Detection voltage output circuit of charge generation type sensing device

Claim 2

A detection voltage output circuit of a charge generation type sensing device comprising: a sensing device composed of a dielectric for generat­ing charges in accordance with a change in a physical quantity applied from the outside; a capacitor at a first stage which is connected in parallel to a sensing device and stores the charges generat­ed on said sensing device; a capacitor at a second stage which stores said charges transferred from said capacitor at the first stage; a transfer switch which is provided between said capacitor at the first stage and said capacitor at the second stage so as to transfer said charges stored in said capacitor at the first stage to said capacitor at the second stage; an operational amplifier which is connected to said capacitor at the second stage so as to convert said charges stored in said capacitor at the second stage into a voltage and outputting said voltage obtained; and an output switch which is connected to the output side of said operational amplifier so as to be turned off while at least a part of said charges stored in said capacitor at the first stage are transferred to said capacitor at the second stage and turned on after said transfer switch is turned off to output said voltage from said operational amplifier.

Claim 3

A detection voltage output circuit according to Claim 1, wherein the electrostatic capacity of said sensing device is used as said capacitor at the first stage.

Claim 4

A detection voltage output circuit according to Claim 2, further comprising a sensing device for correction which is composed of a dielectric for generating charges in accordance with a background noise applied to said sensing device and which is connected to said operational amplifier so as to have the opposite polarity to the polarity of said sensing device with respect to the input side of said operational amplifier, whereby the noise charges at said capacitor at the second stage which is caused by the noise charges generated on said sensing device in accordance with said background noise are removed and the output voltage of said operational amplifier is corrected.

Claim 5

A detection voltage output circuit according to Claim 3, wherein the electrostatic capacity of said sensing device for correction is used as said capacitor at the second stage.

Claim 6

A detection voltage output circuit according to Claim 1, further comprising a sensing device for correction which is composed of a dielectric for generating charges in accordance with a background noise applied to said sensing device and which is connected to said operational amplifier so as to have the opposite polarity to the polarity of said sensing device with respect to the input side of said operational amplifier, whereby the noise charges at said capacitor at the second stage which is caused by the noise charges generated on said sensing device in accordance with said background noise are removed and the output voltage of said operational amplifier is corrected.

Claim 7

A detection voltage output circuit according to Claim 5, wherein the electrostatic capacity of said sensing device for correction is used as said capacitor at the second stage.

Claim 8

A detection voltage output circuit according to Claim 1, further comprising a reset switch which is connect­ed in parallel to said capacitor at the second stage so as to discharge said charges stored in said capacitor at the second stage therefrom.

Claim 9

A detection voltage output circuit of a charge generation type sensing device comprising: a sensing device composed of a dielectric for generat­ing charges in accordance with a change in a physical quantity applied from the outside; a capacitor at a first stage which is connected in parallel to a sensing device and stores the charges generat­ed on said sensing device; a capacitor at a second stage which stores said charges transferred from said capacitor at the first stage; a transfer switch which is provided between said capacitor at the first stage and said capacitor at the second stage so as to transfer said charges stored in said capacitor at the first stage to said capacitor at the second stage; an operational amplifier which is connected to said capacitor at the second stage so as to convert said charges stored in said capacitor at the second stage into a voltage and outputting said voltage obtained; an output switch which is connected to the output side of said operational amplifier so as to be turned off while at least a part of said charges stored in said capacitor at the first stage are transferred to said capacitor at the second stage and turned on after said transfer switch is turned off to output said voltage from said operational amplifier; a sensing device for noise elimination which has the opposite polarlity to the polarity of said sensing device with respect to the input side of said operational amplifier and which removes the noise charges generated on said sensing device in accordance with a background noise; a capacitor for noise elimination which is connected to in parallel to said sensing device for noise elimination and which stores the charges generated on said sensing device for noise elimination; and a transfer switch for noise elimination which is provided between said capacitor for noise elimination and said capacitor at the second stage and which transfers said charges stored in said capacitor for noise elimination to said capacitor at the second stage; whereby said detection voltage output circuit is capable of removing the noise charges generated on said sensing device in accordance with said background noise, converting said charges generated in accordance with said change in a physical quantity applied from the outside into a voltage and outputting said voltage obtained.

Claim 10

A detection voltage output circuit of a charge generation type sensing device comprising: a sensing device composed of a dielectric for generat­ing charges in accordance with a change in a physical quantity applied from the outside; a capacitor at a first stage which is connected in parallel to a sensing device and stores the charges generat­ed on said sensing device; a capacitor at a second stage which stores said charges transferred from said capacitor at the first stage; a transfer switch which is provided between said capacitor at the first stage and said capacitor at the second stage so as to transfer said charges stored in said capacitor at the first stage to said capacitor at the second stage; an operational amplifier which is connected to said capacitor at the second stage so as to convert said charges stored in said capacitor at the second stage into a voltage and outputting said voltage obtained; an output switch which is connected to the output side of said operational amplifier so as to be turned off while at least a part of said charges stored in said capacitor at the first stage are transferred to said capacitor at the second stage and turned on after said transfer switch is turned off to output said voltage from said operational amplifier; a sensing device for noise elimination which has the opposite polarlity to the polarity of said sensing device with respect to the input side of said operational amplifier and which removes the noise charges generated on said sensing device in accordance with a background noise; a capacitor for noise elimination which is connected to in parallel to said sensing device for noise elimination and which stores the charges generated on said sensing device for noise elimination; and a transfer switch for noise elimination which is provided between said capacitor for noise elimination and said capacitor at the second stage and which transfers said charges stored in said capacitor for noise elimination to said capacitor at the second stage; whereby said detection voltage output circuit is capable of removing the noise charges generated on said sensing device in accordance with said background noise, converting said charges generated in accordance with said change in a physical quantity applied from the outside into a voltage and outputting said voltage obtained.

Claim 11

A detection voltage output circuit according to Claim 8, wherein the electrostatic capacity of said sensing device is used as said capacitor at the first stage.

Claim 12

A detection voltage output circuit according to Claim 9, further comprising a sensing device for correction which is composed of a dielectric for generating charges in accordance with a background noise applied to said sensing device and which is connected to said operational amplifier so as to have the opposite polarity to the polarity of said sensing device with respect to the input side of said operational amplifier, whereby the noise charges at said capacitor at the second stage which is caused by the noise charges generated on said sensing device in accordance with said background noise are removed and the output voltage of said operational amplifier is corrected.

Claim 13

A detection voltage output circuit according to Claim 10, wherein the electrostatic capacity of said sensing device for correction is used as said capacitor at the second stage.

Claim 14

A detection voltage output circuit according to Claim 9, wherein the electrostatic capacity of said sensing device for noise elimination is used as said capacitor for noise elimination.

Claim 15

A detection voltage output circuit according to Claim 8, further comprising a sensing device for correction which is composed of a dielectric for generating charges in accordance with a background noise applied to said sensing device and which is connected to said operational amplifier so as to have the opposite polarity to the polarity of said sensing device with respect to the input side of said operational amplifier, whereby the noise charges at said capacitor at the second stage which is caused by the noise charges generated on said sensing device in accordance with said background noise are removed and the output voltage of said operational amplifier is corrected.

Claim 16

A detection voltage output circuit according to Claim 13, wherein the electrostatic capacity of said sensing device for correction is used as said capacitor at the second stage.

Claim 17

A detection voltage output circuit according to Claim 14, wherein the electrostatic capacity of said sensing device for noise elimination is used as said capacitor for noise elimination.

Claim 18

A detection voltage output circuit according to Claim 13, wherein the electrostatic capacity of said sensing device for noise elimination is used as said capacitor for noise elimination.

Claim 19

A detection voltage output circuit according to Claim 8, wherein the electrostatic capacity of said sensing device for noise elimination is used as said capacitor for noise elimination.

Claim 20

A detection voltage output circuit according to Claim 8, wherein said sensing device for noise elimination is connected in series to said sensing device.

Claim 21

A detection voltage output circuit according to Claim 8, wherein said sensing device for noise elimination is connected in parallel to said sensing device.

Claim 22

A detection voltage output circuit according to Claim 11, further comprising a reset switch which is con­nected in parallel to said capacitor at the second stage so as to discharge said charges stored in said capacitor at the second stage therefrom, wherein said sensing device for noise elimination is connected in parallel to said sensing device and the electrostatic capacity of said sensing device for noise elimination is used as said capacitor for noise elimination.