JPH0735988B2 - Dynamic surface access measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotary polygon mirror used in a laser printer or the like,
The present invention relates to an evaluation device for an optical deflector such as a vibrating mirror.

(Prior Art) Conventionally, in an optical deflector, the accuracy of rotation and the tilt of the surface have been regarded as important characteristics, but the position of the reflecting surface from the center of rotation changes (hereinafter referred to as "moving in and out"). When,
Since these characteristics are affected, as a method of measuring the entrance and exit of the surface during rotation, as shown in FIG. 3, the incident and reflected light paths are arranged so as to be in the surface including the rotation axis of the optical deflector 28. A light source 24, an optical system 25, a beam splitter 26, a trigger detector 27, and a light source 21 configured so that light is incident on and reflected by a mirror at an angle when the trigger occurs, and an optical system.
22 and a surface position detection system including a beam position detector 23,
A surface entrance / exit measuring device has been proposed that measures the surface entrance / exit from the output of the detector 23 when a trigger occurs.

(Problems to be Solved by the Invention) In the surface entrance / exit measuring device proposed hitherto, the light emitted from the light source 21 is directly focused on the detector 23.
In such a configuration, the mirror surface is 28a as shown in FIG.
When a distance d is moved from 28 to 28b, the principal ray of the light emitted from the mirror is moved from L22 to L23, and the focal position is from F21 to F22.
Then, the incident point on the detector moved from F21 to S21, and the amount of entrance / exit was calculated from the amount of movement X2. However, since the surface of the mirror surface cannot be a perfect flat surface, if an angle error of the light emitted from the mirror occurs like L24 due to the ripple of the surface state, the incident point becomes S22 and the error Y2 occurs. However, there was a problem that accurate measurement was not possible.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and will be described with reference to FIGS. 1 and 2 corresponding to the embodiments. Trigger detection systems 5, 6 and 7 for generating a trigger signal by detecting the passage time of the reflected light which includes the incident and reflected light paths in the plane including the rotation center line of the optical deflector 9 which scans the light by rotating the mirror. , 8, and the position of the reflected light in a direction substantially perpendicular to the reflected light within the plane including the incident / reflected light at the time when the trigger signal is generated by the trigger detection system having incident and reflected light paths that are not perpendicular to the mirror surface. In the dynamic surface entrance / exit measuring device provided with the surface position detection systems 1, 2, 3, and 4, as an optical system of the surface position detection system, the incident light L1 has a focus on the mirror surface 9a, and a reflected light optical system. Reference numeral 3 forms an image F1 conjugate with the focal point O1 on the mirror 9a on the reflected light position detector 4. This is a dynamic surface entrance / exit measuring device characterized by being an optical system.

(Operation) In this case, since the focus O1 on the mirror surface 9a and the image point F1 on the detector 4 are conjugate, the reflected light L2 is always detected even if the angle of the reflected light changes depending on the surface state of the mirror surface 9a. Image point on container 4
Focus on F1. Further, when there is a plane entry / exit, the reflection point on the mirror surface moves, so the image point also moves, so that the plane entry / exit can be detected by the amount of movement.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 1,5 are light sources, 2 is an optical system for converging incident light on a mirror surface, and 3 is converging emitted light on a detector. Is an optical system, 4 is a beam position detector, 6 is an optical system for converging outgoing light on a trigger detector 8, 7 is a beam splitter, 8 is a trigger detector, and 9 is a rotary polygon mirror. Since the light emitted from the light source 5 and entering the trigger detector 8 is in the plane including the rotation axis of the rotary polygon mirror 9, the trigger detector 8 is not affected by the entrance and exit of the plane and generates a trigger signal. At this time, the light emitted from the light source 1 enters the beam position detector 4. The light emitted from the light source 1 is condensed on the mirror surface by the optical system 2, and the reflected light is condensed and incident on the beam position detector 4 by the optical system 3. Since the direction of the mirror surface at the time of trigger generation is constant, the fluctuation of the output of the beam position detector at that time is considered to be due to the surface entrance / exit, and the surface entrance / exit can be measured from this.

Next, the optical path will be described in detail with reference to FIG. Incident light L1
Forms a focus O1 on the mirror surface 9a, and the reflected light L2 forms a focus F1 on the detector 4 by the optical system 3. Here, as shown in the mirror surface 9b, when surface entering / exiting occurs, the reflection moves to the optical path L3,
Apparent focus shifts from O1 to O2 and detector 4 conjugate with it
The upper focus moves from F1 to F2. As a result, the light incident point on the detector 4 becomes S1, and the surface entrance / exit amount d is obtained from the distance X1 between F1 and S1. Further, even if the reflected light causes an angle error like L4 depending on the state of the mirror surface, the light incident point on the detector 4 at that time is S2, and the difference Y1 between S1 and S2 is Y2 in the conventional method. It is extremely small compared to, and enables highly accurate measurement.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to configure a highly accurate surface entrance / exit measuring device that is less affected by the state of the reflecting surface of the optical deflector as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a principle diagram of the present invention, FIG. 3 is a configuration diagram of a conventional example, and FIG. 4 is a principle diagram of a conventional example. 1,2,21,24… Light source 2,3,6,22,25… Condensing optics 4,23… Beam position detector 7,26… Beam splitter 8,27… Trigger detector 9,28… Optical deflection Device (rotating polygon mirror) 9a, 9b, 28a, 28b… Mirror surface L1, L2, L3, L4, L21, L22, L23, L24… Optical path

Claims (1)

[Claims] 1. A trigger detection system for generating a trigger signal by detecting a passage point of reflected light, which includes an incident light path and a reflected light path in a plane including a rotation center axis of an optical deflector for scanning light by rotating a mirror. And a surface position for detecting the position of the reflected light in a direction substantially perpendicular to the reflected light within the surface including the incident / reflected light at the time when the trigger signal is generated by the trigger detection system having incident and reflected light paths that are not perpendicular to the mirror surface. In a dynamic surface entrance / exit measurement device equipped with a detection system, as an optical system of the surface position detection system, incident light has a focus on a mirror surface, and a reflected light optical system reflects an image conjugate with the focus on the mirror. A dynamic surface entrance / exit measuring device characterized by being an optical system connected to an optical position detector.