JPH0682084B2 - Polygon scanner surface entrance / exit measuring device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon scanner surface entrance / exit measuring device for measuring surface entrance / exit of a polygon scanner using a light beam.

(Conventional Technology) FIG. 2 shows an example of conventional technology.

The substantially parallel light beam L1 emitted from the light source 1a is reflected by the polygon scanner 3 and is incident on the first prism mirror 5a to split the light beam L3. The first and second sensors 6c, 6
incident on d. Further, the light beam L12 emitted from the light source 1b is reflected by the polygon scanner 3 and then reflected by the beam splitter 4, and then split by the prism mirror 5b and incident on the third and fourth sensors 6a, 6b. At the moment when the output powers of 6a and 6b become equal, the ratio of the output powers of the first and second sensors 6c and 6d is measured,
The amount of horizontal displacement of the light beam L3 is detected. The amount of surface movement of the polygon scanner 3 is detected based on the amount of positional deviation.

(Problems to be Solved by the Invention) In the conventional polygon scanner surface entrance / exit measuring device, the power of the light beam fluctuates due to air fluctuations in a portion where the optical path through which the light beam passes through the air is long, and the measured value is noisy. Appears. Since the noise due to the fluctuation of the air is large, it is not possible to perform the surface coming-in / out measurement with higher accuracy.

(Means for Solving the Problems) The present invention has been made to solve the above problems. Referring to FIG. 1 corresponding to an embodiment, the present invention is a substantially parallel light beam emitted from a light source 1a. The light beam L3 reflected by the polygon scanner 3 by L1 is the first prism mirror
The light beam L2 emitted from the light source 1 is reflected by the beam splitter 4 after being incident on the beam splitter 5a and split into the first and second sensors 6c and 6d. 5b divides and is incident on the third and fourth sensors 6a, 6b,
At the moment when the output powers of 6b become equal, the output powers of the first and second sensors 6c and 6d are measured to detect the position of the light beam L3. 1, the optical axis between the prism mirror 5a and the polygon mirror 3 and the beam splitter 4
The windshields 2a, 2b, and 2c made of plastic or metal are arranged so that the optical axis between them and the optical axis between the polygon mirror 3 and the light source 1a penetrate therethrough.

(Operation) According to the present invention, since the pipe made of plastic or metal is provided so that the light beam passes through the optical path of the measuring device, the air outside the pipe and the air through which the light beam passes are blocked, Noise in measured values due to air fluctuations is reduced.

(Embodiment) FIG. 1 is a polygon scanner surface entrance / exit measuring apparatus showing a configuration diagram of an embodiment according to the present invention, in which 1a and 1b are light sources and 2a, 2b and 2 are shown.
Reference numeral c is a plastic or metal pipe, 3 is a polygon scanner, 4 is a beam splitter, 5a and 5b are prism mirrors, and 6a, 6b, 6c and 6d are sensors. Light source 1a
The light beam generated from the laser beam is reflected by the polygon scanner 3 through the pipe 2a, is split by the prism mirror 5a after passing through the pipe 2c, and is incident on the sensors 6c and 6d. The light beam generated from the light source 1b is a beam splitter 4
Through the pipe 2b, is reflected by the polygon scanner 3, passes through the pipe 2c again, and is bent downward by the beam splitter 4 to form a prism mirror.
It is divided by 5b and is incident on the sensors 6a and 6b. Sensor 6
a and 6b play the role of a trigger, and measure the power of the light beam incident on the sensors 6c and 6d at the moment when the powers measured by the sensors 6a and 6b become equal, and by the ratio, Calculate the position shift. Since this positional deviation is caused by the surface entering / exiting of the polygon scanner 3, the surface entering / exiting amount can be detected from the positional deviation amount.

By providing the pipes 2a, 2b, 2c, noise of measured values due to fluctuation of air is reduced.

If the internal shapes of the pipes 2a, 2b, 2c are liquid when viewed in the longitudinal direction, diffuse reflection of the light beam scanned by the polygon scanner 3 in the pipes 2a, 2b, 2c can be prevented.

(Effect of the Invention) As described in detail above, according to the present invention, it is possible to reduce noise due to air fluctuations by providing a pipe made of plastic or metal in a portion having a long optical path length in the measuring device. This has the advantage that an effect can be obtained, which enables more accurate measurement of the entrance and exit of the polygon scanner.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment according to the present invention, and FIG. 2 is a block diagram showing a conventional example. 1 …… Light source 2a, 2b, 2c …… Plastic pipe 3 …… Polygon scanner 4 …… Beam splitter 6a, 6b, 6c, 6d …… Sensor L1, L2, L3 …… Light beam

Claims (1)

[Claims] 1. A substantially parallel light beam emitted from a light source 1a.
The light beam L3 reflected by the polygon scanner 3 by L1 is made incident on the first prism mirror 5a and split into first and second light beams.
Of the light beam L2 emitted from the light source 1b and reflected by the polygon scanner 3 is reflected by the beam splitter 4 and then split by the prism mirror 5b. Sensor 6a, 6
A polygon scanner surface formed by detecting the position of the light beam L3 by measuring the ratio of the output powers of the first and second sensors 6c, 6d at the moment when the output powers of the sensors 6a, 6b become equal to each other at b. In the entrance / exit measuring device, an optical axis between the polygon scanner 3 and the first prism mirror 5a, an optical axis between the polygon mirror 3 and the beam splitter 4, and an optical axis between the polygon mirror 3 and the light source 1a. A polygon scanner surface entrance / exit measuring device characterized in that windproof pipes (2a, 2b, 2c) are arranged so as to penetrate therethrough.