Position encoder device

Abstract

An encoder reading head for reading an encoder scale is described. The encoder reading head includes a detector, such as a one-dimensional optical imaging array, having multiple sensor elements (302) that generate multiple analog sensor signals. A digitizer is provided to convert the multiple analog sensor signals into digitized sensor values, and an incremental position generator (308) is configured to receive the digitized sensor values ​​and generate an incremental position output (310) therefrom. The digitizer includes multiple analog-to-digital converters (304), and the incremental position generator receives multiple digitized sensor values ​​in parallel from the multiple analog-to-digital converters (304). Both the multiple analog-to-digital converters (304) and the incremental position generator (308) may be located on a first microchip (300). An absolute position generator (402) may be located on a second microchip (400) to generate an absolute position output from the digitized sensor values. The encoder enables faster position calculation, thereby improving measurement accuracy.

Description

Technical Field

[0001] The present invention relates to a position encoder device, and more particularly to an improved encoder reading head that can extract position information from an associated encoder scale more quickly.

Background Art

[0002] Position encoder devices for measuring the relative position between two movable objects are known. Typically, one object is provided with an encoder scale including a series of markings, and the other object is provided with a reading head for reading those markings. Position encoders are generally classified as incremental position encoders or absolute position encoders. In an incremental position encoder, the scale has a series of periodic scale markings detected by the reading head. The incremental movement of the scale relative to the reading head is measured to enable determination of changes in the relative position, and the accuracy can often be much higher than the period of the scale markings. In an absolute encoder, the reading head detects a series of unique scale markings (e.g., codes, etc.) and measures the relative displacement by converting those codes to an absolute position. This generally provides a lower resolution measurement than an incremental encoder, but it has the advantage that the absolute position of the reading head relative to the scale is clearly known. It is also known to provide an encoder arrangement that uses an absolute scale track together with an incremental scale track. This enables the combination of the higher position resolution of an incremental encoder with the advantages of absolute position measurement. In other words, more accurate incremental position measurements can be used to "fine-tune" the absolute position measurement.

[0003] US7499827 describes embedding absolute position data into an incremental scale by removing the scale line. The entire scale maintains sufficient periodicity to provide the incremental information, but it also makes it possible to detect the removed scale line and thereby extract a codeword that defines the absolute position information. WO2010 / 116144 describes a method for reading such a scale by taking a snapshot image of the scale. In particular, it describes a CMOS image sensor that includes a linear array of pixels and is configured to output an image of the scale to a central processing unit on request. The central processing unit then analyzes the received image to extract both absolute and incremental position information. This type of arrangement is used in the so-called "RESOLUTE" series of optical encoders currently sold by Renishaw plc in Wotton-Under-Edge, UK.

[0004] The inventors recognized that while the above-described configuration provides a compact and reliable encoder, there may be an upper limit on the speed at which location information can be reliably extracted by reading data from an image sensor. [Overview of the project]

[0005] According to a first aspect of the present invention, an encoder reading head for reading an encoder scale is provided. This encoder reading head is A detector having multiple sensor elements that generate multiple analog sensor signals, A digitizer for converting multiple analog sensor signals into digital sensor values, An incremental position generator configured to receive digitized sensor values ​​and generate an incremental position output from them, Equipped with, The digitizer includes multiple analog-to-digital converters, and the incremental position generator is characterized by receiving multiple digitized sensor values ​​in parallel from the multiple analog-to-digital converters.

[0006] Thus, the present invention relates to an encoder reading head configured to read an associated encoder scale. The encoder scale may consist of an incremental scale, or it may consist of a combination of an incremental scale and an absolute scale. The reading head includes a detector comprising a plurality of sensor elements that generate a plurality of analog sensor signals. For example, the detector may include an optical detector having a linear (one-dimensional) array of N photosensor elements (pixels). These photosensor elements generate N analog sensor signals representing the intensity of light received by each sensor element. This provides a one-dimensional image of the encoder scale. The reading head may also include suitable elements for reading the associated encoder scale (e.g., a light source, a beam splitter, a lens, etc.). For example, it may be equipped with optical components that enable the detector to form an image of the encoder scale.

[0007] Furthermore, the detector is equipped with a digitizer for converting multiple analog sensor signals output from the detector's sensor elements into digitized sensor values. Therefore, for an optical detector, each digitized sensor value is a digital representation of the intensity of light received by each sensor element. These digitized sensor values ​​are received by an incremental position generator and used to generate incremental positions. For example, such a set of digitized sensor values ​​may provide a digital image (e.g., a one-dimensional digital image) of the relevant encoder scale that can be analyzed to extract position information. As will be described later, the calculated incremental positions, combined with coarser absolute position information, may provide a resulting position value output by a reading head.

[0008] The present invention features a digitizer that includes multiple analog-to-digital converters instead of the single analog-to-digital converter found in prior art read heads of the type described in WO2010 / 116144. This allows the incremental position generator to receive multiple digitized sensor values ​​in parallel rather than in series. In a preferred embodiment, N sensor elements and N analog-to-digital converters are provided. This allows all analog sensor signals to be digitized together (i.e., in parallel). This significantly improves the speed of digitization compared to the prior art (e.g., by almost N times). This makes it possible to pass the digitized image acquired by the detector to the incremental position generator faster than was previously possible using (serial) video signals. As a result, it becomes possible to generate incremental positions faster than previously possible. Reducing the total time required to calculate the position from the digitized image is advantageous because it results in more accurate position estimation. During the calculation time, the encoder continues to move relative to the encoder scale, but this movement is not necessarily constant. Therefore, movement during calculation time becomes unpredictable, potentially leading to measurement errors. However, reducing the time required for position calculation reduces these measurement errors. In particular, it has been found that halving the calculation time typically reduces the displacement error to one-quarter. Thus, the present invention provides an encoder reading head with improved measurement accuracy.

[0009] Advantageously, the detector and multiple analog-to-digital converters are located on a first microchip. The term microchip refers to an integrated circuit chip that can be mounted on a printed circuit board (PCB) or similar. An incremental position generator may also be located on the first microchip. In other words, the detector (i.e., multiple sensor elements) can be formed on the same microchip substrate (i.e., the first microchip) on which the multiple analog-to-digital converters and the incremental position generator are also formed. Therefore, the digitization circuit and / or incremental position calculation circuit can be added to the detector chip. This configuration makes it possible to transmit analog sensor signals from the sensor elements to adjacent ADCs via multiple dedicated signal lines formed on the microchip, eliminating the need for cables or serial buses to transmit such signals. Thus, high-speed digitization of analog sensor signals, along with rapid calculation of incremental positions, becomes possible. This allows for faster position calculation than before.

[0010] A digitizer may include N analog-to-digital converters, and a detector may include N sensor elements, where N is an integer greater than or equal to 2. Therefore, one analog-to-digital converter may be provided for each sensor element. In other words, one analog-to-digital converter from a plurality of analog-to-digital converters may be provided for each sensor element. This makes it possible to digitize the analog sensor signals from all of the sensor elements in parallel (i.e., by the associated ADCs). Furthermore, the number of ADCs may be less than the number of sensor elements. For example, a digitizer may include N analog-to-digital converters, and a detector may include M sensor elements, where N is an integer greater than or equal to 2, and M is greater than N (preferably, M is an integer multiple of N). For example, one ADC can be shared by two or more sensor elements. This requires sequentially digitizing the analog signals supplied to each ADC, but overall, it is faster than using only a single ADC to digitize all analog signals.

[0011] Advantageously, the incremental position generator is configured to calculate an incremental position output from multiple digitized sensor values ​​using at least one lookup table or function. The incremental position extractor may be configured to analyze the captured image using frequency analysis. More specifically, spatial frequency analysis may be used to analyze the captured image. In particular, it is preferable that the incremental position generator implements a spatial frequency transform to generate the incremental position output. The spatial frequency transform is preferably a discrete Fourier transform. In other words, the incremental position extractor may analyze the captured image using Fourier analysis techniques. The incremental position generator may include memory for storing sine and cosine lookup tables that perform the discrete Fourier transform, and the digitized sensor values ​​are multiplied by coefficients in the sine and cosine lookup tables to provide the incremental position output. In other words, the sensor output value can be multiplied and summed by values ​​in a cosine lookup table to provide a real value, and the same sensor output value can be multiplied and summed by values ​​in a sine lookup table to provide an imaginary value. Both the real and imaginary values ​​can then be used together to provide a global phase value. Thus, the incremental position output of an incremental position generator can consist of real and imaginary phase components (e.g., orthogonal phase sine / cosine signals), or a global phase value can be calculated.

[0012] Weighting (e.g., a window function) may be applied to the digitized sensor values. This weighting may be applied before the digitized sensor values ​​are received by the incremental position generator, or it may be applied by the incremental position generator. For example, a lookup table may be used to weight the digitized sensor values, or the weighting may be applied to values ​​in a lookup table (such as a sine lookup table and a cosine lookup table) used by the incremental position generator. In other words, it is preferable that multiple digitized sensor values ​​be weighted or adjusted.

[0013] The encoder reading head may also preferably include an absolute position generator. The absolute position generator may be configured to continuously receive digitized sensor values. The digitized sensor values ​​can then be analyzed by the absolute position generator to generate an absolute position output. The absolute position generator may operate similarly to a conventional reading head, except that the digitized image of the scale is generated by multiple ADCs rather than a single ADC. Therefore, the calculation of the absolute position may be slower than the calculation of the incremental position.

[0014] In a preferred embodiment, the first microchip includes a detector, a plurality of analog-to-digital converters, and an incremental position processor, and the second microchip includes an absolute position generator. In other words, the calculation of the absolute position may be performed on a (second) microchip that is different from the (first) microchip on which the detector, digitizer, and incremental position generator are formed. The first and second microchips may be physically isolated from each other by an electrical connection between them (e.g., wiring). A serial data bus or link may be used to pass multiple digitized sensor values ​​from the first microchip to the second microchip. The first and second microchips may be manufactured from different wafers and may be manufactured using different manufacturing techniques. For example, the first microchip may include a CMOS microchip (which would be very suitable for providing an optical detector). The second microchip may be an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), etc., which are typically less expensive and easier to reconfigure than a CMOS microchip.

[0015] The encoder reading head, and therefore the associated scale, can detect any suitable type of radiation (for example, the encoder device may be magnetic, inductive, optical, etc.). Advantageously, an optical encoder reading head is provided for reading an optical encoder scale. Therefore, the detector preferably includes an optical detector having an array of photodetectors. The photodetectors may be arranged in a regular or irregular array. All photodetectors may be the same size, or they may be of different sizes (for example, to achieve weighted photodetection). Preferably, the optical detector includes a one-dimensional optical detector array. The reading head may also include a light source. The reading head may be configured to acquire a snapshot image (e.g., a one-dimensional image) of the associated encoder scale. Conveniently, the optical detector may be formed using complementary metal-oxide-semiconductor (CMOS) technology. In other words, the first microchip may be a CMOS microchip.

[0016] A further aspect of the present invention provides an encoder reading head for reading an encoder scale. This encoder reading head comprises: a detector array having a plurality of sensor elements that generate a plurality of analog sensor signals; and a processing circuit for converting the plurality of analog sensor signals into a plurality of digitized sensor values ​​and generating an incremental position output from the plurality of digitized sensor values. Herein, the detector array and the processing circuit are formed on a single microchip. This reading head may include any of the features described herein, either alone or in combination with other features.

[0017] A further aspect of the present invention provides an encoder reading head for reading an encoder scale. This encoder reading head comprises: a detector array having a plurality of sensor elements; and a plurality of analog-to-digital converters. Each of the plurality of sensor elements generates an analog sensor signal. Each of the plurality of analog-to-digital converters is configured to convert the analog sensor signal into a digitized sensor value. Here, each sensor element outputs its analog signal to a different converter among the plurality of analog-to-digital converters, thereby converting the plurality of analog signals into a plurality of digitized sensor values ​​in parallel. This reading head may include any of the features described herein, either alone or in combination with other features.

[0018] This specification also describes an encoder reading head, which may be for reading an encoder scale. The encoder reading head may include a detector, which may include multiple sensor elements, which may generate multiple analog sensor signals. A digitizer may be provided, which may convert the multiple analog sensor signals into digitized sensor values. The reading head may also include an incremental position generator, which may be configured to receive digitized sensor values, which may be configured to generate an incremental position output (for example, from the received digitized sensor values). The digitizer may include multiple analog-to-digital converters.

[0019] The incremental position generator may be configured to receive multiple digitized sensor values ​​in parallel from multiple analog-to-digital converters. The reading head may include any of the features described herein, either alone or in combination with other features.

[0020] Furthermore, the present invention also extends to an encoder device comprising an encoder reading head and an encoder scale as described above. [Brief explanation of the drawing]

[0021] The present invention will be described below by way of example only with reference to the accompanying drawings.

[0022] [Figure 1] It is a diagram showing the arrangement of prior art encoder reading heads. [Figure 2] It is a schematic diagram showing a prior art encoder reading head. [Figure 3] It is a diagram illustrating the electrical components in the prior art encoder reading head in FIG. 2. [Figure 4] It is a diagram illustrating the electronic devices in the reading head of the present invention.

Mode for Carrying Out the Invention

[0023] Referring to FIG. 1, an overall view of an encoder device 2 including a reading head 4 and a scale 6 is shown. The reading head 4 and the scale 6 are respectively attached to a first object and a second object (not shown) during use. The reading head 4 is movable back and forth along the scale 6. In particular, the reading head 4 is movable relative to the scale 6 along the X-axis illustrated in the figure.

[0024] The scale 6 is an absolute scale including a scale track 7 including a series of scale lines extending perpendicular to the X-direction movement of the reading head, that is, the scale lines extend along the y-axis shown in the figure. In this example, the scale lines are composed of a series of reflective lines 8 and non-reflective lines 10. The reflective lines 8 and the non-reflective lines 10 are usually arranged alternately at a predetermined period. However, the selected non-reflective lines 10 are omitted from the track 7 in order to encode absolute position data on the scale track 7. For example, the presence of a non-reflective line can be used to represent a "1" bit, and the absence of a non-reflective line can be used to represent a "0" bit. The encoded absolute position data can be provided in the form of a pseudo-random sequence or a discrete code word.

[0025] Figure 2 shows the internal components of the prior art head 4 in more detail. The reading head 4 includes a light source in the form of a light-emitting diode (LED) 12, a collimating lens 13, a beam splitter assembly 15 having a reflective surface 17 and a beam splitting surface 19. It also includes an imaging lens 21 and a complementary metal-oxide-semiconductor (CMOS) image sensor 20.

[0026] During use, the collimating lens 13 aligns the light emitted from the LED 12 with the beam 23. The beam 23 is reflected by the reflective surface 17 of the splitter assembly toward the beam splitting surface 19. The beam splitting surface 19 reflects the beam 23 toward the scale 6 through the window 22. The light reflected from the scale 6 passes through the window 22 and returns toward the beam splitting surface 19. The beam splitting surface 19 allows the reflected light to travel in a straight line through it. The reflected light then passes through the imaging lens 21, which forms an image of the scale 6 on the image sensor 20.

[0027] In this example, the CMOS image sensor 20 is a one-dimensional sensor array formed on a single microchip. Specifically, the CMOS image sensor 20 consists of a single row of 256 elongated pixels (sensor elements) extending parallel to the lengths of the reflective line 8 and the non-reflective line 10. The microchip of the image sensor 20 also includes electronic circuitry for sequentially reading light intensity data (i.e., analog sensor signals) from the pixel row and generating an analog video signal for outputting the analog sensor signals. Therefore, the analog video signal output from the microchip of the CMOS image sensor provides a serial stream of analog sensor signals from the 256 pixels.

[0028] The signal processing circuit 24 receives an analog video signal from the image sensor 20. The signal processing circuit 24 includes a single analog-to-digital converter that converts the analog sensor signal stream into a digitized sensor value stream. The signal processing circuit 24 is configured to analyze the digitized scaled image, and the interface 38 outputs the calculated position information to the data bus 40.

[0029] Referring to Figure 3, a functional diagram is provided that illustrates in more detail the electronic layout of a prior art reading head of the type described with reference to Figure 2.

[0030] The reading head includes a detector microchip 100 which contains a linear imaging array 102 having 256 pixels. The detector microchip 100 also includes a video readout circuit 104 for sequentially reading out the measured light intensity from the pixel array 102 and generating an analog video output signal which contains a stream of analog light intensity signals. A flexible wire 106 transmits the video signal output by the video readout circuit 104.

[0031] The reading head also includes a printed circuit board (PCB) 200 having various components for processing the video signal output from the detector microchip 100. The printed circuit board 200 has an analog-to-digital converter (ADC) 202 in the form of a microchip mounted thereon. The ADC 202 is connected to wiring 106 that transmits the video signal from the detector microchip 100. Thus, the ADC 202 converts the received analog video signal into a stream of digitized sensor values ​​representing the light intensity measured at each pixel of the array 102. In particular, the light intensity signals from each of the pixels of the imaging array 102 are converted into digital values ​​sequentially (i.e., one after the other). Once all signals from the 256 pixels have been digitized, the digitized one-dimensional image acquired by the imaging array 102 can be analyzed to extract positional information. As described above, the positional information is calculated by analyzing the same captured image in two different ways and extracting incremental positional information and absolute positional information.

[0032] The captured images are analyzed using a digital signal processor (DSP) 203, which is provided in the form of a separate microchip mounted on the PCB 200. Conductive tracks formed on the PCB 200 transmit digitized sensor values ​​from the ADC 202 to the DSP 203.

[0033] The DSP203 is programmed to provide an incremental position generator 204 that uses a Discrete Fourier Transform (DFT) to determine incremental position information from the intensity pattern of the captured image. From the real and imaginary components of the DFT, it is possible to extract the global phase of the captured image, for example, by calculating the arctangent of the imaginary component divided by the real component. In this way, the global phase value is calculated from all the information in the captured image, and an incremental position value corresponding to a fraction of the fundamental scale period is given. For example, if the encoder scale has a fundamental scale period of 30 μm, the calculated incremental position will be a value in the range of 0 to 30 μm, and will have a resolution of 1 nm or more.

[0034] Furthermore, the DSP203 is programmed to provide an absolute position generator 206 that uses global phase information from the incremental position generator 204 to analyze the captured image and identify the center of each potential line on the scale. Next, correlation processing is performed on the captured image at each of these positions to check whether dark lines are present. For example, if each captured image of the scale extends by approximately 2 mm in the measurement direction, this makes it possible to extract a 65-bit binary number corresponding to the scale pattern of the captured image (i.e., the image of the part of the scale directly below the read head). Additionally, a lookup table stored in the memory chip 220, also mounted on the PCB200, can be used by the absolute position generator 206 to determine the absolute position value from the extracted binary number. It should be noted that only about a quarter of the 65 bits are needed to define a unique position, and the remaining bits provide redundant information, allowing the correct position to be identified even if part of the scale is unclear. This process makes it possible to detect the absolute position of the reading head with an accuracy of within one scale period (for example, within 30 μm for an encoder scale with a basic scale period of 30 μm).

[0035] Furthermore, the DSP203 is programmed to provide a position coupler 208 that synthesizes coarse absolute position information (i.e., integer multiples of the scale period) from the absolute position generator 206 with global phase information (i.e., having a resolution much smaller than the scale period) from the incremental position generator 204 to generate high-resolution absolute position values ​​output from the PCB200 via the output signal line 210 using a standard encoder output protocol. It should be noted that the absolute position values ​​may be output periodically or on demand as needed.

[0036] The prior art configuration described with reference to Figure 3 enables the generation of position information in a highly reliable manner. However, the inventors recognized that the speed at which position can be calculated may introduce measurement errors. Rather than simply attempting to increase the speed of all electronic devices used in the position measurement process, the inventors have devised a novel architecture that significantly improves the speed at which position can be calculated in a cost-effective manner.

[0037] Referring to Figure 4, a functional diagram illustrating the electronic circuit layout of the reading head of the present invention is provided. In this example, the optical arrangement (including the encoder scale) is the same as that of the prior art encoder system described above, but it is certainly possible to provide a reading head with an alternative optical arrangement.

[0038] The encoder of the present invention comprises a first (CMOS) microchip 300 including a linear imaging array 302 having 512 pixels. An array of 512 ADCs 304 (together providing a digitizer) is formed on the first microchip 300 adjacent to the 512 pixels of the imaging array 302. The analog output from each of the pixel groups is supplied by a dedicated electrical connection to the input corresponding to one of the ADCs 304. In other words, the analog sensor signals from the pixel groups are passed in parallel to the corresponding ADCs. This makes it possible to digitize all analog sensor signals from all pixels of the imaging array 302 in parallel. Therefore, for each image acquired by the imaging array 302, a set of 512 digitized sensor values ​​is generated at high speed. The digitized sensor values ​​are stored in a memory buffer 306.

[0039] The first microchip 300 also includes an incremental position generator 308. In other words, the incremental position generator 308 is located on the same CMOS microchip that provides the linear imaging array 302. The incremental position generator 308 reads sensor values ​​from the memory buffer 306 and uses a discrete Fourier transform (DFT) to determine incremental position information from the intensity pattern of the captured image. From the real and imaginary components of the DFT, it is possible to extract the global phase of the captured image. For example, the global phase can be determined by calculating the arctangent of the imaginary component divided by the real component, or by using a lookup table or a coordinate rotation digital computer (CORDIC), etc. In this way, the global phase value is calculated from all the information in the captured image, thereby giving the incremental position value, which is a fraction of the basic scale period. The incremental position is output by the incremental position generator 308 via the first (incremental position) data bus 310. This incremental position can be output in any appropriate format. For example, the incremental position may be output as a sinusoidal and cosine (orthogonal phase) signal. A second serial data bus 312 is provided to output digitized sensor values ​​from the memory buffer 306. This configuration allows the incremental position generator 308 to calculate the incremental position at a much faster speed than possible in the prior art configuration where the sensor values ​​are digitized and passed in series to the incremental position generator.

[0040] A second microchip 400 is also provided. In this example, the second microchip consists of a field-programmable gate array (FPGA) microchip, but other types of microchips (e.g., ASIC, DSP, etc.) can be used instead. The second microchip includes an absolute position generator 402 that reads digitized sensor values ​​stored in a memory buffer 306 via a second (serial) data bus 312. Incremental (global phase) information provided via the first data bus 310 is used to identify the center of each potential line on the scale. As described above, correlation processing is then performed on the captured image to check for the presence of dark lines and to extract binary numbers corresponding to the scale pattern of the captured image. A lookup table stored in memory 404 is used by the absolute position generator 402 to determine the absolute position value from the extracted binary numbers. Memory 404 also contains Fourier coefficients used by the incremental position generator 308, which may be preloaded into memory within the incremental position generator 308 via data bus 406. The incremental position generator 308 is shown to be indirectly connected to the memory 404 via the second microchip 400, but it could also be directly connected to the memory 404, or the memory could be integrated into the first and / or second microchip instead.

[0041] The second microchip 400 also includes a position combiner 410 that uses coarse absolute position information (i.e., integer multiples of the scale period) from the absolute position generator 402 to incremental information (i.e., with a resolution much smaller than the scale period) from the incremental position generator 308 to generate a high-resolution absolute position value output via an output line signal 412 using a standard encoder output protocol.

[0042] Unlike the configuration of prior art, incremental information provided via the first data bus 310 can be generated and received much faster than absolute position information calculated by the absolute position generator 402. This also allows the resulting position output obtained by the position combiner 410 to be calculated more quickly. Incremental changes in position that occur during the calculation of new absolute position information can be used to update the resulting position output, thereby improving the overall speed at which the relative positions of the scale and the read head can be calculated. This improvement in position calculation speed reduces the measurement error of the read head by reducing the effect of acceleration or deceleration of the read head relative to the scale during the calculation time. Thus, an encoder read head with improved accuracy is provided.

[0043] It should be noted that the examples outlined above are merely representative of the present invention. Those skilled in the art will understand that numerous alternative read head configurations are possible according to the present invention.

Claims

1. An encoder reading head for reading the encoder scale, A detector having multiple sensor elements that generate multiple analog sensor signals, A digitizer for converting the aforementioned multiple analog sensor signals into digital sensor values, An incremental position generator configured to receive the digitized sensor value and generate an incremental position output therefrom, Equipped with, The digitizer includes a plurality of analog-to-digital converters, and the incremental position generator is characterized by receiving a plurality of the digitized sensor values ​​in parallel from the plurality of analog-to-digital converters. Encoder reading head.

2. The encoder reading head according to claim 1, wherein the detector, the plurality of analog-to-digital converters, and the incremental position generator are provided on a first microchip.

3. The encoder reading head according to claim 1 or 2, wherein one analog-to-digital converter is provided for each of the aforementioned sensor elements.

4. The encoder reading head according to any one of claims 1 to 3, wherein the incremental position generator is configured to calculate the incremental position output from the plurality of digitized sensor values ​​using at least one lookup table or function.

5. The encoder reading head according to claim 4, wherein the incremental position generator performs spatial frequency conversion to generate the incremental position output.

6. The encoder reading head according to claim 5, wherein the spatial frequency transform is a discrete Fourier transform.

7. The encoder reading head according to claim 6, wherein the incremental position generator includes a memory for storing a sine lookup table and a cosine lookup table for performing the discrete Fourier transform, and the digitized sensor value is multiplied by the coefficients of the sine lookup table and the cosine lookup table to generate the incremental position output.

8. The encoder reading head according to any one of claims 1 to 7, wherein the plurality of digitized sensor values ​​are weighted or adjusted.

9. An encoder reading head according to any one of claims 1 to 8, comprising an absolute position generator, wherein the absolute position generator is configured to continuously receive the digitized sensor values, analyze the digitized sensor values, and generate an absolute position output.

10. The encoder reading head according to claim 9, wherein the first microchip includes the detector, the plurality of analog-to-digital converters, and the incremental position generator, and the second microchip includes the absolute position generator.

11. The encoder reading head according to any one of claims 1 to 10, wherein the detector includes an optical detector having an array of photodetectors.

12. The encoder read head according to claim 11, wherein the optical detector includes a one-dimensional optical detector array, and the read head is configured to acquire a snapshot image of the encoder scale.

13. The encoder reading head according to claim 10 or 11, wherein the optical detector is formed using complementary metal-oxide-semiconductor (CMOS) technology.

14. An encoder reading head for reading the encoder scale, A detector array having multiple sensor elements that generate multiple analog sensor signals, and a processing circuit for converting the multiple analog sensor signals into multiple digitized sensor values ​​and generating an incremental position output from the multiple digitized sensor values. Equipped with, The detector array and processing circuit are characterized by being formed on a single microchip. Encoder read header.

15. An encoder reading head for reading the encoder scale, A detector array having multiple sensor elements, each of which generates an analog sensor signal, A plurality of analog-to-digital converters, each of which is configured to convert an analog sensor signal into a digitized sensor value, and Equipped with, Each sensor element outputs its analog signal to a different converter among the plurality of analog-to-digital converters, thereby converting the plurality of analog signals in parallel into a plurality of digitized sensor values. Encoder reading head.

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