Environmental sensors and sheets

Abstract

This invention provides an environmental sensor capable of sensing environmental changes over a certain range at high speed and with low power consumption. [Solution] m × n pixel circuits PIX are arranged in a matrix at the intersections of m scan lines SL and n data lines DL. Each pixel circuit PIX includes a resistive switching element 112 and a rectifier element D1 connected in series. The resistance of the resistive switching element 112 changes abruptly when the environment crosses the eigenvalue of the resistive switching element. The logic circuit 140 includes n readout circuits 150 corresponding to the n data lines DL. Each readout circuit 150 includes an impedance element 152 and a latch circuit 154 that receives the voltage signal Vs of the corresponding data line DL. The output of each latch circuit 154 indicates a binary value obtained by quantizing the environment at the resistive switching element 112 connected to the corresponding data line DL, with the eigenvalue as the threshold.

Description

Technical Field

[0001] The present disclosure relates to an environmental sensor.

Background Art

[0002] In various circuits such as integrated circuits, power devices, photonics, sensors, and μ-TAS (Total Analysis Systems) (hereinafter referred to as semiconductor devices), local temperature management is important. In conventional semiconductor devices, a temperature-sensitive element in which the resistance value or voltage drop continuously and monotonically changes with temperature, such as a PN junction (diode) or a thermistor, is generally used, and the voltage generated in the temperature-sensitive element is processed using an analog circuit such as a voltage comparator or an A / D converter.

[0003] The present inventor has proposed a single-bit sensor that achieves both low power consumption and high speed (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There are cases where it is desired to sense changes in the environment, such as temperature, two-dimensionally over a certain range rather than at a single point. In two-dimensional sensing, similar to an image sensor, a method can be considered in which a plurality of scanning lines are arranged in the row direction and a plurality of data lines are arranged in the column direction, and elements having sensitivity to the environment to be monitored are arranged in a matrix at the intersections thereof.

[0006] Here, when using a thermistor or the like as an element, reading by an A / D converter becomes necessary. When arranging the A / D converter for each data line, the circuit board area and power consumption increase. When sharing the A / D converter among a plurality of data lines, additional selector elements and their control become necessary, and problems such as an increase in reading time, an increase in reading power, an increase in crosstalk, and a decrease in accuracy due to parasitic components may occur.

[0007] The present disclosure has been made in such a situation, and an exemplary object of one aspect thereof is to provide an environmental sensor capable of sensing changes in the environment over a certain range at high speed and with low power consumption.

Means for Solving the Problems

[0008] An environmental sensor according to one aspect of the present disclosure includes m (m≧1) scanning lines extending in a first direction, a plurality of n (n≧2) data lines extending in a second direction, m×n pixel circuits arranged in a matrix at intersections of the m scanning lines and the n data lines, and a logic circuit including n reading circuits corresponding to the n data lines. The pixel circuit at the i-th row and j-th column (1≦i≦m, 1≦j≦n) includes a resistance change element and a rectifying element connected in series between the i-th scanning line and the j-th data line, and the resistance value of the resistance change element changes steeply when the environment crosses the characteristic value of the resistance change element. Each reading circuit includes an impedance element connected between the corresponding data line and a reference line, and a latch circuit that receives the voltage signal of the corresponding data line. The output of each latch circuit indicates a value obtained by quantizing the environment in the resistance change element connected to the corresponding data line into binary values with the characteristic value as a threshold.

[0009] Another aspect of the present invention is a sheet. This sheet comprises m (m≧1) scan lines extending in a first direction, a plurality of n (n≧2) data lines extending in a second direction, and m × n pixel circuits arranged in a matrix at the intersections of the m scan lines and the n data lines. The i-th row, j-th column (1≦i≦m, 1≦j≦n) pixel circuit includes a resistive switching element and a rectifier element connected in series between the i-th scan line and the j-th column data line, wherein the resistance value of the resistive switching element changes sharply when the environment crosses the eigenvalue of the resistive switching element.

[0010] Furthermore, any combination of the above components, as well as conversions of the expression of the present invention between devices, methods, systems, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0011] According to this disclosure, it is possible to measure environmental changes over a certain range at high speed and with low power consumption. [Brief explanation of the drawing]

[0012] [Figure 1] This is a circuit diagram of the environmental sensor according to Embodiment 1. [Figure 2] This figure shows the temperature dependence of the resistance value RMIT of a resistive switching element. [Figure 3] This is a circuit diagram showing an example of a readout circuit configuration. [Figure 4] This diagram illustrates temperature sensing using environmental sensors. [Figure 5] This figure shows an example of an environmental sensor configuration. [Figure 6] This is a circuit diagram of the environmental sensor according to Embodiment 2. [Figure 7] This is a circuit diagram of the environmental sensor according to Embodiment 3. [Figure 8] This is a circuit diagram of the environmental sensor according to Embodiment 4. [Figure 9] This is a circuit diagram of the environmental sensor according to Embodiment 5. [Modes for carrying out the invention]

[0013] (Summary of the embodiment) This section outlines some exemplary embodiments of the present disclosure. This outline is intended to provide a basic understanding of the embodiments and to simplify some concepts of one or more embodiments, serving as a prelude to the more detailed descriptions that follow. It does not limit the scope of the invention or disclosure. Furthermore, this outline is not a comprehensive overview of all possible embodiments and does not limit the essential components of the embodiments. For convenience, "one embodiment" may refer to one or more embodiments (examples or variations) disclosed herein.

[0014] An environmental sensor according to one embodiment comprises m (m≧1) scan lines extending in a first direction, a plurality of n (n≧2) data lines extending in a second direction, m×n pixel circuits arranged in a matrix at the intersections of the m scan lines and the n data lines, and a logic circuit including n readout circuits corresponding to the n data lines. The i-th row, j-th column (1≦i≦m, 1≦j≦n) pixel circuit includes a resistive switching element and a rectifier element connected in series between the i-th scan line and the j-th column data line, wherein the resistance value of the resistive switching element changes sharply when the environment crosses the eigenvalue of the resistive switching element. Each readout circuit includes an impedance element connected between the corresponding data line and a reference line, and a latch circuit that receives the voltage signal of the corresponding data line. The output of each latch circuit indicates a binary value obtained by quantizing the environment at the resistive switching element connected to the corresponding data line, with the eigenvalue as the threshold.

[0015] Because the resistance of a resistive switching element changes abruptly when the environment crosses the element's eigenvalue, the electrical signal generated at the resistive switching element behaves essentially as a digital binary signal. "Abrupt change in resistance" includes cases where the resistance changes by an order of magnitude or more when the physical quantity characterizing the monitored environment is near a threshold, or where the resistance changes in a step-like manner. Therefore, there is no need to amplify the electrical state of the resistive switching element with a sense amplifier, and an A / D converter is also unnecessary. The electrical signal generated at the resistive switching element can be received directly by a latch circuit. In this embodiment, since multiple latch circuits are provided to correspond to multiple data lines, a selector element is not required, and multiple data lines can be read simultaneously, thus shortening the readout time. Furthermore, since latch circuits have significantly smaller area and power consumption compared to A / D converters, miniaturization and low power consumption are also possible.

[0016] In one embodiment, the environment may be temperature, voltage, magnetic field, pressure, light, or the concentration of a specific substance, and the environmental sensor may be used to detect voltage, magnetic field, pressure, light, or the concentration of gases or liquids.

[0017] In one embodiment, the impedance element may be a transistor to which a bias voltage is applied to a control electrode. In a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), the control electrode refers to the gate electrode, and in a bipolar transistor, it refers to the base electrode.

[0018] In one embodiment, m≧2, and the environmental sensor may further include a scan driver that sequentially applies pulsed drive voltages to m scan lines. This makes it possible to detect which column and which row an environmental change has occurred.

[0019] In one embodiment, m ≥ 2, and the readout circuit may include m latch circuits corresponding to the m scan lines. Each latch circuit may latch the voltage signal of the corresponding data line when the corresponding scan line is selected. Because the circuit area of ​​the latch circuits is small, it is possible to provide a latch circuit for each scan line without impacting the chip size. In this case, the state of all resistive switching elements can be stored in the latch circuits.

[0020] In one embodiment, m ≥ 2, and m scanning lines may be selectable simultaneously. The logic circuit may be capable of generating a change detection signal indicating that at least one of the n latch circuits has changed. This makes it possible to identify the column that caused the environmental change. In this case, since scanning is not required, power consumption can be further reduced.

[0021] In one embodiment, the environmental sensor may start scanning m scan lines when a change detection signal is asserted. In other words, by starting the scanning process triggered by the occurrence of an environmental change, the line where the environmental change occurred can be identified.

[0022] In one embodiment, the environmental sensor may output a change detection signal to the outside. This allows external notification to be sent when an environmental change occurs somewhere within the plane.

[0023] In one embodiment, address information indicating which of the n latch circuits has an asserted output may be further output. This allows external notification to be sent to which column has experienced an environmental change.

[0024] In one embodiment, the environmental sensor may further include m × n resistive elements, m × n analog sensors arranged adjacent to each other, and an analog sense circuit including an A / D converter capable of converting the electrical signals generated by each of the m × n analog sensors into digital signals. An analog sensor is an element whose electrical characteristics change in response to the same environment as the environmental sensor, and whose electrical characteristics change smoothly in an analog manner in response to environmental changes.

[0025] In one embodiment, the environmental sensor may convert the electrical signals generated in the resistive switching element and the adjacent analog sensor, where the environmental change is detected, into digital signals using an A / D converter. After detecting the environmental change with the resistive switching element, the environment can be measured with high accuracy using the analog sensor located at the point where the environmental change occurred. This configuration is low power consumption because it does not require the analog sensor and A / D converter to be constantly operating.

[0026] In one embodiment, the environmental sensor may output the output of the A / D converter and address information of m × n analog sensors.

[0027] In one embodiment, the environmental sensor comprises m × n resistive switching elements and m × n second resistive switching elements provided adjacent to each other, and the resistive switching elements and the second resistive switching elements may have different eigenvalues. This allows the environment to be quantized into multiple levels at high speed.

[0028] Another aspect of the present invention is a sheet. This sheet comprises m (m≧1) scan lines extending in a first direction, a plurality of n (n≧2) data lines extending in a second direction, and m × n pixel circuits arranged in a matrix at the intersections of the m scan lines and the n data lines. The i-th row, j-th column (1≦i≦m, 1≦j≦n) pixel circuit includes a resistive switching element and a rectifier element connected in series between the i-th scan line and the j-th column data line, wherein the resistance value of the resistive switching element changes sharply when the environment crosses the eigenvalue of the resistive switching element.

[0029] (Embodiment) The present invention will be described below with reference to the drawings, based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Furthermore, the embodiments are illustrative and not limiting to the invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention.

[0030] In this specification, "member A connected to member B" includes cases where member A and member B are physically and directly connected, as well as cases where member A and member B are indirectly connected via other members that do not substantially affect their electrical connection or impair the functions or effects produced by their connection.

[0031] Similarly, "the state in which member C is provided between member A and member B" includes not only cases where member A and member C, or member B and member C, are directly connected, but also cases where they are indirectly connected via other members that do not substantially affect their electrical connection state or impair the functions or effects produced by their combination.

[0032] (Embodiment 1) Figure 1 is a circuit diagram of the environmental sensor 100 according to Embodiment 1. The environmental sensor 100 senses the environment in two dimensions at the location where it is placed. The environment to be monitored includes, but is not limited to, temperature, voltage, magnetic field, pressure, light, and the concentration of specific substances.

[0033] The environmental sensor 100 comprises a sheet 110, a scan driver 120, a controller 130, and a logic circuit 140.

[0034] Sheet 110 comprises m (m≧1) scan lines SL1 to SLm extending in a first direction (also called the horizontal direction or column direction of the paper), n (n≧2) data lines DL1 to DLn extending in a second direction (also called the vertical direction or row direction of the paper), and m × n pixel circuits PIX.

[0035] The m × n pixel circuits PIX are arranged in a matrix at the intersections of m scan lines SL and n data lines. The pixel circuit PIX(i,j) in the i row and j column (1≦i≦m,1≦j≦n) includes a resistive switching element 112 and a rectifier element D1 connected in series between the i-th scan line SLi and the j-th column data line DLj. The resistance value of the resistive switching element 112 changes abruptly when the environment crosses the eigenvalue of the resistive switching element 112. The pixel circuit PIX in the i row and j column (1≦i≦m,1≦j≦n) is denoted as PIX(i,j). The positions of the resistive switching element 112 and the rectifier element D1 may be swapped. The orientation of the rectifier element D1 should be such that leakage current and sneak-pass current are blocked.

[0036] The logic circuit 140 includes n readout circuits 150_1 to 150_n corresponding to n data lines DL1 to DLn. Each readout circuit 150 includes an impedance element 152 and a latch circuit 154. In the j-th readout circuit 150_j, the impedance element 152 is connected between the corresponding data line DLj and a reference line. In this embodiment, the reference line is the ground line. In Figure 1, the impedance element 152 is shown with a resistor symbol, but the impedance element 152 may be a transistor that acts as a current source, or a combination of a resistor and a transistor. The impedance R0 of the impedance element 152 is R L <R0<R H Selected to satisfy the requirements.

[0037] The latch circuit 154 receives a voltage signal corresponding to the electrical state of the corresponding data line DLj, compares this voltage signal with a threshold value, and latches the result as a digital binary signal. The latch circuit 154 may also latch the voltage signal corresponding to the electrical state of the data line DLj in synchronization with a timing signal supplied from the controller 130.

[0038] The outputs S1 to Sn of each latch circuit 154 indicate values obtained by quantizing the environment (temperature) in the corresponding resistance change element 112 into binary values with the eigenvalue as a threshold. The environment sensor 100 outputs the output signals S1 to Sn of the n latch circuits 154_1 to 154_n as an n-bit output signal SENSOR_OUT. The bit Sj output when the i-th scanning line SLi is selected indicates the result of comparing the environment at the position where the resistance change element 112(i,j) is arranged with a threshold value.

[0039] In this embodiment, the environment is temperature. The resistance change element 112 has an eigenvalue related to temperature (environment) according to the physical properties of its material. The resistance value of the resistance change element 112 changes abruptly when the temperature (environment) crosses a threshold value corresponding to the eigenvalue.

[0040] For example, the resistance change element 112 is a metal-insulator transition (Metal-Insulator Transition) material such as VO2, and at a predetermined threshold temperature (also referred to as transition temperature) T TH the resistance value R MIT changes discontinuously. FIG. 2 is a diagram showing the temperature dependence of the resistance value R MIT of the resistance change element 112. The resistance value R MIT of the resistance change element 112 has a low value R TH when the temperature T is higher than the threshold temperature T L , and has a high value R TH when the temperature T is lower than the threshold temperature T H , and transitions between the insulator and metal states with the threshold temperature T TH as a boundary. The resistance change element 112 has hysteresis, and the threshold temperature T TH transitions at two values T THH , T THL . As will be described later, the threshold temperature T TH can be adjusted according to the material of the resistance change element 112 and the material of the underlying layer (substrate) forming the resistance change element 112.

[0041] Returning to Figure 1, the scan driver 120 sequentially applies pulsed drive voltages to m scan lines SL1 to SLm. When a pulsed drive voltage is applied to the i-th (1 ≤ i ≤ m) scan line SLi, multiple resistive switching elements 112(i,1) to 112(i,n) connected to the scan line SLi become the targets of sensing.

[0042] The controller 130 controls the scan driver 120 in synchronization with, for example, the clock signal CLK, causing the scan driver 120 to sequentially select scan lines SL1 to SLm. The controller 130 also controls multiple latch circuits 154 of the logic circuit 140 in synchronization with the clock signal CLK.

[0043] Figure 3 is a circuit diagram showing an example configuration of the readout circuit 150. The impedance element 152 is a MOSFET, and a predetermined bias voltage Vb is applied to its gate. The resistance value R0 of the MOSFET can be adjusted according to the bias voltage Vb. For example, the bias voltage Vb is the power supply voltage V DD That's fine.

[0044] The latch circuit 154 is supplied with a clock signal CLK that goes high when the corresponding scan line SLi goes high. This clock signal CLK may be the voltage generated on the scan line SLi itself. The latch circuit 154 is configured to latch the voltage signal of the data line DLj when the clock signal CLK is high.

[0045] The configuration of the latch circuit 154 is not particularly limited, but may include an AND gate 156, an inverter (negation gate) 159, a NOR gate 160, and an SR flip-flop (latch) 158. The AND gate 156 generates a logical AND of the signal Vsj generated on the corresponding data line DLj and the clock signal CLK. The SR flip-flop 158 is set in response to the output of the AND gate 156. The inverter 159 inverts the clock signal CLK. The NOR gate 160 generates a negative OR of the output of the inverter 159 and the signal Vsj generated on the corresponding data line DLj. The SR flip-flop 158 is reset in response to the output of the NOR gate 160. The latch circuit 154 may be composed of other circuits, such as a latched comparator.

[0046] The above describes the configuration of the environmental sensor 100. Next, the operation of the environmental sensor 100 will be explained. When the scan driver 120 selects the i-th scan line SLi during the high interval of the clock signal CLK, the power supply voltage V DD The following shall be applied.

[0047] The sensing of the environmental sensor 100 is explained. The voltage signal V at the connection node between the resistive element 112 and the impedance element 152. S This is expressed by equation (1). V S =(V DD -Vf)×R MIT / (R0+R MIT ) …(1) Vf is the forward voltage of the rectifier element D1. The temperature T of the resistive switching element 112 is equal to the threshold temperature T. TH When R is lower, MIT =R H Therefore, the voltage signal at that time is V S Voltage level (high voltage V H ) is expressed by equation (2). V H =(V DD -Vf)×R H / (R0+R H ) …(2)

[0048] Temperature T is threshold temperature T TH When R is higher, MIT =R L Therefore, the voltage signal at that time is V S Voltage level (low voltage V L ) is expressed by equation (3). V L =(V DD -Vf)×R L / (R0+R L ) …(3)

[0049] Vf≪VDD and R L ≪R0≪R H When the relationship holds, V H ≒V DD , V L It becomes approximately 0V. In other words, the voltage signal V S The temperature T is the threshold T. TH This is a digital signal indicating whether the value is higher or lower. A series connection circuit of a resistive element 112 and an impedance element 152 is called a binary thermistor.

[0050] Figure 4 illustrates temperature sensing by the environmental sensor 100. The vertical axis represents the voltage signal V of the data line DLj. S The horizontal axis represents temperature T. Focusing on the process of temperature increase, when temperature T reaches the threshold T... THH At lower levels, the output voltage V OUT Yes (=V H ) The temperature T is the threshold T THH When it exceeds this, the output voltage V OUT is low (V L ) transitions to ).

[0051] Focusing on the process of temperature decrease, when temperature T reaches the threshold T THL At higher levels, the output voltage V OUT is low (=V L ) and the temperature T is the threshold T THL When it falls below this level, the output voltage V OUT Yes (V H ) transitions to ).

[0052] The above describes the operation of the environmental sensor 100. According to this environmental sensor 100, the binary thermistor behaves like a digital circuit, and therefore its output signal V S This can be directly received by the readout circuit 150 of the logic circuit 140. That is, the output signal V of the binary thermistor 106. S Because it does not require passing through analog interface circuits or front-end circuits such as amplifiers, voltage comparators, and D / A converters, it enables higher speed, lower power consumption, and a smaller footprint.

[0053] According to the environmental sensor 100, it is possible to determine which part of the sheet 110 has experienced an environmental change (temperature change) that crosses a threshold. Specifically, when the i-th scanning line SLi is selected and the output of the j-th readout circuit 150_j changes, it can be determined that an environmental change occurred at the position of the resistive element 112(i,j).

[0054] Figure 5 shows an example configuration of the environmental sensor 100. The scan driver 120 includes a selector (demultiplexer) 122. The selector 122 receives a pulse signal Sp and supplies it to one of the multiple scan lines SL1 to SLm according to the row selection signal SEL.

[0055] In Figure 3, an inverter 159 for inverting the clock signal CLK was provided for each latch circuit 154, but in Figure 5, the inverter 159 is shared by multiple readout circuits 150_1 to 150_n.

[0056] Those skilled in the art will understand that a configuration other than that described herein may be adopted for the readout circuit 150.

[0057] (Embodiment 2) In Embodiment 1, the environmental sensor 100 sequentially output bit sequences for each of the multiple scanning lines SL. In contrast, in Embodiment 2, the readout circuit 150 retains the data for all rows.

[0058] Figure 6 is a circuit diagram of the environmental sensor 100A according to Embodiment 2. Similar to Embodiment 1, the logic circuit 140A has a plurality of readout circuits 150_1 to 150_n.

[0059] In Embodiment 2, the readout circuit 150_j (1≦j≦n) comprises an impedance element 152 and m latch circuits 154_1 to 154_m. That is, the logic circuit 140A includes m×n latch circuits 154 corresponding to m×n resistive switching elements 112. The i-th latch circuit 154_i generates a voltage signal Vs on the corresponding data line DLj when the corresponding i-th scan line SLi is selected. j This latches the elements. As a result, the output signal of each latch circuit 154 indicates the environmental change of the corresponding resistive switching element 112.

[0060] The state of the m × n latch circuits 154 may be made readable from the outside in the form of address access.

[0061] (Embodiment 3) Figure 7 is a circuit diagram of the environmental sensor 100B according to Embodiment 3.

[0062] The environmental sensor 100B can switch between a non-scan mode, which simultaneously selects multiple scan lines SL1 to SLm, and a scan mode, which sequentially selects multiple scan lines SL1 to SLm.

[0063] First, the controller 130B controls the scan driver 120 to operate in non-scan mode. In non-scan mode, a high voltage V is applied simultaneously to multiple scan lines SL1~SLm. DD It will be supplied.

[0064] Logic circuit 140B includes logic gate 164 in addition to read circuits 150_1 to 150_n. Logic gate 164 generates a scan start signal (change detection signal) SCAN_START, indicating the occurrence of an environmental change, when at least one output of read circuits 150_1 to 150_n is asserted. In response to the scan start signal SCAN_START, controller 130B transitions from non-scan mode to scan mode.

[0065] Let's focus on the readout circuit 150_j. In non-scan mode, if an environmental change occurs in any of the j-th column resistive switching elements 112(1,j) to 112(m,j), the output of the latch circuit 154_j is asserted. In a positive logic system where the assertion is high, the logic gate 154 can be constructed as an OR gate. In a negative logic system where the assertion is low, the logic gate 154 can be constructed as a NAND gate.

[0066] Therefore, the scan start signal SCAN_START is asserted when an environmental change crossing a threshold occurs in at least one of the m × n resistive change elements 112. At this stage, it is determined which column the environmental change occurred in, but it is unknown which row the environmental change occurred in.

[0067] Then, by sequentially scanning multiple scan lines SL1 to SLm in response to the scan start signal SCAN_START, it is possible to identify which line the environmental change occurred on.

[0068] In this configuration, power consumption can be reduced by starting the scan using the scan driver 120 only when an environmental change occurs, rather than performing the scan continuously.

[0069] The logic circuit 140B may further include a memory 166. When an environmental change occurs in any data line DL in non-scan mode, the logic circuit 140B records address information indicating the column where the environmental change occurred in the memory 166.

[0070] Furthermore, in scan mode, if it is determined which row has experienced an environmental change, the memory 166 may record address information indicating the row where the environmental change occurred.

[0071] This memory 166 is accessible from the controller 130B or from other circuits. By accessing memory 166, the location where an environmental change has occurred can be determined from the outside. Note that memory 166 may also be integrated into the controller 130B.

[0072] (Embodiment 4) Figure 8 is a circuit diagram of the environmental sensor 100C according to Embodiment 4. Although only the configuration of row i and column j is shown in Figure 8, the other rows and columns are configured similarly. Sheet 110C comprises m × n resistive elements (referred to as first resistive elements) 112 and m × n second resistive elements 112a provided adjacent to them. The first resistive elements 112 and the second resistive elements 112a have different eigenvalues, i.e., threshold values ​​for the environment. A third resistive element 112b may be provided adjacent to them. The multiple resistive elements 112, 112a, and 112c are close enough to be considered to be in substantially the same location.

[0073] Additional data lines DLaj and DLb are provided corresponding to the resistive switching elements 112a and 112b, and readout circuits 150a_j and 150b_j are provided corresponding to each data line.

[0074] According to this environmental sensor 100C, the environment can be quantized into multiple levels using several thresholds.

[0075] (Embodiment 5) Figure 9 is a circuit diagram of the environmental sensor 100D according to Embodiment 5. Sheet 110D includes an analog sensor 114 adjacent to a resistive switching element 112. The analog sensor 114 may be a thermistor. The corresponding resistive switching element 112 and the analog sensor 114 are located so close together that they can be considered to be in substantially the same position.

[0076] A gate line GL is provided adjacent to the data line DL, and a sense line OL is provided adjacent to the scan line SL. The gate line GLj in the j-th column is connected to the gate of the transistor 116 in the corresponding column. One end (source) of the transistor 116 in the i-th row and j-th column is connected to the scan line (also called the source line) SLi in the i-th row. The other end (drain) of the transistor 116 in the i-th row and j-th column is connected to one end of the corresponding analog sensor 114(i,j). The other end of the analog sensors 114(i,1) to 114(i,n) in the i-th row is connected to the sense line OLi in the i-th row. The analog sense circuit 180 includes an A / D converter 182 that converts either the analog voltage, current, or charge generated in the sense line OL into a digital signal.

[0077] The gate driver 170 is controlled by a selection signal SEL2 generated by the controller 130D and is configured to select one of several gate lines GL1 to GLn. Specifically, by applying a low voltage (for example, 0V) to gate line GLj, the j-th column analog sensor 114 becomes the sensing target.

[0078] The above describes the configuration of the environmental sensor 100D. Next, we will explain its operation.

[0079] First, the controller 130D operates the scan driver 120 to perform a scan and sense the resistive element 112. The sensor output SENSOR_OUT generated by the logic circuit 140 is supplied to the controller 130. If the j-th bit of the sensor output SENSOR_OUT changes while row i is selected, it indicates that a temperature change has occurred in row i and column j.

[0080] Controller 130D targets the analog sensor 114 in the i-th row and j-th column for sensing. Specifically, the scan driver 120 generates a selection signal SEL to select the i-th row. The gate driver 170 also generates a selection signal SEL2 to select the j-th column. As a result, the transistor 116 in the j-th column turns on, making the analog sensor 114 ready for sensing, and an electrical signal indicating the temperature of the analog sensor 114 (i,j) in the i-th row and j-th column is generated on the sense line in the i-th row. The electrical signal can be voltage, current, or charge. The analog sense circuit 180 converts the electrical signal in the i-th row into a digital signal.

[0081] The controller 130D may output externally address information ADR indicating the position of the analog sensor 114(i,j) that is the target of sensing.

[0082] The above describes the operation of the environmental sensor 100. This environmental sensor 100D uses a resistive switching element 112 to detect temperature changes at high speed and with low power consumption. It then identifies the location where the temperature change has occurred and performs analog sensing on the analog sensor 114 located at that location, thereby accurately measuring the temperature. This method consumes less power than methods that scan and measure analog sensors.

[0083] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing steps, and that such modifications also fall within the scope of the present invention. Such modifications will be described below.

[0084] (Variation 1) While temperature sensing has been described in the embodiments, the application of this disclosure is not limited thereto. The resistance of oxidized MIT materials changes abruptly around a certain threshold not only in response to temperature, but also to voltage, magnetic field, pressure, light, the concentration of a particular substance, and so on. Therefore, the environmental sensor 100 described in the embodiments can be used to detect voltage, magnetic field, pressure, light, the concentration of gases and liquids, and so on.

[0085] (Modification 2) Although the embodiments describe a case with multiple scanning lines, this disclosure is not limited thereto, and the scanning line SL may be just one.

[0086] Although the present invention has been described using specific terminology based on embodiments, embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted in embodiments, provided they do not depart from the spirit of the present invention as defined in the claims. [Explanation of Symbols]

[0087] 100 environmental sensors 110 seats 112 Resistive switching element 114 Analog Sensors 116 transistors DL Dataline SL scanning line GL Gate Line 120 Scan Drivers 130 Controllers 140 Logic Circuits 150 Readout Circuit 152 Impedance elements 154 Latch Circuit 170 Gate Driver 180 Analog Sense Circuit

Claims

1. m scanning lines (m≧1) extending in the first direction, Multiple n (n≧2) data lines extending in the second direction, m × n pixel circuits arranged in a matrix at the intersections of the m scan lines and the n data lines, wherein the i-th row and j-th column (1 ≤ i ≤ m, 1 ≤ j ≤ n) pixel circuit includes a resistive switching element and a rectifier element connected in series between the i-th scan line and the j-th column data line, and the resistance value of the resistive switching element changes sharply when the environment crosses the eigenvalue of the resistive switching element, A logic circuit including n readout circuits corresponding to n data lines, Equipped with, Each reading circuit is: An impedance element connected between the corresponding data line and the reference line, A latch circuit that receives the voltage signal of the corresponding data line, An environmental sensor comprising the above, wherein the output of each latch circuit indicates a binary value obtained by quantizing the environment in the resistive element connected to the corresponding data line, with the eigenvalue as the threshold value.

2. The environmental sensor according to claim 1, characterized in that the impedance element is a transistor to which a bias voltage is applied to the control electrode.

3. The environmental sensor according to claim 1 or 2, further comprising a scan driver that applies pulsed drive voltages sequentially to the m scan lines, wherein m ≥ 2.

4. The environmental sensor according to claim 1 or 2, wherein m ≥ 2, and the readout circuit includes m latch circuits corresponding to the m scan lines, each latch circuit latching the voltage signal of the corresponding data line when the corresponding scan line is selected.

5. m ≥ 2, and the m scanning lines can be selected simultaneously. The environmental sensor according to claim 1 or 2, characterized in that the logic circuit is capable of generating a change detection signal indicating that at least one of the n latch circuits has changed.

6. The environmental sensor according to claim 5, characterized in that when the change detection signal is asserted, scanning of the m scanning lines is started.

7. The environmental sensor according to claim 5, characterized in that it outputs the change detection signal to an external source.

8. The environmental sensor according to claim 7, further characterized in that it outputs address information indicating which of the n latch circuits has changed output.

9. The m × n resistive elements are provided adjacent to m × n analog sensors, An analog sense circuit including an A / D converter capable of converting the electrical signals generated by each of the m × n analog sensors into digital signals, The environmental sensor according to claim 1 or 2, further comprising:

10. The environmental sensor according to claim 9, characterized in that it outputs the output of the A / D converter and the address information of the m × n analog sensors.

11. The environmental sensor according to claim 9, characterized in that the electrical signals generated in the resistive switching element and the adjacent analog sensor when an environmental change is detected are converted into digital signals by the A / D converter.

12. The environmental sensor according to claim 1 or 2, comprising m × n resistance changing elements and m × n second resistance changing elements provided adjacent to the aforementioned m × n resistance changing elements, wherein the resistance changing elements and the second resistance changing elements have different eigenvalues.

13. The environmental sensor according to claim 1 or 2, characterized in that the environment is temperature.

14. m scanning lines (m≧1) extending in the first direction, Multiple n (n≧2) data lines extending in the second direction, m × n pixel circuits arranged in a matrix at the intersections of the m scan lines and the n data lines, wherein the i-th row and j-th column (1 ≤ i ≤ m, 1 ≤ j ≤ n) pixel circuit includes a resistive switching element and a rectifier element connected in series between the i-th scan line and the j-th column data line, and the resistance value of the resistive switching element changes sharply when the environment crosses the eigenvalue of the resistive switching element, A sheet characterized by having the following features.

15. The sheet according to claim 14, characterized in that the environment is temperature.

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