Pressure measuring method, pressure measuring device, and tonometer

• US 7,713,197 B2
• Filed: 03/18/2005
• Issued: 05/11/2010
• Est. Priority Date: 04/23/2004
• Status: Expired due to Fees

• Current Assignee: KOWA Company Limited, Waseda University (Waseda University Educational Association)
• Original Assignee: KOWA Company Limited, Waseda University (Waseda University Educational Association)
• Inventors: Nakai, Makoto, Fujita, Akihiro, Uchiyama, Akihiko, Takeda, Sunao, Yoshizawa, Itaru, Yanashima, Kenji
• Primary Examiner(s): Hindenburg; Max
• Assistant Examiner(s): Pani; John
• Application Number:
  US11/578,910
• Publication Number:
  US 20070197893A1
• Time in Patent Office: 1,880 Days
• Field of Search: 600398-406, 702/138, 702/139, 73570-562, 737/21, 73760-860
• US Class Current: 600/402
• CPC Class Codes: A61B 3/16 for measuring intraocular pressure, e.g. tonometers
• CPC Class Codes: A61B 5/0051 by applying vibrations
• CPC Class Codes: G01L 9/0022 of a piezoelectric element
• CPC Class Codes: G01L 9/008 using piezoelectric devices piezoelectric resonators G01L9/0022; surface acoustic waves G01L9/0025

Abstract

A tonometry device includes a contact device for contacting the object, means for vibrating the contact device and the object, means for applying a voltage to the vibration means, means for measuring a current flowing through the vibration means, and an information processing means. The information processing means determines two resonance points of the device and the measured object by measuring current through the system at a plurality of vibrational frequencies. The information processing means then determines the internal pressure of the object by determining that a first pressure is higher than a second pressure by determining that the first pressure has a lower measured current than the second pressure at frequencies outside of the range of frequencies between the resonance points, and that the first pressure has a higher measured current than the second pressure at frequencies within the range of frequencies between the resonance points.

Claims

1. A pressure measuring device, comprising:

contact means for making contact with an object to be measured, in which the object to be measured has a predetermined shape and a pressure is applied in an outward direction from the object to be measured;

vibration means which is connected with the contact means and configured to vibrate at a plurality of frequencies upon application of a voltage signal;

voltage applying means for applying the voltage signal to the vibration means;

measuring means for measuring a current flowing through the vibration means at the plurality of frequencies; and

information processing means for determining two resonance points of a system including the object to be measured and for determining the pressure based on the current measured by the measuring means at the plurality of frequencies, wherein the information processing means determines that a first pressure is higher than a second pressure by determining that the first pressure has a lower measured current than the second pressure at frequencies outside a frequency range between the two resonance points and by determining that the first pressure has a higher measured current than the second pressure at frequencies within the frequency range between the resonance points.

2. A pressure measuring device according to claim 1, further comprising support means,

wherein the support means is provided outside a movable region of the contact means and a movable region of the vibration means.

3. A pressure measuring device according to claim 1, further comprising calibration means for minimizing the influence of temperature on the determination of pressure.

4. A tonometer, comprising:

contact means for making contact with an eyeball indirectly;

vibration means which is connected with the contact means and configured to vibrate at a plurality of frequencies upon application of a voltage signal and configured to vibrate at a plurality of frequencies upon application of a voltage signal;

voltage applying means for applying the voltage signal to the vibration means;

measuring means for measuring a current value flowing through the vibration means at a plurality of frequencies; and

information processing means for determining two resonance points of a system including the object to be measured and for determining the pressure based on the current measured by the measuring means at the plurality of frequencies, wherein the information processing means determines that a first pressure is higher than a second pressure by determining that the first pressure has a lower measured current than the second pressure at frequencies outside a frequency range between the two resonance points and by determining that the first pressure has a higher measured current than the second pressure at frequencies within the frequency range between the resonance points.

5. A tonometer according to claim 4, further comprising support means,

wherein the support means is provided outside a movable region of the contact means and a movable region of the vibration means.

6. A tonometer according to claim 4, further comprising calibration means for minimizing the influence of temperature on the determination of intraocular pressure.

7. A pressure measuring device, comprising:

a contactor configured to contact the surface of an object to be measured, wherein the object to be measured has a predetermined shape and an internal pressure to be measured;

a vibrator connected with the contactor and configured to vibrate at a plurality of frequencies upon application of a voltage signal;

driver circuitry configured to apply the voltage signal to the vibrator;

measurement circuitry configured to measure a current value flowing through the vibrator at the plurality of frequencies; and

an information processing device configured to determine two resonance points of a system including the object to be measured and configured to determine the pressure based on the current measured by the measurement circuitry at the plurality of frequencies, wherein the information processing device determines that a first pressure is higher than a second pressure by determining that the first pressure has a lower measured current than the second pressure at frequencies outside a frequency range between the two resonance points and by determining that the first pressure has a higher measured current than the second pressure at frequencies within the frequency range between the resonance points.

8. A pressure measuring device according to claim 7, further comprising a calibration device configured to minimize the influence of temperature on the determination of pressure.

9. A pressure measuring device according to claim 7, further comprising a reference base having a predetermined pressure.

10. A pressure measuring device according to claim 9, wherein the information processing means is further configured to determine the pressure based on a measurement of the reference base.