JPH0531816Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> This invention relates to a battery pack that is a collection of a plurality of batteries and is used as a power source for cameras, etc.

<Prior Art> As such a battery pack, one is known in which a power generating element made up of a plurality of unit cells is housed in an outer case.

In this type of battery pack, a disconnection switch is connected in series in the current path of the power generation element as a countermeasure in case the internal circuit of the camera is damaged due to dew point, condensation, etc., for example.

As such a disconnection switch, for example, as described in Japanese Patent Laid-Open No. 63-164159, a PTC element whose resistance value increases dramatically with temperature rise is used. By dramatically increasing the resistance value of the PTC element due to the heat generated by the power generation element and the power generating element, the current in the circuit is limited during battery shoot-off.

<Problem that the invention seeks to solve> However, for example, due to battery shortening,
Even if a device such as a camera does not work due to the PTC element working, the camera may not work due to the lack of battery life (for example, by accidentally using an expired battery), or due to a short circuit in the internal circuit of the device. It is impossible to tell from the outside whether the PTC element in the pack battery is working and the device is not working.

For this reason, the camera user is under the illusion that the battery has reached the end of its life even though the device does not operate due to the battery shot, and this is extremely inconvenient, such as making it impossible to take appropriate measures in the event of a problem.

This idea allows the user to easily know from the outside whether there is an abnormality with the battery or the equipment when the equipment does not operate normally with the battery pack installed in the equipment as described above. Our objective is to provide a pack battery that is devised to achieve the desired performance.

<Means for Solving the Problems> The pack battery of this invention is constructed by housing a power generation element formed by electrically connecting a plurality of unit cells in an exterior case, and also includes a power generation element in the current path of the power generation element. In a pack battery consisting of PTC elements connected in series, the surface of the PTC element is covered with an insulating tape coated with thermoreversible temperature-indicating paint, and a through hole is provided in the outer case, through which the temperature can be measured. The gist is that the surface to which the paint is applied is displayed on the outside of the battery.

Moreover, instead of this through hole, at least a part of the outer case may be made into a transparent part, and the surface coated with the temperature-indicating paint may be displayed to the outside of the battery through this transparent part.

As the above-mentioned insulating tape, for example, a polyester tape may be used. Further, the temperature-indicating paint may be a color change agent made of a pigment such as a halide such as mercury and its complex salt or double salt and dispersed in a color vehicle such as lacquer varnish.

In addition, the color change temperature of the temperature-indicating paint may be set to the temperature at which the PTC element generates heat when the battery is shot, or a temperature slightly lower than this temperature.
For example, a temperature of about 60 to 80°C is sufficient.

Further, in the present invention, as the above-mentioned PTC element, for example, one using conductive polymer pieces made by dispersing conductive powder such as carbon powder in a thermoplastic resin can be used. In addition, for example, barium-titanium (BaTiO ₃ etc.)
You may also use a ceramic type material made from.

<Function> Insulating tape coated with thermoreversible temperature-indicating paint.
If the PTC element is coated and the surface coated with this temperature-indicating paint is displayed on the outside of the battery, for example, if the battery is shorted when inserted into a device and a large current flows, the PTC element will suppress the short-circuit current. At the same time, the temperature-indicating paint changes color due to the temperature rise of the PTC element.

Since the user can detect this discoloration through the above-mentioned through hole or transparent part, the user can immediately know that there is an abnormality on the equipment side (on the other hand, if there is no discoloration of the temperature-indicating paint, the battery (You can know that the lifespan of the device has come to an end).

In addition, since we used a reversible temperature-indicating paint, the temperature-indicating paint will return to its original color when the battery is removed from the device. Therefore, when the battery is reinserted into the device after repairing the circuit short section of the device, the temperature-indicating paint will change color. It is possible to confirm whether the equipment has been repaired correctly by the presence or absence of the error.

Furthermore, since the PTC element is covered with an insulating tape, there is an advantage that the PTC element can be insulated at the same time.

<Example> This invention will be explained in detail below using the accompanying drawings.

Figure 1 shows a power generation element constructed by arranging unit cells 1 such as cylindrical lithium batteries upside down and connecting these unit cells 1 in series with a PTC element 2 at the bottom. be.

This PTC element 2, as shown in FIG.
It is constructed by connecting a conductive polymer piece 2a in which carbon powder is dispersed in a polyolefin thermoplastic resin between two metal plates 2b and 2c, such as "Polyswitch" manufactured by Raychem.
It can be obtained as.

This PTC element 2 has a property that due to the expansion of the conductive polymer pieces 2a due to heat generation during battery shooting, the contact between the carbon powders decreases and the electrical resistance rapidly increases. It functions to block the route.

On the surface of the PTC element 2, a temperature-indicating tape 3 made by applying a temperature-indicating paint (for example, Kaken Thermo Paint of the Chemical Research Institute) to the surface of an insulating tape made of polyester tape is pasted with the temperature-indicating paint coated side facing up. has been done.

Also, Figure 3 shows a pack battery (2CR5・H) constructed using this power generation element.
The above-mentioned power generation element is housed in an exterior case constructed by combining the split case materials 4 and 5 and fixing their joints by ultrasonic welding, adhesive, or the like.

A through hole 6 is provided in a portion of the outer case of these case materials 4 and 5 that faces the temperature indicating tape 3, and through this hole 6, a part or all of the temperature indicating tape 3 is displayed on the outside of the battery. It is visible from the outside.

In a pack battery with the above configuration, when the battery is shorted and a large current flows, the large current causes the power generation element to heat up to about 40 to 45°C, and this heat immediately flows to the PTC element 2 at the bottom of the power generation element. introduce.

Then. Conductive polymer piece 2a of PTC element 2
expands due to heat generation and its electrical resistance increases, which further increases the temperature of the PTC element 2 and causes it to rise to 80
As the temperature rises to around 0.3°C, its electrical resistance increases rapidly, which limits the current flowing through the current path of the power generating element, and this current path becomes disconnected.

Then, due to the temperature rise of this PTC element 2,
The color of the temperature indicator tape 3 closely attached to the PTC element 2 changes. Due to this color change, for example, if this battery pack is used as a power source for a camera,
The camera user can clearly recognize that the camera does not operate normally due to battery shorting, and can also know that some kind of abnormality has occurred in the camera's electrical circuit.

FIG. 4 is a flowchart showing an example of a series of steps when installing a battery pack using a temperature-indicating paint, which is normally yellow but changes to red when the temperature rises, into a device.

In the figure, when inserting a battery pack into a device, first check the color of the temperature indicator tape. If this color is yellow, you know that the device is in a normal state with no shorts, and then check the operation of the device. This will tell you if there is an abnormality on the battery side (reverse insertion, used battery, etc.).

Furthermore, if the color of the temperature indicator tape is red, it is immediately known that the device is being shunted, and necessary measures can then be taken, such as removing the battery from the device or repairing the device.

In addition, in the above example, a through hole is provided in the part of the battery case opposite to the temperature indicating tape, but in addition to this,
The exterior case portion corresponding to the through-hole portion may be made of a transparent member, or furthermore, the entire exterior case may be made of a transparent body.

<Effects of the invention> As described above, according to this invention, when a device does not operate normally, it is possible to clearly identify whether or not the problem is caused by a battery shot caused by an abnormality on the device side. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the power generation element used in the example, Fig. 2 is an explanatory diagram of the PTC element constituting the power generation element, Fig. 3 is a perspective view of the pack battery of the example, and Fig. 4 is the book. This is a flowchart showing a series of steps for installing the invented battery pack into a device. 1...Battery, 2...PTC element, 3...Temperature-indicating tape, 6...Through hole.

Claims (1)

[Claims for Utility Model Registration] 1 A power generation element formed by electrically connecting a plurality of unit cells is housed in an exterior case, and a PTC element is connected in series in the current path of the power generation element. In the pack battery made of
The surface of the PTC element is covered with an insulating tape coated with a thermoreversible temperature-indicating paint, and a through hole is provided in the outer case, and the surface coated with the temperature-indicating paint is displayed on the outside of the battery through the through hole. Features a pack battery. 2. In a pack battery configured by housing a power generation element formed by electrically connecting a plurality of unit cells in an exterior case, and having a PTC element connected in series in the current path of the power generation element,
The surface of the PTC element is covered with an insulating tape coated with a thermoreversible temperature-indicating paint, and at least a portion of the exterior case is made transparent, and the surface coated with the temperature-indicating paint is displayed on the outside of the battery through this transparent part. A pack battery that is characterized by: