Abstract: A sensor control apparatus controls a gas sensor which measures the concentration of oxygen contained in exhaust gas. A current DA converter of the sensor control apparatus supplies a current having a current value designated by a control section (hereinafter referred to as the designated current value) to a label resistor having a resistance previously set so as to represent the characteristic of the gas sensor (hereinafter referred to as the characteristic resistance). Further, the control section of the sensor control apparatus sets the designated current value to a plurality of values in accordance with the characteristic resistance of the label resistor.

Abstract: A sensor control apparatus of a gas detection system includes a digital computation section having a PID computation section, a first filter section, and a second filter section as functional sections. The first filter section digitally extracts a DAC control signal (first filter signal) from a digital signal representing a supply control current Tip computed by the PID computation section. The DAC control signal is a digital signal which represents the supply control current Tip for pump current and in which noise components superimposed as a result of digital computation in the PID computation section have been attenuated.

Abstract: In a sensor control apparatus of a gas detection system, a multiplexer having received an instruction from a digital computation section outputs analog signals in the order of, for example, “signal 1, signal 2, signal 1, signal 3, signal 1, signal 4.” By outputting the analog signals while classifying each of them as a high occurrence-frequency signal which is high in output frequency or a low occurrence-frequency signal which is low in output frequency, the multiplexer can increase the sampling frequency of signal (analog signal of Vs+-COM voltage) which is the high occurrence-frequency signal. The sensor control apparatus can increase the sampling frequency in AD conversion of signal to a digital value, while suppressing an increase in the cost of an AD conversion section.

Abstract: When a voltage applied to a heater assumes a low-level potential, a control section of a load drive apparatus instantaneously supplies an anomaly judgment current to the heater, and computes the electrical resistance of the heater on the basis of the anomaly judgment current. The control section judges whether or not any of anomalous states of the heater, including at least a deteriorated state of the heater and wiring anomalous states of the heater, has occurred on the basis of the electrical resistance of the heater.

Abstract: A gas sensor system (1) including a gas sensor (2) and a sensor control section (40) including detection circuits (41), (42) and (43) for detecting the terminal potentials V1, V2, and V3 of first to third terminal T1 through T3. The sensor control section (40) includes a circuit (44) for applying an examination potential Vex to the second terminal T2, a first circuit (45) which has a predetermined resistance R1c and disconnectably connects the first terminal T1 and the second terminal T2, a second circuit (46) which has a predetermined resistance R2c and disconnectably connects the second terminal T2 and the third terminal T3, and terminal potential detection means S5 for detecting the terminal potentials V1, V2, and V3 using the detection circuits in a state in which the examination potential Vex is applied to the second terminal T2 and switches SW1 and SW2 are turned on.

Abstract: A gas sensor system (1) includes a gas sensor (2) having a cell (14) electrically communicating with a first terminal T1 and a second terminal T2, and a cell (24) electrically communicating with T2 and a third terminal T3; and a sensor control section (40) including detection circuits (41, 43) for detecting the terminal potentials V1, V3. The sensor control section includes circuit (44) for bringing T2 to an examination potential Vex; constant current circuits (47, 48) for supplying examination currents Ipoc, Icp; terminal potential detection means S5 for detecting V1, V3 before the gas sensor detects the gas concentration in an activated state, and in a state in which T2 is brought to examination potential Vex and Ipoc, Icp are supplied to the cells (14, 24); and wire breakage determination means S6, S10 for determining a wire breakage anomaly and its location based on the V1, V3.

Abstract: A sensor control apparatus controls a gas sensor by means of digital control and restrains a decrease in accuracy of pump current control. A gas detection system includes such a sensor control apparatus. The sensor control apparatus includes a reference voltage generation section, and can change the maximum current range of pump current Ip in the current DA conversion section. The sensor control apparatus can set the maximum current range of the pump current Ip to a proper range in accordance with the type or characteristic of a gas sensor to be controlled. Namely, in the case where a gas sensor has a small sensor maximum current, the maximum current range of the current DA conversion section is changed to a range determined in consideration of the sensor maximum current of the gas sensor, which restrains a decrease in the accuracy in controlling the pump current Ip.

Abstract: A sensor control apparatus (2) of a gas detection system (1) includes a first low-pass filter (46), a second low-pass filter (48), and a multiplexer (50) so as to provide different time constants for detection of a sensor output signal Vs1 and for detection of a response signal Vs2. When the sensor output signal Vs1 is detected, a signal whose frequency band is the same as that of Vs1 is input to the analog-to-digital conversion section (31) through the first low-pass filter (46). Therefore, the detection accuracy of Vs1 is increased. When Vs2 is detected, a signal whose frequency band is the same as that of Vs2 is input to the analog-to-digital conversion section (31) through the second low-pass filter (48).

Abstract: A sensor control apparatus which receives from a gas sensor (10) a sensor output signal Ip corresponding to the concentration of a specific gas component, and a pressure signal P output from a pressure sensor (20). The sensor control apparatus includes a computation section (38) which computes a specific component concentration which is corrected based on the pressure signal P so as to eliminate the influence of the pressure of the gas. The sensor control apparatus includes response adjustment sections (34) and (36) for adjusting the response rates of the sensor output signal Ip and the pressure signal P before being input to the computation section (38), the response rate exhibiting a time variation of the corresponding signal to a change in the pressure of the gas, such that the response rate of the sensor output signal Ip or the response rate of the pressure signal P, whichever is faster, approaches the slower of the two.

Abstract: An output correction apparatus that corrects offset drift of a cylinder internal pressure sensor, and a cylinder internal pressure detection apparatus that accurately detects cylinder internal pressure of an internal combustion engine through use of the output correction apparatus. The cylinder internal pressure detection apparatus includes a detection circuit section which detects a change in the resistance of a piezoresistor element as an electrical signal; an amplification circuit section which amplifies and outputs the electrical signal (output value); and a correction circuit section which corrects the output value. The correction circuit section includes a reset control section which resets the output value of the amplification circuit section to a reference value, and a reset timing detection section which determines a timing of the resetting.

Abstract: A pressure detection apparatus has a pressure-sensitive resistor whose first resistance varies according to pressure and a change of its own temperature, a temperature-sensitive resistor which has a same resistance-temperature coefficient as the pressure-sensitive resistor and whose second resistance varies according to the change of the temperature, a current source supplying first and second constant-currents to the pressure-sensitive and temperature-sensitive resistors respectively, and a pressure signal generation output section. The current source adjusts the first and second constant-currents so that when the pressure is an initial pressure, a reference first voltage appearing across the pressure-sensitive resistor and a reference second voltage appearing across the temperature-sensitive resistor become equal to each other.

Abstract: A pressure sensor has a Si device having a first main surface that has a bonded area, a second main surface parallel to the first main surface, a pressure-sensitive resistor formed on the first main surface, and a joining assist pattern formed on the first main surface, and a pressing member bonded to the bonded area on the first main surface and compressing the Si device in a thickness direction. The pressure-sensitive resistor has a first bonded section which is placed within the bonded area of the first main surface and is bonded to the pressing member. The joining assist pattern has a second bonded section which is made of the same material as the first bonded section of the pressure-sensitive resistor and is placed within the bonded area of the first main surface and is bonded to the pressing member.

Abstract: An output correction apparatus that corrects offset drift of a cylinder internal pressure sensor, and a cylinder internal pressure detection apparatus that accurately detects cylinder internal pressure of an internal combustion engine through use of the output correction apparatus. The cylinder internal pressure detection apparatus includes a detection circuit section which detects a change in the resistance of a piezoresistor element as an electrical signal; an amplification circuit section which amplifies and outputs the electrical signal (output value); and a correction circuit section which corrects the output value. The correction circuit section includes a reset control section which resets the output value of the amplification circuit section to a reference value, and a reset timing detection section which determines a timing of the resetting.

Abstract: A pressure sensor has a Si device having a first main surface that has a bonded area, a second main surface parallel to the first main surface, a pressure-sensitive resistor formed on the first main surface, and a joining assist pattern formed on the first main surface, and a pressing member bonded to the bonded area on the first main surface and compressing the Si device in a thickness direction. The pressure-sensitive resistor has a first bonded section which is placed within the bonded area of the first main surface and is bonded to the pressing member. The joining assist pattern has a second bonded section which is made of the same material as the first bonded section of the pressure-sensitive resistor and is placed within the bonded area of the first main surface and is bonded to the pressing member.

Abstract: A pressure detection apparatus has a pressure-sensitive resistor whose first resistance varies according to pressure and a change of its own temperature, a temperature-sensitive resistor which has a same resistance-temperature coefficient as the pressure-sensitive resistor and whose second resistance varies according to the change of the temperature, a current source supplying first and second constant-currents to the pressure-sensitive and temperature-sensitive resistors respectively, and a pressure signal generation output section. The current source adjusts the first and second constant-currents so that when the pressure is an initial pressure, a reference first voltage appearing across the pressure-sensitive resistor and a reference second voltage appearing across the temperature-sensitive resistor become equal to each other.