JPS63113517A - Scanner for laser printer - Google Patents

Abstract

PURPOSE:To obtain a miniature and inexpensive scanner by providing a light reflecting surface of a curved surface shape or a polyhedral surface shape on other vibrator than a rotational center axis of the vibrator, radiating a laser light to the reflecting surface, and scanning it by a vibration of the vibrator. CONSTITUTION:The titled scanner is provided with a metallic turning fork 11, a base 12 for supporting the tuning fork, a piezoelectric element 13 attached to the tuning fork, and an amplifier 14 for maintaining a vibration of the tuning fork, and an irradiation light 17 is radiated to the reflecting material of a rod material 15 by a laser light source 16. The reflecting surface of the rod material forms a curves surface having a small radius of curvature (r) and the diameter of a luminous flux of the irradiation light 17 is smaller than (r). Also, by following up the vibration of the tuning fork 11, the rod material 15 hits against the irradiation light 17 and moves in the direction vertical to this light. As a result, on the reflecting surface of the rod material 15, an angle theta made by the irradiation light 17 and a normal of the reflecting surface is varied periodically, and a reflected light can execute a scan extending over the width from 0 deg. to 180 deg.. In such a way, in an extremely small vibrator amplitude, a scan amplitude of a large laser light is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for scanning laser light when creating an electrostatic latent image by applying laser light to a photosensitive drum of a laser printer.

[Conventional technology]

FIG. 7 schematically depicts only the portion of the prior art that is related to the present invention. A laser beam 72 emitted from a laser oscillator 71 is reflected by a mirror light reflecting surface 76 fixed to a metal torsional oscillator 75 supported at both ends by fixed plates 76 and 74, and is reflected onto a rotating photosensitive drum 77. Creates an electrostatic latent image while scanning. The torsional vibrator 75 is maintained in vibration by a magnetic vibrating means 78.

[Problem that the invention seeks to solve]

However, the conventional torsional vibrator 75 described above has difficult problems such as the need for high natural vibration, the safe allowable torsional stress for an extremely large number of vibrations, and the prevention of vibration due to the length of the span. It is complicated because there are coils 78a, etc. Therefore, the number of parts is large, space is taken up, and adjustment is time-consuming. SUMMARY OF THE INVENTION An object of the present invention is to provide a smaller and cheaper scanner for laser IJ printers.

[Means for solving problems]

The present invention provides a vibrator with a curved light reflecting surface, irradiates the reflective surface with a laser beam, and performs scanning by the vibration of the vibrator, thereby achieving a large scanning amplitude of the laser beam with an extremely small amplitude of the vibrator. It is what makes it possible to obtain.

〔Example〕

A first embodiment of the present invention is shown in FIGS. 1A, B, and C. 11
is a tuning fork made of metal; 12 is a base that supports the tuning fork; 13 is a base that supports the tuning fork;
14 is a piezoelectric element attached to the tuning fork, and 14 is an amplifier for forming an oscillation circuit and maintaining the vibration of the tuning fork. 15 is a rod member attached to the free end of the tuning fork, and the surface thereof is a reflective surface. 5 is the rotation axis of virtual vibration separated from the tip of the tuning fork (
(hereinafter referred to as the rotation center axis). Reference numeral 16 denotes a laser light source, which irradiates the reflective surface of the rod material 15 with irradiation light 17. The reflective surface of the rod material is a curved surface having a small radius of curvature r, and the diameter of the luminous flux of the irradiated light 17 is smaller than the above-mentioned r. tuning fork 1
1, the rod member 15 moves in a direction perpendicular to the irradiation light 17 while being hit by the irradiation light 17. As a result, rod material 15
The angle θ between the irradiated light 17 and the normal to the reflective surface on the reflective surface is
changes periodically. When the vibration frequency of the tuning fork 11 is f and the tip amplitude is A, the vibration displacement of the rod material 15 is XG end, x=ASin2πft ・・・・・・・・・・・・・・・
(1) The central axis 0 of the rod material 15 is X from the optical axis of the irradiation light 17 before the start of vibration. It is offset slightly downward. At this time, if the angle between the irradiation light 17 and the normal to the reflecting surface is 00, and the radius of curvature of the rod material is r, then xo=rsinθ.・・・・・・・・・・・・・・・
・・・・・・・・・(2) becomes. If the amount of offset during vibration is XS, and the angle between the normal of the irradiated light 17 and the reflected light 18 is θ, then xs=rsinθ=x, -x==rsin
θ. −ASin2πft (3). The initial value of the offset can be selected within an appropriate range, but for example, if it is selected to be r/2 and the amplitude A is set to r/2, the maximum value of xs during vibration will be r, the minimum value will be zero, and θ varies from 0 degrees to 90 degrees. Since the angle between the irradiated light 17 and the reflected light 18 is 20, the reflected light ranges from 0 degrees to 18 degrees.
It is possible to scan with a width of 0 degrees. The angular width actually required for scanning is 180 degrees or less, and can be obtained by controlling the tip amplitude of the tuning fork 11 to an appropriate value of r/2 or less.

A second embodiment of the present invention is shown in FIGS. 2A and 2H.

The difference from the case shown in FIG. 1 is that a concave mirror 25 is used instead of the rod material 15 as a reflecting member.

As the amount of deviation between the center of curvature O' of the reflecting surface of the concave mirror 250 and the optical axis of the irradiated light 17 changes during vibration, the normal angle θ' of the reflecting surface changes, and the angle of the reflected light 18 changes accordingly. This is the same as in the embodiment shown in FIG. However, although the direction of the reflection angle is reversed, the same effect can be obtained regarding the scan width.

FIG. 3 shows a third embodiment of the present invention. The difference from the embodiment shown in FIG. 1 is that instead of a tuning fork, a vertical vibrator 31 made of a piezoelectric material such as crystal is used as the vibrator. 66 is a vibration/detection electrode attached to the vertical vibrator 61. The vertical vibrator vibrates in the longitudinal direction, and the rod member 15 attached to the tip vibrates in a direction perpendicular to the irradiated light 17, producing the same effect as the embodiment shown in FIG. 4, 5 and 6 are other embodiments of the present invention, respectively,
The ends of the tuning fork 11 shown in FIG. 1 are formed into a convex surface 64, a concave surface 36, and a polygonal surface 68 similar to the convex surface, respectively, and these surfaces are used as light reflecting surfaces.

Although the embodiments have been described above, the present invention is not limited to these examples. The reflective surface moves across the optical axis of the irradiated light, and it broadly includes scanners for laser printers that scan the light by utilizing the change in the angle of the normal at the intersection of the reflective surface and the optical axis. It is applicable to almost all types of vibrators, such as free-free bars, torsional vibrators, and sliding vibrators.In addition, not only piezoelectric vibration but also electromagnetic vibration can be used for vibrator vibration. It can also be realized by

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, it is possible to obtain a large scanning amplitude of light with a small amplitude of the vibrator. The advantages are extremely large because the amplitude of the signal can be set and the device can be constructed with a simple structure and small size.

[Brief explanation of the drawing]

1 to 6 show embodiments based on the present invention;
Figure A is a perspective view of a part of the scanner of the first embodiment, Figure 1B,
C is an enlarged sectional view of the light reflecting part in FIG. 1A, FIG. 2A
is a perspective view of the scanner section of the second embodiment, and FIG. 2B is a perspective view of the second embodiment.
FIG. 3 is a perspective view of a part of the scanner of the third embodiment; FIGS. 4, 5, and 6 are enlarged views of the light reflecting section of other embodiments. FIG. 7 is a schematic perspective view of a conventional laser printer scanner. 11...Tuning fork, 12...Base, 16.
...Piezoelectric element, 14...Amplifier, 15.
...Rod material, 16...Laser light source, 1
7...Irradiated light, 18...Reflected light, 25
・・・・・・Concave mirror, 61 ・・・Vertical oscillator, 2nd
Figure (B) Figure 3

Claims (1)

[Claims] In a scanner that scans a laser beam to write an electrostatic latent image on a photosensitive drum, a curved or multifaceted light reflecting surface is provided on the vibrator other than the central axis of rotation of the vibrator, and the laser beam is irradiated onto the reflective surface. A scanner for a laser printer, characterized in that scanning is performed by vibration of the vibrator.