GB2264801A - Computer keyboard - Google Patents

Description

1 1 2264801m 1 COMPUTER KEYBOARD The present invention relates to a

computer keyboard and more particularly to a computer keyboard with a keyboard interface.

There are a number of so-called standard computer keyboards, and generally these fall into two groups. In the f irst group there are provided 101 keys and in the second 102 keys. However keyboards using a variable scan code require at least 103 keys.

Conventionally computer keyboards comprise a number of indicator lamps, usually LEDs, for example, a lamp indicating "number lock", a lamp indicating "scroll lock" and a lamp indicating "capitals lock".

Different circuit arrangements may be used for driving these indicator lamps, prior art circuits for this purpose being shown in Figures 1-3.

The hardware shown in Fig. 1, uses known firmware and adds a decoder to the scanning part so as to extend the scanning lines. In this hardware, independent control lines are provided for controlling the three LED indicator lamps separately. The main disadvantage of this hardware design is that the decoder increases the cost of the keyboard. Advantages are that the LED indicator lamps are separately controlled and free from the interference of other output lines, and that the keyboard can scan as much as 120 keys (15 x 8 = 120).

2 The hardware shown in Fig. 2 uses known firinware and adds a transistor to the LED indicator lamps. This eliminates the use of the decoder in the scanning port.

The transistor does not work during scanning operation, and during that period the LED indicator lamps are off. once a scanning operation is completed, the transistor works immediately, and, the LED indicator lamps are turned to their respective mode. An advantage of this design is that it reduces the cost. Disadvantages are that the LED indicator lamps produce weak intensity of light because the transistor is intermittently turned on and off, and that the keyboard an only scan 104 keys (8 x 13 = 104).

The hardware shown in Fig. 3 also uses known firmware.

By comparison with Fig. 2, this hardware avoids the use of the transistor and connects one terminal of each LED indicator lamp to the power supply. Acer Corporation filed an application on May 25, 1588 (under Serial No.

77,204,894) which utilizes the circuit as illustrated in Fig. 2 and eliminates the use of the transistor. According to Acer's application, firmware must be matched so that users can accept the design and the effects similar to the hardware-designs of Figs. 1 and 2 can be achieved.

However, in Acer's disclosure, there is no modification or improvement in the firmware, and the phenomenon of persistence of vision is relied upon. Although the status of the LED indicator lamps may be caused to change during scanning operation, it will be renewed after a certain length of time. Acer explains that people do not observe such rapid changes (at 10-20Ms) in the status of the LED indicator lamps, i.e. the LED 3 indicator lamps appear to remain unchanged. Actually, the LED indicator lamps will produce weak light during the scanning operation (if the LED indicator lamps are 5 originally maintained at an OFF mode). As indicated in Acer's disclosure, what is seen may vary with the intensity of ambient light. of course, people do not notice any change in the status of the LED indicator lamps under high intensity of ambient light (under direct sunlight).

However, any status change of the LED indicator lamps will become apparent indoors or when the intensity of ambient light is no very strong.

It has been the common method to eliminate the aforesaid problem by increasing the impedance of the resistors Rl, R2 and R3 in the circuit as indicated in Fig. 3 up to 390ohns. By means of increasing the impedance of the resistors, the normal intensity of light of the LED indicator lamps is relatively reduced (because electric current is reduced), and therefore, any status change of the LED indicator lamps (which causes the LED indicator lamps to produce dim light) will not be easily seen. This method is applicable but still not satisfactory in use.

The present invention aims to at leastpartially mitigate the foregoing disadvantages and problems. The present invention can free space in the memory of the single chip for other purposes.

As an example a 80491C may be used for the single chip, and the programmable memory has only 2K byte capacity in which each key comprises three codes (SET1, SET2 and SET3) and the third code (SET3) of each key can be 4 separately set to instruct its Output Code (1), Make Code (2), Break Code (3) to be or not to be provided with repeat-action. Therefore, all models including XTIATIPS2 can be compatible and connected together for on-line operation. A keyboard as constructed according to Acer's disclosure provides XTIAT, PS2 with one key code only and which key code can not be separately set because there is not sufficient space for such functional operation.

According to the present invention there is provided a keyboard f or a computer comprising plural indicators, said indicators having a common terminal, said common terminal being selectively alternatively connectable directly to a supply terminal, or via a gating means to said supply terminal.

Advantageously a control device for producing a periodic enabling signal at an output thereof wherein, when said common terminal is connected to said supply terminal via said gating means, said output of said control device is applied to a control terminal of said gating means whereby said periodic enabling signal provides time division operation of said indicators.

Conveniently when said common terminal is directly connected to said supply terminal, said output or said control device is coupled to a scanning line of said keyboard.

Alternatively when said common terminal is directly connected to said supply terminal said output of said control device is coupled to an audible signalling means for operation thereof by said periodic enabling signal.

Preferably said control device scans the keys of said keyboard using a periodic scanning signal, said periodic scanning signal also being applied to the respective other terminal of each respective indicator.

Advantageously the pulse width of said periodic scanning signal is sufficiently short as to produce no perceptible visible effect on said indicators.

The invention will now be described by way of example with reference to the accompanying drawings in which:- Figures 1-3 show keyboard circuits of the prior art;

Figure 4 is a circuit diagram of a keyboard in accordance with the present invention; Figure 5 is a timing diagram f or the circuit of Figure and Figures 6-13 show flow charts of the keyboard software or f irmware, useful in understanding the present invention.

In the keyboard shown in Fig. 4, there are provided 13 basic scanning lines for scanning 1-4 keys (8 x 13 = 104) which are sufficient for a standard keyl?oard. There are two dotted lines (a) and two dotted lines (b) which are formed as jumper connectors on a PCB which includes a gating transistor Ti. If the two jumper connections (b) are connected, the jumper connections (a) are not connected, i.e., (a) and (b) shall not co-exist, and therefore, two different circuit configurations are available. When connections (a) are made, the LED common terminal 40 is coupled to the supply terminal Vcc directly. If the two dotted lines (b) are connected, the circuit will be same as to the circuit of Fig. 2 with the LED common terminal 40 coupled via gating transistors to the terminal Vcc. With this arrangement, a processing technique (later 6 described herein) controls the scanning of keyboard, the detection of ghost key and the renewal of LED indicator lamps by means of time- division, and will eliminate the dim light problem. If the two dotted lines (a) are connected instead, an additional control line will be available for scanning purpose or for controlling a buzzer, and the LED indicator lamps are connected to the power supply. With this arrangement again, a processing technique controls the scanning of keyboard, the detection of ghost key and the renewal of LED indicator lamps by means of time-division, so as to completely eliminate dim light problem. If the additional control line is used for scanning, as much as 112 keys can be scanned (8 x 14 = 112); if the additional control line is used for controlling a buzzer, a key switch can be matched to control a buzzer producing a sound of two segments, i.e. a "click-click" sound.

Because an instruction from a single chip must be executed within a fixed length of time, the mode of the LED indicator lamps shown will be altered when the status of the common pins for the LED control line and the scanning line is changed, and the LED indicator lamps will be returned to their original status upon completion of scanning operation. The key point in eliminating the dim light problem is how to utilize the time which is saved from shortening the scanning time (i.e. the time at which the status of the LED indicator lamps is temporarily changed). The aim of the present invention is to complete all judging jobs before the change of the scanning lines, so as to read the status of all keys and renew the status of the LED indicator lamps immediately after the change of the scanning lines. The execution time is reduced to about 5-10gs.

7 If the time during which the status of the LED indicator lamp is temporarily changed, is shortened so as to eliminate the dim light problem the independent control line effect of Fig. 1 may not be achieved. Therefore, the total scanning time should be properly arranged. The present invention utilizes a time- division technique permitting each scanning line to be scanned within one cycle, and 4ms is available for one cycle. Therefore, actual total scanning time is 1.82 ms (260 x 7 = 1820) leaving a time of 2.18ms. It takes two cycles (4 x 2 8ms) to have all the scanning lines complete one scanning operation.

However, only 3 scanning lines control the LED indicator lamps while performing scanning operation. Therefore, there are three chances within two cycles to alter the status of the LED indicator lamps. Fig. 5 is provided for reference. In conclusion, there are three chances within two cycles to change the status of the LED indicator lamps, each of which lasts for 5-10Ms. A period of two cycles, (8ms) is very large relative to 5-10gs (the time f or which the status of the LED indicator lamps is temporarily changed). As a result, the impedance of the resistors RI, R2 and R3 in the circuit as illustrated in Fig. 3 can be reduced to 220ohms approximately so as to increase the intensity of light of the led indicator lamps. Under this arrangement, human eyes perceive no alteration in the state of the LED indicator lamps, and therefore, the effect achieved by using three independent control lines to control the LED indicator lamps as shown in Fig. 1 can be achieved by the present invention.

8 Fig. 6 is a flow chart of the start program segment. As the system was started, the read only memory and the program memory are tested in proper order, then the conditions of the pins are set and the buzzer control pin is shut off, then the time delay, the keys and LEDs of the keyboard are set and the start code is piled tip in the buffer and the flag is set for repeat-action, and then the program judges the model of the system. if the system model is identified being of a XT mainframe, then the XT program (B) is executed; if the system model is identified being of an AT/PS2 mainframe, then the program immediately judges if there is any instruction given by the system to the keyboard? If there is an instruction given by the system to the keyboard, then the program stops scanning and code sendin'g (C); if there is no any instruction given by the system to the keyboard, then the keyboard is judged if it was disabled? If the keyboard is judged been disabled, then the buffer is checked if there is any data stored? If the buffer is checked having data stored therein, then the program sends the code M; if the buffer has no data, then the program starts scanning the keyboard (F).

t 9 Fig. 7 is a flow chart of the program segment of scanning the keyboard. As the scanning keyboard program segment is executed, the program firstly sets the master scan flag and scans one line and resets the LEDs, then judges if it is a master scan or skip scan? If the master scan flag was not set, then skip scan is deleted (0). Then, the program judges if there is key switched? If there is no any key switched, program executes the subprogram of comparison original keys. If the comparison result indicates same, namely, no any key is released, then the index is added with 1 and a next line is scanned, any the with the scan and then the program proceeds to the subprogram (H) and the next procedures continuously. If the comparison result shows a key released, the program immediately returns to delete the skip program. On the contrary, if there are keys switched, the keys are compared with the original keys, and the repeat-action speed processing program segment (Gl) is executed if the comparison results indicates a repeat-action. The repeat-action speed processing program segment (Gl) is to reduce 1 from the repeat-action flag and judge the result if there is zero-reading. If non-zero reading is judged, the subprogram (I) of adding the scan index with 1 and scanning the next line is executed; if zero reading is judged, the buffer is checked if there is any data stored therein. If the buffer is checked being stored with data, the subprogram (J) of setting repeat- action and starting to wait time flag, and then the subprogram (V of adding the scan index with 1 and scanning the next line is executed. If the buffer is checked having no data stored therein, the key being switched is judged. If the key being switched is judged not a special key, the make code is put in the buffer, and then the subprogram (J) of setting repeataction and starting to wait time flag is executed. If the comparison result is different, it means there is a new key pressed, and the sub-program (G) of returning to deleting the skip program is executed.

Fig. 8 is a flow chart of the program segment of reading out and executing system instruction. As the subprogram of system instruction to keyboard is executed, it reads out the instruction code from the system. If the reading process fails, the program executes the subprogram M of judging keyboard disabled and then keep executing the next procedures. If the reading process is successful, the subprogram (M) of judging the instruction code to be a first or second instruction code. If a second instruction code is identified, the subprogram executes the command (L); if a first instruction code. is identified, it is judged to be F1 or EF or not. If the instruction code is identified being F1 or EF, a repeat code is sent out, and the subprogram (K) of judging keyboard disabled is executed, and then the next procedures are followed.

If the instruction code is identified neither F1 nor EF, it is judged to be FE or not. If the instruction code is identified being FE, the last sending code is sent out; if the instruction code is identified not being FE, the 10 of answer back code FAH is sent out. code sending fails, instruction.

If the process the program reads in new If the repeat reading is successful, the subprogram (M) of judging the instruction code to be a first or second instruction code is executed, and then the next procedures are followed. If the repeat reading fails, the program executes the sub-program (N) of jidging the instruction code to be F1 or EF or not, and then keep executing the next procedures. If the process of code sending is successful, the program judges the type of the instruction code to be a double set or single-set instruction code. If the instruction code is identified being a double-set instruction code, a double-set instruction code flag is set, then the subprogram M of judging kevboard disabled is executed, and then the next procedures are followed. If the instruction code is identified being a single-set instruction code, the instruction is respectively executed, then the subprogram M of judging keyboard disabled is executed, and then the next procedures are followed.

12 Fig. 9 is a flow chart of the novell/workstation processing subprogram (E), the code sending subprogr am (R) and the novel subprogram (P). when entered the novell/workstation processing program segment, the novell/workstation processing program (E) is executed. If a novell/workstation is identified, the program calls the novell subprogram (P); if not, the program calls the code sending subprogram (R) and then sends the code. If the process of code sending fails, the keyboard scanning subprogram (F) is executed; if the process of code sending is successful, the program executes the time delay between codes and reduces 1 from the buffer flag, and then executes the keyboard scanning subprogram (F).

When entered the code sending subprogram (R), the subprogram judges what system the code is sent and executes the job, then sends out 8 information codes, and then judges if the system is of the model AT/PS2. If the system is not the model AT/PS2, return to the code sending subprogram (R); it the system is the model AT/PS2, send out bit inspection flag value and then return to novell/workstation processing subprogram (E).

When entered novel subprogram (P), the novel subprogram sets novel counter 3 times and sets the time, then calls code sending subprogram (R) to see if there is any system instruction so as to send out the key is 13 code. If the process of sending out the key code is successful, the subprogram executes the time delay between codes (Q) and then keep executing the next procedures; if the process of sending out the key code fails, the subprogram reduces 1 from the novel counter, and then returns to call the code sending subprogram (R) and see if there is any system instruction if the novel counter has a non-zero reading, or returns to the novel/workstation processing subprogram (E).

Fig. 10 is a flow chart of the key-pressed module judgment program segment. As any key is pressed, the program judges if the key is of the module 3 or not. If the key is identified being of the module 3, then the program Dudges if a repeat-action is required. If a repeat-action is not required, a respective key code is then put in the buffer, and then the buffer is checked. If the buffer is checked being not full, then the program checks if there is any key of the same array pressed?, so as to make a calculation and set the repeat-action flag value and execute the subprogram (I) of adding 1 to the scanning index and scanning the next line. If the buffer is checked being full, then the program a respective overflow indicator code is put to the buffer at the top, and then the program keeps 14 searching if there is any key of the same array pressed? and proceeds to the next procedures. If a repeat- action is required after the module 3 has been identified. the program judges if the repeat-action sound flag has been set? If the repeat-action sound flag has been set, the enable line of the buzzer is then pulled to high for permitting the buzzer to make a sound, then the repeat-action enable flag is set and the key code. is put in the buffer, and then the program 1. proceeds to the next procedures. If the repeataction sound flag has not been set when a repeat-action is required after the module 3 has been identified, the program directly sets the repeat-action enable flag and puts the key code in the buffer and then proceeds to the next procedures. If the key being pressed is judged not being of the module 3, the program judges if it is a special key? If the key being pressed is not a special key, the program judges if the repeat-action next procedures; if the key being pressed is a special key, the program calls the special key processing program (W) and sets the special key repeat-action flag, then puts the key code in the buffer and then proceeds to the next 1Drocedures.

sound flag has been set? and then proceeds to the Fig. 11 is a flow chart of the novell/workstation processing subprogran (E), the code sending subprogram (R) and the novel subprogram (P). When entered the processing program segment, the novell/workstation processing program (E) is executed.

If a novell/workstation is identified, the program calls novell/workstation the novell subprogram (P); if not, the program calls the code sending subprogran (R) and then sends the code. If the process of code sending fails, the keyboard scanning subprogram (F) is executed; if the process of code sending is successful, the progran executes the time delav between codes and reduces 1 from the buffer flag, and then executes the keyboard scanning subprogram (F).

When entered the code sending subprogram (R), the subprogram judges what system the code is sent and executes the job, then sends out 8 information codes, and then judges if the system is of the model AT/PS2. If the system is not the model AT/PS2, return to the code sending subprogram (R); it the system is the model AT/PS2, send out bit inspection flag value and then 30 return to novell/workstation processing subprogram (E).

When entered novel subprogram (P), the novel subprogram sets novel counter 3 times and sets the time, then calls code sending subprogram (R) to see if there is any system instruction so as to send out the key 16 is code. If the process of sending out the key code is successful, the subprogram executes the time delay between codes (Q) and then keep executing the next procedures; if the process of sending out the key code fails, the subprogram reduces 1 from the novel counter, and then returns to call the code sending subprogram (R) and see if there is any system instruction if the novel counter has a non-zero reading, or returns to the novel/workstation processing subprogram (E).

Fig. 12 is a flow chart of the key-pressed module judgment program segment. As any key is pressed, the program judges if the key is of the module 3 or not. If the key is identified being of the module 3, then the program judges if a repeat-action is required. If a repeat-action is not required, a respective key code is then put in the buffer, and then the buffer is checked. If the buffer is checked being not full, then the program checks if there is any key of the same array pressed?, so as to make a calculation and set the repeat-action flag value and execute the subprogram (I) of adding 1 to the scanning index and scanning the next line. If the buffer is checked being full, then the program a respective overflow indicator code is Put to the buffer at the top, and then the program keeps 17 searching if there is any key of the same array pressed? and proceeds to the next procedures. If a repeat action is required after the module 3 has been identified, the program judges if the repeat-action sound flag has been set? If the repeat-action sound flag has been set, the enable line of the buzzer is then pulled to high for permitting the buzzer to make a sound, then the repeat-action enable flag is set and the key code is put in the buffer, and then the program proceeds to the next procedures. If the repeat action sound flag has not been set when a repeat-action is required after the module 3 has been identified, the program directly sets the repeat-action enable flag and puts the key code in the buffer and then proceeds to the next procedures. If the key being pressed is judged not being of the module 3, the program judges if it is a special key? If the key being pressed is not a special key, the program judges if the repeat-action sound flag has been set? and then proceeds to the next procedures; if the key being pressed is a special key, the program calls the special key processing program (W) and sets the special key repeat-action flag, then puts the key code in the buffer and then proceeds to the next procedures.

18 is Fig. 13 is a flow chart of the key-released module judgment program segment. As any key is released, the program judges if the key is of module 3? If the key is identified of module 3, then the program judges if to send out a break code? If no break code is to be sent out, then the program judges if there is any key of the same array released? If there is any key of the same array released, then the program proceeds to the subprogram (S) to judge any key pressed or released and then proceeds to the next procedures; if there is no key of the same array released, then the program executes the subprogram M to add 1 to the scan index and scan the next line and then proceed to the next procedures.

If a break code is needed to be sent out after the module 3 has been identified, then the program puts the break code in the buffer, and then judges if there is any key of the same array released and proceeds to the next procedures. If a key is identified being not of module 3 as it was released, the program judges if it is a special key? If the key is identified being not a special key, then the program puts the break code in the buffer and then proceeds to the next procedures; if the key is identified being a special key, then the program calls the special key processing subprogram M and puts the break code in the buffer, and then proceeds to the n-xt procedures.

19 Fig. 14 is a flow chart of the skip key clearing processing program segment. when entered the skip key clearing processing program segment, the program firstly calls the clear skip key scanning program, then proceeds to the skip key clear transfer, and then judges if there is any ghost key? If there is a ghost key, then the program judges if there is any repeat-action? If a repeat-action is identified, then the program (R); if no repeat-action is identified, then the program proceeds to the subprogram (I) to add 1 to the scan index and scan the next line, and then proceeds to the next procedures. It there is no ghost key after the procedure of calling the clear skip key scanning program, the program sets the mother key and the related flag execute mother key siibprogram (Z) then judges the model of the system. If the system is identified being of XT model, then the program searches the key code and proceeds to the subprogram (S) to judge any key pressed or released?and then to proceed to the next procediires; if the system is identified being of AT/PS2 model, then the program judges what mode? and searches the key code and then judges any key pressed or released? If there is a key released then the program executes the.

subprogram (T); if there is a key pressed, then the program executes the subprogram (U).

proceeds to the code sending subprogram Fig. 15 is a flow chart of the special function processing program segment. When entered the special function processing program segment, the program firstly sets CTRL, ALT, SHIFT, NUM LOCK flags, then judges if any mother key has been pressed? If no mother key is pressed, then the program judges if the lock out flag has been locked? If the lock out flag has been locked, then the program returns to the subprogram (Z) to set the mother key and the related flags; if the lock out flag is not locked, then the program continues.

If there is a mother key pressed after the setting of CTRL, ALT, SHIFT, NUM LOCK flags, then the program judges if there is any specific daughter key been pressed? If there is a specific daughter key 1- 5 been pressed, then the program alters the repeat-action parameter; if either daughter key 6 or 7 was pressed, then the program alters the keyboard lock out flag; if the daughter key 8 was pressed, then the program alters the buzzer enable flag and the control line; if the daughter key 9 was pressed, then the program alters the repeat-action sound flag; if there is any undefined key been pressed, then the program repeats searching until a defined daughter key is pressed or a mother key is released. If there is no any daughter key been pressed, then the program keeps searching until a defined daughter key is pressed or a mother key is released. If a motherkey is identified been released, then the program executes the subprogram M).

21 to judge if the lock out f lag has been locked and then proceeds to the next procedures.

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Claims (7)

CLAIMS:

1. A keyboard for a computer comprising plural indicators, said indicators having a common terminal, said common terminal being selectively alternatively connectable directly to a supply terminal, or via a gating means to said supply terminal.

2. A keyboard for a computer according to claim 1, further comprising a control device for producing a periodic enabling signal at an output thereof wherein, when said common terminal is connected to said supply terminal via said gating means, said output of said control device is applied to a control terminal of said gating means whereby said periodic enabling signal provides time division operation of said indicators.

3. A keyboard for a computer according to claim 2 wherein when said common terminal is directly connected to said supply terminal, said output of said control device is coupled to a scanning line of said keyboard.

4. A keyboard for a computer according to claim 2 wherein when said common terminal is directly connected to said supply terminal said output of said control device is coupled to an audible signalling means for operation thereof by said periodic enabling signal.

5. A keyboard f or a computer according to any one of claims 2-4 wherein said control device scans the keys of said keyboard using a periodic scanning signal, said periodic scanning signal also being applied to the respective other terminal of each respective indicator.

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6. A keyboard f or a computer according to claim 5 wherein the pulse width of said periodic scanning signal is sufficiently short as to produce no perceptible visible effect on said indicators.

7. A keyboard f or a computer constructed and arranged substantially as herein described with reference to Figures 4-13 of the accompanying drawings.