The invention relates to a device for monitoring the contact of a workpiece (1) or tool on a spindle (2) of a machine tool, which device has a contact surface (3) for the workpiece (1) or tool. At least one measurement nozzle (4) is arranged in the region of the contact surface in order to produce a fluid flow directed away from the contact surface (3). Upstream of the measurement nozzle, the fluid flow is conducted through a vacuum nozzle, which can comprise a jet nozzle (7c) and a collector nozzle (7b). When the fluid medium flows through the vacuum nozzle, the vacuum nozzle produces a negative pressure in a negative pressure chamber (9c). A pressure sensor (6) or pressure switch senses a measurement pressure (p3) in the negative pressure chamber.

The invention relates to a device for monitoring the contact of a workpiece (1) or tool on a spindle (2) of a machine tool, which device has a contact surface (3) for the workpiece (1) or tool. At least one measurement nozzle (4) is arranged in the region of the contact surface in order to produce a fluid flow directed away from the contact surface (3). Upstream of the measurement nozzle, the fluid flow is conducted through a vacuum nozzle, which can comprise a jet nozzle (7c) and a collector nozzle (7b). When the fluid medium flows through the vacuum nozzle, the vacuum nozzle produces a negative pressure in a negative pressure chamber (9c). A pressure sensor (6) or pressure switch senses a measurement pressure (p3) in the negative pressure chamber.

In a vacuum gauge that controls a temperature of a sensor section to a high temperature, a circuit board can be sufficiently cooled without applying air to the vacuum gauge from outside. The vacuum gauge includes a sensor section that communicates with a measurement space via a connection port and outputs an output signal according to a pressure in the measurement space, a heater provided around the sensor section to heat the sensor section, a circuit board arranged on a side opposite to the connection port with respect to the sensor section, a first inner case that accommodates the sensor section and the heater, a second inner case that accommodates the circuit board, and an outer case that surrounds the first inner case and the second inner case and forms a flow path, through which outside air flows, together with the first inner case and the second inner case.

In a vacuum gauge that controls a temperature of a sensor section to a high temperature, a circuit board can be sufficiently cooled without applying air to the vacuum gauge from outside. The vacuum gauge includes a sensor section that communicates with a measurement space via a connection port and outputs an output signal according to a pressure in the measurement space, a heater provided around the sensor section to heat the sensor section, a circuit board arranged on a side opposite to the connection port with respect to the sensor section, a first inner case that accommodates the sensor section and the heater, a second inner case that accommodates the circuit board, and an outer case that surrounds the first inner case and the second inner case and forms a flow path, through which outside air flows, together with the first inner case and the second inner case.

A diaphragm vacuum gauge includes: a sensor chip that includes a first electrode provided on a base and a second electrode provided on a diaphragm so as to face the first electrode, the diaphragm and the base being disposed with a gap therebetween, and in which a distance between the first electrode and the second electrode changes in accordance with displacement of the diaphragm caused by pressure of a measurement target medium; an operational amplifier that converts a current output from the first electrode to a voltage and amplifies the voltage; and a coaxial cable that connects the first electrode and the operational amplifier with each other. The first electrode is connected to a virtual ground of the operational amplifier by a core wire of the coaxial cable.

A diaphragm vacuum gauge includes: a sensor chip that includes a first electrode provided on a base and a second electrode provided on a diaphragm so as to face the first electrode, the diaphragm and the base being disposed with a gap therebetween, and in which a distance between the first electrode and the second electrode changes in accordance with displacement of the diaphragm caused by pressure of a measurement target medium; an operational amplifier that converts a current output from the first electrode to a voltage and amplifies the voltage; and a coaxial cable that connects the first electrode and the operational amplifier with each other. The first electrode is connected to a virtual ground of the operational amplifier by a core wire of the coaxial cable.

A diaphragm vacuum gauge includes: a pressure receiving unit having an electrical property that changes in accordance with displacement of a diaphragm caused by pressure of a measurement target medium; a heater that heats the pressure receiving unit; a temperature sensor that measures a temperature of the pressure receiving unit; a pressure measurement unit that converts a change in the electrical property of the pressure receiving unit to a pressure measurement value; a storage unit that stores a plurality of heating temperature settings; a heating temperature setting unit that selects one heating temperature setting from among the plurality of heating temperature settings in accordance with a digital input signal that is externally input; and a control unit that controls power supply to the heater on the basis of the temperature measured by the temperature sensor and the heating temperature setting selected by the heating temperature setting unit.

A pressure sensor includes a diaphragm of a thin plate shape, the diaphragm forming part of a wall surface of a pressure chamber into and out from which a measurement target fluid flows. Multiple recesses are formed in the diaphragm on a side in contact with the measurement target fluid, and an interval between adjacent two of the multiple recesses is 10 μm or less.

The invention relates to a method and to a measurement cell assembly for determining a pressure in a pressure cell (2) are given, wherein the method consists in that a measurement signal (x) is determined, which is at least proportional to a measured pressure in the pressure cell (2), and in that the measurement signal (x) is filtered by means of a first filter unit (10) having a low-pass characteristic in order to produce an output signal (y), wherein the low-pass characteristics of the first filter unit (10) is defined by means of a first damping factor (α.sub.1). The method is characterized in that an input difference (x_diff), which results from a difference between the output signal (y) and the measurement signal (x), is filtered by means of a second filter unit (20) having a low-pass characteristic to determine an output difference, wherein the low-pass characteristic of the second filter unit (20) is defined by means of a second damping factor (α.sub.2), and in that the first damping factor (α.sub.1) of the first filter unit (10) is determined on the basis of the output difference of the second filter unit (20).

The invention relates to a method and to a measurement cell assembly for determining a pressure in a pressure cell (2) are given, wherein the method consists in that a measurement signal (x) is determined, which is at least proportional to a measured pressure in the pressure cell (2), and in that the measurement signal (x) is filtered by means of a first filter unit (10) having a low-pass characteristic in order to produce an output signal (y), wherein the low-pass characteristics of the first filter unit (10) is defined by means of a first damping factor (α.sub.1). The method is characterized in that an input difference (x_diff), which results from a difference between the output signal (y) and the measurement signal (x), is filtered by means of a second filter unit (20) having a low-pass characteristic to determine an output difference, wherein the low-pass characteristic of the second filter unit (20) is defined by means of a second damping factor (α.sub.2), and in that the first damping factor (α.sub.1) of the first filter unit (10) is determined on the basis of the output difference of the second filter unit (20).