CN1787719A

CN1787719A - Button scanning circuit for electrostatic discharge protection

Info

Publication number: CN1787719A
Application number: CN 200410100328
Authority: CN
Inventors: 蓝宗祥; 吴政道
Original assignee: BenQ Corp
Current assignee: BenQ Corp
Priority date: 2004-12-06
Filing date: 2004-12-06
Publication date: 2006-06-14

Abstract

An electronic device with electrostatic discharge protection key scanning circuit layout comprises n row wires and m column wires formed on a printed circuit board in an array type. At least one row conductor or one column conductor is grounded, and the remaining row conductors and m column conductors are connected to a plurality of data output terminals and input terminals of a keypad coding Integrated Circuit , respectively. The row line (connected to the data output end) intersected with the grounded column line or the column line (connected to the data input end) intersected with the grounded row line is used for arranging keys which are relatively easy to be attacked by static electricity, particularly side keys, so that the aim of only striking the ground but not an IC when the static electricity discharge occurs is fulfilled.

Description

The key scanning circuit of electrostatic discharge protective

Technical field:

The present invention relates to the key scanning circuit relevant, particularly relate to a kind of key scanning circuit with antistatic protection function with a kind of electronic installation.

Background technology

In recent years, the improvement of portable electronic consumer products, except outward appearance and function intensified, short and small and frivolous designer trends are dealer's common recognition especially.The mobile phone of Wireless Telecom Equipment particularly, chord ring and colorful display screen are basic outfits.The button that meets ergonomics also often is the attraction of the frequent demand of dealer.In addition, the folding type mobile phone needn't be established press-key lock in addition and dial to prevent mistake, and can utilize lid to increase camera function, time, color Presentation Function when reaching incoming call.Therefore, generally speaking, folding type is more welcome than non-folding type mobile phone.

For taking the convenience of one-handed performance into account, mobile phone, particularly folding type mobile phone, how can design mobile phone side key (side key) in the mobile phone side to provide when being hold by one hand, can dial, use when recording or sound regulation.Yet in the mobile phone miniaturization, mobile phone is subjected to static discharge and the chance of damaging IC interior circuit or display panels ITO lead heightens relatively.Particularly high at the camera cell phone pixel, mobile phone side key area hour, the anti-electrostatic-discharge design of mobile phone more seems highly difficult.

When button was exposed, the mobile phone in pocket or suitcase may produce buildup of static electricity because of friction, further invaded IC by mobile phone side key and caused electrostatic breakdown.The another kind of situation person of being to use is when dry environment is operated, and the static of human body accumulation just may reach 1KV to 2kY very easily and invade IC by mobile phone side key.

Also therefore, Electromagnetic Interference protection design is also can carry out the electrostatic defending design to mobile phone except meeting is carried out, and for example, the assembly of mobile phone is added cover silver foil and/or work hard scanning button.

With regard to the design of working hard of scanning button, the design of known determinant scanning button is row and the row that data output end and input with keyboard coding IC are respectively array, and the ranks intersection point is the button contact.Will make this i bar DOL Data Output Line and j bar Data In-Line be pulled to same current potential when for example the button of i bar DOL Data Output Line and the intersection of j bar Data In-Line is pressed, just can use and judge that this button is pressed, integrated circuit will be exported a signal this moment, in order to the keying signal of expression input electronic installation.And in order to reach electrostatic discharge protective, the many offices of portion that the row and the

contact zone

10,20 of row (row) can be similar to baked donut of the layout of printed circuit board (PCB).As shown in Figure 1, the less capable contact zone 10 of impedance (connecting the IC input) is at the center, and the bigger row contact zone 20 (connecting the IC input) of impedance is in the periphery.This is because the output impedance is little than sending-end impedance usually, and ESD usually can be due to the little path of impedance.

Although it is the impedance of row contact zone 20 is bigger, stronger relatively to antistatic capacity.If but this button is when being side switch, mobile phone thickness deficiency, to cause tradition to be similar to the deficiency of 10 besieged of the too little and feasible capable contact zones of baked donut row contact zone 20 areas, and further cause the Electrostatic Discharge easily may by what import the keyboard coding integrated circuit into by side switch.Therefore, generally need extra ESD guard assembly before signal input keys dish coding integrated circuit, can not suffer the damage of Electrostatic Discharge to guarantee the keyboard coding integrated circuit.

The invention provides an electronic installation and have new electrostatic discharge protective layout thinking, do not need extra ESD guard assembly, but can obviously improve above-mentioned problem.

Summary of the invention

A kind of electronic installation comprises the key scanning circuit layout of keyboard coding integrated circuit (IC) and electrostatic discharge protective, comprises the capable lead of n bar and m bar column wire is formed on the printed circuit board (PCB) with the array pattern.At least one row lead or a column wire are grounded, and remaining row lead is connected a plurality of data output ends and the input that the keyboard coded set becomes circuit (IC) respectively with m bar column wire.Wherein with the column wire intersection of this ground connection connect capable lead (being connected data output end), or with the column wire (being connected data input pin) of the capable lead intersection of this ground connection, it is in order to arrange to be subject to relatively the button that static is attacked, side switch particularly, when taking place to reach static discharge, only can hit the earth, rather than the purpose of IC.

According to design of the present invention, do not need extra assembly, the therefore problem that does not have assembly to wear out, and nearly all ESD can directly be led the earth, therefore can solve coding IC smoothly and be subjected to the problem that ESD attacks.

Description of drawings

Preferred embodiment of the present invention will be described with reference to the accompanying drawings in the specification of back.

Fig. 1 shows in the known keyboard scanning circuit row contact zone at the center, and the row contact zone is at outer shroud, the schematic diagram of the similar baked donut of both shapes.

Fig. 2 shows according to wherein a line or the alignment schematic diagram that is connected to ground in the method keyboard scanning circuit of the present invention.

Fig. 3 shows according to method of the present invention, the schematic diagram of an electronic installation, and wherein the row contact zone is at the center in the keyboard scanning circuit, and the row contact zone is ground connection then, the schematic diagram of the similar baked donut of both shapes.

Fig. 4 shows according to the row contact zone is at the center in the method keyboard scanning circuit of the present invention, and the row contact zone is the schematic diagram of ground connection then.

The reference

numeral explanation

Line

110,10	Alignment 120,20
110,10	Alignment 120,20	The line 110A of ground connection	The alignment 120A of ground connection
Coding IC 105	Button 130	The line 110A of ground connection	The alignment 120A of ground connection
Coding IC 105	Button 130	Electronic installation 100

Embodiment

Because the mobile phone of known employing determinant scanning button design has only easy electrostatic discharge protective.And static directly allows the row or column contact zone at button place be subjected to the static strike easily by the slit of mechanism periphery.Add that guard assembly also has aging problem.Therefore, how to strengthen electrostatic discharge protective and just become very important problem.The present invention proposes new design therefore at the problems referred to above, not needing additionally to increase under the prerequisite of cost, just can realize the purpose of electrostatic defending.

According to a preferred embodiment of the present invention, electronic installation comprises the key scanning circuit of keyboard coding integrated circuit (IC) and electrostatic discharge protective, its electrostatic defending principle is the button with part, particularly is vulnerable to the side switch that static discharge is attacked, and uses ground connection formula key scan.Please refer to an electronic installation 100 shown in Figure 2, comprise connected line 110 of coding IC 105 and many and alignment 120, except an alignment 120A exception at edge, it is not connected to coding IC 105 but is grounded in the icon keyboard printed circuit board layout.Line 110 is a button 130 with alignment 120 confluces.As long as button is depressed, will make the line and the alignment of this intersection be pulled to equal potentials, integrated circuit will be exported a signal this moment.

Therefore, according to method of the present invention, also can select a line 110 is substituted alignment 120A ground connection.Or line 110 and an alignment 120A ground connection (except the plotted point) at the most, but two (comprising two) above alignment ground connection can not be arranged simultaneously.Otherwise when detecting a certain line and word line is connected to earthing potential, have can't judge study carefully be that alignment the button quilt by problem.What deserves to be mentioned is: the button that is designed to the alignment 120A of ground connection or line 110A place is being subject to the button that static discharge is attacked, and particularly those are exposed to the side switch of mobile phone side.

Fig. 3 shows the embodiment according to the printed circuit board (PCB) alignment ground connection of method of the present invention, and is similar to Fig. 1, and the row contact zone is the filled circles of copper-foil conducting electricity, and row row contact zone is the annulus of a copper-foil conducting electricity, isolated with an insulated substrate that exposes between the two.Different is that the row contact zone is the earth terminal that is connected in IC, rather than the row data terminal.Fig. 4 shows another embodiment according to the printed circuit board (PCB) alignment ground connection of method of the present invention.It is banded that the row contact zone is, and isolated with an insulated substrate that exposes between the capable contact zone of filled circles.

Advantage of the present invention:

1. utilize the earth of outer ring, tightly surround the capable contact zone of inner ring, can make the circuit that joins with IC be coated, when static takes place, only can hit the earth by the earth.

2. static discharge is that an electrostatic charge of accumulating flows to an opposite electrical charge concentration district or a low charge concentration district from a high static electrical charge concentration zones, and when the outer ring is the earth, also is low charged region, and it can directly be released electrostatic charge to system's the earth.

3. the button outer ring is a earth, is the exposed Copper Foil of this layer of PCB, and PCB itself increased and soak gold and handle, and prevents that Copper Foil from expose oxidation, therefore the problem that does not have assembly to wear out.

4. because reduce the use of electrostatic discharge protective assembly, directly just increase many spaces, help dwindling and weight saving of electronic product.

5. save the assembly use cost.

The above is preferred embodiment of the present invention only, is not in order to limit the scope of claim of the present invention; All other do not break away from the equivalence of being finished under the disclosed spirit and changes or modification, all should be included in the scope of claim of the present invention.

Claims

1. A button scanning circuit layout for electrostatic discharge protection, at least comprising:

n row wires and m column wires are formed on a printed circuit board in an array, wherein n row wires and m-1 column wires are respectively connected to a plurality of data output terminals of the keyboard coding integrated circuit (IC) and At the input, a column conductor is grounded, and the intersection of the ith row conductor and the jth column conductor is connected to the same potential when a key is pressed.

2. The key scanning circuit layout as claimed in claim 1, wherein the key in the electronic product that is more vulnerable to electrostatic discharge is the key designed at the intersection point of the grounded column conductor and the n column conductors.

3. The key scanning circuit layout as claimed in claim 2, wherein the side key in the electronic product that is more vulnerable to electrostatic discharge is the key that is most preferentially designed at the intersection point of the above-mentioned grounded column conductor and n column conductors.

4. The key scanning circuit layout as claimed in claim 1, further comprising the n+1th row wire intersecting with the m column wires, and the n+1th row wire is grounded.

5. The key scanning circuit layout as claimed in claim 4, wherein there is no key at the intersection point of the n+1th row conductor and the mth column conductor.

6. A button scanning circuit layout for electrostatic discharge protection, at least comprising:

n row wires and m column wires are formed on a printed circuit board in an array, wherein n row wires and m-1 column wires are respectively connected to a plurality of data input terminals and output terminals of the keyboard coding integrated circuit, A column conductor is grounded, and is connected to the same potential when the intersection of the ith row conductor and the jth column conductor can be pressed by a button.

7. The key scanning circuit layout as claimed in claim 6, wherein the key in the electronic product that is relatively vulnerable to electrostatic discharge is the key designed at the intersection point of the above-mentioned grounded column conductor and n column conductors.

8. The button scanning circuit layout as claimed in claim 7, wherein the side buttons in the electronic product that are vulnerable to electrostatic discharge attacks are the buttons with the highest priority to design the intersection points of the above-mentioned grounded column conductors and n column conductors.

9 . The key scanning circuit layout according to claim 6 , further comprising that the n+1th row wire is intersected with the m column wires, and the n+1th row wire is grounded.

10. The key scanning circuit layout as claimed in claim 9, wherein there is no key at the intersection point of the n+1th row conductor and the mth column conductor.

11. An electronic device comprising:

A keypad coding integrated circuit;

n rows of wires;

m column wires, the m row wires and the n column wires intersect at multiple intersection points, and the m-1 column wires and n row wires of the m column wires are respectively connected to multiple data inputs of the keyboard coding integrated circuit terminal and output terminal, the other column conductor in the m column conductors is grounded; and

A plurality of keys are relative to the plurality of intersections, and are used to short-circuit the corresponding intersections when any key is pressed, so that the keyboard coding integrated circuit outputs a signal.

12 . The electronic device as claimed in claim 11 , wherein a key vulnerable to ESD attack selected from the plurality of keys is the key at the intersection point of the grounded column conductor and the n column conductors. 13 .

13. The electronic device as claimed in claim 12, wherein the key vulnerable to electrostatic discharge is a side key of the electronic device.

14 . The electronic device as claimed in claim 11 , further comprising an n+1th row wire intersecting with the m column wires, and the n+1th row wire is grounded.

15. The electronic device as claimed in claim 14, wherein the intersection point of the (n+1) th row wire and the m th column wire has no key.