JPS60186704A - Angle measuring instrument - Google Patents

Abstract

PURPOSE:To calculate a surface tilt error with high precision and efficiency by providing the 1st angle measuring part which measures the arrangement angle of eah flank of a body to be measured and the 2nd angle measuring part which measures the arrangement angle of the upper end surface of the body to be measured to a reference surface. CONSTITUTION:The angle measuring instrument has the 1st angle measuring part 4 which measures arrangement angles of respective flanks 3... of the body 1 to be measured and the 2nd angle measuring part 6 which measures the arrangement angle of the upper end surface 5 of the objective body 1 to the reference surface. Those measuring parts have position sensors 15 and 21 which have photodetection surfaces 15a and 21a. Then, deviations of photodetection points on the photodetection surfaces 15a and 21a from center positions correspond to surface tilt errors, and surface tilt extents of the flanks 3... and end surface 5 are shown by the same unit through an amplifier. Consequently, the surface tilt errors are calculated with high precision and efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an angle measuring device for measuring the surface tilt accuracy of a rotating polygon mirror used, for example, in a scanning optical system of a laser printer.

[Technical background of the invention and points of interest]

2. Description of the Related Art Recently, laser printers have been put into practical use as a printing method that uses a combination of laser technology and electrophotography technology. This laser printer irradiates a rotating polygon mirror with laser light from a laser light source, deflects the light, and then obtains a desired beam spot on a photoreceptor drum via an optical system. by the way.

The rotating polygon mirror has the shape of a polygonal prism, and its multiple side surfaces serve as reflective surfaces for laser light. and.

Accuracy of the angle between each side surface and one end surface serving as the reference surface,
The accuracy of the tab head inclination is one of the important factors that determines the printing performance of a laser printer.

Therefore, single-rotation polygon mirrors are machined so that the error in single-side tilting accuracy is within a few seconds, and then the single-sided tilting accuracy is inspected. In this case, the rotating polygon mirror is placed on a high-precision rotary table with one end surface side facing down, and the measurement is performed using an optical angle measuring device such as an autocollimator fixed at a fixed position. Or, conversely, with an optical angle measuring device placed on a high-precision rotary table, the accuracy of the surface inclination of the rotary polygon mirror is inspected with one end surface facing down, which will serve as the reference surface, at a fixed position. ing. However, Hiko pointed out that the above-mentioned conventional surface inclination accuracy inspection method includes the rotational accuracy of the single-turn table in the measurement value, and that there are foreign substances such as oil film and dust interposed between the reference surface and the mounting surface. Combined with the influence of

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an angle measuring device that can stably and accurately measure between two surfaces without being affected by the installation state of an object to be measured. With the goal.

[Summary of the invention]

Laser light is irradiated onto each of the two surfaces of the object to be measured, and the reflected laser light is received and converted into two electrical signals indicating the receiving position, and the difference between these two electrical signals is calculated. This difference is used to calculate the angular error of the angle formed by the two measurement surfaces with respect to the reference angle.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

1 and 2 show the angle measuring device of this embodiment. This angle measuring device consists of a workpiece holder (2) on which a workpiece (1), which is a rotating polygon mirror in the form of a regular octagonal prism, is placed and rotated; )... A first angular change measuring section (4) that measures the arrangement angle of the object (1), and a second angle that measures the arrangement angle of the upper end surface (5) that forms the reference surface of the object to be measured (1). A measurement unit (6), a rotation angle detection unit (F), and the first and second angle measurement units (4) i6 that detect the rotation angle of the object to be measured (2), and a rotation angle detection unit (7). an arithmetic processing unit (8) that is electrically connected to and calculates the surface tilt accuracy of each side surface (3) with respect to the end surface (5) (see Fig. 3);
It is composed of. However, the object holding part (2
) is connected to a cylindrical base (9), a disc-shaped table (10) rotatably supported on the upper part of this base (9), and this table 000 rotation axis Cl0B''). It consists of a motor aυ that rotationally drives the table all.

The object to be measured (1) is machined so that each side surface (3)... and both end surfaces form exactly right angles.
The coaxial button is placed on the Chee Lumi Q on the lower end surface side. Furthermore, the motor aη is connected to a rotation angle detection section (a four-tary encoder that generates force. This four-tary encoder is connected to a 1-branch unit and outputs 45 degrees and K Hals signals. ing.

On the other hand, the first angle measurement unit (4) includes a laser oscillator (13) that irradiates the side surface (3) of the object to be measured (1) placed on the table OQ with a laser beam Q; The body sensor α9 receives the laser reflected light (14) from the camera and converts it into a signal indicating the light receiving position.The body temperature sensor (L!19) has a light receiving surface (15a), A voltage corresponding to the amount of deviation along the arrow θe (direction parallel to the rotational axis of the force direction table CI+1) from the center position of the light receiving surface (1511) is induced. The angle measuring unit (6) 2 uses a laser oscillator α force that oscillates the laser beam al, and a second angle measuring unit that reflects the laser beam aQ toward the end surface (5) of the object to be measured (11) placed on the table OG. 1 reflecting mirror 08 and end face (5)
A second reflecting mirror that laterally reflects the laser reflected light aI from the second reflected light (a), and receives the laser reflected light α value reflected by this second reflected light (a) and converts it into a signal indicating the light receiving position. It consists of a physical detection sensor l2I). This position sensor (2+) has a light-receiving surface (21a), and the amount of deviation along the arrow θ direction (parallel to the IQ direction) from the center position of the light-receiving surface (21JI) A voltage of a corresponding magnitude is induced.

Therefore, the light receiving position on the light receiving surface (15a) of the center sensor (2) and the light receiving surface (21a) of the center sensor (2) is such that the measurement surface (3) and the end surface (5) are in the reference state, that is, the surface is tilted. They are each set to be at the center position when the angular error is zero. Then, each light receiving surface (
158) and (21M), the amount of deviation of the light receiving position from the center position shows the surface tilt angle error. Therefore, each position sun sensor (151° (21
) are connected to amplifiers (to), 124), respectively;
At these amplifiers (23+, +24), the side (3)...
and the amount of surface tilt of the end surface (5) is amplified to become a signal indicating the amount of surface inclination in the same unit.

The output sides of these amplifiers (C) and Q (A) are connected to the input side of the subtracter (C). Further, the output side of the subtracter (c) is connected to the input side of the comparator 2. This comparator (to) K has an upper threshold value VTI and a lower threshold value VTl set, and the subtracter (
When the signal from 29 is outside the range between the upper limit threshold value VTI and the lower limit threshold value VTI, a single side tilt abnormality detection signal is output to the storage display. This memory display device (Foundation) is RAM (Random Access M
memory ) and CRT (Cathode)
The measurement results of the surface tilt angle error of each measurement surface (3) are stored, and the measurement results can be displayed in a timely manner.

Furthermore, subtractor Q! 5 input side and memory display c17)
A one-rotation angle detection section (7) is connected to the input side of the sensor, and outputs a signal when each side surface (3)... comes to a measurement position. Thus, amplifiers c, i, ca, subtractor (
The two, the comparator (a) and the storage display (27), constitute a subtraction processing section (8).

Next, how to use the angle measuring device of this embodiment will be described.

First, the object to be measured O) is placed coaxially on the table (10) with the end surface that is not the reference surface facing down. Then,
Laser light α2), θ6) from laser oscillator α■, a7)
oscillates and starts the motor circle to release the tape fi.
/QI is rotated at a speed of once per minute. Then, the laser beam (12) is reflected by the side surface (3)..., and the laser reflected beam 0 is received by the front sensor (i).The laser beam αe is reflected by the first reflecting mirror After being reflected by the laser beam, the end face, and the second reflecting mirror, it is received by the laser reflected light (19 is the body sensor 01). Signals 8A and 8B indicating the amount of deviation from the center position of the receiving position of the laser reflected beams α and αl are transmitted to the amplifier (second floor, t24), respectively.
is output to. Then, in this amplifier (2nd floor, Ltd.), the signals SA, SB are amplified into signals 8C and 8D indicating the surface tilt angle error of each side surface (3) . . . and end surface (5). These signals SC and SB are output to a subtracter (c) K and the difference between them is calculated. This difference indicates the surface tilt error of a certain side surface (3) with respect to the end surface (5). Therefore, a certain side surface The angle between (3) and end face (5) is exactly 90
The above difference is calibrated in advance so that it becomes zero when it is formed at the same time.

At this time, even if a foreign object exists between the lower end surface of the object to be measured (1) and the upper surface of the table a0, the presence of this foreign object causes an error amount of twisting on the side surface (3) and end surface (5). Therefore, it is canceled out by the subtraction process. On the other hand, one rotation angle detection part (
From 7), a timing signal ST is output to the subtractor (A) every time each side surface (3)... comes to the measurement position.

Then, from the subtracter (2 [present]), the surface tilt error signal SF
I.

Each time the timing signal ST is input, the comparator 06
) is output. In this comparator (a), the voltage value V of the double-sided tilt error signal 8E is the upper limit threshold vTI and the lower limit threshold V
Comparison processing is performed to determine whether or not there is a difference with TI. The above upper limit threshold VTI is, for example, 5 seconds in angle, and the above lower limit threshold is
TI is set to correspond to, for example, 15 seconds in angle. If the single side tilt error signal SE is outside the range between the upper limit threshold VTI and the lower limit threshold VTI, the side tilt abnormality detection signal SF is output to the storage display (5). Then, in this storage display (5), each side (3)...
It memorizes the quality data of surface tilt accuracy and CR.
Display T.

In this way, the angle measuring device of this embodiment can be used for the object to be measured (1
) It is possible to quickly and accurately determine whether the surface inclination error, which is a relative angular error of each side surface (3)... with respect to the upper end surface (5) of the device, is good or bad. In particular, if there are large errors in the rotational accuracy and assembly accuracy of the workpiece holder (2) on which the workpiece (1) is placed, or if there is a problem between the top surface of the table On and the workpiece (1). Even when foreign matter (dust, oil film, etc.) is present, in this embodiment, the end face (5) and each side face (3)
)... Since we are trying to take into account the relative angle error,
It is completely unaffected by the above error factors.

In the above embodiment, the signals from the two subtracters are applied to the microcomputer, and the microcomputer stores and displays the absolute value of the single-sided tilt angle error, and also determines the quality of the single-sided tilt angle error. Furthermore, in the above embodiment, a rotating polygon mirror with an angle of 90° between two surfaces is exemplified as the object to be measured, but the angle error between the two surfaces is not limited to this. If it's something you want to measure.

It can be applied to objects to be measured at any angle. Also.

The object to be measured may be placed on a fixed table instead of a one-turn table for measurement. Yet again.

The positions of the laser oscillators (13), (17) and the position sensor (ls, on) may be set arbitrarily.Furthermore, other sensors such as a three-dimensional photo array may be used instead of the position sensor. good.

〔Effect of the invention〕

The angle measuring device of the present invention can measure surface inclination error, which is a relative angular error between two measurement surfaces formed on an object to be measured, with high precision and high efficiency. In particular, it is remarkable that the measured object is completely unaffected by the mounting condition of the measured object, such as placement error of the holding part that holds the measured object, or foreign objects interposed on the mounting surface. be effective.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an angle measuring device according to an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a diagram of an electric circuit system. (1): Object to be measured, (2): Object to be measured holding section. (3): Side surface (between measurements), (4B first angle measurement section. (5): End surface (measurement surface), (6): Second angle measurement section. (8): Arithmetic processing section, α side , α0: Laser light. Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 3 (7

Claims (1)

[Claims] A measurement object holding part that holds a measurement object on which two measurement surfaces for angle measurement are formed; a first angle measuring section that receives the reflected laser beam and converts it into an electrical signal corresponding to the light receiving position; and a laser beam that is irradiated onto the other flat surface and reflected at the other measurement surface. a second angle measuring section that receives light and converts it into an electrical signal corresponding to the light receiving position; and inputting an electrical signal from the first angle measuring section and an electrical signal from the second angle measuring section. An angle measuring device comprising: an arithmetic processing section that performs subtraction processing to calculate an angular error of the angle formed by the two measurement surfaces with respect to a reference angle.