CN105091747B - A kind of cursor type grating scale - Google Patents

Abstract

The invention discloses a vernier type grating ruler, which comprises a static grating, an active grating and a vernier grating. In the lens group, lens A modulates the outgoing light of the light source into parallel light, and lens B amplifies the light after the light source passes through the grating and projects it onto the CCD. The present invention adopts the vernier principle to improve the measurement accuracy of the grating ruler. Common engraved lines are used on the stationary grating, and ordinary engraved lines can also be used for the active grating for measuring the grating, but a certain length is selected on the vernier grating. The engraved line of the root. During the moving process of the grating, the vernier grating and the static grating must have the situation that the reticle lines of the three moving gratings are completely occupied by the reticle lines of the three static gratings, and this situation is unique. Read the vernier value according to the degree of the vernier grating, add the degree of the active grating to read the degree of the grating.

Description

A Vernier Grating Ruler

technical field

The invention relates to a grating ruler, in particular to a grating ruler with a vernier.

Background technique

At present, the grating scales on the market use the principle of grating moiré fringes or the shading or reflection of light by the grating to count. Specifically, when the active grating moves to a certain position, the optical path of the static grating will be blocked or reflected by the passive grating, and the active grating continues to move, and the optical path of the static grating will be opened again, and the grating ruler will emit a pulse signal at this time. Due to the average effect of the grating lines, such a measurement method can achieve high accuracy, but it is often affected by the processing technology when processing the grating. The number of lines per mm is often between 10 and 100 lines, and although the processing technology is relatively mature, it is also complicated. .

At present, the grating measurement only uses the pulses generated by the relative motion of the active grating and the static grating to measure the moving distance, and each pulse corresponds to a certain displacement. The movement displacement can be obtained by counting the number of pulses and multiplying by the distance corresponding to each step. However, the measurement accuracy of such a measurement method is limited, and it is difficult to achieve high-precision measurement.

Contents of the invention

In order to solve the above-mentioned technical problems in the prior art, the present invention provides a vernier grating scale, including a stationary grating, an active grating and a vernier grating, the active grating is placed on the static grating, and the vernier grating is fixed on the side of the active grating , the stationary grating, the active grating and the vernier grating are placed in a set of lenses, the lens A modulates the outgoing light of the light source into parallel light, and the lens B amplifies the light after the light source passes through the above grating and projects it onto the CCD.

Furthermore, the positions of lens A, lens B and the light source are relatively fixed, and they move together with the active grating.

Furthermore, the CCD converts the optical signal into an electrical signal and transmits it to the computer. The computer judges the position of the active grating by counting the number of light pulses, and then judges the reading value of the vernier by the light intensity transmitted through the vernier grating.

Further, the vernier scale is a linear scale.

Further, the vernier scale is a circular scale.

Further, there are three vernier grating reticle images within the length where the images of the three stationary grating reticle lines appear in the electrical signal transmitted by the CCD. The middle one of the three vernier reticle lines is the vernier reading, and the light intensity at this point is the maximum.

Further, the sum of the active grating reading and the vernier grating reading is the overall reading of the grating scale.

The present invention adopts the vernier principle to improve the measurement accuracy of the grating ruler. Specifically, common engraved lines are used on the static grating, and common engraved lines are used for the active grating for measuring the grating, but a certain length is selected on the vernier grating. The grating lacks one reticle. During the moving process of the grating, the vernier grating and the static grating must have the situation that the reticle lines of the three moving gratings are completely occupied by the reticle lines of the three static gratings, and this situation is unique. Read the vernier value according to the degree of the vernier grating, and add the degree of the active grating to read the degree of the grating.

Description of drawings

Figure 1 is a schematic diagram of the structure of a linear grating ruler;

Fig. 2 is a schematic diagram of a linear grating cursor;

Fig. 3 is a schematic diagram of a circular grating structure;

Fig. 4 is a schematic diagram of a circular grating cursor;

Fig. 5 is a schematic diagram of the variation of the vernier grating luminous flux extremum point;

The meanings of reference signs in the figure: 1.1 light source, 1.2 lens A, 1.3 stationary grating, 1.4 active grating, 1.5 vernier grating, 1.6 lens B, 1.7 CCD; 2.1 stationary grating reticle, 2.2 vernier grating reticle; 3.1 light source, 3.2 Lens A, 3.3 Static grating, 3.4 Active grating, 3.5 Vernier grating, 3.6 Lens B, 3.7CCD; 4.1 Static grating reticles, 4.2 Vernier grating reticles; 5.1 Static grating distance, 5.2 Luminous flux extreme point change curve, 5.3 Luminous flux.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

Embodiment one

As shown in Figure 1, the active grating 1.4 is placed on the stationary grating 1.3, the vernier grating 1.5 is fixed on the side of the active grating 1.4, the stationary grating 1.3, the active grating 1.4 and the vernier grating 1.5 are placed in a group of lenses, and the lens A The outgoing light of the light source is modulated into parallel light, and the lens B amplifies the light after the light source passes through the grating and projects it onto the CCD. The positions of lens A, lens B and the light source are relatively fixed, and they move together with the active grating 1.4. CCD1.7 converts optical signals into electrical signals and transmits them to the computer. The computer judges the position of the active grating by counting the number of light pulses, and then judges which position is the reading value of the vernier by the light intensity transmitted through the vernier grating 1.5.

No matter which position the cursor moves to, the situation shown in FIG. 2 exists. At this time, the electrical signal transmitted by the light through the CCD will show the images of three static grating lines, and there will be three vernier grating line images within the length, and the middle one of the three vernier lines is the vernier reading. At this moment, the luminous flux at the grating reaches the maximum value.

The sum of the active grating reading and the vernier grating reading is the overall reading of the grating scale.

The sensitivity obtained by this reading method is higher than that of the traditional grating, but the requirements for the grating line process have not been improved.

The specific embodiment of the present invention is described in conjunction with accompanying drawing 1. The static grating 1.3 is engraved with a grating of 10 lines per millimeter, the active grating 1.4 is engraved with a grating at the same interval as the static grating 1.3, and a section of 1.9 mm in length is selected on the vernier grating and engraved with 20 gratings. According to the principle of the vernier, the grating can be read The minimum scale value is 0.005mm. Compared with the ordinary grating ruler with only active grating, the accuracy is increased by 20 times.

The static grating 1.3 adopts ordinary reticle lines, and the active grating 1.4 of the measuring grating also adopts ordinary reticle lines, but the vernier grating 1.5 is engraved with one less reticle line than the static grating 1.3 on a certain length. During the moving process of the grating, the vernier grating 1.5 and the stationary grating 1.3 will have the situation that the reticle lines of the three vernier gratings are completely in the interval of the reticle lines of the three static gratings, and this situation is unique. Read the vernier value according to the degree of the vernier grating, and add the degree of the active grating to read the degree of the grating.

No matter which position the cursor moves to, the situation shown in FIG. 2 exists. At this time, the electrical signal transmitted by the light through the CCD will appear as the images of the three stationary grating lines. There are three vernier grating line images within the length of the length, and the middle one of the three vernier lines is the vernier reading. The light intensity at this point will also reach the maximum value.

The sum of the active grating reading and the vernier grating reading is the overall reading of the grating scale.

Embodiment two

Another embodiment of the patent of the present invention is described in conjunction with accompanying drawings 3 and 4 . What this implementation mode will adopt is a kind of circular grating, engraved with the grating of every degree 10 lines on the static grating 3.3, active grating 3.4 is engraved with the grating that is consistent with the interval of the static grating 3.3, selects a section of 1.9 ° length engraved on the vernier grating 3.5 There are 20 gratings, according to the vernier principle, the minimum scale value that can be read is 0.005°. Compared with the ordinary grating ruler with only active grating, the accuracy is increased by 20 times.

Degree mode and all the other are consistent with embodiment one.

Claims (7)

1. A vernier grating scale, comprising stationary grating, active grating and vernier grating, is characterized in that: active grating is placed on stationary grating, and vernier grating is fixed on the side of active grating, and stationary grating, active grating and vernier grating are placed In a set of lenses, lens A modulates the outgoing light of the light source into parallel light, and lens B amplifies the light after the light source passes through the grating and projects it onto the CCD; Ordinary reticles are used on the stationary grating, and the active grating of the measuring grating also uses ordinary reticles, but a certain length of vernier grating is engraved with one less reticule than the static grating. 2. The vernier type grating ruler according to claim 1, characterized in that the positions of lens A, lens B and light source are relatively fixed, and move together with the active grating. 3. The vernier grating ruler according to claim 1 or 2, characterized in that: the CCD converts the optical signal into an electrical signal and transmits it to the computer, and the computer judges the position of the active grating by counting the number of light pulses, and then passes through the vernier The light intensity of the grating judges the reading value of the vernier. 4. The vernier type grating scale according to claim 1 or 2, characterized in that: the vernier type grating scale is a linear grating scale. 5. The vernier type grating scale according to claim 1 or 2, characterized in that: the vernier type grating scale is a circular grating scale. 6. The vernier type grating scale as claimed in claim 3, characterized in that: there are three vernier grating reticle images in the length where the images of three static grating reticle lines appear in the electrical signal transmitted by the CCD, and the middle of the three vernier reticle lines One is the cursor reading, and the light intensity at this point is the maximum value. 7. The vernier type grating ruler according to claim 6, characterized in that: the sum of the active grating reading and the vernier grating reading is the overall reading of the grating ruler.