JPH0682085B2 - Polygon scanner jitter measurement device - Google Patents

Description

The present invention relates to a polygon scanner jitter measuring apparatus for measuring the jitter of a polygon scanner using the light beam of the present invention.

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

The substantially parallel light beam L1 emitted from the light source 1 is reflected by the polygon scanner 3 and the light beam L2 is reflected by the fθ lens 4
The light is split by the prism mirror 5a within a certain time after passing through and is incident on the sensors 6a and 6b, and is split by the prism mirror 5b and is incident on the sensors 6c and 6d within another time.

Jitter is detected by measuring the time interval from the moment when the powers of the light beams output from the sensors 6a and 6b are equal to the moment when the powers of the light beams output from the sensors 6c and 6d are equal.

(Problems to be Solved by the Invention) In the conventional polygon scanner jitter measuring apparatus, the power of the light beam fluctuates due to air fluctuations in a portion where the light beam passes through the air and the optical path length is long, which causes noise in the measurement value. Appears. Since the noise due to the fluctuation of the air is large, the jitter cannot be measured with higher accuracy.

(Means for Solving the Problems) The present invention has been made to solve the above problems. The present invention will be described with reference to FIG. 1 corresponding to an embodiment.
The substantially parallel light beam L1 emitted from the laser beam is reflected by the polygon scanner 3 and the light beam L2 passes through the fθ lens 4 and is split by the prism mirror 5a.
And the time when the light beam L1 reflected by the polygon scanner 3 passes through the fθ lens 4 and is split by the prism mirror 5b, and the power equal to the sensors 6c and 6d is detected. In the polygon scanner jitter measuring apparatus configured to measure the distance between the light source 1 and the polygon scanner 3, the optical axis between the fθ lens 4 and the prism mirror 5a, and the fθ lens 4 through the prism mirror. Wind-proof plastic or metal pipes 2a, 2b, 2c are arranged so that the optical axis between the pipes 5b and 5b penetrates.

(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 block diagram showing an embodiment according to the present invention, in which 1 is a light source, 2a, 2b and 2c are plastic or metal pipes, 3 is a polygon scanner, 4 is an fθ lens, and 5a, 5b is a prism mirror, and 6a, 6b, 6c, 6d are sensors.

The light beam generated from the light source 1 passes through the pipe 2a,
It is reflected by the polygon scanner 3. After passing through the fθ lens 4, the reflected light is split by the prism mirror 5a through the pipe 2b and is incident on both the sensors 6a and 6b for a required time, and is split by the prism mirror 5b through the pipe 2c and the sensor. It is incident on both 6c and 6d for the required time. The jitter is calculated by measuring the time from the moment when the powers measured by the sensors 6a and 6b become equal to the moment when the powers measured by the sensors 6c and 6d become equal. Pipes 2a, 2b,
By providing 2c, the noise of the measured value due to the fluctuation of air is reduced.

If the internal shapes of the pipes 2a, 2b, 2c are wavy when viewed in the longitudinal direction, it is possible to prevent irregular reflection of the light beam scanned by the polygon scanner 3 in the pipes 2a, 2b, 2c.

(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 is obtained, which allows a more accurate measurement of polygon scanner jitter.

[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 or metal pipe 3 …… Polygon scanner 4 …… fθ lens 5a, 5b …… Prism mirror 6a, 6b, 6c, 6d …… Sensor L1, L2, L3… … Light beam

Claims (1)

[Claims] 1. A substantially parallel light beam emitted from a light source 1.
The light beam L2 reflected by the polygon scanner 3 passes through the fθ lens 4, is split by the prism mirror 5a, and the time when the power equal to that of the sensors 6a and 6b is detected and the light beam L1 is reflected by the polygon scanner 3 Light beam L3 passes through fθ lens 4 and prism mirror 5b
In the polygon scanner jitter measuring apparatus, which is formed by measuring the interval between the time when the power equal to that of the sensors 6c and 6d is detected by the
Between the optical axis and the fθ lens 4 to prism mirror 5a
Optical axis between and, fθ lens 4 to prism mirror 5b
Windproof pipes 2a, 2b, 2c so that the optical axis between
A polygon scanner jitter measuring device characterized in that each of them is provided.