Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2001-05-03
2002-04-09
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S212100, C359S201100, C359S900000, C359S223100, C359S226200, C347S233000, C347S243000
Reexamination Certificate
active
06369929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for scanning an inner face of a cylindrical drum with dual or more light beams, and more particularly to a method and an apparatus for scanning an inner face of a cylindrical drum with plural light beams which are combined and introduced into a common optical scanning system to scan the inner face of the drum.
2. Description of the Prior Art
There is known an inner face scanning type of a light beam scanning device, wherein a light beam such as a laser beam is introduced into a cylindrical drum to scan an interior surface of the drum. To increase a recording speed in the apparatus of this type, a system with plural light beams, i.e., a multi-beam scanning system is proposed.
In the inner face scanning type of apparatus, plural light beams are introduced along a central axis of the cylindrical drum to a rotating deflector (spinner) disposed on and rotated about the central axis of the cylindrical drum. The spinner deflects incident light beams in a radial direction of the rotating drum. The spinner comprises, for example, a reflective mirror which rotates at a high speed with an angle of about 45° with respect to the central axis of the drum. However, when plural light beams are simply introduced to the spinner with maintaining the relative positions of the light beams, relative position of the light beams after deflected by the spinner periodically varies as a rotation angle of the spinner changes. Disposition of the light beam tracks on the inner face of the drum are varied with the rotational position of the reflective surface of the spinner. Therefore, plural scanning lines recorded on the recording drum are periodically curved and cross one another. A correct scanning cannot be achieved.
To avoid the curvatures and crossover of the scanning lines, it is proposed that one light beam among the plural light beams be used as a reference beam. The reference beam is aligned with a central axis of an optical scanning system (the central axis of the recording drum) and the other light beams are rotated about the reference beam in synchronism with rotation of the spinner. With such arrangement, since an interval between the respective light beams is constant, the curved scanning lines can be straightened. Also, by changing an interval between the reference beam and the other light beams, an interval between the scanning lines can be changed with maintaining the line separation thereof.
For example, the Japanese Laid-Open Patent Publication (KOKAI) Nos. 5-27188 (corresponding to U.S. Pat. No. 5,504,619) and 5-276335 disclose a system in which a deflecting element (prism or the like) with a fixed deflection quantity is rotated in synchronism with rotation of a spinner. Also, U.S. Pat. Nos. 5,097,351 and 5,502,709 propose a system in which light beams other than a reference beam are deflected two-dimensionally.
In the former system for rotating the deflecting element with the fixed deflection quantity, there is a problem that because of the constant deflection quantity, it is impossible to change a beam interval, therefore a scanning line interval cannot be changed. Although the scanning line interval is preferably changed with a recording density, the prior system cannot vary a scanning line density in accordance with the recording density. Also, stably to rotate the deflecting element in synchronism with the spinner rotating at a high speed, a highly precise mechanical rotation transmitting mechanism is necessary. However, this mechanism is hardly available, and expensive.
In the latter system for two-dimensionally deflecting the light beams, it is necessary to use plural deflectors, such as piezo-mirrors and acousto-optic elements (acousto-optic modulators, hereinafter referred to as AOM). Further, light beams need to be deflected two-dimensionally in opposite directions in a complicated manner while keeping a constant mutual relationship in two orthogonal directions (X, Y directions). Therefore, a complicated and precise control is required, and scanning quality is hardly stabilized. This leads to an expensive device.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the circumstances as aforementioned, and a first object thereof is to provide a method of simultaneously scanning an inner face of a cylindrical drum with dual light beams, in which scanning lines are straightened under a simple control without using a two-dimensional light beam deflecting element, and a scanning line interval can be changed, thereby simplifying a constitution of a system.
A second object of the present invention is to provide an apparatus for simultaneously scanning an inner face of a cylindrical drum with dual light beams, in which scanning lines are straightened under a simple control without using a two-dimensional light beam deflecting element, and a scanning line interval can be changed, thereby simplifying a constitution.
A third object of the present invention is to provide a method of simultaneously scanning an inner face of a cylindrical drum with two or more light beams, in which scanning lines are straightened under a simple control, and a scanning line interval can be easily varied with a simple constitution.
A fourth object of the present invention is to provide an apparatus for simultaneously scanning an inner face of a cylindrical drum with two or more light beams, in which scanning lines are straightened under a simple control, and a scanning line interval can be easily varied with a simple constitution.
The first object of the present invention is attained by the provision of a method for dual light beams scanning an inner face of a cylindrical drum which comprises a spinner rotating within said drum, said spinner deflecting two light beams introduced into the drum toward the inner face of the drum to scan the inner face with the two deflected light beams,
wherein said two light beams are one-dimensionally deflected in mutually orthogonal directions with each other, respectively, in synchronism with a rotation of said spinner, with keeping constant an interval between said two light beams, and then said two light beams are introduced to the spinner to be deflected to the inner surface of the drum.
In this case, on an image forming or focusing plane of the light beams, an X-Y rectangular coordinate system is assumed. The interval (distance) r between two light beams is set constant, an angular velocity of the spinner is set as &ohgr;, and an offset angle of the spinner from a maximum deflecting direction is set as &psgr;. The light beams are one-dimensionally deflected on an X-axis and on an Y-axis, so that a coordinate of one of the light beams on the image forming plane is (x=r·cos(&ohgr;t+&psgr;), y=0) and a coordinate of the other light beam on the image forming plane is (x=0, y=r·cos(&ohgr;t+&psgr;)).
The second object of the present invention is attained by the provision of an apparatus for simultaneously dual light beams scanning an inner face of a cylindrical drum, comprising:
a) two deflecting elements for one-dimensionally deflecting the two light beams in mutually orthogonal directions, respectively;
b) a spinner rotating coaxially with said cylindrical drum for deflecting said two light beams incident along a central axis of the cylindrical drum to scan the inner face of the cylindrical drum;
c) angle detecting means for detecting a rotation angle of the spinner;
d) a memory for storing deflection quantities of said deflecting elements necessary for one-dimensionally deflecting the light beams in mutually orthogonal directions in synchronism with the rotation of said spinner while keeping constant an interval between the two light beams; and
e) deflecting element control means for driving said deflecting elements based on the deflection quantities stored in said memory.
In a preferable embodiment, a mechanism for compensating positions of the light beams is provided. The mechanism can be constituted
Fuji Photo Film Co. , Ltd.
Phan James
Sughrue & Mion, PLLC
LandOfFree
Method and apparatus for inner face scanning with multi beams does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for inner face scanning with multi beams, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for inner face scanning with multi beams will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2909796