JPH05820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a small electronic device that houses a paper battery.

[Conventional technology]

2. Description of the Related Art Recently, small electronic devices such as small electronic calculators, generally called calculators, have started to use solar cells as their power source. Small electronic devices that use solar cells as power batteries use button-type batteries (mercury batteries, silver oxide batteries, lithium batteries, etc.) as the power battery because the solar cells are extremely thin, about 200μ thick. It has become possible to make the device much thinner than other small electronic devices, and although the details of its structure have not been made public, an ultra-thin calculator called a card-type calculator has already been announced.

[Problem that the invention seeks to solve]

However, if a solar cell is used as a power source in a small computer equipped with a memory function, a clock function, etc., the power supply voltage will run out when the solar cell cannot receive enough light and stops generating electricity, such as at night. Button-type batteries should not be used as power batteries for small electronic devices with memory or clock functions. Therefore, this type of small electronic equipment cannot be made very thin due to the thickness of the battery, so it is considerably thicker than those that use solar cells.

This invention was made in view of the above-mentioned circumstances, and its purpose is to use a battery that constantly generates electricity,
An object of the present invention is to provide a small electronic device that can be made much thinner than a small electronic device using a conventional button-type battery.

[Means for solving problems]

The small electronic device of this invention has a power generation section and a main power source.
Three-layer paper-like batteries with polymerized negative electrode sheets are housed side by side with a wiring board in an equipment case, and at least the bottom portion of the equipment case is formed of a thin metal plate.

[Effect]

That is, the present invention aims to reduce the thickness of the battery itself by constructing a paper-like battery with a three-layer structure by making the electrode sheet function as both a current collecting member and a connecting electrode member. Since the batteries are housed next to the wiring board inside the equipment case, and at least the bottom of the equipment case is made of a thin metal plate, it maintains mechanical strength even though it uses batteries that constantly generate electricity. It is possible to significantly reduce the thickness of small electronic devices.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking as an example a small electronic calculator generally called a calculator.

Figure 2 shows the appearance of a small electronic calculator;
The figure shows a cross section of the main part. 1 and 2, reference numeral 10 is a case of a small electronic calculator, and this case 10 includes a frame 11, an upper sheet 12, and a top sheet 1 having a shape as shown in FIG.
3, a lower sheet 14, and a lower sheet 15 are laminated. Inside this case 10, a wiring board 20 having a shape as shown in FIG. 3 and an ultra-thin display panel (for example, a liquid crystal display panel) 30
and a paper-like battery 40 are disposed on the upper surface of the wiring board 20.
A spacer 50 made of a synthetic resin film having approximately the same external shape as the spacer 50 is polymerized. On the wiring board 20, an LSI chip 21 and chip parts 22, 22 such as chip capacitors are attached.Furthermore, on the upper surface of the wiring board 20, a pair of contacts 23a,
Multiple sets of split type fixed contacts 2 with 23b as one set
3... are formed in an array. Said LSI chip 2
1 and the chip parts 22, 22 are fitted into through-holes formed in the wiring board 20, and are mounted in a state in which the height of protrusion onto the wiring board 20 is reduced. Further, the spacer 50 is provided with a large number of openings 51, . . . corresponding to the fixed contacts 23, .
Through holes 52 and 53 are provided to provide relief for the parts of the chip 21 and chip parts 22 and 22 that protrude above the wiring board 20, and the spacer 50
The wiring board 2 is assembled by fitting the LSI chip 21 and chip components 22, 22 into the through holes 52, 53.
0 is glued on top. Then, the wiring board 2
0 and the spacer 50 are the frame 1 of the case 10.
1 is fitted inside. This frame 11 is formed by punching out a thin metal plate such as stainless steel, and inside this frame 11 are a fitting part A of the wiring board 20, a display panel fitting part B, and a battery fitting part. The display panel 30 is fitted into the display panel fitting part B of the frame 11 and arranged side by side with the wiring board 20 at one end edge of the wiring board 20. Display panel connection terminals 24 are arrayed on the lower surface of one edge of the substrate 20.
... by a film-like heat seal connector 31. Moreover, the paper-like battery 4
0, a wiring board 2 is fitted into the battery fitting part C of the frame 11 and is placed on the side of one edge of the wiring board 20.
0, and the electrodes (negative electrode and positive electrode) on the upper and lower surfaces of this paper battery 40 and the wiring board 2
Battery connecting terminals 25a and 25b formed on the upper and lower surfaces of one side edge of the 0 are connected by a pair of film-like connectors 60 and 60. The paper battery 40 has a film connector 60,
In addition to making the electrodes on the upper and lower surfaces flat so that the electrodes 60 can be easily bonded, special measures have been taken to make the overall thickness extremely thin. The structure is shown in FIG.

The paper battery 40 is produced by polymerizing a flat negative electrode sheet 41a made of a metal sheet such as aluminum or stainless steel and a positive electrode sheet 41b through a holding frame 42 made of an insulating material. In between, a power generation unit containing lithium metal 43 as a negative electrode active material, manganese dioxide 44 as a positive electrode active material, and a separator 45 made of polypropylene nonwoven fabric or the like impregnated with an organic electrolyte is filled, and the holding frame is 42, a negative electrode sheet 41a and a positive electrode sheet 41b are polymerized and adhered to each of the upper and lower surfaces of the power generation section using an adhesive 46 to form a three-layer structure, and the negative electrode sheet 41a and the positive electrode sheet 41b That is, the top and bottom surfaces of the battery serve as full-surface electrodes. In this way, this paper-like battery 4
0, the negative electrode sheet 41a and the positive electrode sheet 41b serve both as a current collecting member and as an electrode member for connection to external electronic components. Further, the negative electrode sheet 41a and the positive electrode sheet 41b have a sealed structure in which the outer periphery of the holding frame 42 is bonded and solidified with an adhesive, so that the peeling resistance of the sealed portion and the fracture resistance of the electrode are excellent. For this reason, each sheet is kept flat even at the sealed portion, and its thickness is extremely thin (dimensions will be described later). The structure is designed to be significantly thinner and provide better connection with the connector. The electromotive principle of this paper-like battery is basically the same as that of a well-known button-type lithium battery, so its explanation will be omitted.
To explain the thickness of this paper-like battery,
The thickness of the negative electrode sheet 41a and the positive electrode sheet 41b is 50 μm each, and the layer thickness of the metal lithium 43 is also 50 μm.
The layer thickness of the manganese dioxide 44 and the separator 45 are both 150μ, and the total battery thickness is 450μ.
It is much thinner than the thinnest button-type lithium battery (1.6mm thick) among the button-type batteries currently on the market. In this embodiment, a rectangular paper battery 40 with a planar dimension of approximately 45 mm x 25 mm is used. The lifespan is approximately 2 years when used in a small electronic calculator equipped with a battery. Note that the battery life can be further extended by improving the electronic circuit of the small electronic calculator and the display panel 30 used to save power.

FIG. 5 shows the paper battery 40 and film connectors 60, 6 that connect it to the wiring board 20.
0, the film-like connectors 60, 60 are connected to the paper-like battery 4.
It has a shape in which a wiring board connecting piece 60b is formed protruding from one side of a battery bonding part 60a having an area slightly larger than the planar dimension of 0. The film-like connectors 60, 60 have a synthetic resin film as a base film, and a conductive part 61 is formed on the upper surface of the base film across the battery adhesive part 60a and the wiring board connection piece 60b, and this conductive part 61 and this part are removed. The conductive part 61 is of a so-called heat sheet type in which the other part 62 is coated with a hot-melt adhesive that melts at a relatively low temperature of about 130° C. and solidifies at room temperature. A highly conductive metal film of gold, silver, copper, etc. is formed on the film by means such as vapor deposition or screen printing, and a conductive fine powder such as carbon, a thermoplastic polymer material, and a solvent are mixed and dissolved thereon. It has a double-layer structure that is formed by screen printing a conductive suspension and drying it by heating at a low temperature (approximately 100°C). Note that the thickness of this film-like connector 60 is 50 to 100 microns.
To connect the film connectors 60, 60 to the paper battery 40, first, the entire upper and lower surfaces of the paper battery 40 (the surfaces of the negative electrode sheet 41a and the positive electrode sheet 41b) are flashed with a conductive metal such as nickel. The battery adhesive part 60a of the film connector 60 is placed on top of the dense smooth surface, and the peripheral edge of the battery adhesive part 60a is folded over the battery peripheral side and heated and pressurized to form the film connectors 60, 60. This is done by adhering the battery to the surface of the battery. In this way, the film connectors 60, 60 are attached to the paper battery 40.
When the paper-like battery 40 is bonded, the entire electrode surface, that is, the surface and circumferential surface of the negative electrode sheet 41a and the surface and circumferential surface of the positive electrode sheet 41b, are completely connected by the film-like connectors 60, 60 having synthetic resin films as base films. Since the paper-like battery 40 is covered by the paper battery 40, there is no need to worry about electrical leakage from the paper battery 40 to the frame 11 and the like. Further, since the film connectors 60, 60 use a hot melt adhesive that is activated at a relatively low temperature of about 130° C., the film connectors 60, 60 are bonded to the paper battery 40. This can be carried out at a relatively low heating temperature, so there is no fear of thermal damage to the paper battery 40 when bonding the film connectors 60, 60. Furthermore, the paper battery 40 can be flashed with conductive metal. By making the battery surface a dense and smooth surface and adhering the film connectors 60, 60 thereon, the adhesion of the film connectors 60, 60 can be improved and the adhesive strength thereof can be increased. However, flashing of the conductive metal onto the surface of the paper battery 40 is not necessarily required. Note that in this embodiment, the film-like connectors 60, 6
0 in which the conductive part 61 is formed only in a part, but this film-like connector 6
0 and 60 may be of a fully conductive type in which a conductive adhesive is applied to the entire upper surface of the base film.

The film connectors 60, 60 bonded to the upper and lower surfaces of the paper battery 40 as described above are
By heat-pressing the wiring board connection pieces 60b, 60b to the portions on the upper and lower surfaces of the wiring board where the battery connection terminals 25a, 25b are formed, they are also adhered to the wiring board 20, and both electrodes of the paper battery 40 and the wiring board are bonded. 20 battery connection terminals 25a, 25b are electrically connected.

On the other hand, the upper sheet 12 and the lower sheet 14 of the case 10 are each made of metal sheets such as stainless steel or beryllium steel, and the upper sheet 12 has holes that match the openings 51 and 51 provided in the spacer 50. Openings 121, 121 and a fitting hole 122 into which the upper part of the display panel 30 fits.
is perforated, and furthermore, this upper sheet 12
The lower surface has recesses 123 and 124 for receiving the LSI chip 21 and the portions of the chip components 22 and 22 that protrude above the spacer 50, and a recess for receiving the film connector 60 bonded to the upper surface of the paper battery 40. The entry portion 125 is formed by half etching. The upper sheet 12 is integrated with the frame 11 by bonding its lower surface to the upper surface of the frame 11, and the spacer 50 is bonded to the lower surface of the upper sheet 12. Further, a recessed portion 141 is formed on the upper surface of the lower sheet 14 by half etching to receive the film connector 60 bonded to the lower surface of the paper battery 40. It is adhered to the lower surface of the frame 11. The lower sheet 14 is bonded to the upper sheet 12 to the frame 11, and then the spacer 50 is bonded to the lower surface of the upper sheet 12, and then the display panel 30 and the paper battery 40 are attached to the lower surface of the spacer 50. At the same time, the display panel 30 and the paper battery 40 are attached to the frame 1.
1, and after filling the frame 11 with the filler 16 from the lower surface side of the wiring board 20. The filler 16 is applied to the LSI chip 21 and chip parts 22, 22 attached to the wiring board 20.
(These also protrude slightly from the bottom surface of the wiring board 20), and are used to position and fix the display panel 30 and paper-like battery 40.The filler 16 is a quick-drying material that hardens at room temperature. A liquid adhesive (for example, an acrylic or epoxy two-component adhesive) is used, and this liquid adhesive is dripped and filled into the wiring board 20 with the lower surface thereof facing upward. Further, the bonding of the lower sheet 14 is performed immediately after dropping the liquid adhesive, so that the lower sheet 14 is bonded to the frame body 1.
1 as well as to the wiring board 20 via the filler 16. In addition, the outer circumferential surface of the case body constructed by bonding the frame 11, the upper sheet 12, and the lower sheet 14 is not completely airtight at the bonding surface between the frame 11 and the upper and lower sheets 12, 14. For convenience, it is covered with an outer coating 17. This outer coating film 17 is formed by applying the same type of adhesive as the liquid adhesive used for the filler 16 to the outer peripheral surface of the case body and curing it. The outer peripheral surface is finished by cutting the outer peripheral portion after curing the adhesive.

On the other hand, the upper sheet 13 and the lower sheet 15 of the case 10 are each made of a synthetic resin sheet, each of which is made of the upper sheet, and each of which is made of the upper sheet 1.
2 and the surface of the lower sheet 14. The top sheet 13 also includes numbers, letters, symbols, etc. 131 indicating the operation section on the bottom surface of the transparent resin sheet.
...and display window 1 on the entire bottom of the sheet.
32 is printed with opaque paint, and the display panel 30 is made of this top sheet 13.
The display window 132 is bonded to the lower surface of the display window 132 with a transparent adhesive. Then, on the lower surface of the portion of the upper sheet 13 where the numbers, letters, symbols, etc. 131, etc. are printed, each opening 12 of the upper sheet 12 is
1. The contact seats 133, which enter... are formed by means such as thick film screen printing of adhesive, and the lower surfaces of these contact seats 133,... are formed by printing carbon ink, etc. movable contact 13
4.... is deposited. This movable contact 13
4.... is the operation section of the top sheet 13 (the part where numbers, letters, symbols, etc. 131,... are printed) by pressing with a finger and elastically deforming it downward, so that the surface of the wiring board 20 is pressed. A pair of contacts 23a, 23 that are pressed against the fixed contact 23 for the switch and form the fixed contact 23 for the switch.
This movable contact 134,...
. . . and the fixed contact 23, . . . constitute an operating switch.

However, in this small electronic calculator,
As described above, a paper battery 40 with a three-layer structure in which positive and negative electrode sheets, which serve both as a conductive member and as a connecting electrode member, are superposed on each of the upper and lower surfaces of the power generation part is connected to the wiring board 20. Since they are stored side by side, the thickness of the small electronic calculator can be significantly reduced. That is, to give an example, in the above embodiment, the thickness of the wiring board 20 is
200μ, spacer 50 thickness 100μ, filler 16
The thickness of the upper sheet 12 is 130μ, the thickness of the upper sheet 12 is 150μ,
The thickness of the top sheet 13 is 70μ, the thickness of the bottom sheet 14 is 150μ, and the thickness of the bottom sheet 15 is 50μ. Therefore, the total thickness of this small electronic calculator is
At 850μ, it is almost as thick as a card-type electronic calculator that uses solar cells as its power source. The thickness of the frame 11 of the case 10 is determined by the thickness of the upper sheet 12 and the lower sheet 14 and the gap between the wiring board 20, the spacer 50, and the filler 16.
(430μ). In the above embodiment, the paper battery 40 has a thickness of 450 μm.
If the thickness of the upper and lower film-like connectors 60, 60 is added, the thickness of the entire battery section becomes 550 to 590μ, which is larger than the gap between the upper sheet 12 and the lower sheet 14. , recesses 125 with a depth of 60 to 80 μ on the lower surface of the upper sheet 12 and the upper surface of the lower sheet 14 as in the above embodiment,
141 so that the film-like connectors 60, 60 and the upper and lower surfaces of the battery can be received in the recessed portions, the above-mentioned structure can be formed between the upper sheet 12 and the lower sheet 14 without affecting the overall thickness of the device. A paper battery 40 can be stored therein.

In the above embodiment, the case 10 has a structure in which the frame 11, the upper sheet 12, the upper sheet 13, the lower sheet 14, and the lower sheet 15 are laminated. The upper sheet 12 and the upper sheet 14 may also be integrated, and the lower sheet 15 may be omitted. Further, although the small electronic calculator of the above embodiment is a disposable type in which the paper battery 40 cannot be replaced, the upper sheet 12 or the lower sheet 14 of the case 10 is made removable by screwing or the like, and the paper battery 40 is a disposable type. If the film-like connectors 60, 60 for connecting the paper-like battery 40 and the broken line board 20 are made of adhesive tape with a conductive portion formed on its surface, the paper-like battery 40 can be replaced. Also, at this time, the negative electrode 41a and the positive electrode 41b of the paper battery 40
Upper sheet 12 and lower sheet 14 facing
If the peripheral edges of the film connectors 60, 60 are firmly fixed with an adhesive or a fastening member as described above, and the film connectors 60, 60 interposed between each electrode and the sheet are securely held in pressure contact, the film connectors 60, 60,
Conductive part 61 of 60 and other parts 6 except this
It is not necessary to impart adhesiveness to one or both of 2. However, in this case as well, the wiring board 20
It is desirable that the portions connected to the battery connection terminals 25a and 25b be provided with adhesive properties. In addition,
The present invention is of course applicable not only to small electronic calculators but also to other small electronic devices.

〔Effect of the invention〕

The present invention aims to reduce the thickness of the battery itself by configuring a paper-like battery with a three-layer structure in which a power generation section and positive and negative electrode sheets are polymerized, and also to integrate this paper-like battery into a wiring board inside a device case. Since they are stored side by side and at least the bottom of the device case is made of a thin metal plate, it maintains its mechanical strength even though it uses a battery that constantly generates electricity, and is compact enough to use a conventional button-type battery. It can be made much thinner than electronic devices.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention.
Figures 2 and 2 are an enlarged sectional view and external perspective view of the main parts of a small electronic calculator, and Figure 3 is an exploded perspective view.
Figure 4 is an enlarged cross-sectional view of one side of the paper battery;
FIG. 5 is a perspective view of a paper battery and a film connector. 10... Case, 20... Wiring board, 40...
Paper battery, 60... film connector.

Claims (1)

[Claims] 1 A separator impregnated with an electrolyte is interposed between the positive and negative active materials, and a separator is placed between the positive and negative active materials.
Paper-like batteries with polymerized positive and negative electrode sheets that also serve as current collectors on each lower surface are stored side by side on the wiring board inside the device case, and each electrode sheet of the paper-like batteries is connected to the wiring board. 1. A small electronic device, which is electrically connected to a battery connection terminal formed on a substrate, and at least a bottom portion of the device case is made of a thin metal plate to support the paper battery and the wiring board.