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US 11,112,877 B2Granted
Keyboard scanning circuit and control method thereof
AssigneeChicony Electronics Co., Ltd.
InventorChien-Tsung Chen
Life of this patent
Estimating the term…
Abstract
A keyboard scanning circuit and control method thereof are provided. The method is adapted to detect states of a plurality of switching circuits arranged in an array manner, wherein each of the switching circuits includes a key switch and a first resistor connected in series; the switch circuits are coupled to a plurality of scan lines and a plurality of feedback lines; each of the scan lines is coupled to the switch circuits of the same column in a first direction, and each of the feedback lines is coupled to the switch circuits of the same row in the second direction.
Claims11
A keyboard scanning circuit, comprising:
- a digital output circuit for outputting a high state output voltage (V.sub.OH) and a low state output voltage (V.sub.OL);
- a digital input circuit for receiving output signals, and determining a logic signal corresponding to each of the output signals to be a high logic level or a low logic level, according to a high state threshold voltage (V.sub.TH) and a low state threshold voltage (V.sub.TL);
- a plurality of switch circuits arranged in an array manner, and each of the switch circuits comprising:
- a key switch;
- and a first resistor connected in series to the key switch;
- a plurality of scan lines, each of the scan lines comprising:
- an input terminal coupled to the digital output circuit for receiving an input signal output by the digital output circuit, wherein in a scanning round, the input signal received by one of the scan lines is a detection signal (V2), the input signal received by rest of the scan lines is a level signal (V1), the detection signal (V2) and the level signal (V1) are a combination of the high state output voltage (V.sub.OH) and the low state output voltage (V.sub.OL);
- and a plurality of switch terminals, wherein the switch terminals of each of the scan lines are respectively coupled to, in a one-to-one manner, the switch circuits of the same column in a first direction;
- a plurality of feedback lines, each of the feedback lines comprising:
- a connecting terminal coupled to the switch circuits of the same row in a second direction;
- and an outputting terminal coupled to the digital input circuit for outputting the output signal;
- and a controller coupled to the digital output circuit and the digital input circuit, wherein the controller is adapted to control the digital output circuit to perform the scanning round, receive the logic signals from the digital input circuit, and determine the key switches of the switch circuits coupled to the scan line receiving the detection signal (V2) is in a connection state or a disconnection state respectively, according to whether each of the logic signals is the high logic level or the low logic level in the scanning round;
- and wherein the high state output voltage (V.sub.OH), the low state output voltage (V.sub.OL), the high state threshold voltage (V.sub.TH), and the low state threshold voltage (V.sub.TL) satisfy a threshold inequality, the threshold inequality is:
- {
- V
- OH
- >
- V
- TH
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- TL
- >
- V
- OL
- ,
- when
-
-
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- TL
- V
- OH
- >
- V
- TH
- ≥
- V
- TL
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- OL
- ,
- when
-
-
- V
- TL
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- wherein n is the number of the connection states of the key switches of the switch circuits coupled to any feedback line.
114 more elements
A control method for keyboard scanning circuit, adapted to detect states of a plurality of switching circuits arranged in an array manner, wherein each of the switching circuits comprises a key switch and a first resistor connected in series;
- the switch circuits are coupled to a plurality of scan lines and a plurality of feedback lines;
- each of the scan lines is coupled to, in a one-to-one manner, the switch circuits of the same column in a first direction, and each of the feedback lines is coupled to the switch circuits of the same row in the second direction;
- the control method comprises:
- setting a detection signal (V2) and a level signal (V1) to be a combination of a high state output voltage (V.sub.OH) and a low state output voltage (V.sub.OL) according to the high state output voltage (V.sub.OH) and the low state output voltage (V.sub.OL);
- outputting an input signal to the scan lines respectively, wherein in a scanning round, the input signal received by one of the scan lines is a detection signal (V2), the input signal received by rest of the scan lines is a level signal (V1);
- receiving a plurality of output signals generated in response to the states of the switch circuits, the detection signal (V2), and the level signal (V1) from the feedback lines;
- and determining a logic signal corresponding to each of the output signals is a high logic level or a low logic level according to the high state threshold voltage (V.sub.TH) and the low state threshold voltage (V.sub.TL), and determining the key switches of the switch circuits coupled to the scan line receiving the detection signal (V2) is in a connection state or a disconnection state respectively, according to whether each of the logic signals is the high logic level or the low logic level in the scanning round, and wherein the high state output voltage (V.sub.OH), the low state output voltage (V.sub.OL), the high state threshold voltage (V.sub.TH), and the low state threshold voltage (V.sub.TL) satisfy a threshold inequality, the threshold inequality is:
- {
- V
- OH
- >
- V
- TH
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- TL
- >
- V
- OL
- ,
- when
-
-
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- TL
- V
- OH
- >
- V
- TH
- ≥
- V
- TL
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- >
- V
- OL
- ,
- when
-
-
- V
- TL
- >
- V
-
-
- 2
- +
- (
- n
- -
- 1
- )
- *
- V
-
-
- 1
- n
- wherein n is the number of the connection states of the key switches of the switch circuits coupled to any feedback line.
108 more elements
Dependencies are inferred from the claim text.