outline of a light beam recording device according to an embodiment of the present invention, FIG. 2 is a side view of a rotating polygon mirror in the device, and FIG. 3 is a diagram showing the number of surfaces of the rotating polygon mirror. FIG. 3 is a schematic diagram showing changes in deflection angle due to changes. 2...Light beam 3...Rotating polygon mirror 3Δ...First rotating polygon mirror 3B...Second rotating polygon mirror 3C...Third rotating polygon Mirror 8... θ lens 9... Recording surface 13... Control section Fig. 2 Fig. 3

Claims (1)

[Scope of Claims] A light beam modulated based on image information is reflected and deflected by a rotating polygon mirror to scan the recording medium in the main scanning direction, and the light beam and the recording medium are set relative to each other. In a light beam recording device that records the image information by moving the light beam in a sub-scanning direction substantially perpendicular to the main-scanning direction to scan the light beam two-dimensionally on the recording medium, the rotating polygon mirrors may mutually A rotating polygon mirror body is formed by coaxially stacking a plurality of rotating polygon mirrors each having a different number of reflecting surfaces, and the rotating polygon mirror body is configured such that any one of the plurality of rotating polygon mirrors is placed in the optical path of the light beam. It is possible to change the scanning width corresponding to the width of the recording medium in the main scanning direction by selectively positioning one of the two, and the speed of the movement in the sub-scanning direction and the light beam A light beam recording device characterized in that the moving speed in the sub-scanning direction and/or the rotational speed of the rotating polygon mirror are changed so that the product of time required to perform one main scan is approximately constant. .