JPH0452576Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention relates to electric carpets, and in particular detects the presence of objects on the carpet in each section in order to control the heater in each section. Regarding electric carpets.

(b) Prior Art Conventionally, in this type of electric carpet of, for example, two-sided independent control type, as shown in FIG. , piezoelectric sheet 12A, 1
2B is buried in each section A and B of the carpet 11, and each of the piezoelectric sheets 12A and 12B is connected to a detection circuit in the control box 14 via lead wires 13A and 13B.

By the way, in general, in this type of electric carpet, the parts buried in the carpet have heat resistance,
Durability and high insulation properties are required. In particular, regarding insulation, the insulation resistance of the part excluding the control box when submerged in water is 10MΩ according to the JIS standard.
or more is required.

Therefore, as shown in cross section in FIGS. 5 and 6, electrodes 16 are formed on both sides of the insulating film 15, and the electrodes 16 are coated with an insulating material using an organic material, and the lead wires 13 are covered with an insulating material 17. However, the connection between the piezoelectric sheet 12 and the lead wires 13 is made by applying conductive adhesive tape 1 to the electrodes 16 on both sides of the piezoelectric sheet 12.
8, glue the lead wire 13 on top of it, and then paste the conductive adhesive tape 19 over it again to connect it, and coat it with an insulating material 20 with a heat resistance of 150° C. or more and a high adhesion strength. There is.

(c) Problems to be solved by the invention However, in the conventional electric carpet of this type, the piezoelectric sheet 12 is in the form of a band, and since the shape does not change much when stepped on, it is difficult to coat the piezoelectric sheet 12 with an organic material. Although it is possible to maintain sufficiently high insulation properties with piezoelectric sheet 1
2 and the lead wire 13, it is difficult to coat it with an organic material due to its shape, material, and pressure applied by stepping on it, so it must be coated by embedding it in an insulating material such as silicone rubber. However, there was a problem that sufficient insulation could not be obtained.

This idea was made taking these circumstances into consideration, and by extending the piezoelectric sheet in each compartment coated with an organic material insulating material and connecting it to the detection circuit in the control box,
By eliminating the connection between each piezoelectric sheet and the lead wire,
To provide an electric carpet that does not require the use of special insulating materials such as silicone rubber.

(d) Means for solving the problem This invention is an electric carpet in which piezoelectric sheets are buried in each predetermined section of the carpet and each piezoelectric sheet is connected to a detection circuit in a control box installed at a predetermined position. An electric carpet characterized in that a piezoelectric sheet is extended from each compartment and drawn directly into a control box, and the sensitivity of each extended portion is lowered by heat treatment in advance than the sensitivity of the piezoelectric sheet in each of the compartments. It is.

(E) Effect The piezoelectric sheet is extended from each compartment and drawn directly into the control box, and the sensitivity of the extended portion is lowered by heat treatment in advance than the sensitivity of the piezoelectric sheet in each compartment. This eliminates the need for lead wires between the piezoelectric sheet and the control box. Furthermore, the presence of an object on the carpet cannot be falsely detected in the area of the extension.

Therefore, there is no need to connect the piezoelectric sheet and the lead wire, which is difficult to connect, so there is no need for an insulating material such as silicone rubber, which reduces the number of parts and makes manufacturing easier, reducing manufacturing costs. As a result, product failures are reduced and reliability is improved.

(f) Examples This invention will be described in detail below based on examples shown in the drawings. Note that this invention is not limited to this.

FIG. 1 is a plan view showing the structure of an embodiment in which this invention is applied to a two-sided independently controlled electric carpet.

In FIG. 1, 1 is a carpet, 2 is a piezoelectric sheet for detecting the presence of an object on the carpet 1, and 3 is a control box in which a detection circuit (not shown) for detecting the output voltage from the piezoelectric sheet 2 is stored. It is.

Carpet 1 is the first section 1 surrounded by the broken line in the figure.
A and a second section 1b, and a first piezoelectric sheet 2a and a second piezoelectric sheet 2b are independently buried in each section 1a and 1b.

2a and 2b show the piezoelectric sheet 2 of FIG. 1, with FIG. 2a being a partially sectional side view and FIG. 2b being a plan view.

As shown in these figures, the piezoelectric sheet 2 is made by depositing aluminum on both sides of an insulating film 4 made of a PVDF film with a thickness of about 30 μm to form electrodes 5, and connecting them to a control box 3.
In order to connect to the detection circuit inside, all but the connecting portion 6 is coated with an insulating coating material 7 made of a fluorine-based material.

Then, as shown in FIG. 1, each piezoelectric sheet 2
a and 2b are extended by the first extending portion 8 of the first piezoelectric sheet 2a and the second extending portion 9 of the second piezoelectric sheet 2b, which are indicated by diagonal lines in FIG. The connection part 6 (see FIG. 2) is connected to the detection circuit by means of a rubber connector. Therefore, carpet 1
The presence of the object above is detected independently in the first section 1a and the second section 1b, and a heat insulating heater (not shown) buried in the same way as the piezoelectric sheet 2 is used to detect the presence of the object in each section 1.
Heat retention control can be performed for each of a and 1b.

The first extending portion 8 of the first piezoelectric sheet 2a is drawn into the control box 3 through the second section 1b in which the second piezoelectric sheet 2b is buried. If the presence of an object is detected, the first section 1a of the carpet 1 will be kept warm by the heater. Therefore, in order to prevent this, the sensitivity of the first extending portion 8 is
The sensitivity is lowered by heat treatment in advance than that of the first and second piezoelectric sheets 2a and 2b in the first and second sections 1a and 1b, respectively.

Generally, the piezoelectric constant of the piezoelectric sheet 2 tends to decrease as the heat treatment temperature increases and the treatment time increases.

FIG. 3 is a graph showing an example of the general relationship between the heat treatment temperature of the piezoelectric sheet 2 and the piezoelectric constant when the heat treatment time is constant for 2 hours.
In order to reduce the sensitivity of the extending portion 8, heat treatment may be performed by applying a high temperature to a portion thereof. for example,
When applied at 150°C for 2 hours or more, the piezoelectric constant becomes 10% of the original piezoelectric constant, and when applied at 160°C, the piezoelectric constant approaches 0, and no electrical displacement occurs due to external force. Therefore, if such heat treatment is performed in advance, the first piezoelectric sheet 2
The presence of an object on the carpet will not be erroneously detected at the first extending portion 8 of section a.

Furthermore, the piezoelectric sheet used in electric carpets has a maximum temperature of 110°C when the carpet is in use.
Considering that the temperature will be 110 degrees Celsius, the whole
I try to age it at ℃ for several hours.

With this configuration, unlike conventional electric carpets, there is no need for connections between each piezoelectric sheet and the lead wires from the control box, and there is no need for an insulating material such as silicone rubber, making production easier. Because it is easier and the number of parts is reduced,
It is possible to reduce manufacturing costs and improve product reliability.

(g) Effects of the invention According to this invention, the piezoelectric sheet embedded in each section of the carpet is extended and drawn directly into the control box, and the sensitivity of the extended part is changed by heat treatment in advance. Since the sensitivity is lower than the sensitivity of the piezoelectric sheets in each section, there is no need for lead wires between each piezoelectric sheet and the control box, reducing the number of parts and reducing manufacturing costs. Improves reliability and durability.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the configuration of an embodiment in which this invention is applied to a two-sided independently controlled electric carpet;
Figures 2a and b show the piezoelectric sheet of Figure 1;
Figure 2a is a partially sectional side view, Figure 2b is a plan view,
Figure 3 is a graph showing an example of the general relationship between the heat treatment temperature and piezoelectric constant of a piezoelectric sheet when the heat treatment time is constant for 2 hours, and Figures 4 to 6 are two-sided independently controlled electric carpets. The fourth example shows the conventional example of
The figure corresponds to FIG. 1, FIG. 5 is a partially sectional front view showing the state of connection between the piezoelectric sheet and the lead wire, and FIG. 6 is a partially sectional side view of FIG. 1...carpet, 1a...first section, 1b...
...Second section, 2...Piezoelectric sheet, 2a...First piezoelectric sheet, 2b...Second piezoelectric sheet, 3...Control box, 4...Insulating film, 5...
Electrode, 6... Connection portion, 7... Coating material, 8
...first extension part, 9...second extension part.

Claims (1)

[Scope of Claim for Utility Model Registration] In an electric carpet in which piezoelectric sheets are buried in each predetermined section of the carpet and each piezoelectric sheet is connected to a detection circuit in a control box provided at a predetermined position, the piezoelectric sheet is extended from each section. An electric carpet, characterized in that the electric carpet is drawn directly into a control box, and the sensitivity of each extending portion is lowered by heat treatment in advance than the sensitivity of the piezoelectric sheet in each section.