Device for detecting signal of sensing cells interconnected in a matrix

• US 20020067175A1
• Filed: 11/30/2001
• Published: 06/06/2002
• Est. Priority Date: 12/01/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kiribayashi, Shinichi, Fujitsuka, Hiroshi, Ozaki, Tadashi
• Granted Patent: US 6,694,826 B2
• Time in Patent Office: Days
• US Class Current: 324/713
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

A detecting device (1) is provided to detect signals from a sensing mat (2) including a plurality of sensing cells (R) electrically interconnected to each other in a matrix. Each sensing cell (R) is changeable in resistance with a change in a load to be applied. The detecting device (1) comprises a detecting circuit (Rp) and voltage applying means (5). The detecting circuit (Rp) detects a signal through a conversion of changes in the resistance to changes in voltage. When detecting a sensing cell (R₁₁) connected to a specified line path (2a), the voltage applying means (5) applies a particular voltage to the remaining line paths (2a). The particular voltage is for example voltage of which potential is the same as a voltage detected from the selected sensing cell (R₁₁). Applying the particular voltage prevents current from bypassing the other line paths irrelevant to the detection.

Claims

1. A detecting device (1) for detecting a signal from a sensing mat (2) in which a plurality of sensing cells (R) are electrically interconnected to each other in a matrix by a plurality of line paths (2a) each connecting the sensing cells (R) along each line (2a) and a plurality of column paths (2b) each connecting the sensing cells (R) along each column (2b), each sensing cell (R) having resistance of which amount changes with a change in a load to be applied, the detecting device (1) comprising:

a detecting circuit (Rp) for detecting the signal through a conversion of changes in the amount of the resistance to changes in voltage; and

voltage applying means (5) for applying a particular voltage, when detecting the signal of a sensing cell (R₁₁) selected among the sensing cells (R) connected to a specified line path (2a) selected among the line paths (2a) of the sensing mat (2), to the remaining one or more line paths (2a) of the sensing mat (2).

2. The detecting device according to claim 1, wherein the particular voltage applied by the voltage applying means (5, 7) is voltage of which potential is the same as a voltage detected from the selected sensing cell (R₁₁).

3. The detecting device according to claim 2, wherein the voltage applying means (5) includes a buffer circuit (5) having an output terminal (5b) for outputting the voltage of which potential is the same as the voltage detected from the selected sensing cell (R₁₁).

4. The detecting device according to claim 3, further comprising a switching element (3) having a plurality of first terminals (3a) each connected to each line path (2a) of the sensing mat (2) and a plurality of second terminals (A) selectively connecting the plurality of first terminals (3a) to the output terminal (5b) of the buffer circuit (5).

5. The detecting device according to claim 4, wherein the buffer circuit (5) is one in number.

6. The detecting device according to claim 5, wherein the switching element (3) further includes a plurality of third terminals (B) selectively connecting the plurality of first terminals (3a) to the detecting circuit (Rp).

7. The detecting device according to claim 6, wherein each of the first, second and third terminals (3a, A, B) arranged in the switching element (3) is equal in number to the line paths (2a) of the sensing mat (2).

8. The detecting device according to claim 1, wherein the particular voltage applied by the voltage applying means (5, 7) is voltage of which potential is the same as a voltage applied to the selected line path (2a).