JPH0522889Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a holding mechanism for a flexible cylindrical lens used in a light beam scanning device or the like.

(Background of the invention) A cylindrical lens is a lens whose incident surface and exit surface are usually formed as cylindrical surfaces with generatrix parallel to each other, and is called a cylindrical lens.
Also called lens. The cylindrical lens does not have a refractive effect in a plane including the generatrix direction, but produces a refractive effect similar to that of a lens in a plane perpendicular to the generatrix. Thereby, for example, the image of a point light source becomes a straight line parallel to the generatrix.

One type of such cylindrical lenses is one that is formed to have flexibility along the longitudinal direction. The flexible cylindrical lens is used, for example, in a light beam scanning device that performs scanning by reflecting a light beam from a light source on a rotating polygon mirror and applying it to a surface to be scanned via a condensing lens. This is used to obtain a uniform spot size and to prevent scan line pitch unevenness. That is, this type of light beam scanning device originally consists of a rotating polygon mirror 1, as shown schematically in FIG.
The light beam from the laser 2, etc. that enters the mirror is reflected by the mirror surface of the rotating polygon mirror 1 that rotates in the direction of the arrow, and passes through the condensing lens (f/θ lens) 3 onto the scanned surface.
It is configured to connect light spots moving at a uniform speed in the scanning direction (x direction) along a scanning line SP1 above SP. However, if the mirror surfaces are not parallel to the rotation axis of the rotating polygon mirror 1 and their angles are irregular (inclination angle error), the light spot shifts unevenly in the direction perpendicular to the scanning direction (y direction). For example, as shown in FIG. 5, if the inclination angle error of the reflective surface 1a is Δθ, then Δd=2f·
A shift amount of Δθ (where f is the focal length of the condenser lens 3) occurs. Since this inclination angle error and rotational shaft wobbling cause unevenness in the pitch of the scanning lines, it is necessary to take some countermeasures.

Therefore, the applicant has already filed an application for a light beam scanning device using the above-mentioned flexible cylindrical lens in the optical system.

FIG. 6 is a schematic configuration diagram of the optical system and the light beam between the rotating polygon mirror and the surface to be scanned in such a light beam scanning device, b is a top sectional view, a is a side sectional view at the center of scanning, and c shows a side sectional view at the scanning end. In the figure, reference numeral 4 denotes a rotating polygon mirror similar to the above-mentioned rotating polygon mirror 1, and its reflecting surface (mirror surface) has a beam shaping means (not shown) that is wide in the scanning direction, flat, and parallel to the optical axis direction. A nearby light beam is incident. Reference numeral 5 denotes a condenser lens having the same function as the condenser lens 3 described above, which receives the reflected beam from the rotating polygon mirror 4 (an f/θ lens is used here). Reference numeral 6 denotes a flexible convex cylindrical lens placed near the scanned surface (usually a plane or a surface that can be considered as a substantially plane with respect to the scanning line) SP, and is arranged in the direction perpendicular to the scanning direction (x direction) ( It has refractive power in the y direction). This cylindrical lens 6
is curved and held by the holding mechanism 7 so that its end (only one end 6a is shown in FIG. 6b) approaches the scanned surface SP side.

In such an optical system, the relative positions of the rotating polygon mirror 4, the condensing lens 5, the cylindrical lens 6, and the scanned surface SP, the focal length, the diameter of the light beam incident on this system, the radius of wavefront curvature, etc. are determined appropriately. By this,
A desired spot can be obtained on the scanned surface SP, and the shape of this spot (not necessarily a perfect circle, but may be an ellipse) can be made uniform over the entire scanning width.

By the way, conventionally, as the holding mechanism 7, for example, one shown in FIG. 7 has been used. 7th
In the figure, 8 is a base side guide member, 9 is a presser side guide member, and the cylindrical lens 6 is pressed by the base side guide member 8 and the presser side guide member 9, thereby maintaining a predetermined curved shape. . This curved shape is the arcuate curved surface 8b, 9b of the guide members 8, 9.
The desired curved shape can be obtained by appropriately setting the shape.
Note that both guide members 8 and 9 have a light transmission window 8 in order to ensure the optical path of the light beam passing through the cylindrical lens 6.
a, 9a are bored, and the two are connected by screws, adhesive, etc. (not shown).

(Problem that the invention attempts to solve) However, according to such a conventional holding mechanism,
Since the curved shape of the cylindrical lens 6 is determined by the shapes of the arcuate curved surfaces 8b and 9b of the guide members 8 and 9, in order to adjust the curved shape, these two arcuate curved surfaces 8b and 9b are machined, etc. It is necessary to twist and match. However, when two guide members 8 and 9 are used in this way, there is a problem that the holding mechanism becomes expensive.

The present invention was made in view of the above-mentioned problems, and its purpose is to provide an inexpensive holding mechanism that allows easy setting of the curved shape of a flexible cylindrical lens.

(Means for Solving the Problems) The present invention for solving the above-mentioned problems includes a holder base in which a light transmission window is formed and one surface of the transmission window is formed as a substantially arc-shaped curved surface; A mounting member secured to both ends of the holder base, a pressing member for pressing the flexible cylindrical lens at both ends to curve it along the arcuate curved surface of the holder base, and a pressing member engaged with the pressing member. and an adjustment screw screwed into the mounting member so as to push and move the pressing member.

(Function) In the flexible cylindrical lens holding mechanism of the present invention, the cylindrical lens is held in position by pressing the pressing member against the cylindrical lens using the adjusting screw screwed into the mounting members that are locked at both ends of the holder base. It can be curved into a predetermined shape.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure and FIG. 3 are exploded views of each part of FIG. 1. In each of these figures, 11 is a holder base.
The holder base 11 is provided with a light transmission window 11a for securing the optical path of the light beam passing through the flexible cylindrical lens 6.
One surface 11b of the flexible cylindrical lens 6 is formed as an arcuate curved surface that is in contact with one surface of the flexible cylindrical lens 6. A stepped portion 11c is provided at the lower part of the arcuate curved surface 11b.
is formed, and screw holes 11d are carved near both ends of the stepped portion 11c. Incidentally, screw holes 11f (only one shown in FIG. 2) are also formed near both upper ends of the other surface 11e of the light transmitting window 11a. Reference numerals 12 and 13 designate attachment members that are bent and formed in a left-right symmetrical shape and are secured to both ends of the holder base 11. For example, the mounting member 12 has a front surface 12a facing the arc-shaped curved surface 11b at the end of the holder base 11, and a stepped portion 11.
a bottom surface 12b that comes into contact with the end of c;
The upper surface of the holder base 11 and the stepped part 11 are parallel to
an upper surface 12c opposite to c, and a rear surface 12 parallel to the front surface 12a and in contact with the surface 11e of the holder base 11.
d is also formed in the shape of a rectangular frame with a portion cut out. The front surface 12a of the mounting member 12 has a screw hole 12e into which the adjustment screw 14 is screwed, the bottom surface 12b has a mounting hole 12f into which the mounting screw 15 is inserted, and the top surface 12c has a mounting screw. A U-shaped cutout 12g is formed for attaching and detaching the mount 15, and a mounting screw 16 is provided on the rear surface 12d.
A mounting hole 12h is provided for inserting the. The adjustment screw 14 has a threaded groove 14c in the middle thereof which engages with the screw hole 12e of the mounting member 12, and the other end thereof has a stepped part 14 into which the pressing member 17 is fitted.
d and an annular groove 14e into which the retaining E-ring 18 fits. The pressing member 17 is approximately L
A plane 17a that is bent into a letter shape and faces the front surface 12a of the mounting member 12;
and a vertical side surface 17b are formed. A mounting hole 17c that fits into the stepped portion 14d of the adjustment screw 14 is formed in the flat surface 17a of the mounting member 12, and protruding pieces 17d for pressing the cylindrical lens 6 are formed at both ends of the side surface 17b. There is.

These are assembled as a holding mechanism as follows.

First, insert the adjustment screw 14 into the screw hole 1 of the mounting member 12.
Screw into 2e. Next, the pressing member 17 is fitted into the stepped portion 14d of the adjustment screw 14, and the annular groove 14e is
Insert E-ring 18 into. Thereby, the pressing member 17 is movably screwed into the mounting member 12. After the pressing member 17 is attached to the mounting members 12 and 13 in this manner, each of the mounting members 12 and 13 is fixed to both ends of the holder base 11 via the mounting screws 15 and 16, respectively.
Thereafter, the pressing member 17 is sufficiently spaced from the arcuate curved surface 11b of the holder base 11, and both ends of the flexible cylindrical lens 6 are pressed against the arcuate curved surface 11b of the holder base 11.
1b and the pressing member 17. At this time, the bottom surface of the flexible cylindrical lens 6 is the holder base 1.
1 so as to come into contact with the stepped portion 11c of No. 1. next,
By screwing in the adjustment screw 14, both ends of the flexible cylindrical lens 6 are pushed by the pressing members 12 and 13,
The flexible cylindrical lens 6 is curved along the arcuate curved surface 11a of the holder base 11.

In the above embodiment, the mounting member was formed in the shape of a rectangular frame with a part cut out, and the pressing member was bent into a substantially L shape. The pressing member may be any member as long as it is fixed and can press the flexible cylindrical lens that is in contact with the holder base.

(Effects of the Invention) As explained above, according to the present invention, a flexible cylindrical lens can be curved into a predetermined shape. Moreover, the surface that serves as the curve reference at that time is only one arcuate surface of the holder base, so
Cost reduction can be achieved.

In other words, by setting the curvature based on only one side, there is no need to consider matching the curved surface shape of the concave and convex surfaces that press the lens, and an inexpensive holding mechanism can be provided.Moreover, the optimum curvature can be set by adjusting with the adjustment screw. Settings (deflection settings) can be easily performed.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
Figures 3 and 3 are exploded views of each part of Figure 1, Figure 4 is a basic configuration diagram of the main parts of the light beam scanning device, Figure 5 is an explanatory diagram of tilt angle error, and Figure 6 is a flexible FIG. 7 is a schematic diagram showing an example of the holding mechanism in FIG. 6. 6... Flexible cylindrical lens, 11... Holder base, 12, 13... Mounting member, 14... Adjustment screw, 15, 16... Mounting screw, 17... Pressing member.

Claims (1)

[Scope of utility model registration request] A holder base in which a light transmitting window is formed and one surface of the transmitting window is formed as a substantially arc-shaped curved surface, a mounting member secured to both ends of the holder base, and a flexible cylindrical lens. a pressing member for pressing at both ends to curve the holder base along the arcuate curved surface; and an adjusting screw screwed into the mounting member so as to engage with the pressing member and push the pressing member. A flexible cylindrical lens holding mechanism characterized by comprising: