Absolute measurement scale system

Claim 2

An absolute measuring scale system including a scale which extends a measuring length, and a measuring head which is movable relative to the scale, and which further includes a fine-measurement sensor which is operative in measuring the absolute values within each of a number of intervals located sequentially along the scale, and a coarse-measurement sensor operative in measuring the absolute values with regard to the interval in which the fine-measurement sensor is located at that moment, where the scale (2) includes a carrier (38) made of a transparent and form-stable material, which has provided on its surface a coating which forms an opaque pattern (3, 4; 3', 4'); which pattern forms along the length of the scale (2) transparent, mutually parallel binary code tracks (12) for use by said coarse measurement sensor and where the measuring head (1) incorporates light-emitting (5) and light-sensitive (6) devices by means of which the measuring head (1) is intended to sense the code track (12), the coarse-measurement sensor including the code-tracks (12) and said light emitting (5) and light sensitive (6) devices; and where said pattern (3, 4; 3', 4') along the length of the scale (2) also forms a plurality of sensing members which are intended to co-act with the fine-measurement sensor, said fine measurement sensing members including electrodes (18) which are formed by means of said surface coating and which, in coaction with electrodes (23-27, 28) provided in the measuring head (1), are included in a capacitive measuring system forming said fine measurement sensor.

Claim 3

The system as defined as in claim 1 wherein the electrodes (18) are mutually identical and are placed at mutually equal distances apart along the length of the scale (2).

Claim 4

The system as defined in claim 2 wherein at least one each of the light-emitting (5) and light-sensitive (6) devices are assigned to each code track (12); and in that there is provided a sensing circuit (21) which is intended to read the respective code tracks (12), by igniting the different light-emitting devices (5) sequentially, such that only one device is ignited at a time.

Claim 5

The system as defined in claim 3 wherein the coarse-measurement sensor with associated code tracks (12) is assigned a division which is a multiple of half the greatest significant measuring length assigned to the fine-measurement sensor.

Claim 6

The system as defined in claim 2 wherein the surface coating consists of chromium.

Claim 7

The system as defined in claim 1 wherein at least one each of the light-emitting (5) and light-sensitive (6) devices are assigned to each code track (12); and in that there is provided a sensing circuit (21) which is entended to read the respective code tracks (12), by igniting the different light-emitting devices (5) sequentially, such that only one device is ignited at a time.

Claim 8

The system as defined in claim 1 wherein the coarse-measurement sensor with associated code tracks (12) is assigned a division which is a multiple of half the greatest significant measuring length assigned to the fine-measurement sensor.

Claim 9

The system as defined in claim 7 wherein said patterned surface coating is formed by first applying a covering surface layer of uniform thickness and by subsequently removing parts of the surface layer by means of a photolithographic etching process.

Claim 10

The system as defined in claim 1 wherein said patterned surface coating is formed by first applying a covering surface layer of uniform thickness and by subsequently removing parts of the surface layer.

Claim 11

The system as defined in claim 8 wherein the surface coating consists of chromium.

Claim 12

The system as defined in claim 9 wherein portions of said covering layer are removed by means of a photolithographic etching process.

Claim 13

The system as defined in claim 1 wherein the surface coating consists of chromium.

Claim 14

The system as defined in claim 1 wherein said transparent material is glass.

Claim 15

The system as defined in claim 1 wherein said mutually parallel binary code tracks are formed in accordance with the so-called Grey-code.

Claim 16

An absolute measuring scale system including a scale which extends a measuring length, and a measuring head which is movable relative to the scale, and which further includes a fine-measurement sensor which is operative in measuring the absolute values within each of a number of intervals located sequentially along the scale, and a coarse-measurement sensor operative in measuring the absolute values with regard to the interval in which the fine-measurement sensor is located at that moment, where the scale (2) includes a carrier (38) made of a transparent and form-stable material which has provided on its surface a coating which forms an opaque pattern (3, 4; 3', 4') which pattern forms along the length of the scale (2) transparent, mutually parallel binary code tracks (12) for use by said coarse measurement sensor and where the measuring head (1) incorporates light-emitting (5) and light-sensitive (6) devices by means of which the measuring head (1) is intended to sense the code track (12), the coarse-measurement sensor including the code-tracks (12) and said light-emitting (5) and light sensitive (6) devices; and where said pattern (3, 4; 3', 4') along the length of the scale (2) also forms a plurality of sensing members which are intended to co-act with the fine-measurement sensor, said fine measurement sensor being an optical sensor including light-permeable openings (10) which are formed by means of the surface coating and which are placed along a line extending along the length of the scale (2); in that there is located on one side of the scale (2) a light-emitting device (30) which is intended to transmit light through said openings (10); and in that there is located on the other side of the scale (2) a light-sensitive device in the form of a position-sensitive photo-sensor (11) which has an extension in the longitudinal extension of the scale (2) which exceeds the distance (A) between two mutually adjacent openings and which is intended to produce a voltage which is proportional to the position of a light spot on the photo-sensor this light spot deriving from light transmitted by said light-emitting device (30) through one of the openings (10) said light-emitting device (30) further including two light-emitting devices (32, 33) which are located at a mutual distance apart (B) which slightly exceeds the distance (A) between two mutually adjacent light-permeable openings (10); and in that a sensing circuit (34) is intended to firstly ignite solely one light-emitting device (32) and then ignite solely the other device (33), and in that the sensing circuit (34) is intended therewith to sense the output voltage from the photo-sensor (11) deriving from illumination by means of each of the two light-emitting devices (32, 33); and in that the sensing circuit (34) is constructed to accept solely that output voltage of said two output voltages which lies within a pre-determined voltage range (V1 to V2) corresponding to a given length interval (L1 to L3) of the photo-sensor (11).

Claim 17

An absolute measuring scale system including a scale which extends a measuring length, and a measuring head which is movable relative to the scale, and which further includes a fine-measurement sensor which is operative in measuring the absolute values within each of a number of intervals located sequentially along the scale, and a coarse-measurement sensor operative in measuring the absolute values with regard to the interval in which the fine-measurement sensor is located at that moment, where the scale (2) includes a carrier (38) made of a transparent and form-stable material which has provided on its surface a coating which forms an opaque pattern (3, 4; 3', 4') which pattern forms along the length of the scale (2) transparent, mutually parallel binary code tracks (12) for use by said coarse measurement sensor and where the measuring head (1) incorporates light-emitting (5) and light-sensitive (6) devices by means of which the measuring head (1) is intended to sense the code track (12), the coarse-measurement sensor including the code-tracks (12) and said light-emitting (5) and light sensitive (6) devices; and where said pattern (3, 4; 3', 4') along the length of the scale (2) also forms a plurality of sensing members which are intended to co-act with the fine-measurement sensor, said fine measurement sensor being an optical sensor including light-permeable openings (10) which are formed by means of the surface coating and which are placed along a line extending along the length of the scale (2); in that there is located on one side of the scale (2) a light-emitting device (30) which is intended to transmit light through said openings (10); and in that there is located on the other side of the scale (2) a light-sensitive device in the form of a position-sensitive photo-sensor (11) which has an extension in the longitudinal extension of the scale (2) which exceeds the distance (A) between two mutually adjacent openings and which is intended to produce a voltage which is proportional to the position of a light spot on the photo-sensor this light spot deriving from light transmitted by said light-emitting device (30) through one of the openings (10) said light-emitting device (30) further including two light-emitting devices (32, 33) which are located at a mutual distance apart (B) which slightly exceeds the distance (A) between two mutually adjacent light-permeable openings (10); and in that a sensing circuit (34) is intended to firstly ignite solely one light-emitting device (32) and then ignite solely the other device (33), and in that the sensing circuit (34) is intended therewith to sense the output voltage from the photo-sensor (11) deriving from illumination by means of each of the two light-emitting devices (32, 33); and in that the sensing circuit (34) is constructed to accept solely that output voltage of said two output voltages which lies within a pre-determined voltage range (V1 to V2) corresponding to a given length interval (L1 to L3) of the photo-sensor (11).

Claim 18

The system as defined in claim 15 wherein the coarse-measurement sensor with associated code tracks (12) is assigned a division which is a multiple of half the greatest significant measuring length assigned to the fine-measurement sensor.