CA1293065C - Key input device - Google Patents
Key input deviceInfo
- Publication number
- CA1293065C CA1293065C CA000549564A CA549564A CA1293065C CA 1293065 C CA1293065 C CA 1293065C CA 000549564 A CA000549564 A CA 000549564A CA 549564 A CA549564 A CA 549564A CA 1293065 C CA1293065 C CA 1293065C
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- microcomputer
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- key
- keys
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Abstract
ABSTRACT OF THE DISCLOSURE
In a key input device, the depression of any one of keys of a keyboard applied to same voltage to one of a plurality of analog-digital conversion input terminal contacts connected to an analog-digital conversion input terminal and one of a plurality of ordinary input terminal contacts each connected to one of a plurality of ordinary input terminals so that in accordance with the resulting analog-digital input terminal voltage and ordinary input terminal voltage, a microcomputer discriminates the depressed key.
In a key input device, the depression of any one of keys of a keyboard applied to same voltage to one of a plurality of analog-digital conversion input terminal contacts connected to an analog-digital conversion input terminal and one of a plurality of ordinary input terminal contacts each connected to one of a plurality of ordinary input terminals so that in accordance with the resulting analog-digital input terminal voltage and ordinary input terminal voltage, a microcomputer discriminates the depressed key.
Description
~Z93~65 The present invention relates generally to input means for apparatus of the type having a digital control-ler and more particularly to a key input device so 4 designed that the kind of a key depressed is determined by the combined use of an analog-type signal and a digital-type signal.
The recent development in the field of semicon-ductors has been so remarkable that the construction of control systems with electronic circuits has advanced rapidly. Thus, the constructions of control systems and the shapes of control panels have undergone considerable changes and the constructions of their input means have also undergone changeover from the mechanical switches mainly to those types which discriminates the respective keys by means of a microcomputer through the medium of electric signals, thereby performing the contro}.
In addition, a wave of this digitization has resulted in the addition of new functions one after another and the trend has been toward increasing the number of operating keys for effecting such functions.
However, the increase in the number of such keys has resulted in an increase in the input and output terminals of the microcomputer and hence the number of ~293~5 peripheral circuits has been increased from the construction standpoint of the system.
In the following discussion of the prior art, reference will be made to the accompanying drawings in which:
Figs. lA and lB are diagrams showing conventional key input systems.
Fig. 2 is an external view of a high-frequency heating apparatus incorporating an embodiment of the invention.
Fig. 3 is a circuit diagram of the apparatus of Fig. 2.
Fig. 4 is a diagram showing a detailed construction of one key input portion in the embodiment of Fig. 2.
Fig. 5 is a sectional view for explaining the operation of one key input portion in the embodiment of Fig. 2.
Fig. 6 is a diagram showing the construction of the key input section in the embodiment of Fig. 2.
Fig. 7 is a diagram for explalning the control of the embodiment of Fig. 2.
Fig. 8 is a diagram showing the construction of a key input section in a modiflcation of the embodiment of Fig. 2.
Fig. 9 is a pattern diagram of the key input section in the embodiment of Fig. 2.
Fig. 10 is a pattern diagram of a key input section in another modification of the embodiment of Fig. 2.
"` lZ93~65 In view of these circumstances, as shown in Fig. lA of the accompanying drawingsr attempts heretofore made to decrease the number of input and output terminals increasing in proportion to an increase in the number of operating keys has been mainly of a key-scan matrix type in which a matrix circuit is formed by an output signal system and an input signal system so as to discriminates the kinds of the respective depressed keys with the reduced inputs and outputs.
This type of system includes a plurality of output ports and a plurality of ordinary input terminals so that scan pulses of a controlled timing are generated from the output ports and the corresponding pulse is applied to the input terminal connected to the depressed key, thereby discriminating the key.
However, this system is also not a method which drastically decreases the number of the required input and output terminals and therefore it is limited by the number of the input and output terminals of the microcomputer. Thus, if these input and output terminals are used only for operating key inputting purposes, there is a shortage of the input and output terminals for the other essential control purposes. Moreover, it leads to a pressure for the capacity of the ROM of the microcomputer used with this system for scan output control purposes, etc.
- 2a -,~
"` 1~93~65 1 Also, as another example of the conventional methods, there has been a system which utilizes analog inputs. AS shown in Fig. lB, this system is of an analog-to-digital conversion (AJD conversion) type in which voltages generated by the depression of the respec-tive keys differ from one another in accordance with their kinds and each key is discriminated by converting the corresponding analog voltage to digital form.
Since this system includes an A/D conversion input terminal and each key is discriminated in accordance with a variation in the voltage generated by its depression, when the key at the fifth row from above in Fig. lB is depressed, the following voltage is generated 5V x ( R5 + R6 + --- + R15 VA/D= - -(Rl + R2 + --------- + R
However, this system is also disadvantageous in that an increase in the number of keys requires a resolu-tion for the A/D conversion and therefore it is necessary to use high-precision resistors for generating a voltage corresponding to each key, thus making the system unfavorable from the standpoint of cost and working performance.
SUMMARY OF THE INVE N T I ON
In view of the background as mentioned above, it ~ 1;293(~65 is an ob~ect of the present invention to provide an effective key input device so designed that operating key inputs are taken in by a novel means combining the A/D conversion system and the matrix system.
It is another ob;ect of the invention to provide an inexpensive key input device capable of easily mee-ting the requirement for an increase in the operating keys which is expected in future.
The invention will now be more closely described by way of example and with reference to the drawings already introduced above.
3~65 Referring to Fig. 2~ there is illustrated a perspective view of the body of a high-frequency healing apparatus incorporating an embodiment of the invention. Numeral 1 designates the body of a high-frequency heating apparatus. A
heating chamber 2 is formed inside the body l. Disposed within the heating chamber 2 is a stirrer or turn table (not shown) for ensuring more uniform wave distribution so as to improve the finish of food. Numeral 3 designates a hinged door fitted in the opening of the heating chamber 2, and 4 a control panel arranged on the front part of the body 1 to allow the user to set a cooking sequence such as cooking power and time. The control panel 4 contains a control circuit unit s including a microcomputer and a keyboard 6 for feeding the intension of the user into the microcomputer. In response to the input signals or information applied from the keyboard 6, the microcomputer 5a shown in Fig. 3 performs and controls the cooking sequence in accordance with the preprogrammed contents.
Fig. 3 shows a circuit diagram for the apparatus of Fig. 2. The apparatus includes a magnetron 7 serving --" -lZ93Q6S
1 as a high-frequency oscillator, a transformer 8 for supplying power to the magnetron 7, and switches 9a and 9b for switching on and off the power supplied to the transformer 8 to switch on and off the high-frequency output of the magnetron 7.
The microcomputer 5a includes ordinary input terminals Kl to K4 and an A/D conversion input terminal A/Dl and the terminals are wired in correspondence to the respective keys of the keyboard 6. Also connected to the keyboard 6 is a + voltage (+ 5 V) which serves as a power supply for the microcomputer 5a and as an A/D conversion input power supply. The keyboard 6 includes a plurality of keys such as cooking power keys, cooking time keys and a start key and each of the keys has a separate switch function. These switch functions serve to open and close the circuits of the input terminals (Kl ~ K4, A/Dl) of the microcomputer 5a.
Referring to Fig. 4, there is illustrated the construction of the switch function of one key portion in the keyboard 6. Numeral 10 designates a panel showing the positions of the keys and providing an external appear-ance. The panel 10 is designed so that it can be recog-nized easily by the user. Numeral 11 designates a conductive sheet forming contacts for the switch func-tions, 12a spacer providing contact gaps, arranged toensure the insulation for those portions other than the contact portions of the keys and also formed with an opening at its portion corresponding to each contact 1~9306S
1 portion to cause the conductive sheet 11 to directly face the openings, and 13 a pattern sheet having a plurality of contact patterns formed thereon to touch the conductive sheet 11 through the spacer 12 in response to the 5 depression of the respective keys. In addition, a reinforcing sheet 14 is provided to reinforce the whole assembly.
Also, the conductive sheet 11 is connected to the metal portion of the high-frequency heating apparatus body with small screws or the like and the control circuit unit 5 is similarly connected electrically to the heating apparatus body, thereby connecting the 5-volt power supply of the microcomputer 5a to the conductive sheet 11 of the keyboard 6 through the metal portion of the heating apparatus body.
With the construction described above, the operation of the embodiment will now be described. When food is placed in the heating chamber 2 and any one of the keys on the keyboard 6 of the control panel 4 is depressed to set the desired cooking time or power, as shown in Fig.
5, the conductive sheet 11 is bent and the power of + 5 V
is applied to the plurality of patterns formed on the pattern sheet 13 through the opening in the spacer sheet 12 and the conductive sheet 11.
Next, the operation of the signal system will be described with reference to Fig. 6 showing a connection diagram for the patterns on the pattern sheet 13 of the keyboard 6 and the microcomputer 5a. In the case of Fig.
lZ93G65 1 6, the keys include 16 different ones so that if, for example, the POWER key is depressed, the voltage of 5 V is applied to the ordinary input terminal Kl of the micro-computer 5a by the pattern P2 of Fig. 6 and also the divided voltage by ladder resister Rl, R2, R3 and Rx is applied to the A/D conversion input terminal A/Dl through the pattern Pl. In Fig. 6, the resolution of this ladder circuit is selectively set to four levels and therefore the voltage applied to the microcomputer 5a through the input terminal A/Dl changes in response to the depression of the respective keys as follows.
(In case of POWER, S12~ S13, S14) A/Dl = 5 V (designated as a level 1) (In case of S21, S22, S23, S24) x A/Dl = 5 x . (designated as a level 2) Rx + Rl (In case of S31, S32, S33, 34 Rx A/Dl = 5 x - - (designated as a level 3) Rx + Rl + R2 (In case of S41, S42, S43, S44) Rx A/Dl = 5 x -- (designated as a level 4) Rx + Rl + R2 + R3 On the other hand, the keys are also connected in groups of four keys each to the ordinary input terminals Kl, K2, K3 and K4, respectively, and the matrix -"` lZ93~;P65 1 table of Fig. 7 is prepared in accordance with the various combinations of two input signals. In other words, the microcomputer Sa discriminates each key in accordance with the corresponding combination of two different input signals.
More specifically, in the previously mentioned cases the POWER key corresponds to the level 1 and the associated input is a Kl input. On the other hand, the key S33 corresponds to the level 3 and the associated input is a K3 input. The microcomputer 5a determines first the kind of the ordinary input (Kl ~ K4) and it then determines the level of the A/D conversion input, thereby determining the kind of the depressed key. Also, the POWER, S12, S13 and S14 keys, connected to the voltage of the level 1, are each placed in the preferential position in the corresponding row. Eor instance, when the POWER
and S21 keys are depressed simultaneously, the voltage of the level 1 is generated at the A/Dl terminal and smaller the level number higher the priority level is.
Therefore, the preferential keys can be attained by simply determining the corresponding matrix positions and there is no need to increase the ROM capacity and the RAM
capacity for any program.
Thus, in accordance with the present embodiment, the key scanning input terminals of the microcomputer 5a can be reduced as compared with the conventional key matrix system and also any increased number of the keys on the keyboard can be easily met with by increasing the _ g _ lZ93~5 1 A/D resolution levels for AJD conversion inputs. In addition, there is no need to use the output terminals for key scan outputs of the microcomputer 5a and therefore it is possible to expand the utilization of sensors, switches, etc., and the number of control functions.
Also, the output terminals of the microcomputer 5a are ensured amply and therefore the degree of freedom of designing is increased from the program designing stand-point of the microcomputer Sa with the resulting effect of causing some superfluous portion in the ROM capacity of the microcomputer 5a and allowing additional utilization thereof.
Also, in accordance with the invention, the application of voltage to the patterns is effected only when any key is depressed and therefore the invention is advantageous with respect to the problem of interpattern migration which is encountered in the construction of the actual membrane. Moreover, as shown by the embodiment, only the reduced resolution levels are required for the A/D conversion resolution and this is a great advantage from the accuracy standpoint of forming a resistor pattern on the actual membrane.
Referring now to Fig. ~, a second embodiment of the invention will be described. This embodiment shows a case in which the number of keys is increased by two times by simply adding a single A/D conversion input terminal.
In other words, the number of keys can be doubled by combining the similar matrix with the 1~3C~
1 additional A/D conversion input terminal and using the same ordinary input terminals Kl and K2 without any addition.
The corresponding key discrimination table is as shown in Fig. 8. Also, the same dividing resistors Rl, R2, R3 and Rx for A/D conversion may be used for the terminals A/Dl and A/D2 or the dividing resistors for the two may be different from each other, and the provi-sion of these dividing resistors can be realized easily.
Referring now to Fig. 9, the construction of the patterns formed on the pattern sheet 13 of the keyboard 6 will be described. With the key contact portions on the pattern sheet 13, the pattern Pl and the patterns P2, P3, P4 and P5 are respectively arranged in comb form. The group of ladder resistors Rl, R2 and R3 prepared by, for example, forming carbon to the desired thickness, width, etc., to provide a high resistance value can be formed on a part of the pattern Pl by the same operation as the other patterns. Since the present invention requires no increase in the resolution of the ladder resistors, the precision attained by this carbon resistor method can be considered sufficient for the ladder resistors. In addition, these resistors can be easily attained by the operation of printing and baking carbon on the pattern sheet 13. Also, as mensioned previously, the resistance value can be increased by decreasing the width of the carbon pattern and conversely the resistance value can be reduced by increasing the width of the carbon pattern.
1~93C65 1 Also, with a view to reducing the resistance value, the patterns other than the resistors Rl, R2 and R3 may be formed with carbon mixed with such material as silver, thereby producing patterns having a very small resistance value. Also, a resist RG is placed at each of the points where the patterns overlap one another to prevent the patterns from contacting with one another. In other words, by using these techniques, the provision of the ladder resistor group of R1, R2 and R3 of a high resist-ance value and the patterns Pl, P2, P3, P4 and P5 of a lowresistance value and the provision of the resist portions RG at the patttern intersections can be easily effected.
Thus, there is an advantage from the cost point of view and also the number of the wires used for connect-ing the keyboard 6 and the microcomputer 5a is reduced tofive (5) as compared with the eight (8) wires in the conventional key matrix system.
Moreover, the construction of this invention has the effect of greatly improving the quality in that excepting when any key is depressed so that the conductive sheet 11 supplied with 5 V is brought into contact with the pattern sheet 13 through the spacer sheet 12, no voltage is applied to the patterns on the pattern sheet 13 and the A/D conversion pattern Pl and the ordinary input patterns P2, P3, P4 and P5 are all at the same potential, thereby preventing the occurrence of migration caused in the silver material which has been used frequently for such patterns.
~93C~65 1 Re~erring now to Fig. 10, there is illustrated a second embodiment of the pattern sheet 13 in which a pattern PV connected to the 5-volt power supply is formed as a third contact pattern on the pattern sheet 13, and the conductive sheet 11 simply forms a conductive film which is supplied with no voltage. With this construc-tion, when any key is depressed, the patterns Pl and PV and any one of the patterns P2 to P5 are connected through the conductive sheet 11 and the depressed key is discriminated by the previously mentioned operation.
From the foregoing description it will be seen that the key input apparatus with digital control means according to the invention has the following effects.
(1) The number of the microcomputer input terminals can be reduced as compared with the conventional key matrix system and also any increase in the number of the keyboard keys can be easily dealt with by increasing the resolution levels for the A/D conversion input terminal.
The recent development in the field of semicon-ductors has been so remarkable that the construction of control systems with electronic circuits has advanced rapidly. Thus, the constructions of control systems and the shapes of control panels have undergone considerable changes and the constructions of their input means have also undergone changeover from the mechanical switches mainly to those types which discriminates the respective keys by means of a microcomputer through the medium of electric signals, thereby performing the contro}.
In addition, a wave of this digitization has resulted in the addition of new functions one after another and the trend has been toward increasing the number of operating keys for effecting such functions.
However, the increase in the number of such keys has resulted in an increase in the input and output terminals of the microcomputer and hence the number of ~293~5 peripheral circuits has been increased from the construction standpoint of the system.
In the following discussion of the prior art, reference will be made to the accompanying drawings in which:
Figs. lA and lB are diagrams showing conventional key input systems.
Fig. 2 is an external view of a high-frequency heating apparatus incorporating an embodiment of the invention.
Fig. 3 is a circuit diagram of the apparatus of Fig. 2.
Fig. 4 is a diagram showing a detailed construction of one key input portion in the embodiment of Fig. 2.
Fig. 5 is a sectional view for explaining the operation of one key input portion in the embodiment of Fig. 2.
Fig. 6 is a diagram showing the construction of the key input section in the embodiment of Fig. 2.
Fig. 7 is a diagram for explalning the control of the embodiment of Fig. 2.
Fig. 8 is a diagram showing the construction of a key input section in a modiflcation of the embodiment of Fig. 2.
Fig. 9 is a pattern diagram of the key input section in the embodiment of Fig. 2.
Fig. 10 is a pattern diagram of a key input section in another modification of the embodiment of Fig. 2.
"` lZ93~65 In view of these circumstances, as shown in Fig. lA of the accompanying drawingsr attempts heretofore made to decrease the number of input and output terminals increasing in proportion to an increase in the number of operating keys has been mainly of a key-scan matrix type in which a matrix circuit is formed by an output signal system and an input signal system so as to discriminates the kinds of the respective depressed keys with the reduced inputs and outputs.
This type of system includes a plurality of output ports and a plurality of ordinary input terminals so that scan pulses of a controlled timing are generated from the output ports and the corresponding pulse is applied to the input terminal connected to the depressed key, thereby discriminating the key.
However, this system is also not a method which drastically decreases the number of the required input and output terminals and therefore it is limited by the number of the input and output terminals of the microcomputer. Thus, if these input and output terminals are used only for operating key inputting purposes, there is a shortage of the input and output terminals for the other essential control purposes. Moreover, it leads to a pressure for the capacity of the ROM of the microcomputer used with this system for scan output control purposes, etc.
- 2a -,~
"` 1~93~65 1 Also, as another example of the conventional methods, there has been a system which utilizes analog inputs. AS shown in Fig. lB, this system is of an analog-to-digital conversion (AJD conversion) type in which voltages generated by the depression of the respec-tive keys differ from one another in accordance with their kinds and each key is discriminated by converting the corresponding analog voltage to digital form.
Since this system includes an A/D conversion input terminal and each key is discriminated in accordance with a variation in the voltage generated by its depression, when the key at the fifth row from above in Fig. lB is depressed, the following voltage is generated 5V x ( R5 + R6 + --- + R15 VA/D= - -(Rl + R2 + --------- + R
However, this system is also disadvantageous in that an increase in the number of keys requires a resolu-tion for the A/D conversion and therefore it is necessary to use high-precision resistors for generating a voltage corresponding to each key, thus making the system unfavorable from the standpoint of cost and working performance.
SUMMARY OF THE INVE N T I ON
In view of the background as mentioned above, it ~ 1;293(~65 is an ob~ect of the present invention to provide an effective key input device so designed that operating key inputs are taken in by a novel means combining the A/D conversion system and the matrix system.
It is another ob;ect of the invention to provide an inexpensive key input device capable of easily mee-ting the requirement for an increase in the operating keys which is expected in future.
The invention will now be more closely described by way of example and with reference to the drawings already introduced above.
3~65 Referring to Fig. 2~ there is illustrated a perspective view of the body of a high-frequency healing apparatus incorporating an embodiment of the invention. Numeral 1 designates the body of a high-frequency heating apparatus. A
heating chamber 2 is formed inside the body l. Disposed within the heating chamber 2 is a stirrer or turn table (not shown) for ensuring more uniform wave distribution so as to improve the finish of food. Numeral 3 designates a hinged door fitted in the opening of the heating chamber 2, and 4 a control panel arranged on the front part of the body 1 to allow the user to set a cooking sequence such as cooking power and time. The control panel 4 contains a control circuit unit s including a microcomputer and a keyboard 6 for feeding the intension of the user into the microcomputer. In response to the input signals or information applied from the keyboard 6, the microcomputer 5a shown in Fig. 3 performs and controls the cooking sequence in accordance with the preprogrammed contents.
Fig. 3 shows a circuit diagram for the apparatus of Fig. 2. The apparatus includes a magnetron 7 serving --" -lZ93Q6S
1 as a high-frequency oscillator, a transformer 8 for supplying power to the magnetron 7, and switches 9a and 9b for switching on and off the power supplied to the transformer 8 to switch on and off the high-frequency output of the magnetron 7.
The microcomputer 5a includes ordinary input terminals Kl to K4 and an A/D conversion input terminal A/Dl and the terminals are wired in correspondence to the respective keys of the keyboard 6. Also connected to the keyboard 6 is a + voltage (+ 5 V) which serves as a power supply for the microcomputer 5a and as an A/D conversion input power supply. The keyboard 6 includes a plurality of keys such as cooking power keys, cooking time keys and a start key and each of the keys has a separate switch function. These switch functions serve to open and close the circuits of the input terminals (Kl ~ K4, A/Dl) of the microcomputer 5a.
Referring to Fig. 4, there is illustrated the construction of the switch function of one key portion in the keyboard 6. Numeral 10 designates a panel showing the positions of the keys and providing an external appear-ance. The panel 10 is designed so that it can be recog-nized easily by the user. Numeral 11 designates a conductive sheet forming contacts for the switch func-tions, 12a spacer providing contact gaps, arranged toensure the insulation for those portions other than the contact portions of the keys and also formed with an opening at its portion corresponding to each contact 1~9306S
1 portion to cause the conductive sheet 11 to directly face the openings, and 13 a pattern sheet having a plurality of contact patterns formed thereon to touch the conductive sheet 11 through the spacer 12 in response to the 5 depression of the respective keys. In addition, a reinforcing sheet 14 is provided to reinforce the whole assembly.
Also, the conductive sheet 11 is connected to the metal portion of the high-frequency heating apparatus body with small screws or the like and the control circuit unit 5 is similarly connected electrically to the heating apparatus body, thereby connecting the 5-volt power supply of the microcomputer 5a to the conductive sheet 11 of the keyboard 6 through the metal portion of the heating apparatus body.
With the construction described above, the operation of the embodiment will now be described. When food is placed in the heating chamber 2 and any one of the keys on the keyboard 6 of the control panel 4 is depressed to set the desired cooking time or power, as shown in Fig.
5, the conductive sheet 11 is bent and the power of + 5 V
is applied to the plurality of patterns formed on the pattern sheet 13 through the opening in the spacer sheet 12 and the conductive sheet 11.
Next, the operation of the signal system will be described with reference to Fig. 6 showing a connection diagram for the patterns on the pattern sheet 13 of the keyboard 6 and the microcomputer 5a. In the case of Fig.
lZ93G65 1 6, the keys include 16 different ones so that if, for example, the POWER key is depressed, the voltage of 5 V is applied to the ordinary input terminal Kl of the micro-computer 5a by the pattern P2 of Fig. 6 and also the divided voltage by ladder resister Rl, R2, R3 and Rx is applied to the A/D conversion input terminal A/Dl through the pattern Pl. In Fig. 6, the resolution of this ladder circuit is selectively set to four levels and therefore the voltage applied to the microcomputer 5a through the input terminal A/Dl changes in response to the depression of the respective keys as follows.
(In case of POWER, S12~ S13, S14) A/Dl = 5 V (designated as a level 1) (In case of S21, S22, S23, S24) x A/Dl = 5 x . (designated as a level 2) Rx + Rl (In case of S31, S32, S33, 34 Rx A/Dl = 5 x - - (designated as a level 3) Rx + Rl + R2 (In case of S41, S42, S43, S44) Rx A/Dl = 5 x -- (designated as a level 4) Rx + Rl + R2 + R3 On the other hand, the keys are also connected in groups of four keys each to the ordinary input terminals Kl, K2, K3 and K4, respectively, and the matrix -"` lZ93~;P65 1 table of Fig. 7 is prepared in accordance with the various combinations of two input signals. In other words, the microcomputer Sa discriminates each key in accordance with the corresponding combination of two different input signals.
More specifically, in the previously mentioned cases the POWER key corresponds to the level 1 and the associated input is a Kl input. On the other hand, the key S33 corresponds to the level 3 and the associated input is a K3 input. The microcomputer 5a determines first the kind of the ordinary input (Kl ~ K4) and it then determines the level of the A/D conversion input, thereby determining the kind of the depressed key. Also, the POWER, S12, S13 and S14 keys, connected to the voltage of the level 1, are each placed in the preferential position in the corresponding row. Eor instance, when the POWER
and S21 keys are depressed simultaneously, the voltage of the level 1 is generated at the A/Dl terminal and smaller the level number higher the priority level is.
Therefore, the preferential keys can be attained by simply determining the corresponding matrix positions and there is no need to increase the ROM capacity and the RAM
capacity for any program.
Thus, in accordance with the present embodiment, the key scanning input terminals of the microcomputer 5a can be reduced as compared with the conventional key matrix system and also any increased number of the keys on the keyboard can be easily met with by increasing the _ g _ lZ93~5 1 A/D resolution levels for AJD conversion inputs. In addition, there is no need to use the output terminals for key scan outputs of the microcomputer 5a and therefore it is possible to expand the utilization of sensors, switches, etc., and the number of control functions.
Also, the output terminals of the microcomputer 5a are ensured amply and therefore the degree of freedom of designing is increased from the program designing stand-point of the microcomputer Sa with the resulting effect of causing some superfluous portion in the ROM capacity of the microcomputer 5a and allowing additional utilization thereof.
Also, in accordance with the invention, the application of voltage to the patterns is effected only when any key is depressed and therefore the invention is advantageous with respect to the problem of interpattern migration which is encountered in the construction of the actual membrane. Moreover, as shown by the embodiment, only the reduced resolution levels are required for the A/D conversion resolution and this is a great advantage from the accuracy standpoint of forming a resistor pattern on the actual membrane.
Referring now to Fig. ~, a second embodiment of the invention will be described. This embodiment shows a case in which the number of keys is increased by two times by simply adding a single A/D conversion input terminal.
In other words, the number of keys can be doubled by combining the similar matrix with the 1~3C~
1 additional A/D conversion input terminal and using the same ordinary input terminals Kl and K2 without any addition.
The corresponding key discrimination table is as shown in Fig. 8. Also, the same dividing resistors Rl, R2, R3 and Rx for A/D conversion may be used for the terminals A/Dl and A/D2 or the dividing resistors for the two may be different from each other, and the provi-sion of these dividing resistors can be realized easily.
Referring now to Fig. 9, the construction of the patterns formed on the pattern sheet 13 of the keyboard 6 will be described. With the key contact portions on the pattern sheet 13, the pattern Pl and the patterns P2, P3, P4 and P5 are respectively arranged in comb form. The group of ladder resistors Rl, R2 and R3 prepared by, for example, forming carbon to the desired thickness, width, etc., to provide a high resistance value can be formed on a part of the pattern Pl by the same operation as the other patterns. Since the present invention requires no increase in the resolution of the ladder resistors, the precision attained by this carbon resistor method can be considered sufficient for the ladder resistors. In addition, these resistors can be easily attained by the operation of printing and baking carbon on the pattern sheet 13. Also, as mensioned previously, the resistance value can be increased by decreasing the width of the carbon pattern and conversely the resistance value can be reduced by increasing the width of the carbon pattern.
1~93C65 1 Also, with a view to reducing the resistance value, the patterns other than the resistors Rl, R2 and R3 may be formed with carbon mixed with such material as silver, thereby producing patterns having a very small resistance value. Also, a resist RG is placed at each of the points where the patterns overlap one another to prevent the patterns from contacting with one another. In other words, by using these techniques, the provision of the ladder resistor group of R1, R2 and R3 of a high resist-ance value and the patterns Pl, P2, P3, P4 and P5 of a lowresistance value and the provision of the resist portions RG at the patttern intersections can be easily effected.
Thus, there is an advantage from the cost point of view and also the number of the wires used for connect-ing the keyboard 6 and the microcomputer 5a is reduced tofive (5) as compared with the eight (8) wires in the conventional key matrix system.
Moreover, the construction of this invention has the effect of greatly improving the quality in that excepting when any key is depressed so that the conductive sheet 11 supplied with 5 V is brought into contact with the pattern sheet 13 through the spacer sheet 12, no voltage is applied to the patterns on the pattern sheet 13 and the A/D conversion pattern Pl and the ordinary input patterns P2, P3, P4 and P5 are all at the same potential, thereby preventing the occurrence of migration caused in the silver material which has been used frequently for such patterns.
~93C~65 1 Re~erring now to Fig. 10, there is illustrated a second embodiment of the pattern sheet 13 in which a pattern PV connected to the 5-volt power supply is formed as a third contact pattern on the pattern sheet 13, and the conductive sheet 11 simply forms a conductive film which is supplied with no voltage. With this construc-tion, when any key is depressed, the patterns Pl and PV and any one of the patterns P2 to P5 are connected through the conductive sheet 11 and the depressed key is discriminated by the previously mentioned operation.
From the foregoing description it will be seen that the key input apparatus with digital control means according to the invention has the following effects.
(1) The number of the microcomputer input terminals can be reduced as compared with the conventional key matrix system and also any increase in the number of the keyboard keys can be easily dealt with by increasing the resolution levels for the A/D conversion input terminal.
(2) Since the key matrix is formed by the ordinary input terminals and the A/D conversion input terminal, any increase in the number of the keys can be easily realized by simply increasing either of the two terminals which affords it.
(3) Since the key matrix is formed by the ordinary input terminals and the A/D conversion input terminal, the A/D conversion accuracy need not be enhanced as compared with the conventional key input formed by the A/D
conversion input terminal only and therefore the patterned 1~93~iS
1 resistors can be easily formed in the membrane, thereby easily realizing the key matrix without increasing the cost.
conversion input terminal only and therefore the patterned 1~93~iS
1 resistors can be easily formed in the membrane, thereby easily realizing the key matrix without increasing the cost.
(4) Since the microcomputer output terminals are utilized in no way in contrast to the conventional key matrix system, it is possible to utilize these output terminals to effect the expansion of control functions such as the utilization and increase of the external devices such as sensors and switches and hence it is possible to meet any requirements more sophisticatedly.
(5) Due to the reduced number of the lead-out patterns as compared with the conventional key matrix system, it is possible to reduce the number of the pins of the connector for connecting the membrane and the P board.
(6) Since the construction of this invention is such that the voltage is applied only when any key is depress-ed, and that when no key is depressed, there is no potential difference and no migration is caused among the patterns, thereby simplifying the pattern designing of the membrane.
(7) Since no key scanning output terminals for the microcomputer are used at all as compared with the conventional key matrix system, the program for key scanning purposes can be eliminated and the margin of the ROM capacity of the microcomputer can be increased.
(8) The device can be constructed by simply arrang-ing the high-priority keys and this can be realized without burdening the ROM with any program.
lZ93~65 l (9) Since the conductive sheet is extended below the whole lower surface of the character sheet and it is then connected directly to the apparatus for grounding, the device is not easily affected by any external noise such as static electricity.
lZ93~65 l (9) Since the conductive sheet is extended below the whole lower surface of the character sheet and it is then connected directly to the apparatus for grounding, the device is not easily affected by any external noise such as static electricity.
Claims (7)
1. A key input device comprising control circuit means including a microcomputer having an analog-digital conversion input terminal and a plurality of ordinary input terminals and having programming functions; and a keyboard for applying input signals to said microcomputer, said keyboard including a plurality of separate-key-contact circuits, a first portion of said circuits connected through one of a plurality of predetermined resistances to said analog-digital conversion input terminal and a second portion connected to said ordinary input terminals, and a plurality of keys, each of said keys corresponding to a selected one of said keycontacts for applying a voltage to said analog-digital conversion input terminal through one of said resistances and to one of said ordinary input terminals so that, said microcomputer discriminates said depressed key through analysis of said input terminals and said analog-digital terminal.
2. A key input device comprising control circuit means including a microcomputer having an analog-digital conversion input terminal and a plurality of ordinary input terminals;
and a membrane-type keyboard for feeding input signals to said microcomputer, said keyboard including a character sheet indicating positions of a plurality of keys, a conductive sheet having a conductive lower surface and arranged below said character sheet, a spacer sheet arranged below said conductive sheet and formed with a plurality of openings each opening corresponding to one of said keys, and a contact sheet arranged below said spacer sheet and formed with first, and second groups of contacts, with one contact of each of said groups provided for each of said keys, each contact of said first group being connected to a corresponding one of said ordinary input terminals of said microcomputer through a low-resistance pattern, each said contact of said second group being connected to said analog-digital conversion input terminal of said microcomputer through one of a plurality of predetermined resistance means, and said conductive sheet being connected to a power source of said microcomputer whereby when said character sheet is depressed at any one of said key positions, said conductive sheet simultaneously contacts one contact of each of said first and second contact groups through one of said openings formed in said spacer sheet, thereby connecting said power source through said conductive sheet to said contacts of said first and second groups.
and a membrane-type keyboard for feeding input signals to said microcomputer, said keyboard including a character sheet indicating positions of a plurality of keys, a conductive sheet having a conductive lower surface and arranged below said character sheet, a spacer sheet arranged below said conductive sheet and formed with a plurality of openings each opening corresponding to one of said keys, and a contact sheet arranged below said spacer sheet and formed with first, and second groups of contacts, with one contact of each of said groups provided for each of said keys, each contact of said first group being connected to a corresponding one of said ordinary input terminals of said microcomputer through a low-resistance pattern, each said contact of said second group being connected to said analog-digital conversion input terminal of said microcomputer through one of a plurality of predetermined resistance means, and said conductive sheet being connected to a power source of said microcomputer whereby when said character sheet is depressed at any one of said key positions, said conductive sheet simultaneously contacts one contact of each of said first and second contact groups through one of said openings formed in said spacer sheet, thereby connecting said power source through said conductive sheet to said contacts of said first and second groups.
3. A device according to claim 2, wherein said plurality of predetermined resistance means are resistance patterns printed in an open space among said contact groups on said contact sheet.
4. A device according to claim 2, wherein a voltage output of said power source is applied to said first and second contact groups only upon depression of said contact sheet, thereby maintaining said groups at an equal potential in the absence of depression.
5. A device according to claim 2, wherein said conductive sheet is connected to the power source of said microcomputer and to a ground of an apparatus employing said keyboard.
6. A key input device comprising control circuit means including a microcomputer having an analog-digital conversion input terminal and a plurality of ordinary input terminals;
and a membrane-type keyboard for feeding input signals to said microcomputer, said keyboard including a character sheet having a print, indicating positions of a plurality of keys and providing an external appearance, a conductive sheet having a conductive lower surface and arranged below said character sheet, a spacer sheet formed with a plurality of openings each corresponding to one of said keys and arranged below said conductive sheet, and a contact sheet arranged below said spacer sheet and formed with first, second and third groups of contacts, with one contact of each of said groups provided for each of said keys, each contact of said first group being connected to one of said ordinary input terminals of said microcomputer through a low-resistance pattern, each contact of said second group being connected to said analogdigital conversion input terminal of said microcomputer through one of a plurality of predetermined resistance means printed on said contact sheet, and said contacts of said third contact group being connected to a power source of said microcomputer whereby when said character sheet is depressed at any one of said key positions, said conductive sheet simultaneously contacts one contact of each of said first, second and third contact groups through one of said openings formed in said spacer sheet.
and a membrane-type keyboard for feeding input signals to said microcomputer, said keyboard including a character sheet having a print, indicating positions of a plurality of keys and providing an external appearance, a conductive sheet having a conductive lower surface and arranged below said character sheet, a spacer sheet formed with a plurality of openings each corresponding to one of said keys and arranged below said conductive sheet, and a contact sheet arranged below said spacer sheet and formed with first, second and third groups of contacts, with one contact of each of said groups provided for each of said keys, each contact of said first group being connected to one of said ordinary input terminals of said microcomputer through a low-resistance pattern, each contact of said second group being connected to said analogdigital conversion input terminal of said microcomputer through one of a plurality of predetermined resistance means printed on said contact sheet, and said contacts of said third contact group being connected to a power source of said microcomputer whereby when said character sheet is depressed at any one of said key positions, said conductive sheet simultaneously contacts one contact of each of said first, second and third contact groups through one of said openings formed in said spacer sheet.
7. A key input device comprising control circuit means including a microcomputer having an analog-digital conversion input terminal and a plurality of ordinary input terminals and having programming functions and a keyboard having a plurality of keys, circuit means connected to said keyboard for detecting actuation of at least one of said keys and for applying a first input signal of a predetermined voltage level corresponding to said actuated key to said analogdigital input of said microcomputer, and a second input signal to a selected one of said ordinary inputs corresponding to said actuated key, said microcomputer further comprising means for identifying said actuated key based on said voltage level and said corresponding ordinary input.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000549564A CA1293065C (en) | 1987-10-19 | 1987-10-19 | Key input device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000549564A CA1293065C (en) | 1987-10-19 | 1987-10-19 | Key input device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1293065C true CA1293065C (en) | 1991-12-10 |
Family
ID=4136670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000549564A Expired - Lifetime CA1293065C (en) | 1987-10-19 | 1987-10-19 | Key input device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1293065C (en) |
-
1987
- 1987-10-19 CA CA000549564A patent/CA1293065C/en not_active Expired - Lifetime
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| MKEX | Expiry |