JPS58189609A - Light beam scanner - Google Patents

Abstract

PURPOSE:To increase a deflection angle by allowing the axis of geometric symmetry of a polygon mirror to cross its axis of rotation slantingly. CONSTITUTION:A rotating shaft 2, driving device 4, and regular polygon mirror 5 as individual constituent members are the same as those of a known device, but the axis 5 of three-dimensional geometric symmetry of this regular polygon mirror 5 is made obliquely cross the axial core 2a of the axis 2 of rotation slantingly at an intersectional angle alpha. When the regular polygon mirror 5 is formed in a regular 2n-angled prism and the axis 2 of rotation is rotated, lateral deflection of the deflection angle phi is 2pi/n radian. Thus, the deflection angle phi is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light beam scanning device for obtaining a two-dimensionally scanned light beam.

Conventionally, an apparatus for two-dimensionally scanning a light beam (t-t) is constructed by arranging two sets of means for one-dimensionally scanning a light beam so as to be orthogonal to each other.

The above one-dimensional scanning means include 0) a set of galvano mirrors using a plane mirror, (b) a set of polygon mirrors using a regular polygon mirror, and (/→ an AO deflection type using an ultrasonic deflection element), etc. There is.

Since the scanning means for the above-mentioned (a) galvano mirror set and (b) polygon mirror set must be equipped with a mirror drive device, arranging t-2 sets of these will result in a large and heavy device. Therefore, it is not suitable for applications that require small size and light weight, such as robot hands. Also A
O-polarization type scanning means has the disadvantage that the polarization angle cannot be increased due to the characteristics of the ultrasonic polarization element, and that it is expensive.

Furthermore, a common drawback of two-dimensional scanning devices configured using each of the above-mentioned primary scanning means t-2 sets is that optical alignment of the two sets of primary scanning means and synchronization of the drive system are required. Therefore, the drive system becomes complicated and expensive, and handling and adjustment is troublesome.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a light beam scanning device that is small in size, inexpensive, easy to handle, and capable of increasing the polarization angle.

To achieve the above object, the present invention provides a light beam scanning device comprising a polygonal columnar mirror and a rotational drive device, which projects and reflects a light beam on the side surface of the polygonal columnar mirror. The polygonal mirror is characterized in that the geometric symmetry axis thereof and the rotation axis of the polygonal prism mirror are obliquely intersected.

FIG. 1 is a schematic diagram illustrating the principle of scanning using a conventional regular polygon mirror. For convenience of explanation, the rotation axis 2t is drawn in the vertical direction, and scanning in the horizontal plane is referred to as horizontal scanning, and scanning in the vertical plane is referred to as vertical scanning (hereinafter,
6th. Fifth. 6th. (Same in Figure 7).

In Figure 1, 4 is a drive device for the rotating shaft 2, and 5 is the rotating shaft 2
A regular polygonal prism mirror is fixed to the mirror.

When the light beam 1 is projected onto the regular polygonal prism mirror 5 while rotating around its axis and reflected from the side surface, the lateral polarization angle θ of the original beam reflected light has a sawtooth waveform as shown in FIG. Become.

Further, as shown in FIG. 3, a cylindrical mirror 6 is formed,
When the intranuclear column is attached with its geometric symmetry axis 3 obliquely intersecting at an angle α with respect to the rotation axis 2, and the light beam 1 is projected while rotating around the rotation axis 2, the reflected light beam scans in the vertical direction. The vertical polarization angle ψ becomes a cosine curve as shown in FIG.

The basic principle of the present invention is that the horizontal scanning is caused by the rotation of the polygonal mirror around the concentric axis shown in FIG. 1, and the vertical scanning is caused by the rotation of the cylindrical mirror around the oblique axis shown in FIG. The scanning is performed in a complex manner by a single reflector.

Next, an embodiment of the present invention will be described with reference to FIG.

The individual components, the rotating shaft 2, the drive device 4, and the regular polygon mirror 5, are the same components as in the conventional device shown in FIG. The difference from the configuration of the conventional device shown in FIG. 1 is that the three-dimensional geometric symmetry axis 5 of the regular polygonal prism 5 and the rotation axis 2a of the rotation axis 2 are obliquely intersected at an intersecting angle α. be.

When the regular polygonal prism mirror 5 is formed into a regular 2n prism and the rotation axis 2 is rotated, the deflection angle of the lateral polarization angle θ becomes 2π/n radians as shown in FIG.

Also, the deflection angle of the vertical deflection angle ψ is 4α radians as shown in FIG. In this embodiment, since scanning is performed by a rotating mirror, the polarization angle can be increased compared to the AO polarization type.

The relationship between rotation speed and scanning speed is as follows. Positive 2
When the n-gon mirror rotates once, it scans once each in the positive and negative directions in the vertical direction, and 2n times only in the positive direction in the horizontal direction, so if the rotation speed is R rotations/sec, it scans in the vertical direction once. This means that 1/2R second is required for one horizontal scan, and 1/2nR second is required for one horizontal scan. Further, the vertical resolution of scanning is n lines.

According to this embodiment, two-dimensional light beam scanning can be realized with a simple configuration, which is extremely effective in reducing the size, weight, and cost of the device.Furthermore, a single driving means is used. This makes handling and adjustment of the drive system easy.

FIG. 6 shows an embodiment different from the above.

In this embodiment as well, the three-dimensional geometrical symmetry axis 5m1 of the regular polygonal prism mirror 5 and the rotation axis 2a of the rotation axis 2 are obliquely intersected at an intersection angle α. For example, the regular polygonal prism cutter 5 is made with its axis of symmetry 5m as follows.
It is configured so that it can also rotate around the .

A dish-shaped conical bearing having a support shaft 11 that penetrates and is fixed to a regular polygonal prism mirror 5 in alignment with its geometrical symmetry axis 5a, the lower end of which is sharpened into a conical shape, and whose bottom angle is larger than its apex angle. 9
At c, the support shaft is supported so that it can freely rotate 11 times, and the support shaft 11 can freely tilt.

A crank arm 2b\r is fixed to the lower end of the rotating shaft 2, and a bearing 9at is provided at the tip thereof to rotatably support the upper end of the support shaft 11.

A bevel gear 8ai is fixed near the upper end of the above-mentioned support shaft 11, and an internal bevel gear 7 is installed horizontally so as to be concentric with the rotating shaft 2.
Engage with a.

According to this embodiment, the deflection angle of the horizontal deflection angle θ is 2π/n radians, as in the previous example, and the deflection angle of the vertical deflection angle ψ is 4α radians.

If the number of teeth of the bevel gear 8a is kms and the number of teeth of the internal bevel gear is h, then when the rotating shaft 2 makes one revolution, it rotates every 1/1 rotation of the regular polygonal mirror 5 formed by the regular 2n prismatic mirror. Therefore, 1 of the rotation axis
Per rotation, it travels once each in the positive and negative directions in the vertical direction, and 2n(k-1) times in the horizontal direction.

Therefore, if the rotational speed of the rotating shaft 2 is eR times/sec, one longitudinal scan takes 1/2R seconds, and one horizontal scan takes 1/2n(k
-1) It takes R seconds. Further, the vertical resolution of scanning is n(k-1) lines. In this way, when a means for rotating the regular polygonal prism mirror around its geometric symmetry axis is provided, the vertical resolution can be improved.

FIG. 7 shows a further different embodiment.

In the embodiment shown in FIG. 6, the lower end of the support shaft 11 is mounted on a conical disc bearing 9
c, but in this embodiment, the support shaft 11 is used instead of this.
It is constructed as follows in the same way as the upper end side.

A bevel gear 8 having the same shape as the bevel gear 8a is attached to the lower end of the support shaft 11.
b is fixed and meshed with an internal bevel gear 7b installed horizontally and concentrically with the rotating shaft 2. This internal bevel gear 7b is the same as 7a.
It is a member with the same shape as . A rotating shaft 12t is provided aligned with the axis 2a of the rotating shaft 2, a crank arm 2cf is fixed to the upper end thereof, and the lower end of the support shaft 11 is rotatably supported via a bearing 9bf.

The power is transmitted to the rotating shaft 12 through the rotary tube gears 10a1, 10b1, 10C1, and 10dt of the rotating shaft 2, and the crank arms 2b and 2C are rotated in the same direction at the same speed while keeping the directions opposite to each other.

According to the embodiment shown in FIG. 7, fluctuations in the distance between the light beam reflection position and the rotation axis 2a can be suppressed lower than in the embodiment shown in FIG. A large angle can be taken, and scanning errors can be kept low.

As explained above, the present invention is small, lightweight, inexpensive, and easy to handle because the three-dimensional geometrical symmetry axis of the polygonal mirror and the rotation axis of the polygonal mirror are t-obliquely intersected. It has an excellent practical effect of being easy to clean.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of horizontal scanning by a polygonal prism mirror, Figure 2 is a diagram showing the relationship between rotation angle and deflection angle, and Figure 5 is a diagram showing the relationship between rotation angle and deflection angle.
The figure is an explanatory diagram of vertical scanning by a cylindrical mirror, and FIG. 4 is a diagram showing the relationship between the rotation angle and the deflection angle. Fifth
The figure is a perspective view schematically showing an embodiment of a light beam scanning device according to the present invention, and FIGS. 6 and 7 are perspective views schematically showing embodiments different from the above. DESCRIPTION OF SYMBOLS 1... Light beam, 2... Rotation axis, 2a... Rotation axis, 6... Geometric symmetry axis of cylindrical mirror, 4...
Drive device, 5... regular polygonal columnar mirror, 5a... same geometric symmetry axis, 6... cylindrical mirror, 7a, 7b... internal bevel gear, 8a, 8b... bevel gear, 9a, 9b-
Bearing, 10m, 10b, 10c, 10d-
-Gear, 11...Support shaft. Agent Patent Attorney Tadashi Akimoto Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. Consisting of a polygonal columnar mirror made of a polygonal column with mirrored side surfaces and a drive device that rotates the mirror at a constant speed, the light beam is projected onto the side surface of the polygonal columnar mirror and reflected. A light beam scanning device in which the geometric symmetry axis of the polygonal mirror and the rotation axis of the polygonal mirror are obliquely intersected. 2. The original beam scanning system according to claim 1, wherein the polygonal pillar mirror is additionally provided with a means for rotating around the geometric symmetry axis of the polygonal pillar mirror. Device.