JPH0431370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a polygon mirror mirror polishing device that uses a novel structure to improve production efficiency while maintaining high precision.

<Prior Art> In recent years, a rotating polygon mirror (hereinafter referred to as a polygon mirror), which is composed of a regular polygonal column and whose corner sides are mirror surfaces, has been used as a scanner for scanning laser light. For example, as shown in Fig. 6, a polygon mirror 1 rotating at a high speed (5000 to 1500 rpm) is irradiated with laser light emitted from a laser light generator in order to scan the photoreceptor drum of a laser printer with laser light. However, if the reflected light is irradiated onto the photosensitive drum through a lens unit, the laser light is scanned in the horizontal direction of the photosensitive drum, allowing high-speed printing. This laser printer is attracting great expectations because it can achieve much faster printing speeds than conventional line printers and serial printers, and is also superior in image quality and noise. be. The above-mentioned polygon mirror is an extremely important element in this laser printer. Polygon mirrors require high precision due to their intended use. Because of its shape and high precision, it is a very expensive component, and it can be said that this polygon mirror is a major obstacle in reducing the price of laser printers. In other words, how to provide a polygon mirror processed with high precision at a low cost is an extremely important technical issue.

A side sectional view of a conventional polygon mirror 1 is shown in FIG. This polygon mirror 1 was provided with a mounting hole 2 for a drive motor for driving the polygon mirror 1 to rotate at high speed, and had a substantially uniform thickness except for the mounting hole 2. In order to reduce the cost of polygon mirrors such as those described above, it is necessary to improve production efficiency. One way to do this is to stack multiple polygon mirrors (blanks) 3 in the state immediately before mirror polishing, which is the final process of polygon mirrors.
There is a method that attempts to obtain multiple polygon mirrors at the same time by final finishing mirror finishing using cycle machining. FIG. 5 shows an example in which a plurality of conventionally shaped polygon mirror blanks are stacked and mirror-finished.

In the figure, reference numeral 4 denotes a jig for polishing a polygon mirror, and six polygon mirror blanks 3 are set on a cylindrical protrusion of the jig 4. 5
is a presser foot for the polygon mirror blank 3, and 6 is a presser spring that applies a pressing force to the presser foot 5. Reference numeral 7 denotes a screw, and pressure is applied to the presser spring 6 by lowering the screw 7 from above while rotating it. 8 is a single-crystal diamond cutting tool, and 9 is a balance weight for keeping rotational balance with the single-crystal diamond cutting tool 8. The single-crystal diamond cutting tool 8 rotates in a circular motion in the direction of the arrow in the figure. Then, while performing the rotational movement, the laminated polygon mirror blank 3 is approached, and one side surface of the polygon mirror blank 3 is machined to have a mirror surface. At this time, the jig 4 is moved horizontally in a direction perpendicular to the rotation axis of the single crystal diamond cutting tool 8. When the cutting of the mirror surface on one side of the polygon mirror blank 3 is completed, the jig 4 is rotated by 30 degrees, and the cutting of the mirror surface on the next side is executed.

In order to maintain the quality of polygon mirrors with high precision during the cutting process described above, the upper and lower surfaces of each polygon mirror blank 3 that come into contact with each other when superimposing the plurality of polygon mirror blanks 3 must be cut with very high precision. They must be machined flat and parallel to each other. However, as shown in Figure 5, machining errors accumulate especially in the upper polygon mirror blanks, but with conventionally shaped polygon mirrors, the contact area of each polygon mirror is wide, so the entire contact surface can be made with high accuracy. It is technically difficult to perform plane processing and parallel processing on the material, and this has been a factor in increasing costs. Another problem is that when setting the polygon mirror blank for mirror finishing, there is a high possibility that the accuracy will deteriorate due to dust, cutting chips, etc. in the processing chamber getting caught between the wide contact surfaces of the polygon mirror blank. It was hot.

<Objective> In view of the above points, it is an object of the present invention to provide a polygon mirror mirror finishing apparatus that satisfies both the productivity and processing accuracy requirements for polygon mirror blanks.

<Example> Hereinafter, an example of a polygon mirror according to the present invention will be described in detail with reference to the drawings.

FIG. 1a shows a plan view of a polygon mirror according to the present invention, and FIG. 1b shows a side sectional view thereof. A mounting hole 2 is provided in the center of the polygon mirror 10 for mounting on a drive motor for driving the polygon mirror 10 in high-speed rotation. Reference numeral 11 denotes a screw hole for a fixing screw for fixing the polygon mirror 10 to the drive motor. Reference numeral 12 denotes a balance weight mounting groove formed in a circular shape centered on the center of the polygon mirror 10. This balance weight mounting groove 12 can be formed by grooving using a lathe or the like. By bonding a balance weight (adhesive may be used) at a predetermined position inside the balance weight mounting groove 12, it is possible to maintain balance when the polygon mirror is rotated at high speed. The polygon mirror 10 is attached to the balance weight mounting groove 12.
It is divided into an inner peripheral part A, which is thinner, and an outer peripheral part B, which is thicker.

The polygon mirror of the above shape before mirror finishing (i.e. polygon millie blank) is used as the second
As shown in the figure, only eight pieces are set on the cylindrical protrusion of the polygon mirror polishing jig 4. 6 is a presser spring that presses only the outer circumferential portion B of the polygon mirror blank 10, and 7 is a screw that applies pressure to the presser spring 6 by lowering it while rotating. 8 is a single crystal diamond bite,
9 is a balance weight for keeping rotational balance with the single crystal diamond cutting tool 8. The single-crystal diamond cutting tool 8 rotates in a circular motion in the direction of the arrow in the figure. The single-crystal diamond cutting tool 8 approaches the laminated polygon mirror blank 10 while rotating, and cuts one side of the polygon mirror blank 10 into a mirror surface. At this time, the jig 4 is moved horizontally in a direction perpendicular to the rotation axis of the single-crystal diamond cutting tool 8. Polygon mirror blank 10
When mirror surface cutting is completed on one side of the jig 4, the jig 4 is rotated by 30 degrees, and mirror surface cutting is performed on the next side.

If the polygon mirror blank has the above shape, as shown in FIG. Parallel plane processing may be performed. In other words, the burden of parallel plane processing can be reduced. Furthermore, when setting the polygon mirror blank 10 on the polygon mirror mirror finishing jig 4, there is a risk that dust, cutting chips, etc. in the processing chamber may enter between the upper and lower polygon mirror blanks 10 and threaten parallelism. You can do less. It should be noted that the plurality of polygon mirror blanks 10 have the maximum thickness at the outer peripheral part B near the side surface where the mirror cutting process is performed;
Since the pressure from the presser spring 6 is applied to the portion, it is possible to effectively prevent the quality of the mirror-finished surface from deteriorating due to chatter during processing.

FIG. 3 shows a side sectional view of another embodiment of the polygon mirror according to the present invention. The figure a shows a structure in which a balance weight mounting groove 12 is provided within the range of the inner periphery A, the figure b shows a structure in which a balance weight mounting groove 12 is provided within the outer periphery B, and the figure c shows the bottom surface. It has a structure with different levels. In all the structures shown in the figure, the thickness is maximum near the side surface where mirror cutting is performed.
It has a structure in which only the portions above and below contact each other when stacked in multiple stages.

<Effects of the Invention> According to the present invention described above, it is possible to provide a polygon mirror mirror polishing apparatus that can achieve both reduction in manufacturing cost and improvement in quality.

[Brief explanation of drawings]

FIG. 1a is a plan view of an embodiment of a polygon mirror according to the present invention, FIG. 1b is a side sectional view thereof, FIG. 2 is an explanatory diagram of a cutting device, and FIG. 4 is a side sectional view of a conventional polygon mirror, FIG. 5 is an explanatory diagram of a cutting device, and FIG. 6 is an explanatory diagram of the internal structure of a laser printer. In the diagram, 2... mounting hole, 6... presser spring, 7...
Screw, 8... Single crystal diamond bite, 9...
Balance weight, 10... Polygon mirror blank, 11... Screw hole, 12... Balance weight mounting groove.

Claims (1)

[Claims] 1 comprising a central portion having a first thickness and a peripheral portion having a second thickness larger than the first thickness,
A plurality of polygon mirror blanks for producing a polygon mirror by mirror-finishing the side surfaces of the peripheral portions are stacked so that the peripheral portions of the second thickness are in contact with each other, and the polygon mirror blanks of the stacked polygon mirror blanks are A mirror finishing device for a polygon mirror, comprising a pressing means for pressing only a portion of the second thickness.