JPS59116603A - Actuator for moving light source - Google Patents

Abstract

PURPOSE:To enable movement of the position of a semiconductor laser or lens at a high speed by fitting a light source or lens to a movable part constituted of a spring plate in center beam construction driven by piezo-electric elements. CONSTITUTION:A movable part 12 consists of a flat plate-shaped leaf spring 12B in center beam construction having narrow parts in the mid-way and a semiconductor laser 10 is attached to the central part thereof and are provided piezo- electric elements 41-44. As a driving voltage is impressed increasingly largely from zero on the elements 41-44 from the outside, an elongation and contraction arise in thickness and longitudinal direction according to the impressed voltage. An AC voltage varying at a specified period according to the oscillation angle of, for example, a laser beam, is impressed on the elements 41-44, whereby the distance between the laser 10 and a lens 11 is made variable and the imaging position of the laser beam is dynamically corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light source moving actuator that is effective when applied to, for example, means for correcting imaging position errors in a laser printer.

Conventionally, laser printers that use a laser beam as a light source are known.

FIG. 1 is a configuration diagram showing an example of a known laser printer. This device includes a semiconductor laser 1o and an imaging lens 11.
and a rotating polygon mirror (polygon mirror) that receives the laser beam from the light source 1. ! : and a photosensitive drum 3 scanned by laser light reflected from the polygon mirror. In such a laser printer, the distance M a between the laser 10 and the lens 11 and the distance between the lens 11 and the photosensitive drum 3 are set so that the laser beam from the light source 1 is focused, for example, near the center of the photosensitive drum 3. If the distance is adjusted, the imaging position will be on the broken line e1
As shown in FIG. 2, an image forming position error occurs near both ends of the photosensitive drum 3.

In order to correct such imaging position errors, the applicant first proposed a method of adjusting the distance a and b by moving the position of the laser 10 or the position of the lens 11 according to the deflection angle of the laser beam. I figured it out.

An object of the present invention is to provide a light source moving actuator that can move the position of a semiconductor laser or the position of a lens (hereinafter collectively referred to as the light source position) at high speed in order to realize such a method. This is what we are trying to achieve.

FIG. 2 is a cross-sectional view showing an embodiment of the light source moving actuator according to the present invention, and FIG. 3 is a cross-sectional view taken along line x-x in FIG.
FIG. Here, a case is illustrated in which the position of the semiconductor laser 10 is moved.

In these figures, 11 is a lens, and 1o is a semiconductor laser, which are arranged so that the laser beam from them passes through the lens 11 and is emitted. 12 is a semiconductor laser 10
is the cover attached near the center of the 11th hole.

FIG. 4 is a configuration explanatory view showing the main parts of the movable part 12, in which (a) is a perspective view and (b) is a side view. As shown in the figure, this movable part 12 uses a flat spring plate 12B having a double-supported beam structure with a constricted part in the middle, and a semiconductor laser 1o is attached to the central part of the flat spring plate 12B. Piezoelectric elements such as pZT 41, 42, 43.
44 is installed. Note that 51 and 52 are screws for fixing both ends to the support block 13.

The operation of the device configured in this way will be described next.

Now, in the apparatus shown in FIG. 2, the piezoelectric element 4 is
Apply a driving voltage of 1 to 44 Vc. Initially, when the applied voltage is DV, there is no change in each piezoelectric element.

Piezoelectric elements 41 and 42.43 installed opposite each other
and 44, the directions of expansion and contraction are opposite (one element 4
1 extends, while the other element 42 contracts), and as a result, the central part of the movable part 12, that is, the position of the semiconductor laser element 0, is aligned with the broken line in FIG. 4(b). Displace as shown. This displacement ftd corresponds to the magnitude of the drive voltage. Furthermore, if the polarity of the drive voltage is changed, the direction of displacement will be reversed.

However, t: Thickness of piezoelectric element and spring plate t: Length d3 □: Piezoelectric constant V: Applied voltage α: Coefficient When the central part of the movable part 2 is displaced in this way, the semiconductor laser beam O and the lens 11 The distance between the two also changes according to this amount of displacement.

Therefore, the device having the configuration shown in FIG.
For example, by applying an alternating current voltage that changes at a constant period according to the deflection angle of the laser beam to 44, the distance between the semiconductor laser 10 and the lens can be varied, and the imaging position of the laser beam can be dynamically corrected. It can be used as a light source moving actuator.

In the device configured in this way, the movable part 12 is displaced by a piezoelectric element attached to the movable part 12,
The structure is simple, and the piezoelectric element can respond up to a relatively high frequency, making it suitable for high-speed operation.

FIG. 5 shows another example of the structure of the movable part 12, which is attached to a flat spring plate.

In each of the above embodiments, four piezoelectric elements were used, but two piezoelectric elements may be used. Further, although here a semiconductor laser is attached to the movable part, a lens may be arranged and the position of this lens may be displaced.

As described above, according to the present invention, it is possible to realize a light source moving actuator that can change the distance between the lens and the light source at high speed in accordance with a drive signal.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a known laser printer, FIG. 2 is a configuration sectional view showing an example of a device according to the present invention, and FIG.
The figure is a sectional view taken along the line xx in FIG. 2, and FIGS. 4 and 5 are configuration diagrams showing an example of the movable part in the device shown in FIG. 2, in which (A) is a perspective view and (B) is a side view. It is. DESCRIPTION OF SYMBOLS 1... Light source, 1o... Semiconductor laser, 11... Lens, 12... Movable part, 12B... Flat spring plate,
41-44...Piezoelectric elements.

Claims (1)

[Claims] (1) A light source, a lens that transmits the beam light from the light source, and a movable part composed of a spring plate with a double-supported beam structure driven by a piezoelectric element, and the light source or the lens is attached to the movable part. Light source movement actuator installed.