Detection device and signal compression method

Abstract

When transmitting sensor data using a bandwidth-limited transmission system, reduce the amount of data sent per unit time. [Solution] The detection device includes a plurality of detection elements, a plurality of scan lines connected to a scan circuit, a plurality of signal lines connected to the detection circuit, and a control circuit. Each of the plurality of detection elements is connected to a corresponding scan line and a corresponding signal line. The detection circuit is configured to sequentially read the detected values ​​of the signals of the plurality of detection elements via the plurality of signal lines. When the control circuit outputs the detected value of the signal of the detection element of interest to the outside, it outputs the difference data between the detected value of the signal of the detection element of interest and a value based on the detected value of the signal of the detection element of interest read before the detection timing of the detected value of the signal of the detection element of interest, as transmitted difference data.

Description

Technical Field

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[0001] The present disclosure relates to a detection device and a signal compression method.

Background Art

[0002] As a wireless network system for transmitting sensor data, for example, Japanese Patent Application Laid-Open No. 2012-129805 has been proposed.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure has found that when transmitting sensor data using a transmission system with bandwidth limitations, such as wireless communication, the amount of data transmitted per unit time is large and the transmission bandwidth is insufficient. ]

[0005] An object of the present disclosure is to provide a technique capable of reducing the amount of data transmitted per unit time when transmitting sensor data using a transmission system with bandwidth limitations.

[0006] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0007] The outline of a typical example of the present invention will be briefly described as follows.

[0008] That is, a detection device according to an aspect of the present disclosure includes a plurality of detection elements arranged in a matrix, and Multiple scan lines extending in a first direction and arranged in a second direction intersecting the first direction, connected to a scan circuit, Multiple signal lines extending in a second direction and arranged in a first direction, connected to a detection circuit, Includes a control circuit, Each of the plurality of detection elements is connected to a corresponding scan line and a corresponding signal line. The detection circuit is configured to sequentially read the detected values ​​of the signals from the plurality of detection elements via the plurality of signal lines. When the control circuit outputs the detected value of the signal of the detection element of interest to the outside, it outputs the difference data between the value based on the detected value of the signal of the detection element read before the detection timing of the detected value of the signal of the detection element of interest and the detected value of the signal of the detection element of interest as transmitted difference data.

[0009] Furthermore, a signal compression method according to another aspect of this disclosure is: A method for compressing the signal of a detection value (detection data) of a detection device in which multiple detection elements are arranged in a matrix, The first operation on the first data, which is encoded based on the difference in the detected signal value between each line of the current frame and the corresponding line of the previous frame, A second operation is performed on the second data encoded based on the difference with the average of a predetermined range of the current frame, Between the first data and the second data, select the data with the smaller amount of data. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the overall configuration of a sensor system including a detection circuit and a host device according to an embodiment. [Figure 2] Figure 2 shows an example of the sensor array configuration of the detection device shown in Figure 1. [Figure 3] Figure 3 illustrates a first example of the encoding method according to the embodiment. [Figure 4] Figure 4 illustrates a second example of the encoding method according to the embodiment. [Figure 5] FIG. 5 is a diagram for explaining a third example of the encoding method according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining a fourth example of the encoding method according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining the data format according to the embodiment. [Figure 8] FIG. 8 is a block diagram of the encoding circuit according to the embodiment. [Figure 9] FIG. 9 is a block diagram of the decoding circuit according to the embodiment. [Figure 10] FIG. 10 is a flowchart for explaining the encoding procedure according to the embodiment. [Figure 11] FIG. 11 is a flowchart for explaining the differential value encoding process of FIG. 10. [Figure 12] FIG. 12 is a diagram for explaining a fifth example of the encoding method according to the modification. [Figure 13] FIG. 13 is a diagram for explaining the data format according to the modification. [Figure 14] FIG. 14 is a diagram for explaining a configuration example of the continuous compression unit according to the modification. [Figure 15] FIG. 15 is a flowchart for explaining the encoding procedure according to the modification.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the disclosure is merely an example, and those that can be easily conceived by those skilled in the art with appropriate modifications while maintaining the gist of the disclosure are naturally included in the scope of the present disclosure. In addition, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but this is merely an example and does not limit the interpretation of the present disclosure. Also, in this specification and each figure, the same reference numerals may be assigned to the same elements as those described above with respect to the previously presented figures, and detailed descriptions may be omitted as appropriate.

Examples

[0012] First, a sensor system including a detection circuit and a host device will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing the overall configuration of a sensor system including a detection circuit and a host device according to an embodiment. FIG. 2 is a diagram showing a configuration example of the sensor array of the detection device in FIG. 1.

[0013] As shown in FIG. 1, the sensor system 1 includes a detection device DETA and a host device HST. The detection device DETA includes a sensor unit SEN, a control circuit CNT, a transmission circuit TX, and a transmission antenna AN1. The sensor unit SEN includes a sensor array SARY, a scan circuit (scanning circuit) SC, and a detection circuit DET including an analog-to-digital conversion circuit ADC.

[0014] As shown in FIG. 2, the sensor array SARY includes a plurality of detection elements SN (SNnn, SNnn + 1, SNn + 1n, SNn + 1n + 1) arranged in a matrix (row and column) in the first direction X and the second direction Y intersecting the first direction X, a plurality of scan lines G (Gn, Gn + 1) extending in the first direction X and arranged in the second direction Y intersecting the first direction X and connected to the scan circuit SC, and a plurality of signal lines S (Sn, Sn + 1) extending in the second direction Y and arranged in the first direction X and connected to the detection circuit DET. In this example, a 2-row × 2-column matrix sensor array SARY is exemplarily shown. The matrix of the sensor array SARY may be configured, for example, as 80 rows × 80 columns.

[0015] Multiple detection elements SN are pressure detection elements used, for example, in a pressure sensor that detects pressure. Each of the multiple detection elements SN has the same configuration. Below, the configuration of detection element SNnn is described as a representative example. Detection element SNnn includes a variable resistor element VR1, a resistor element R1, and a thin-film transistor MN. The variable resistor element VR1 and the resistor element R1 are connected in series between a first reference potential V1, such as the ground potential GND (e.g., 0V), and a second reference potential V2, such as the power supply potential VDD. The thin-film transistor MN is an N-channel type MOS semiconductor element and includes a gate electrode connected to the scan line Gn and a source-drain path connected between the common connection point of the variable resistor element VR1 and the resistor element R1 and the signal line Sn. Detection element SNnn is turned ON when the scan circuit SC sequentially scans multiple scan lines Gn and Gn+1, and the scan line Gn is set to a selected level. At this time, the potential at the common connection point between the variable resistor element VR1 and the resistor element R1 is transmitted to the signal line Sn as the detection signal of the detection element SNnn. The analog-to-digital conversion circuit ADC connected to the signal line Sn converts the analog voltage signal into a detected digital voltage signal (the detected value of the detection signal of the detection element SNnn). In this example, the Active Matrix method is described as the method for the sensor array SARY, but the Passive Matrix method may also be used. In the Passive Matrix method, the resistance component due to the gate signal is not isolated, so it is prone to interference from the resistance component in the adjacent second direction Y, which may make it difficult to achieve high resolution. Therefore, it is preferable to adopt the Active Matrix method for the sensor array SARY, which enables high resolution.

[0016] The scan circuit SC sequentially scans multiple scan lines G. In the matrix sensor array SARY, multiple detection elements SN connected to one scan line are supplied with their detection signals via the signal line S to the analog-to-digital conversion circuit ADC. This operation is performed sequentially while changing one scan line, and the detection signals from the multiple detection elements SN in the sensor array SARY are sequentially converted into detected digital voltage signals by the analog-to-digital conversion circuit ADC.

[0017] The control circuit CNT has an encoding circuit ENC that encodes the detected value of the digital voltage signal from the analog-to-digital converter ADC.

[0018] The transmitting circuit TX is configured to receive the encoded signal transmitted by the encoding circuit ENC, and converts the received encoded signal into a wireless signal, which is then transmitted from the transmitting antenna AN1. In other words, the encoded signal is transmitted using a bandwidth-limited transmission system, such as wireless communication using the transmitting antenna AN1.

[0019] The host device HST includes a receiving antenna AN2, a receiving circuit RX, a decoding circuit DEC, and a host control unit CON. The receiving antenna AN2 receives radio signals from the transmitting antenna AN1. The receiving circuit RX is connected to the receiving antenna AN2 and converts the received radio signals into encoded signals. The decoding circuit DEC decodes the converted encoded signals and converts them into detected values ​​of digital voltage signals. The host control unit CON processes the detected values ​​of the converted digital voltage signals and processes the detected values ​​detected by the sensor unit SEN. The host control unit CON also performs desired processing based on the detected values ​​detected by the sensor unit SEN.

[0020] As explained earlier, when transmitting sensor data using a bandwidth-limited transmission system, such as wireless communication, the amount of data sent per unit time is large, resulting in insufficient transmission bandwidth. Therefore, it is necessary to devise an encoding method that minimizes the amount of data sent per unit time.

[0021] Next, the encoding method and the data format of the encoded signal will be explained using Figures 3 to 7. Figure 3 is a diagram illustrating the first example of the encoding method according to the embodiment. Figure 4 is a diagram illustrating the second example of the encoding method according to the embodiment. Figure 5 is a diagram illustrating the third example of the encoding method. Figure 6 is a diagram illustrating the fourth example of the encoding method according to the embodiment. Figure 7 is a diagram illustrating the data format according to the embodiment. Here, for example, it is assumed that the sensor array SARY is provided with multiple scan lines (G1-Gn). That is, the sensor array SARY is provided with scan lines from the first row G1 to the nth row Gn, and the scan circuit SC sequentially scans each scan line from the first row G1 to the nth row Gn, as shown by the arrows in Figure 3.

[0022] As shown in Figure 3, the detection signals of multiple detection elements SN arranged in a matrix on the sensor array SARY are read out first when the first scan line (G1) is selected, and the detection signals of the multiple detection elements SN(G1) connected to the first scan line (G1) are read out. Next, the second scan line (G2) is selected, and the detection signals of the multiple detection elements SN(G2) connected to the second scan line (G2) are read out. This operation is performed for all of the scan lines G(G1-Gn). In other words, the scan lines G(G1-Gn) are scanned one by one sequentially, and the detection signal values ​​of the multiple detection elements SN for one frame are read out.

[0023] The reference value used to determine the difference value of each detection element must be such that the detection value (absolute value) of the detection element SNen of interest can be decoded (the inverse operation of encoding) using the decoded detection value (absolute value) in the DEC decode circuit as a reference.

[0024] In the first example of the encoding method shown in Figure 3, the reference value is the average of the detected values ​​of each detection element SNrng within a predetermined reference range RNG, which is above and to the left of the detection element of interest (referred to as the detection element of interest) SNen.

[0025] As shown in Figure 4, in the second example of the encoding method, if the target detection element SNen01 is a target detection element near the top edge of the sensor array SARY or near the left edge of the sensor array SARY, the reference range RNG will extend beyond the area of ​​the sensor array SARY and will therefore be limited to a possible range. In other words, in this case, the reference range RNG may be set to extend beyond the area of ​​the sensor array SARY. If the target detection element SNen00 is a detection element in the upper left of the area of ​​the sensor array SARY, there is no reference value, so the absolute value of the detection value of the target detection element SNen00 will be recorded or written directly in the data format DAF explained in Figure 7. Also, in the case of the target detection element SN02 located in the first row of the sensor array SARY (corresponding to the scan line (G1) of the first row), in the calculation of the reference value, the range of detection elements SNg1 on the left side of the same row is set as the reference range RNG_g1, and the average value of the detection values ​​of each detection element SNg1 on the left side of the same row within the reference range RNG_g1 is used.

[0026] Thus, when the detection element SNen00 of interest is used with a reference range RNG, excluding the upper left detection element of the sensor array SARY, the difference value is the difference between the detected value of the signal of the detection element SNen of interest (difference data) and the value (average value) of the signal of the detection element SNen of interest, which is based on the detected values ​​of one or more detection elements read before the detection timing of the signal of the detection element SNen of interest. In other words, the average value of the detected values ​​of the signals of multiple detection elements in the reference range RNG is used as the reference value, and the difference between this reference value and the detected value of the signal of the detection element SNen of interest is recorded and transmitted as a data format. As a result, the number of bits in the digital value is smaller than the normal absolute value (digital data with a number of bits that directly represents the detected value of the signal), so the amount of data to be transmitted is reduced.

[0027] The third example of the encoding method in Figure 5 employs a weighted average for calculating the mean value. It is preferable to use a weighted average, such as a Gaussian distribution, where detection elements closer to the target detection element SNen are given more weight, rather than a simple average. This is likely to result in smaller difference values.

[0028] An example of a weighted average is conceptually explained below.

[0029] Weighted average A: A = S / W The sum of the weight coefficients W is W = f(d1) + f(d2) + ... + f(dl). Weighted cumulative value Sv: Sv = f(d1) × L1 + f(d2) × L2 + ... + f(dl) × L Weight coefficient function: f(dn)(n=1, 2, ..., l) d1, d2, ..., dl: Distance between the target detection element SNen and the reference detection element. L1, L2, ..., Ll: Detected values ​​of the reference detection element An example of a weight coefficient function (Gaussian distribution) can be expressed as follows.

[0030] f(d) = e^-(d^2 / 2·σ^2) d: Distance from the pixel of interest (d1, d2, ..., dl, etc.) e: base of the natural logarithm σ: Spread parameter Here, Figure 5 shows, as an example, the case where the distances between the detection element of interest SNen and the reference detection element are d1, d2, d3, and d4. The reference range RNG includes multiple detection elements to the left of the same row as the detection element of interest SNen (multiple detection elements at distances from d1 to d4), and multiple detection elements in the row before the row of the detection element of interest SNen (upper row) that are included in a semicircular region with a radius of distance d4. The weighting coefficient f(d) is configured to be set larger for detection elements that are geographically closer to the detection element of interest SNen. The weighted average value A is the difference data between the weighted average of the detection values ​​of the multiple detection elements in the reference range RNG and the detection value of the signal of the detection element of interest SNen.

[0031] The fourth example of the encoding method in Figure 6 is an example in which the detected value data from the previous frame is used as the reference value. In the case of applications with relatively little time change, the detected value of the signal of the target detection element SNen in the current frame Fn and the detected value of the signal of the detection element SNim, which is located at the same position as the target detection element SNen(im) in the previous frame Fn-1, may be used as the reference value for the difference calculation. Here, a detection element located at the same position means that if the target detection element SNen(im) in the current frame Fn is the detection element located at the m-th position from the left end of the i-th horizontal line (scan line) Hi in the current frame Fn, then the detection element SNim, which is located at the m-th position from the left end of the i-th horizontal line (scan line) Hi in the previous frame Fn-1, is the detection element located at the same position. The detection element SNim, positioned at the same location as the target detection element SNen(im) in the previous frame Fn-1, corresponds to a detection element read out before the detection timing of the signal detection value of the target detection element SNen(im). The difference data between the value based on the signal detection value of detection element SNim and the signal detection value of the target detection element SNen(im) is used as the transmission difference data.

[0032] As explained in Figure 6, when using the difference from the previous frame Fn-1, even if the detection element SNen00 is at the upper left corner of the current frame Fn, a reference value exists based on the detection value of the detection element SN00 at the upper left corner of the previous frame Fn-1. Therefore, the original data, which is the detection value of detection element SNen00, does not need to be stored in the data format, which may reduce the amount of data transmitted.

[0033] In other words, the detection device DETA includes a plurality of detection elements SN arranged in a matrix, a plurality of scan lines G extending in a first direction X and arranged in a second direction Y intersecting the first direction X, and connected to a scan circuit SC, a plurality of signal lines S extending in the second direction Y and arranged in the first direction X, and connected to a detection circuit DET, and a control circuit CNT. Each of the plurality of detection elements SN is connected to a corresponding scan line (Gn, Gn+1) and a corresponding signal line (Sn, Sn+1). The detection circuit DET is configured to sequentially read out the detected values ​​of the signals of the plurality of detection elements SN via the plurality of signal lines S. When the control circuit CNT outputs the detected value of the signal of the detection element SNen of interest to the outside, it outputs the difference data between the detected value of the signal of the detection element SNen of interest and a value based on the detected value of the signal of the detection element SNen of interest read before the detection timing of the detected value of the signal of the detection element SNen of interest, as transmitted difference data. The transmitted difference data is a set of difference data for each line of the current frame, where each of the multiple detection elements included in the corresponding line is designated as the detection element of interest SNen. If the current frame has X lines, the transmitted difference data contains X difference data for each of the X lines. The detection timing of the detected value of the signal of the detection element of interest SNen can be rephrased as the decoding timing of the detected value of the signal of the detection element of interest SNen. In other words, the transmitted difference data is output as the difference data between the value based on the detected value of the detection element's signal read before the decoding timing of the detected value of the signal of the detection element of interest SNen and the aforementioned detected value of the signal of the detection element of interest SNen.

[0034] The control circuit CNT performs a first operation for each line of the current frame, which calculates first difference data (also called first data) encoded based on the difference between the detected value of the signal of the corresponding detection element in the corresponding line of the previous frame and the detected value of the signal of the detection element of interest.

[0035] The control circuit CNT also performs a second operation for each line of the current frame, which calculates second difference data (also called second data) encoded based on the difference between the average value of the detected signals of multiple detection elements included within the reference range RNG as a predetermined range of the current frame and the detected value of the signal of the detection element of interest SNen.

[0036] When a weighted average is used to calculate the average value, in the current frame, when calculating the weighted average of the detected values ​​of the previously read signals from the detection elements, each detected value is multiplied by a coefficient (weight coefficient). At this time, the value of the coefficient is configured to be larger for detection elements that are geographically closer to the detection element of interest, SNen. As will be described later, the control circuit CNT performs the first and second operations and selects the difference data (either the first difference data or the second difference data) with the smaller data amount from the first difference data and outputs it as the transmitted difference data. Here, the data amount is the total number of bits of the data to be transmitted (transmitted difference data).

[0037] Next, Figure 7 will be used to explain the data format DAF for transmitted differential data. The data format DAF is the format for differential data for one line (1HL). The data format DAF has an encoding parameter field ENP and a data field DTF. The encoding parameter field ENP has a first field P01, a second field P02, and a third field P03. The data format DAF includes a base unit BAU, a first extension unit EU1, and a second extension unit EU2.

[0038] The encoding parameter field ENP is used to define the encoding parameters of the data format DAF and is used when decoding the data format DAF.

[0039] The first field P01 defines whether a first operation was performed using the previous frame data for calculating the difference data, or a second operation was performed using the average value of the current frame's reference range RNG for calculating the difference data. The first field P01 is, for example, a value of "0" or "1". For example, "0" defines that a first operation was performed using the previous frame data for calculating the difference data. "1" defines that a second operation was performed using the average value of the current frame's reference range RNG for calculating the difference data. In other words, it has a bit (first field P01) that indicates whether to refer to the detected value data of the signal of the detection element in the previous frame or to refer to the detected value data of the signal of the detection element in the current frame.

[0040] The second field P02 defines the bit length of the base unit BAU. In representing the bit length of the base unit BAU, for example, a 3-bit bit length is represented as "00", a 4-bit bit length as "01", a 5-bit bit length as "10", and a 6-bit bit length as "11", and these are represented using 2 bits.

[0041] The third field P03 defines the bit lengths of the first extension unit EU1 and the second extension unit EU2. In representing the bit lengths of the first extension unit EU1 and the second extension unit EU2, for example, a 3-bit bit length is represented as "00", a 4-bit bit length as "01", a 5-bit bit length as "10", and a 6-bit bit length as "11", and these are represented using 2 bits.

[0042] The basic unit BAU represents the difference in the detected value of the signal of the detection element SNen of interest. In Figure 7, multiple basic unit BAUs are provided, each corresponding to one line (1HL) of detection elements SNi1, SNi2, SNi3, SNi4, ..., SNil. Each basic unit BAU represents the difference using, for example, two's complement representation, and the representation range of -2^(number of bits - 1) + 1 to +2^(number of bits - 1) - 2 is represented by each basic unit BAU. If the difference exceeds this representation range, the first extension unit EU1 or the second extension unit EU2 is added to represent the difference exceeding this representation range. In other words, if the difference data of the detection element is within a predetermined value (for example, the representation range of -2^(number of bits - 1) + 1 to +2^(number of bits - 1) - 2), the difference data of the detection element is represented by the basic unit. If the difference data of the detection element is greater than or equal to the predetermined value, the difference data within the predetermined value is represented by the basic unit, and the difference data greater than or equal to the predetermined value is represented by the extension unit.

[0043] Note that the basic unit BAU of the SNi1 detection element uses the original data when the detection element is the upper left detection element.

[0044] The first extension unit EU1 and the second extension unit EU2 are added as needed when the difference value exceeds the representation range of the base unit. In this example, the number of extension units (EUx) is described as two: the first extension unit EU1 and the second extension unit EU2. The number of extension units (EUx) is not limited to two: the first extension unit EU1 and the second extension unit EU2. Three, four, or more extension units can be added as needed to represent the difference value. In the first extension unit EU1 and the second extension unit EU2, the first bit is a continuation / end bit, indicating whether the extension unit is the last or a continuation. For example, if the first bit is "0", it indicates the end, and if it is "1", it indicates the continuation. The remaining bits of the first extension unit EU1 and the second extension unit EU2, excluding the first bit, are numerical bits (called numeric bits). The value of the numeric bits represents the value that could not be represented by the base unit BAU. Based on the encoding result, as many extension units as needed will be added. The sign of a numeric bit is determined by the base unit. Even in the case of a negative value, the first extension unit EU1 and the second extension unit EU2 are represented as positive values.

[0045] The following examples illustrate the basic unit BAU, the first expansion unit EU1, and the second expansion unit EU2.

[0046] (Example where the base unit BAU and the extension unit EUx (x=1, 2: EU1, EU2) are 4 bits) 1000: Difference = -8 or less (in this case, accompanied by EU1 or EU1 and EU2) 1001: Difference = -7 (Can be represented by the basic unit BAU) ~ 1111: Difference = -1 (Can be represented by the basic unit BAU) 0000: Difference = 0 (Can be represented by the basic unit BAU) 0001: Difference = +1 (Can be represented by the basic unit BAU) ~ 0110: Difference = +6 (Can be represented by the basic unit BAU) 0111: Difference = +7 or greater (in this case, accompanied by EU1 or EU1 and EU2) (Example where the first expansion unit EU1 and the second expansion unit EU2 are both 4 bits) If the difference is -20 Since the base unit can represent values ​​up to -8, the remaining 12 (positive values) are represented by the first extension unit EU1 or by the first extension unit EU1 and the second extension unit EU2.

[0047] The numerical bits included in the expansion unit are 3 bits, and a bit width of 4 bits is required to represent 12, so two expansion units are used as shown below (the first expansion unit EU1 and the second expansion unit EU2 are used).

[0048] (Basic Unit BAU) (First Expansion Unit EU1) (Second Expansion Unit EU2) "1000" "1" "001" "0" "100" -8 or less Continue End The numerical bit is formed by concatenating "001" from the first expansion unit EU1 and "100" from the second expansion unit EU2, resulting in 001100b = 12. The difference in the detected values ​​of this detection element requires a total of 4 + 4 × 2 = 12 bits.

[0049] Next, we will explain the configuration examples of the encoding circuit ENC and the decoding circuit DEC using Figures 8 and 9. Figure 8 is a block diagram of the encoding circuit according to the embodiment. Figure 9 is a block diagram of the decoding circuit according to the embodiment.

[0050] As shown in Figure 8, the encoding circuit ENC includes a current frame peripheral detection element reference unit 81, a (weighted) average value calculation unit 82, a previous frame data holding unit 83, a reference value selection unit 84, and a difference value calculation unit 85. The encoding circuit ENC further includes an encoding condition control unit 86, an encoding calculation unit 87, an encoding result holding unit 88, an encoding result comparison / selection unit 89, and an encoded data output unit 90.

[0051] The current frame peripheral detection element reference unit 81 includes, for example, a line memory with a number of lines that can encompass the vertical reference range, and is a reference circuit that receives the original data Dsrc as the detected value of the signal of the detection element SNen of interest, and references the detected values ​​of the signals of the detection elements in the vicinity of the detection element SNen of interest. The nearby detection elements are multiple detection elements within the reference range RNG described in Figure 3, detection elements based on the description in Figure 4, or multiple detection elements within the reference range RNG described in Figure 5.

[0052] The (weighted) average calculation unit 82 calculates the average value of the detected signals of multiple detection elements, or a weighted average, based on the output of the current frame peripheral detection element reference unit 81. If the output of the current frame peripheral detection element reference unit 81 is multiple detection elements within the reference range RNG as shown in Figures 3 and 4, the (weighted) average calculation unit 82 calculates the average value of the detected signals of multiple detection elements within the reference range RNG. Also, if the output of the current frame peripheral detection element reference unit 81 is multiple detection elements within the reference range RNG as explained in Figure 5, the (weighted) average calculation unit 82 calculates a weighted average of the detected signals of multiple detection elements, for example, based on the example of weighted average described above.

[0053] The previous frame data holding unit 83 is configured to receive the original data Dsrc and to hold all the detected values ​​of the signals of multiple detection elements in the frame before the current frame (previous frame). The previous frame data holding unit 83 has, for example, two frame buffers (two sides) with a storage capacity for one frame. For example, the detected values ​​of the signals of multiple detection elements in the current frame (original data Dsrc) are sequentially written to one of the two frame buffers, and when one of the two frame buffers becomes full, the detected values ​​of the signals of multiple detection elements in the current frame (original data Dsrc) are sequentially written to the other frame buffer. As a result, one of the two frame buffers holds all the detected values ​​of the signals of multiple detection elements in the previous frame. When the other frame buffer becomes full, the detected values ​​of the signals of multiple detection elements in the current frame are sequentially written to the other frame buffer. By repeating this operation, the unit is configured to always hold all the detected values ​​of the signals of multiple detection elements in the previous frame.

[0054] The previous frame data holding unit 83 also has the function of selecting and outputting the detected value of the signal of the corresponding detection element in the previous frame, according to the original data Dsrc. In other words, in Figure 6, if the original data Dsrc is the detected value of the signal of the detection element of interest SNen(im), the previous frame data holding unit 83 selects and outputs the detected value of the signal of the detection element SNim in the previous frame as a reference value based on the original data Dsrc.

[0055] The reference value selection unit 84 is configured to select either the output of the (weighted) average calculation unit 82 or the output of the previous frame data retention unit 83.

[0056] The difference value calculation unit 85 calculates the difference based on the reference value selected by the reference value selection unit 84. If the reference value selection unit 84 selects the average value of the detected signals of multiple detection elements within the reference range RNG as explained in Figure 3 or based on the explanation in Figure 4 as the reference value, the difference value calculation unit 85 calculates the difference between the original data Dsrc and the average value of the detected signals of the multiple detection elements and the detected signal of the detection element of interest SNen. If the reference value selection unit 84 selects the weighted average value of the detected signals of multiple detection elements within the reference range RNG as explained in Figure 5 as the reference value, the difference value calculation unit 85 calculates the difference between the original data Dsrc and the weighted average value of the detected signals of multiple detection elements and the detected signal of the detection element of interest SNen. If the reference value selection unit 84 selects the detected signals of multiple detection elements from the previous frame as the reference value, it calculates the difference between the original data Dsrc and the detected signal of the corresponding detection element from the previous frame and the detected signal of the detection element of interest SNen.

[0057] The encoding condition control unit 86 controls the test encoding conditions for performing test encoding by changing the number of bits of the basic unit BAU and extension units EU1 and EU2 for each line. This allows the system to find the combination that results in the shortest data length of the DAF data format of the transmitted differential data. For example, if the bit length definition is set to 3 bits to 6 bits, the system performs test encoding with 4 × 4 = 16 combinations of setting the bit length of the basic unit BAU and extension units EU1 and EU2 to 3 bits to 6 bits each, and adopts the combination that results in the shortest total bit length of the DAF data format.

[0058] The encoding calculation unit 87 performs encoding of the difference received from the difference value calculation unit 85 based on the test encoding conditions received from the encoding condition control unit 86. The encoding condition control unit 86 sequentially supplies test encoding conditions to the encoding calculation unit 87 that change the number of bits of the basic unit BAU and extension units EU1, EU2 to various numbers of bits for each line, and the encoding calculation unit 87 performs encoding of the difference based on each test encoding condition. In other words, the encoding calculation unit 87 performs a test encoding calculation that includes a first calculation for each line of the current frame, which calculates first difference data encoded based on the difference between the detected value of the signal of the corresponding detection element in the corresponding line of the previous frame and the detected value of the signal of the detection element of interest, and a second calculation for second difference data encoded based on the difference between the average value of the detected values ​​of the signals of the detection elements included within a predetermined range of the current frame. In this first and second calculation, the encoding calculation unit 87 performs test encoding by changing the number of bits of the basic unit BAU and extension units EU1, EU2 to various numbers of bits for each line based on the test encoding conditions. Here, each encoded data may be in the data format DAF, which has an encoding parameter field ENP and a data field DTF, as shown in Figure 7.

[0059] The encoding result storage unit 88 stores the encoding result storage units 88 for each line of the basic unit BAU and extension units EU1 and EU2 that have been encoded based on each test encoding condition.

[0060] The encoding result comparison and selection unit 89 selects one encoded data from among multiple encoded data related to the same line stored in the encoding result holding unit 88 for the same line that has the shortest total bit length of the data format DAF, and sends it to the encoded data output unit 90.

[0061] The encoded data output unit 90 receives the encoded data selected by the encoded result comparison and selection unit 89 and outputs the received encoded data as encoded data Denc. This encoded data Denc is transmitted as transmission difference data to the transmission circuit TX in Figure 1, and is transmitted as a wireless signal from the transmission antenna AN1, for example, and received by the receiving antenna AN2 of the host device HST.

[0062] As shown in Figure 9, the decoding circuit DEC includes an encoding parameter analysis unit 91, a reference value extraction unit 92, a previous frame decoded data retention unit 95, a (weighted) average value calculation unit 93, a current frame decoded data retention unit 94, and a decoding calculation unit 96.

[0063] The radio signal received by the receiving antenna AN2 is converted into encoded data Denc by the receiving circuit RX and supplied to the encoded parameter analysis unit 91 as received difference data. The format of the received difference data is, for example, the data format DAF, which has an encoded parameter field ENP and a data field DTF as shown in Figure 7. The encoded parameter analysis unit 91 analyzes the encoded parameter field ENP of the supplied encoded data Denc. As explained in Figure 7, the encoded parameter field ENP has a first field P01, a second field P02, and a third field P03. Analysis of the first field P01 reveals whether a first operation was performed using the previous frame data for calculating the difference data, or whether a second operation was performed using the average value of the reference range RNG of the current frame for calculating the difference data. Analysis of the second field P02 reveals the bit length of the basic unit BAU. Analysis of the third field P03 reveals the bit lengths of the first extension unit EU1 and the second extension unit EU2.

[0064] The reference value extraction unit 92 receives the encoded data Denc and the analysis results of the encoded parameter field ENP, and performs calculations to extract the reference value used when generating the encoded data Denc. The reference value extraction unit 92 is also configured to receive output values ​​output from the (weighted) average calculation unit 93 and output values ​​output from the previous frame decoded data holding unit 95.

[0065] The decoding calculation unit 96 performs a decoding calculation on the encoded data Denc based on the analysis result of the encoding parameter field ENP and the reference value output from the reference value extraction unit 92, and outputs the decoded data Ddec. The decoded data Ddec is also supplied to the current frame decoded data holding unit 94 and stored therein.

[0066] For example, if the encoded data Denc contains the detected value DSNen00 of the first detection element SNe00 at the leftmost end of the first line of the sensor array SARY, the data of the detected value DSNen00 itself is represented by the first basic unit BAU or basic unit BAU, the first extension unit EU1 and the second extension unit EU2 of the encoded data Denc. Therefore, the reference value extraction unit 92 extracts the detected value DSNen00 and outputs it to the decoding calculation unit 96, and the decoding calculation unit 96 outputs the detected value DSNen00 as decoded data Ddec. The detected value DSNen00 is also supplied to the current frame decoded data holding unit 94 and stored therein.

[0067] Next, if the encoded data Denc includes the encoded data of the detected value DSNen001 of the second detection element SNen001 to the right of the first detection element SNen00 at the left end of the first line of the sensor array SARY, the encoded data of the detected value DSNen001 is the difference between the detected value DSNen00 and the detected value DSNen001 of the detection element SNen001 to the right, with the detected value DSNen00 as the reference value. Therefore, the detected value DSNen00 output from the current frame decode data holding unit 94 is extracted by the reference value extraction unit 92 via the (weighted) average value calculation unit 93 and supplied from the reference value extraction unit 92 to the decode calculation unit 96. The decode calculation unit 96 adds the difference to the detected value DSNen00 to calculate the detected value DSNen001 as the decode data Ddec. The detected value DSNen001 is also supplied to the current frame decode data holding unit 94 and stored there.

[0068] Next, if the encoded data Denc includes the encoded data of the detected value DSNen002 of the third detection element SNen002 to the right of the first detection element SNen001 of the sensor array SARY, the encoded data of the detected value DSNen002 is the difference between the average of the detected values ​​DSNen00 and DSNen001 and the detected value DSNen001 of the detection element SNen002. Therefore, the detected values ​​DSNen00 and DSNen001 output from the current frame decode data holding unit 94 are supplied to the (weighted) average calculation unit 93, where the average value is calculated. The calculated average value is then extracted by the reference value extraction unit 92 and supplied from the reference value extraction unit 92 to the decode calculation unit 96. The decode calculation unit 96 adds the difference to the average value to calculate the detected value DSNen002 as decode data Ddec. The detected value DSNen002 is also supplied to the current frame decode data holding unit 94 and stored there.

[0069] This decoding operation is performed sequentially on the line-by-line data format DAF, thereby obtaining the detected values ​​for all line detection elements of the sensor array SARY related to the current frame. The above decoding operation relates to the decoding operation for the encoding method described in Figures 3 and 4. In the case of the encoding method using weighted average described in Figure 5, the (weighted) average calculation unit 93 calculates the weighted average, and the reference value is extracted by the reference value extraction unit 92.

[0070] In the encoding method described in Figure 6, which uses the detected data of the previous frame as a reference value, the previous frame decoded data storage unit 95 and the current frame decoded data storage unit 94 shown in Figure 9 are used. When the current frame decoded data storage unit 94, which is the first frame, becomes full, all the detected values ​​of the current frame are transferred to, for example, the previous frame decoded data storage unit 95 and stored there, and the data stored in the current frame decoded data storage unit 94 is erased and made empty. Then, if the data format DAF includes the difference of the first detection element SNen00 at the left end of the first line of the sensor array SARY that applies to the current frame as the second frame, the detected value of the first detection element at the left end of the first line of the sensor array SARY, which is stored in the previous frame decoded data storage unit 95, is extracted as a reference value by the reference value extraction unit 92 and supplied from the reference value extraction unit 92 to the decode calculation unit 96. As a result, the decoding unit 96 can decode the detected value of the detected element SNen00 by adding the detected value of the corresponding detected element from the previous frame to the difference of the first detected element SNen00 at the left end of the first line of the sensor array SARY for the current frame. The detected value of the detected element SNen00 is then stored as decoded data Ddec in the current frame decoded data holding unit 94. By performing such calculations sequentially, the data format DAF related to the encoding method described in Figure 6 can be encoded.

[0071] Next, the encoding and decoding procedures will be explained using Figures 10 and 11. Figure 10 is a flowchart illustrating the encoding procedure according to the embodiment. Figure 11 is a flowchart illustrating the difference value encoding process in Figure 10.

[0072] As shown in Figure 10, the encoding procedure has steps 100-108. Each step will be described below. These steps 100-108 are assumed to be performed by the control circuit CNT shown in Figure 1.

[0073] (Step 100) To set the initial encoding position, the line variable is set to the first line, which is the first line of the sensor array SARY.

[0074] (Step 101) The detection element that determines the reference value required for encoding is set to the average value of the detected pixels within the reference range RNG of the current frame (see Figures 3 and 4).

[0075] (Step 102: Differential encoding process) Based on the setting of the reference value in step 101, a second operation is performed, which is an encoding process using the difference between the detected value of the detection element of interest and the average value of the detected pixels within the reference range RNG (see Figures 3 and 4). This encoding process is performed, for example, for one line of detection elements. At this time, as explained in Figure 11, encoding processes are performed with various bit counts for the basic unit BAU and the extension units EU1 and EU2.

[0076] (Step 103) Next, the detection element used to determine the reference value required for encoding is set to the detection element of the previous frame at the same position as the detection element of interest in the current frame (for example, the mth position from the left of the nth line of the current frame) (see Figure 6).

[0077] (Step 104: Differential encoding process) Based on the setting of the reference value in step 103, a first operation is performed, which is an encoding process using the difference between the detected value of the detection element of interest in the current frame and the detected value of the detection element in the previous frame (see Figure 6). This encoding process is performed, for example, for one line of detection elements in the current frame. At this time, as explained in Figure 11, encoding processes are also performed with various bit counts for the basic unit BAU and the extension units EU1 and EU2.

[0078] (Step 105) The number of bits in the data field DTF (encoded result of the second operation) of the encoded data obtained in step 102 is compared with the number of bits in the data field DTF (encoded result of the first operation) of the encoded data obtained in step 104, and the encoding method with the shorter number of bits is adopted. This allows the encoding parameter field ENP to be set.

[0079] (Step 106) Step 105 combines the encoding parameter field ENP and the data field DTF determined in step 105 into transmission difference data, and a transfer process is performed to transfer the encoded data to the host device HST. This transfer is performed using a transmission system with bandwidth limitations, such as wireless communication.

[0080] (Step 107) Next, it is determined whether the line variable is the last line of the sensor array SARY. If the line variable is the last line (Y), the encoding process ends. If the line variable is not the last line (N), proceed to step 108.

[0081] (Step 108) The value of the line variable is incremented by 1, and the process moves to step 101. This initiates the encoding process for the next line in step 101.

[0082] The differential encoding process in steps 102 and 104 will be explained using Figure 11. The differential encoding process has steps 110-122. Each step will be explained below. These steps 110-122 are assumed to be executed by the control circuit CNT in Figure 1. Here, as explained earlier, for example, when the bit length definition is set to 3 bits to 6 bits, a test encoding as differential encoding is performed for 4 × 4 = 16 combinations in which the bit lengths of the basic unit BAU and extension units EU1 and EU2 are set to 3 bits to 6 bits each by brute force. This makes it possible to determine the combination of bit lengths of the basic unit BAU and extension units EU1 and EU2 that results in the shortest total bit length of the data format DAF (data field DTF). In this process, the encoding condition control unit 86 changes the number of bits of the basic unit BAU and extension units EU1 and EU2 to various numbers of bits for each line.

[0083] (Step 110) First, the bit width of the basic unit BAU is set to its initial value. For example, if the bit length definition is set to 3 bits to 6 bits, the initial bit width can be set to 3 bits.

[0084] (Step 111) Next, the bit widths of the extension units EU1 and EU2 are set to their initial values. For example, if the bit length definition is set to 3 bits to 6 bits, the initial bit width can be set to 3 bits.

[0085] (Step 112) Next, the position of the element of interest is set to the leftmost position of the first line, which is the first line of the sensor array SARY.

[0086] (Step 113) Next, we will make the following decisions.

[0087] 1) Is the reference value based on the detection value of the detection element in the current frame? 2) Is the position of the line of the detection element of interest the same as the position of the leading line? 3) Is the position of the detection element of interest at the beginning of the line? If all of the above conditions 1)-3) are met (Y), proceed to step 114. If none of the above conditions 1)-3) are met (N), proceed to step 115.

[0088] (Step 114) The baseline value is set to the original data.

[0089] (Step 115) Based on the reference value, the difference (difference value) of the detected value of the detection element of interest is calculated. Then, based on the calculated difference, the data (code) of the basic unit BAU and the extension units EU1 and EU2 are set.

[0090] (Step 116) Next, it is determined whether the position of the detection element of interest is the position of the last detection element in the line. If the position of the detection element of interest is the position of the last detection element in the line (Y), the process proceeds to step 117. If the position of the detection element of interest is not the position of the last detection element in the line (N), the process proceeds to step 118.

[0091] (Step 117) Determine whether the bit width of extension units EU1 and EU2 is the final value. For example, if the bit length definition is set to 3 bits to 6 bits, determine whether it is 6 bits. If the bit width is the final value (Y), proceed to step 119. If the bit width is not the final value (N), proceed to step 120.

[0092] (Step 118) The position of the element of interest is increased by +1, and the process proceeds to step 113.

[0093] (Step 119) Determine whether the bit width of the basic unit BAU is the final value. For example, if the bit length definition is set to 3 bits to 6 bits, determine whether it is 6 bits. If the bit width is the final value (Y), proceed to step 121. If the bit width is not the final value (N), proceed to step 122.

[0094] (Step 120) The bit width of extension units EU1 and EU2 is increased by +1, and the process proceeds to step 112.

[0095] (Step 121) In the encoded data field DTF, the combination of the bit width of the base unit BAU and the bit widths of the extension units EU1 and EU2 that results in the shortest number of bits in the data field DTF is searched for. Based on this combination, the encoding parameters for the first field P01, second field P02, and third field P03 of the encoding parameter field ENP are set, and the data format DAF of the transmission difference data, which includes the set encoding parameter field ENP and the data field DTF, is output as the encoded result.

[0096] (Step 122) The bit width of the base unit BAU is increased by 1, and the program proceeds to step 112.

[0097] According to the above embodiments, one or more of the following effects can be obtained.

[0098] 1) The reference value, the detected value of the signal from the target detection element SNen, and the difference value are recorded and transmitted as a data format. This results in a digital value with a smaller number of bits than the normal absolute value (digital data with a number of bits that directly represents the detected value of the signal), thus reducing the amount of data transmitted per unit time.

[0099] 2) The DAF data format is configured such that the data length is minimized for each line, with the number of bits in the basic unit BAU and the number of bits in the extension units EU1 and EU2 set to minimize the data length. This improves the compression ratio of the DAF data format.

[0100] 3) As described in 2) above, when transmitting sensor data using a bandwidth-limited transmission system, the amount of data sent per unit time can be reduced.

[0101] (modified version) The modified examples are explained using Figures 12-15. Figure 12 is a diagram illustrating the fifth example of the encoding method related to the modified example. Figure 13 is a diagram illustrating the data format related to the modified example. Figure 14 is a diagram illustrating an example of the configuration of a continuous compression unit related to the modified example. Figure 15 is a flowchart illustrating the encoding procedure related to the modified example.

[0102] First, we will explain the fifth example of the encoding method using Figure 12. The fifth example of the encoding method in Figure 12 is a modified version of the fourth example of the encoding method in Figure 6. In the fourth example of the encoding method, "the detected value of the signal of the detection element SNen of interest in the current frame Fn and the detected value of the signal of the detection element SNim, which is located at the same position as the detection element SNen(im) of interest in the previous frame Fn-1, are used as the reference values ​​for the difference calculation."

[0103] On the other hand, in the fifth example of the encoding method shown in Figure 12, "the average of the differences between the detected value of the signal of the target detection element SNen in the current frame Fn and the detected value (detection data) of the same pixel in the current frame Fn and the previous frame Fn-1 within a predetermined range (reference range) RNG prior to the target detection element SNen in the current frame Fn is used as the reference value for the difference calculation."

[0104] Here, the average difference between the detected value of the current frame Fn and the detected value of the same pixel in the previous frame Fn-1 within a predetermined range RNG prior to the detection element SNen of interest in the current frame Fn can be said to be a value based on the detected value of the detection element's signal read out before the detection timing of the detected value of the detection element's signal of interest.

[0105] This section describes the average value of the difference between the detected value of the same pixel in the current frame Fn and the previous frame Fn-1 within a predetermined range RNG prior to the detection element SNen of interest in the current frame Fn.

[0106] In Figure 12, the detection element of interest SNen is the detection element of interest SNen(im) in the current frame Fn. The predetermined range RNG before the detection element of interest SNen in the current frame Fn is the predetermined range RNG(Fn) of the current frame Fn, and the predetermined range RNG of the previous frame Fn-1 is the predetermined range RNG(Fn-1). The detection value of the same pixel in the current frame Fn and the previous frame Fn-1 within the predetermined range RNG refers to the detection value of the detection element SNrng_im(Fn) within the predetermined range RNG(Fn) of the current frame Fn, and the detection value of the detection element SNrng_im(Fn-1) within the predetermined range RNG(Fn-1) of the previous frame Fn-n1. Here, the same pixel in the current frame Fn and the previous frame Fn-1 means that the value of im is the same for both the detection element SNrng_im(Fn) and the detection element SNrng_im(Fn-1). Here, im used in SNrng_im(Fn) and SNrng_im(Fn-1) is the arrangement number (matrix number) of multiple detection elements arranged within a predetermined range RNG(Fn,Fn-1).

[0107] The difference between the detected value of the same pixel in the current frame Fn and the previous frame Fn-1 is the difference between the detected value of detection element SNrng_im(Fn) and the detected value of detection element SNrng_im(Fn-1) (im is the number of the same arrangement of multiple detection elements in the predetermined range RNG(Fn,Fn-1)).

[0108] This is explained as the average difference between the detected values ​​of the same pixel in the current frame Fn and the previous frame Fn-1. Here, we will explain assuming that im, used in SNrng_im(Fn) and SNrng_im(Fn-1), is schematically between 1 and 10. Also, the difference between the detected value of SNrng_im(Fn) and the detected value of SNrng_im(Fn-1) is denoted as difference(im) (where im is between 1 and 10).

[0109] In this case, the average value Dave, which is the difference between the detected value of the same pixel in the current frame Fn and the previous frame Fn-1, is given by the following formula.

[0110] Dave = ((Diff (1) + Diff (2) + ... + Diff (9) + Diff (10)) / 10 Therefore, the difference calculation is the calculation of the difference between the detected value of the signal of the target detection element SNen in the current frame Fn and the average value Dave.

[0111] In other words, the detection device DETA includes a plurality of detection elements SN arranged in a matrix, a plurality of scan lines G extending in a first direction X and arranged in a second direction Y intersecting the first direction X, and connected to a scan circuit SC, a plurality of signal lines S extending in the second direction Y and arranged in the first direction X, and connected to a detection circuit DET, and a control circuit CNT. Each of the plurality of detection elements SN is connected to a corresponding scan line (Gn, Gn+1) and a corresponding signal line (Sn, Sn+1). The detection circuit DET is configured to sequentially read out the detected values ​​of the signals of the plurality of detection elements SN via the plurality of signal lines S. When the control circuit CNT outputs the detected value of the signal of the detection element SNen of interest to the outside, it outputs the difference data between the detected value of the signal of the detection element SNen of interest and a value based on the detected value of the signal of the detection element SNen of interest read before the detection timing of the detected value of the signal of the detection element SNen of interest, as transmitted difference data. Here, the value based on the detected value of the detection element's signal read out before the detection timing of the detected value of the detection element SNen of interest is set to the average of the difference between the detected value of the same pixel in the current frame Fn and the previous frame Fn-1 within a predetermined range RNG prior to the detection element SNen of interest in the current frame Fn.

[0112] The transmitted difference data is a set of difference data for each line of the current frame, where each of the multiple detection elements included in the corresponding line is designated as the detection element of interest SNen. If the current frame has X lines, the transmitted difference data contains X difference data for each of the X lines. The detection timing of the detected value of the signal of the detection element of interest SNen can be rephrased as the decoding timing of the detected value of the signal of the detection element of interest SNen. In other words, the transmitted difference data is output as the difference data between the value based on the detected value of the detection element's signal read before the decoding timing of the detected value of the signal of the detection element of interest SNen and the aforementioned detected value of the signal of the detection element of interest SNen.

[0113] Next, Figure 13 will be used to explain the data format DAF for transmitted differential data. The data format DAF is the format for differential data for one line (1HL). The data format DAF has an encoding parameter field ENP and a data field DTF. The encoding parameter field ENP has a first field PP01, a second field P02, and a third field P03. The data format DAF includes a base unit BAU, a first extension unit EU1, and a second extension unit EU2.

[0114] As explained in Figure 14, a continuous compression unit may be provided in the DAF data format for transmitted differential data. In this case, the DAF data format will consist of a basic unit BAU, a first extension unit EU1, a second extension unit EU2, and a continuous compression unit CCU.

[0115] The encoding parameter field ENP is used to define the encoding parameters of the data format DAF and is used when decoding the data format DAF.

[0116] The first field PP01 defines whether the calculation of the difference data was performed using the average value of the difference between the detected value (detection data) of the same pixel in the previous frame Fn-1 within a predetermined range (reference range) RNG prior to the detection element SNen of interest in the current frame Fn, or whether a second calculation was performed using the average value of the reference range RNG of the current frame. The first field PP01 is, for example, set to a value of "0" or "1". For example, "0" defines that a second calculation was performed using the average value of the reference range RNG of the current frame for calculating the difference data. "1" defines that the calculation was performed using the average value of the difference between the detected value (detection data) of the same pixel in the previous frame Fn-1 within a predetermined range (reference range) RNG prior to the detection element SNen of interest in the current frame Fn. In other words, the beginning of each line of difference data includes a bit (first field P01) indicating whether the average value of the difference between the same pixel data of the current frame and the previous frame within a predetermined range prior to the detection element of interest in the current frame was adopted, or whether the average value within the reference range in the current frame was adopted.

[0117] The second field P02 defines the bit length of the base unit BAU. In representing the bit length of the base unit BAU, for example, a 3-bit bit length is represented as "00", a 4-bit bit length as "01", a 5-bit bit length as "10", and a 6-bit bit length as "11", and these are represented using 2 bits.

[0118] The third field P03 defines the bit lengths of the first extension unit EU1 and the second extension unit EU2. In representing the bit lengths of the first extension unit EU1 and the second extension unit EU2, for example, a 3-bit bit length is represented as "00", a 4-bit bit length as "01", a 5-bit bit length as "10", and a 6-bit bit length as "11", and these are represented using 2 bits.

[0119] The basic unit BAU represents the difference in the detected value of the signal of the detection element SNen of interest. In Figure 13, multiple basic unit BAUs are provided, each corresponding to one line (1HL) of detection elements SNi1, SNi2, SNi3, SNi4, ..., SNil. Each basic unit BAU represents the difference using, for example, two's complement representation, and the representation range of -2^(number of bits - 1) + 1 to +2^(number of bits - 1) - 2 is represented by each basic unit BAU. If the difference exceeds this representation range, the first extension unit EU1 or the second extension unit EU2 is added to represent the difference exceeding this representation range. In other words, if the difference data of the detection element is within a predetermined value (for example, the representation range of -2^(number of bits - 1) + 1 to +2^(number of bits - 1) - 2), the difference data of the detection element is represented by the basic unit. If the difference data of the detection element is greater than or equal to the predetermined value, the difference data within the predetermined value is represented by the basic unit, and the difference data greater than or equal to the predetermined value is represented by the extension unit.

[0120] Note that the basic unit BAU of the SNi1 detection element uses the original data when the detection element is the upper left detection element.

[0121] The first extension unit EU1 and the second extension unit EU2 are added as needed when the difference value exceeds the representation range of the base unit. In this example, the number of extension units (EUx) is described as two: the first extension unit EU1 and the second extension unit EU2. The number of extension units (EUx) is not limited to two: the first extension unit EU1 and the second extension unit EU2. Three, four, or more extension units can be added as needed to represent the difference value. In the first extension unit EU1 and the second extension unit EU2, the first bit is a continuation / end bit, indicating whether the extension unit is the last or a continuation. For example, if the first bit is "0", it indicates the end, and if it is "1", it indicates the continuation. The remaining bits of the first extension unit EU1 and the second extension unit EU2, excluding the first bit, are numerical bits (called numeric bits). The value of the numeric bits represents the value that could not be represented by the base unit BAU. Based on the encoding result, as many extension units as needed will be added. The sign of a numeric bit is determined by the base unit. Even in the case of a negative value, the first extension unit EU1 and the second extension unit EU2 are represented as positive values.

[0122] The following examples illustrate the basic unit BAU, the first expansion unit EU1, and the second expansion unit EU2.

[0123] (Example where the base unit BAU and the extension unit EUx (x=1, 2: EU1, EU2) are 4 bits) 1000: Difference = -8 or less (in this case, accompanied by EU1 or EU1 and EU2) 1001: Difference = -7 (Can be represented by the basic unit BAU) ~ 1111: Difference = -1 (Can be represented by the basic unit BAU) 0000: Difference = 0 (Can be represented by the basic unit BAU) 0001: Difference = +1 (Can be represented by the basic unit BAU) ~ 0110: Difference = +6 (Can be represented by the basic unit BAU) 0111: Difference = +7 or greater (in this case, accompanied by EU1 or EU1 and EU2) (Example where the first expansion unit EU1 and the second expansion unit EU2 are both 4 bits) If the difference is -20 Since the base unit can represent values ​​up to -8, the remaining 12 (positive values) are represented by the first extension unit EU1 or by the first extension unit EU1 and the second extension unit EU2.

[0124] The numerical bits included in the expansion unit are 3 bits, and a bit width of 4 bits is required to represent 12, so two expansion units are used as shown below (the first expansion unit EU1 and the second expansion unit EU2 are used).

[0125] (Basic Unit BAU) (First Expansion Unit EU1) (Second Expansion Unit EU2) "01000" "1" "001" "0" "100" -8 or less Continue End The initial "0" in the base unit BAU "01000" indicates that it is the base unit BAU.

[0126] The numerical bit is formed by concatenating "001" from the first expansion unit EU1 and "100" from the second expansion unit EU2, resulting in 001100b = 12. The difference in the detected values ​​of this detection element will require a total of 5 + 4 × 2 = 13 bits.

[0127] (Example configuration of a continuous compression unit) If a series of basic units (BAU) that match the conditions set for frequent occurrence during encoding appear consecutively, the continuous compression unit (CCU) can be used. The continuous compression unit (CCU) can be configured with 3 bits, as shown below. Note that the continuous compression unit (CCU) may be configured with a number of bits other than 3.

[0128] 100: When the difference is 0 and the difference is 0 consecutively, 101: When the difference is 0 and the difference is +1, 110: When differences of 0 and -1 are consecutive, 111: When the difference is +1 and the difference is 0, Here, the leading bit "1" indicates a continuous compression unit.

[0129] For example, as shown in Figure 14, the transmission difference data AA, which was originally composed of seven basic units BAU (total 28 bits), can be converted into transmission difference data BB of a total of 14 bits by using three consecutive compression units CCU (9 bits) and one basic unit BAU (5 bits). The first "0" in the basic unit BAU "01111" indicates that it is a basic unit BAU. In other words, when a predetermined number of basic units BAU appear consecutively, the system can be configured to replace those consecutive basic units BAU with consecutive compression units CCU of a predetermined number of bits.

[0130] Next, the encoding procedure for the modified example will be explained using Figure 15. The difference between the flowchart in Figure 15 and the flowchart in Figure 10 is that step 103 in the flowchart in Figure 10 is changed to step 1031, where the reference value is the average value within the reference range of the difference between the pixel of the current frame and the same pixel of the previous frame data, and step 105 in the flowchart in Figure 10 is changed to step 1051, where the reference value is the shorter of the encoded result of the current frame reference range or the average value within the reference range of the difference between the pixel of the current frame and the same pixel of the previous frame data, and the encoding parameters are set.

[0131] Steps 100-102, 104, and 106-108 in the flowchart of Figure 15, excluding steps 1031 and 1051, are the same as steps 100-102, 104, and 106-108 in Figure 10. Therefore, redundant explanations for steps 100-102, 104, and 106-108 are omitted. Also, steps 102 and 104 in Figure 15 utilize the difference value encoding process shown in Figure 11, which is the same as steps 102 and 104 in Figure 10.

[0132] As shown in Figure 15, steps 100 to 102 are carried out. Here, we will explain starting from step 102.

[0133] (Step 102: Differential encoding process) Based on the setting of the reference value in step 101, a second operation is performed, which is an encoding process using the difference between the detected value of the detection element of interest and the average value of the detected pixels within the reference range RNG (see Figures 3 and 4). This encoding process is performed, for example, for one line of detection elements. At this time, as explained in Figure 13, encoding processes are performed with various bit counts for the basic unit BAU and the extension units EU1 and EU2. After that, the process proceeds to step 1031.

[0134] (Step 1031) After step 102, step 1031 is executed. In step 1031, the detection element for determining the reference value required for encoding is set to the detection element of interest SNen in the current frame Fn, and the reference value is set to the average of the difference between the detected value (detection data) of the same pixel in the current frame Fn and the previous frame Fn-1 within a predetermined range (reference range) RNG prior to the detection element of interest SNen in the current frame Fn (see Figure 12).

[0135] (Step 104: Differential encoding process) Based on the setting of the reference value in step 1031, an encoding operation is performed using the average value of the difference between the detected value (detection data) of the same pixel in the current frame Fn and the previous frame Fn-1 within a predetermined range (reference range) RNG prior to the detection element SNen of interest in the current frame Fn. This encoding operation is performed, for example, for one line of detection elements. At this time, as explained in Figure 13, encoding operations are performed with various bit counts for the basic unit BAU and the extension units EU1 and EU2. After that, the process proceeds to step 1051.

[0136] (Step 1051) The number of bits in the data field DTF of the encoded data obtained in step 102 is compared with the number of bits in the data field DTF of the encoded data obtained in step 104, and the encoding method with the shorter number of bits is adopted. This allows the encoding parameter field ENP to be set.

[0137] After step 1051, steps 106 through 108 are executed.

[0138] In steps 102 and 104 of Figure 15, that is, in the differential value encoding process of Figure 11, the application of the continuous compression unit as explained in Figure 14, and the encoding process when the continuous compression unit is applied may be added and performed.

[0139] For example, in step 121, after the encoding parameters for the first field PP01, second field P02, and third field P03 of the encoding parameter field ENP are set based on the combination of the bit width of the shortest basic unit BAU in the data field DTF and the bit widths of the extension units EU1 and EU2, the number of bits when the continuous compression unit CCU is applied is calculated, taking into account the continuity of the basic unit BAU. If it is determined that the number of bits in the data field DTF can be reduced to a predetermined value or less by applying the continuous compression unit CCU, the first field PP01 is changed to the application of the continuous compression unit CCU, and the data field DTF is reconstructed by replacing the parts of the data field DTF that are consecutive basic unit BAU with the continuous compression unit CCU. The system is then configured so that the data format DAF of the transmission difference data, which includes the set encoding parameter field ENP and the data field DTF, is output as the encoding result.

[0140] The above modifications can achieve the same effects as the embodiment. Furthermore, since a continuous compression unit CCU is used in the DAF data format, the compression ratio of the DAF data format is further improved.

[0141] All detection devices and signal compression methods that a person skilled in the art could implement by appropriately modifying the design based on the above-described embodiments of the present disclosure also fall within the scope of the present disclosure, insofar as they encompass the gist of the present disclosure.

[0142] Within the scope of the ideas presented hereto, a person skilled in the art will be able to conceive of various modifications and alterations, and such modifications and alterations will also be understood to fall within the scope of this disclosure. For example, any addition, deletion, or design change of components, or addition, omission, or modification of processes, made by a person skilled in the art to the above-described embodiments, will also fall within the scope of this disclosure, as long as they retain the essence of this disclosure.

[0143] Furthermore, any other effects and advantages brought about by the embodiments described herein that are obvious from this specification or that can be appropriately conceived by a person skilled in the art are naturally provided by this disclosure.

[0144] Various disclosures can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be removed from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of Symbols]

[0145] 1: Sensor system, DETA: Detection device, HST: Host device, SARY: Sensor array, SEN: Sensor unit, SNen: Target detection element, SN: Detection element, SC: Scan circuit, DET: Detection circuit, ADC: Analog-to-digital conversion circuit, CNT: Control circuit, ENC: Encode circuit, AN1: Transmitting antenna, TX: Transmitting circuit, AN2: Receiving antenna, RX: Receiving circuit, DEC: Decode circuit, CON: Host control unit, DAF: Data format, ENP: Encode parameter field, P01, PP01: First field, P02: Second field, P03: Third field, DTF: Data field, BAU: Basic unit, EU1: First expansion unit, EU2: Second expansion unit, Fn: Current frame, Fn-1: Previous frame, CCU: Continuous compression unit.

Claims

1. Multiple detection elements arranged in a matrix, Multiple scan lines are arranged in a second direction that extends in a first direction and intersects the first direction, and are connected to a scan circuit. Multiple signal lines extending in a second direction and arranged in a first direction, connected to a detection circuit, Includes a control circuit, Each of the plurality of detection elements is connected to a corresponding scan line and a corresponding signal line. The detection circuit is configured to sequentially read the detected values ​​of the signals from the plurality of detection elements via the plurality of signal lines. The control circuit outputs the detected value of the signal of the detection element of interest to the outside, and outputs the difference data between the detected value of the signal of the detection element of interest and the detected value of the signal of the detection element of interest, when outputting the detected value of the signal of the detection element of interest to the outside, as transmitted difference data.

2. In the detection device according to claim 1, The aforementioned control circuit is A first operation is performed to calculate first difference data encoded based on the difference between the detected value of the signal of the corresponding detection element of the corresponding line in the previous frame and the detected value of the signal of the detection element of interest for each line of the current frame, A second operation is performed to calculate second difference data encoded based on the difference between the average value of the detected value of the signal of the detection element included within a predetermined range of the current frame and the current difference data. A detection device that selects the difference data with the smaller data volume from the first difference data and the second difference data, and outputs it as the transmitted difference data.

3. In the detection device according to claim 2, The control circuit outputs the transmission difference data for one line for each line of the current frame. The transmitted differential data for each line, including the selected differential data, comprises a base unit and an extension unit. If the difference data of the detection element is within a predetermined value, the difference data of the detection element is represented by the basic unit. A detection device in which, when the difference data of the detection element is greater than or equal to the predetermined value, the difference data of the detection element that is greater than or equal to the predetermined value is represented by the basic unit, and the difference data that is greater than or equal to the predetermined value is represented by the extension unit.

4. In the detection device according to claim 2, In the current frame, when calculating the average value of the detected signals of the previously read detection elements, each detected value is multiplied by a coefficient, A detection device in which the value of the coefficient is larger for detection elements that are closer to the detection element of interest.

5. In the detection device according to claim 3, A detection device having parameters at the beginning of the data of the aforementioned line that define the number of bits of the basic unit and the number of bits of the extension unit.

6. In the detection device according to claim 5, A detection device having a bit at the beginning of the data of the aforementioned line that further indicates whether to refer to the data of the detected value of the detection element of the previous frame or the data of the detected value of the signal of the detection element of the current frame.

7. A method for compressing the signal of a detection value of a detection device in which multiple detection elements are arranged in a matrix, The first operation on the first data, which is encoded based on the difference in the detected signal value between each line of the current frame and the corresponding line of the previous frame, A second operation is performed on the second data encoded based on the difference with the average of a predetermined range of the current frame, A signal compression method that selects the data with the smaller data size from the first data and the second data.

8. In the signal compression method according to claim 7, Each line of data containing one of the selected data sets has a base unit and an expansion unit. If the difference data is within a predetermined value, the difference data is represented by a basic unit. A signal compression method in which, if the difference data is greater than or equal to the predetermined value, the difference data of the detection element that is greater than or equal to the predetermined value is represented by the basic unit, and the difference data that is greater than or equal to the predetermined value is represented by the extension unit.

9. In the signal compression method according to claim 7, A signal compression method in which, when calculating the average value of the signals of previously read detection elements in the current frame, each detection signal is multiplied by a coefficient, and the value of the coefficient is larger for elements closer to the detection element of interest.

10. In the signal compression method according to claim 8, A signal compression method comprising having parameters at the beginning of the data of one line defining the number of bits of the basic unit and the number of bits of the extension unit.

11. In the signal compression method according to claim 10, A signal compression method comprising a bit at the beginning of the data of one line, further indicating whether to refer to the data of the detected value of the signal of the detection element of the previous frame or to the data of the detected value of the signal of the detection element of the current frame.

12. In the detection device according to claim 1, A detection device in which the value based on the detected value of the signal of the detection element read out before the detection timing of the detected value of the signal of the detection element of interest is the average value of the difference between the same pixel data of the current frame and the previous frame within a predetermined range prior to the detection element of interest in the current frame.

13. In the detection device according to claim 12, The control circuit outputs the transmission difference data for one line for each line of the current frame. The transmitted difference data for each line comprises a basic unit and an extension unit. If the difference data of the detection element is within a predetermined value, the difference data of the detection element is represented by the basic unit. A detection device in which, when the difference data of the detection element is greater than or equal to the predetermined value, the difference data of the detection element that is greater than or equal to the predetermined value is represented by the basic unit, and the difference data that is greater than or equal to the predetermined value is represented by the extension unit.

14. In the detection device according to claim 13, A detection device having parameters at the beginning of the transmitted difference data of the one line defining the number of bits of the basic unit and the number of bits of the extension unit.

15. In the detection device according to claim 14, A detection device having a bit at the beginning of the transmitted difference data of one line further indicating whether the average value of the difference between the current frame and the same pixel data of the previous frame within a predetermined range prior to the detection element of interest in the current frame was adopted, or whether the average value within the reference range in the current frame was adopted.

16. In the detection device according to claim 15, A detection device that, when a predetermined number of predetermined basic units are present consecutively, replaces such consecutive basic units with consecutive compression units of a predetermined number of bits.

17. In the detection device according to claim 16 A detection device further having a bit indicating whether it is the basic unit or the continuous compression unit.

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