JPS6047528B2 - Linear encoder scale support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a support device for sliding a scale of a linear encoder.

In general, a linear encoder has a transparent main scale with a so-called light and dark striped pattern in which light-transmitting parts and light-blocking parts are arranged alternately at a constant pitch, and an index scale with the same pattern faces and slides. In addition, a photoelectric conversion element (mainly a phototransistor or a photodiode) is arranged so as to receive light from a light source through both patterns through a slit.

Every time the main scale moves by one pitch relative to the index scale, the photoelectric conversion element detects a change in brightness and darkness by one cycle, and a photoelectric pulse output is obtained. The pitch of light and darkness of each scale that generates this pulse is, for example, a 4μ or 5μ width pattern, so it is possible to measure the length with great precision, but the main scale is always at a constant position relative to the index scale. If there is not a relationship (the distance between the two must be maintained at 0.01 to 0.0577j77l), pulse detection will not be stable and measurement of the amount of movement will not be reliable. [Conventional technology and its problems] However, the conventional linear encoder, for example, as introduced in Japanese Utility Model Application Publication No. 54-91133,
Using the reference numerals in the publication, a head section called a detection mechanism 3 and a fixed slit holder called a slider 13 to which a moving scale is fixed are integrally connected, and the head section is connected to the main body of the linear encoder. When assembling the head, the posture (position) of the head affects the positional accuracy of the fixed slit holder, so care must be taken when assembling, which may require a jig or require machining of the contact area between the two. It needs to be finished with very high precision.

Otherwise, assembly errors and processing errors in the sliding head will immediately affect the delicate relationship between the main scale and the index scale. For example, the gap between both scales is 0 as described above.
．． 01~0.05T! If the gap exceeds 0.05TnIIL, misunderstandings may occur due to the parallelism or diffraction of light between the phototransistor and the light emitting diode, and contact wear of the sliding scales may occur. This results in damage to the fine scale, making it impossible to detect. [Means for Solving the Problems] Accordingly, the present invention provides a linear encoder that is inexpensive and has high measurement accuracy, while eliminating these conventional drawbacks.

Fig. 1 is a partially omitted overall front view, Fig. 2 is a side view with one side cover for fixing the scale in Fig. 1 removed, Fig. 3 is a sectional view taken along line A-A in Fig. 1, and Fig. The figure below shows the parts diagram.
The linear encoder in this example is a fixed linear encoder.
The encoder consists of a main body 1 and a head part 2 that reciprocates on the main body 1 while taking a reference within the main body 1.

The main body 1 is in the form of a tunnel-like box, and a main scale 4 with a band-shaped light and dark pattern is placed approximately in the center of the bottom surface 3 in a horizontally elongated manner (see Figs. 2 and 3).
(see figure). Now, on one side of the main scale 4, there is an index scale 5 with a light and dark pattern that slides facing each other on one side, and this index scale 5 and the main scale 4 are sandwiched in the middle. A phototransistor 6 and a light emitting diode 7 are provided facing each other so that the index scale 5 is fixed to the B side of a fixed slit holder 8 (see FIG. 3), and the phototransistor 6 is printed on a substrate 9. Provided as a substrate,
The substrate J9 is fixed to the C surface with screws 11.

Further, the light emitting diode 7 is provided as a printed circuit board on another substrate 10, and the substrate 10 is provided with a fixed slit holder 8.
It is fixed to the D side with screws 11. This fixed slit holder 8 is in a state where it is held between U-shaped intermediate fittings 12 when viewed from the front (see Fig. 1). The wire spring 13 is inserted into the protrusion 31 provided on the opposite side of the wire spring 1.
A fixed slit holder is attached to the intermediate fitting 12 by inserting one end of 3 into one leg 14 of the intermediate fitting 12 and inserting the other end into the other leg 15 of the intermediate fitting 12 and fixing it with a push bolt 16. 8 is in a suspended state. The fixed slit holder 8 is attached to the horizontal bar 17 of the intermediate fitting 12.
The J-index scale 5 and main scale 4 attached to the fixed slit holder 8 are constantly pressed against the main scale 4 by a compression coil spring 19 centered on a dowel pin 19'' screwed onto the inclined surface 18 of the main scale. The compression coil spring 19 may be omitted if the reaction force of the deflection of the wire spring 13 itself acts as the same pressing force as the coil spring 19.Next, the compression coil spring 19 may be omitted. Attachment members 20 and 21 made of ultra-high density polyethylene as shown in FIG. , 21 are made to slide in contact with the upper surface and lower side surface of the main scale 4, so that the index scale 5 slides smoothly.

On the other hand, the intermediate fitting 12, as shown in FIGS. 2 and 3,
A strike member 23 at the end of the leaf spring 22 provided on the upper surface to eliminate rattling, a strike member 24 provided on the upper surface of the horizontal bar 17, and a strike member 25 provided on the back side of the intermediate metal fitting 12, but the linear - Since it is adapted to slide in contact with the inner surface of the box of the encoder main body 1, the intermediate fitting 12 can also slide smoothly. Furthermore, the head section 2 is placed astride the intermediate metal fitting 12 with a buffer mechanism that is not affected by the posture of the head section 2 interposed therebetween. .

That is, in the buffer mechanism, a front leg 26 is suspended from one side of the head portion 2, a ball 27 is held on the front leg 26, and an intermediate small metal fitting 29 is attached to the other side via a leaf spring 28.
, and push bolts 3 horizontally to this intermediate small metal fitting 29.
This is a configuration in which 0 is screwed. Therefore, the head section 2 is
It is provided so as to abut and straddle the ball 27 on one side with respect to the front and back of the sliding direction of the intermediate metal fitting 12. Therefore, in the head section 2 that moves along the guide section along with the object to be measured, although it is affected by the object to be measured, the leaf spring 28,
Because the buffer mechanism such as the point contact of the ball 27 is used, the posture (position) of the head section 2 is linear ● The positional relationship between the intermediate metal fitting 12 inside the encoder body 1 and, by extension, the index scale 5 and the main scale 4 , it becomes unaffected. Note that the buffer mechanism may be configured as long as it has an elastic body such as the leaf spring 28 so that the posture (position) of the head section 2 does not affect the positional relationship of the middle bracket 12, etc.; Considering the positional accuracy between the head portion 2 and the intermediate fitting 12, it is necessary that at least one side of the head portion 2 and the intermediate fitting 12 be in contact with each other via a rigid member such as a ball 27, for example.

Although the configuration of the embodiment of the present invention is as described above, the shapes of each part are somewhat complicated, so the parts are shown in FIGS. 5 to 7.

FIG. 5 is a front view of the fixed slit holder 8 with the intermediate fitting 12 assembled thereto, FIG. 6 is a side view of FIG. 5, and FIG. 7 is a partially cutaway plan view of the fixed slit holder 8.

Reference numeral 32 in FIG. 5 is a window in which a plurality of phototransistors 6 are provided, reference numeral 33 in FIGS. 6 and 7 is a drilled hole through which the wire spring 13 is inserted, and reference numeral 34 in FIG. 14,
15 shows a drilled hole through which the wire spring 13 is inserted. According to the linear encoder having the above configuration, the head section 2 is moved along the guide together with the object to be measured, and the linear encoder main body 1 is fixed near the object to be measured. If the head section 2 is then moved, the index scale 5 provided inside the main body 1 will slide along one side of the main scale 4.

As a result, the light and dark patterns applied to both scales 4 and 5 are . It polymerizes, which is detected optically and converted into a radio waveform that transmits a pulse. This pulse output is displayed digitally. Therefore, the moving distance of the head section 2 can be digitized and displayed, but the known principle is used as is. In short, since the configuration of the present invention adopts the configuration described in the claims, the following effects are achieved.

〔Effect of the invention〕

1 A buffer mechanism is interposed between the main scale and the index scale and the head part that reciprocates along the guide with the object to be measured on the linear encoder body, so that the moving scale and this Only the fixed slit holder that fixes and holds the main scale and the index scale affects the minimum distance between the main scale and the index scale, and other members do not affect the minimum distance between the main scale and the index scale.

In other words, the posture of the head that is affected by the object to be measured (for example, it is tilted due to the weight of the object to be measured) is irrelevant; in addition, although the head is guided by a separate guide section, the finish of that guide section is irrelevant. It is not affected by errors, and in addition,
Since the moving scale is not integrated with other parts, such as intermediate metal fittings, with a spring interposed between them, overall pulse detection is stable and accurate measurement is possible, and as a result, both scales avoid contact wear. It also does not erase the brightness and darkness patterns that occur. 2. The number of parts to be finished with high precision has been minimized, so there is no need to finish the part where the head part and the linear encoder body are assembled with high precision, so it can be manufactured without the need of a skilled engineer, and processing costs can be reduced. This makes it possible to reduce the cost and make the linear encoder inexpensive.

3. In other words, the presence of the spring and the presence of the buffer mechanism complement each other, making it possible to avoid being influenced by manufacturing errors of the linear encoder itself or the posture of the object to be measured during measurement.

It goes without saying that the linear encoder of the present invention can also be applied to a measuring instrument that combines an optical system comprising a microscope and a photoelectric element.

[Brief explanation of the drawing]

FIG. 1 is a partially omitted overall front view of an embodiment of the present invention, and FIG. 2 is a side view of FIG. 1 with one side cover for fixing the scale removed.
Figure 3 is a sectional view taken along the line A-A in Figure 1, Figure 4 is an external view of the attachment member, Figure 5 is a front view of the fixed scale holder with the intermediate metal fittings assembled, and Figure 6 is a side view of Figure 5. , FIG. 7 shows a plan view of the fixed slit holder. 1...Linear encoder body, 4...
Main scale, 5... Index scale, 8... Fixed slit holder, 12... Intermediate metal fitting, 13... Wire spring, 19... Compression coil spring.

Claims (1)

[Claims] 1. In a linear encoder in which one of the main scale and index scale is fixed and the other scale is moved to face the fixed scale, a fixed slit to which the moving scale is fixed. The holder 8 is suspended from an intermediate metal fitting 12 that slides while being referenced to the linear encoder main body 1, and a spring force is interposed between the fixed slit holder 8 and the intermediate metal fitting 12, and the linear - The head section 2, which is reciprocated along with the object to be measured on the encoder main body 1, is attached to the intermediate metal fitting 12 through a buffer mechanism that makes the posture of the head section 2 irrelevant. A scale support device for linear encoders. 2. The scale of the linear encoder according to claim 1, wherein the buffer mechanism includes a ball 27 disposed on the head portion 2 and an elastic body 28 that urges the intermediate fitting 12 toward the ball 27. Support device.