JPH0223848B2 - - Google Patents

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.

2. Description of the Related Art Laser printers that use a laser beam as a light source are conventionally known.

FIG. 1 is a configuration diagram showing an example of a known laser printer. This device includes a light source 1 consisting of a semiconductor laser 10 and an imaging lens 11;
The photosensitive drum 3 includes a rotating polygon mirror 2 that receives a laser beam from the polygon mirror, and a photosensitive drum 3 that is scanned by the laser beam reflected from the polygon mirror. In such a laser printer,
The distance a between the laser 10 and the lens 1 and the distance b between the lens 11 and the photosensitive drum 3 are adjusted so that the laser beam from the light source 1 is focused, for example, near the center of the photosensitive drum 3. For example, the image forming position will be as shown by the broken line _l1 , and an image forming position error will occur near both ends of the photosensitive drum 3.

In order to correct such an imaging position error, the applicant first moves the position of the laser 10 or the position of the lens 11 according to the deflection angle of the laser beam,
We proposed a method to adjust distance a or b.

An object of the present invention is to provide a light source moving actuator that can move the position of the semiconductor laser or the position of the 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 structural sectional view showing an embodiment of the light source moving actuator according to the present invention, and FIG. 3 is a sectional view taken along the line xx in FIG. 2. Here, a case where the position of the semiconductor laser 10 is moved is illustrated. In these figures, 11 is a lens, and 10 is a semiconductor laser, which are arranged so that the laser beam from them is emitted through the lens 11.
Reference numeral 12 indicates a movable part to which the semiconductor laser 10 is attached near the center thereof, 13 indicates a ring-shaped support block that supports the movable part 12, and 14 indicates support block 1.
3 a position adjustment screw, 15 a spring opposing the support block 13, and 16 a spring 15 and support block 13.
The support plate 17 interposed between the two is a cover.

FIG. 4 is a configuration explanatory diagram 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 with a double-supported beam structure having a constricted part in the middle. Piezoelectric elements 41, 42, 43, and 44 such as PZT are attached. Note that 51 and 52 are screws for fixing both ends to the support block 13.

The operation of the apparatus configured in this way will be explained next. Now, in the apparatus shown in FIG. 2, a driving voltage is applied to the piezoelectric elements 41 to 44 from the outside. Initially, when the applied voltage is 0V, there is no change in each piezoelectric element. Next, as the applied voltage gradually increases, expansion and contraction occurs in the thickness direction and length direction depending on the applied voltage. Here, the piezoelectric elements 41 and 42, 43 and 44, which are attached facing each other, expand and contract in opposite directions (one element 41 extends while the other element 42 contracts). As a result, the central portion of the movable portion 12, that is, the position of the semiconductor laser 10 is displaced as shown by the broken line in FIG. 4B. This amount of displacement d
corresponds to the magnitude of the driving voltage. Furthermore, if the polarity of the drive voltage is changed, the direction of displacement will be reversed.

The displacement amount d can be expressed by the following formula.

d=α・l ² /t ²・d ₃₁・V Where, t: Thickness of piezoelectric element and spring plate l: Length d ₃₁ : Piezoelectric constant V: Applied voltage α: Coefficient The central part of the movable part 12 is When displaced in this way, the distance between the semiconductor laser 10 and the lens 11 also changes according to the amount of displacement.

Therefore, the device having the configuration shown in FIG. 2 applies an AC voltage that changes at a constant cycle depending on the deflection angle of the laser beam to the piezoelectric elements 41 to 44, for example, to connect the semiconductor laser 10 and the lens. It can be used as a light source moving actuator that can make the distance of the laser beam variable and dynamically correct the imaging position of the laser beam.

In the device configured in this way, the movable part 12 is displaced by the piezoelectric element attached to it, and the configuration is simple, and the piezoelectric element can respond up to a relatively high frequency. It has the advantage of being suitable for high-speed operation.

FIG. 5 is a configuration explanatory diagram showing another configuration example of the movable portion 12. In this example, piezoelectric elements 41 and 42 (4
3, 44) are attached to a flat spring plate with a slight offset.

In each of the above embodiments, four piezoelectric elements were used, but two piezoelectric elements may be used. Moreover, although the semiconductor laser is attached to the movable part here, 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 according to a drive signal.

Further, in the present invention, the movable part is particularly constructed of a flat spring plate having a double-supported beam structure having a constricted part and a piezoelectric element as an excitation means attached thereto, and both ends of the flat spring plate are fixed to the support block. Therefore, it is possible to obtain a large amount of displacement in the optical axis direction with a small drive signal, and also to obtain a displacement that is accurately proportional to the drive signal.

[Brief explanation of drawings]

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, FIG. 3 is a sectional view taken along line XX in FIG. 2, FIGS. FIG. 5 is a configuration diagram showing an example of the movable part in the device shown in FIG. 2, in which A is a perspective view;
B is a side view. 1...Light source, 10...Semiconductor laser, 11...
Lens, 12...Movable part, 12B...Flat spring plate, 41-44...Piezoelectric element.

Claims (1)

[Scope of Claims] 1. A light source or lens consisting of a light source, a light source or lens attachment part that holds the light source or a lens through which the beam light from the light source passes in the center thereof, and constricted parts provided on both sides thereof. a movable part composed of a flat spring plate with a double-supported beam structure that moves the flat spring plate in the optical axis direction; a piezoelectric element attached to the constricted part of the flat spring plate; and both ends of the flat spring plate fixed. and a support block for moving the light source.