CN110908520B - Electrostatic capacitance type keyboard - Google Patents

Abstract

The invention provides an electrostatic capacity type keyboard device, which can accurately detect the pressing speed of a pressed key. The solution of the present invention comprises: a key Ky disposed at the crossing points of the plurality of driving lines M and the plurality of sensing lines N; a capacitance element provided in each of the keys, the capacitance element changing capacitance between the drive line M and the sense line N in accordance with the amount of depression of the key; and a depression amount detection unit that scans each key and detects the depression amount of the key based on the change in the electrostatic capacitance of the electrostatic capacitance element. When the amount of depression detected by the depression amount detection unit reaches a preset reference value (Th 0), the control is performed so as to shorten the scanning period of the key.

Description

Electrostatic capacitance type keyboard

Technical Field

The present invention relates to a keyboard having a plurality of keys, and more particularly, to an electrostatic capacity type keyboard apparatus which detects a change in electrostatic capacity and a key-down time when a key is pressed to detect a key-down speed.

Background

There has been proposed a capacitive keyboard apparatus for detecting a key operation based on a change in electrostatic capacitance caused by a key being pressed, and the keyboard has been put to practical use. On the other hand, a keyboard device having a plurality of keys, such as an ASCII (american standard code for information interchange) keyboard, has been proposed, which is used as a MIDI (musical instrument digital interface) keyboard or as an operator of a game machine. Therefore, it is desirable to detect the pressing speed at the time of key operation. In order to detect the pressing speed, the pressing amount of each key is detected by at least 2 points, and the pressing speed is detected based on the time difference between 2 points when the key is pressed. Specifically, the 1 st pressing amount and the 2 nd pressing amount deeper than the 1 st pressing amount are set for each key, and a required time from the 1 st pressing amount to the 2 nd pressing amount is calculated to detect the pressing speed at the time of pressing the key based on the required time.

In the capacitive keyboard device, each key is scanned in sequence in order to detect the amount of pressing of the key. For example, when there are n keys Ky1, ky2, ky3, …, kyn, each key is scanned sequentially in such a manner as "Ky 1→ky2→ … →kyn→ky1→ …", and for example, when the amount of depression at the key Ky1 is detected to reach a1 st threshold (threshold value) Th1, and when the amount of depression is detected to reach a2 nd threshold Th2 at the time of scanning of the next subsequent key Ky1, the depression speed is calculated based on the time required from the time when the 1 st threshold Th1 is detected to the time when the 2 nd threshold Th2 is detected.

However, since the above method is to scan a plurality of keys sequentially, the scanning period is longer, and a longer time is required from the time of the scanning to the time of the next scanning. Therefore, the correct pressing speed may not be detected. This is explained in detail below.

In fig. 11, the horizontal axis represents time and the vertical axis represents voltage. In the capacitive keyboard device, since the capacitance is changed according to the depression of a key or even a voltage is changed at the key, the depression amount of the key is detected based on the measured voltage. Therefore, the vertical axis may also be denoted as "push-down amount". A straight line q1 shown in fig. 11 indicates a voltage generated when an arbitrary key (this key is referred to as "key Ky 1") is pressed, and a timing of scanning the key Ky 1.

As described above, since n keys are scanned sequentially, the scanning timing of the key Ky1 is denoted as times t1, t2, and t3, respectively. That is, the time t1 to t2 and the time t2 to t3 are the scanning periods (the time required from the previous scanning to the present scanning) of the keyboard. Since the amount of depression of the key Ky1 increases with the passage of time, the straight line q1 increases as a linear function. The 1 st threshold and the 2 nd threshold of the depression amount of the key Ky1 are expressed as Th1 and Th2, respectively.

Now, as shown in fig. 11, if it is detected at time T1 that the amount of depression of key Ky1 reaches 1 st threshold Th1 and then at time T3 that it reaches 2 nd threshold Th2, it is possible to detect that time Δt11 from reaching 1 st threshold Th1 to reaching 2 nd threshold Th2 is required from T1 to T3. Therefore, the pressing speed at which the key Ky1 is pressed can be obtained based on the time Δt11.

On the other hand, the line q2 shown in fig. 12 does not reach the 1 st threshold Th1 in the amount of depression at time t 1. Thereafter, the reaching of the 1 st threshold Th1 is detected at time t2, and further the reaching of the 2 nd threshold Th2 is detected at time t3. In this case, a time Δt12 from T2 to T3 is required from the detection of the 1 st threshold Th1 to the detection of the 2 nd threshold Th2. In this case, although the pressing amount actually reaches the 1 st threshold Th1 immediately after the time t1, such a situation is not detected until the time t2, and therefore a large error occurs in the time from the time when the pressing amount reaches the 1 st threshold Th1 to the time when the pressing amount reaches the 2 nd threshold Th2. Therefore, there is a problem that the calculation accuracy of the pressing speed is lowered.

Thus, a keyboard has been known, which aims to improve the accuracy of the operation at the pressing speed, and is disclosed in patent document 1, for example. Patent document 1 discloses an electronic musical instrument including a 2-point switch type key (keyboard) having a1 st switch and a2 nd switch, and patent document 1 discloses a method in which the 1 st switch is periodically scanned and only a key group (keyboard group) including a key in which the 1 st switch is turned ON (ON) is scanned for the 2 nd switch. According to the key group which is not turned on by the 1 st switch, the scanning period of the 2 nd switch can be shortened.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 5-165471.

Disclosure of Invention

Problems to be solved by the invention

However, in the prior art disclosed in patent document 1, since the method of dividing each key into a plurality of key groups is adopted, the key group including the key on which the 1 st switch is turned on is scanned by the 2 nd switch even if the 1 st switch is not turned on, and therefore it is desired to further shorten the scanning period to accurately detect the pressing speed.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a capacitive keyboard device capable of accurately detecting a pressing speed of a pressed key.

Technical proposal for solving the problems

In order to achieve the above object, the present invention comprises: a plurality of drive lines (M) and a plurality of sense lines (N) intersecting the drive lines; a key (Ky) provided at an intersection of each of the drive lines and each of the sense lines; a capacitance element provided in each of the keys, the capacitance element changing capacitance between the drive line and the sense line in accordance with a pressed amount of the key; a pressed amount detection unit for scanning each key and detecting the pressed amount of the key based on the change of the electrostatic capacitance element; and an input control unit for controlling the key so as to shorten the scanning period when the amount of depression detected by the depression amount detection unit reaches a preset reference value (Th 0).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the capacitive keyboard device of the present invention, the pressing speed of the pressed key can be accurately detected.

Drawings

Fig. 1 is an explanatory diagram schematically showing the configuration of a capacitive keyboard device and its peripheral devices according to an embodiment of the present invention.

Fig. 2 is an exploded perspective view showing the detailed configuration of a key used in the capacitive keyboard device according to the embodiment of the present invention.

Fig. 3 is an explanatory diagram schematically showing the relationship between 2 electrodes and coil springs in a key used in the capacitive keyboard device according to the embodiment of the present invention.

Fig. 4 is a block diagram showing detailed configurations of a driving circuit, a sensing circuit, and a control circuit in the capacitive keyboard device according to the embodiment of the present invention.

Fig. 5 is a graph showing a change in the amount of key depression with time, where a straight line a1 shows when the key depression speed is high, and a straight line a2 shows when the key depression speed is low.

Fig. 6 is a flowchart showing a processing method of the capacitive keyboard apparatus according to the embodiment of the present invention.

Fig. 7 is a flowchart showing a processing method of the capacitive keyboard apparatus according to the embodiment of the present invention.

FIG. 8 is a graph showing the change in the amount of depression with time; a graph of the variation of the parameters F0, F1 with time; and a graph of the change of the timer counter Tc with respect to the passage of time.

Fig. 9 is a graph showing changes in scanning timing and the amount of depression when the scanning period of a pressed key is shortened in embodiment 1 of the present invention.

Fig. 10 is a graph showing changes in scanning timing and the amount of depression when the scanning period of a pressed key is shortened in embodiment 2 of the present invention.

Fig. 11 is a graph showing a sequence of measuring the pressed amount of an arbitrary key in the conventional capacitive keyboard apparatus.

Fig. 12 is a graph showing a sequence of measuring the amount of depression of an arbitrary key in the conventional capacitive keyboard apparatus, in which a sequence of the amount of depression reaching Th1 is slightly later than time t 1.

[ means for symbology ]

10. Electrostatic capacitance type keyboard device

11. Driving circuit

12. Sensing circuit

15. Control circuit

16. Host computer

21. Substrate board

22. Outer casing

23. Coil spring

24. Rubber cap

25. Plunger piston

26. Key cap

31. Multiplexer

32. Peak hold circuit

33. Analog/digital conversion circuit

41. Main control part

42. Memory control unit

43. Output interface

44. Memory part

Q1, Q2 electrode

R1, R2 resistor

SW switch

Detailed Description

Hereinafter, embodiments of the present invention will be described based on the drawings. Fig. 1 is an explanatory diagram schematically showing the configuration of a capacitive keyboard device according to an embodiment of the present invention. As shown in fig. 1, the capacitive keyboard device 10 of the present embodiment has a plurality (i in the figure) of drive lines M (M-1, M-2, M-3, …, M-i) and a plurality (j in the figure) of sense lines N (N-1, N-2, N-3, …, N-j) arranged so as to intersect each other. In the following, a symbol "M" is given to denote a particular drive line, and a letter "M-1" is given to denote a letter "tail" when a particular drive line is specified. The same applies to the sense lines, and the symbol "N" is given when the individual sense lines are not specified, and the word-tail is given when the individual sense lines are specified as "N-1".

As shown in fig. 1, each driving line M is connected to a driving circuit 11, and each sensing line N is connected to a sensing circuit 12. The driving circuit 11 and the sensing circuit 12 are connected to a control circuit 15, and driving of the driving circuit 11 and the sensing circuit 12 is controlled according to control of the control circuit 15.

The control circuit 15, the driving circuit 11, and the sensing circuit 12 can be configured as an integrated computer including a Central Processing Unit (CPU), and memory means such as RAM (random access memory), ROM (read only memory), and a hard disk.

Each drive line M and each sense line N are connected at each intersection by a key Ky, and in normal operation (when the key Ky is not pressed), the lines M, N of both sides are not electrically connected at the intersection. As will be described later, since the keys Ky include variable capacitance capacitors (electrostatic capacitance elements), each key Ky is shown by a symbol of a variable capacitance capacitor in the drawing.

As shown in fig. 2, the key Ky includes a substrate 21 and a housing 22, the substrate 21 includes a pair of electrodes Q1 and Q2, and a conical coil spring 23, a flexible rubber cap 24, and a plunger 25 are provided between the substrate 21 and the housing 22. The electrodes Q1 and Q2 and the coil spring 23 are electrically insulated by an insulating layer, not shown, and thus constitute a capacitor. Further, a key cap 26 is provided above the housing 22, and when the operator presses the key cap 26, the coil spring 23 is energized (pressed) to change the electrostatic capacitance between the electrodes Q1 and Q2. That is, the key Ky is configured to increase the electrostatic capacitance between the electrodes Q1 and Q2 in accordance with the amount of depression when the key cap 26 is depressed.

The key Ky shown in fig. 2 is not particularly limited in structure, as long as it is configured to increase the electrostatic capacitance between the electrodes in accordance with the amount of depression when the key cap 26 is depressed. The voltage may be monotonically increased according to the amount of depression of the key. Preferably increases linearly.

In the following description, when any one of the plurality of keys Ky is not specified, the symbol "Ky" is added, and when the individual key is specified, the number of the drive line M and the number of the sense line N which are intersections are added in parentheses. For example, the key set at the intersection of drive line M-4 and sense line N-5 is denoted as "key Ky (4, 5)".

Among the 2 electrodes Q1 and Q2 provided in the key Ky, one electrode Q1 is connected to the drive line M, and the other electrode Q2 is connected to the sense line N. Specifically, as shown in the schematic diagram of fig. 3, the electrode Q1 is disposed opposite to the electrode Q2 with a certain distance therebetween, the electrode Q1 is connected to the driving line M, and the electrode Q2 is connected to the sensing line N. The electrostatic capacitance between the electrodes Q1 and Q2 changes according to the state of extension and contraction of the coil spring 23 (i.e., the amount of depression of the key cap 26 shown in fig. 2) provided between the 2 electrodes Q1 and Q2, and thus the current flowing from the electrode Q1 to the electrode Q2 also changes according to the electrostatic capacitance. Therefore, the voltage detected by the sensing circuit 12 (refer to fig. 1) is changed.

The details of the driving circuit 11, the sensing circuit 12, and the control circuit 15 will be described below with reference to the block diagram shown in fig. 4. The control circuit 15 includes: a main control unit 41, a memory control unit 42, a memory unit 44, and an output interface 43.

The main control unit 41 performs overall control of the control circuit 15, and outputs various control signals to the driving circuit 11 and the sensing circuit 12. Specifically, a driving signal for selectively setting each driving line M to an H (high) level is outputted to the driving circuit 11. The sensing circuit 12 outputs a switching signal of a multiplexer 31 (described later), a reset signal of a peak hold circuit 32 (described later), and a conversion start signal of an a/D (analog/digital) conversion circuit 33 (described later).

The main control unit 41 calculates the amount of depression of the key Ky based on the voltage generated at each key Ky output from the a/D conversion circuit 33. That is, the main control unit 41 has a function as a depression amount detection unit that scans each key Ky and detects the depression amount of the key Ky based on the change in the electrostatic capacitance of the variable capacitance capacitor (electrostatic capacitance element).

Further, the main control unit 41 has a function as an input control unit that controls, when there is a key Ky whose depression amount reaches a reference value Th0 described later, to shorten the scanning period of the key Ky.

The memory unit 44 has a memory area corresponding to each key Ky. Specifically, each of the mth drive line M and the nth sense line N has a memory area, and the voltage detected by the sense circuit 12 is memorized as a voltage Vk (M, N) corresponding to the key Ky (M, N). Further, a timer counter Tc (m, n) for calculating the pressing speed of the key Ky as described later is set in the memory unit 44.

The memory control unit 42 obtains voltages corresponding to the keys Ky provided at the intersections based on the voltages generated on the drive lines M and the sense lines N, which have been set to the H level, and writes the obtained voltages into the memory areas corresponding to the keys Ky set in the memory unit 44. Further, control is performed to read out the voltage stored in the memory area. Based on the count value stored in the timer counter Tc (m, n), the time from the time when the 1 st threshold Th1 to the time when the 2 nd threshold Th2 is reached is measured. That is, the memory control unit 42 has a function as a required time measuring unit.

The reference values Th0, 1 st threshold Th1, and 2 nd threshold Th2 can be arbitrarily set. When the amount of the depression of each key Ky differs from the voltage generated, the reference value Th0, the 1 st threshold Th1, and the 2 nd threshold Th2 may be set to different values for each key in order to correct the deviation.

The output interface 43 converts the information of the depression amount of each key Ky calculated by the main control unit 41 into a key code, and transmits the key code to the host computer 16 (see fig. 1). The host computer 16 can calculate the pressing speed based on the time-dependent change in the pressing amount of the key Ky.

The driving circuit 11 selectively applies a voltage of an H level (high level) for only a predetermined time to each of the driving lines M (M-1 to M-i) based on a control command (driving control signal) output from the control circuit 15. Specifically, the voltages of the driving lines M are set to H level in the order of M-1, M-2, …, M-i, M-1. The voltage of the driving line M is set to L level (low level). The order of applying the voltages is not limited to the above, and the voltages of the drive lines M may be selectively set to the H level at a predetermined cycle.

Further, as described above, each drive line M is switched to the H level and the L level according to the control of the drive circuit 11, and therefore, in fig. 4, the switching is indicated by the switch SW and the arrow indicating the drive control signal for convenience. That is, when a command to set the drive line M to the H level is supplied in accordance with the drive control signal outputted from the control circuit 15, the switch SW is switched from "L" to "H", and the H-level voltage is applied to the key Ky.

As will be described later, when the control circuit 15 detects the amount of depression of the generated voltage to the reference value Th0 in any one of the keys Ky, it performs control to change the scanning order so that the scanning period of the key Ky is shortened. For example, the key Ky of the depression amount reaching the reference value Th0 is controlled such that 1 scan is performed on the key every 4 scans are performed.

The sensing circuit 12 detects a voltage corresponding to a current flowing through each sensing line N, which will be described in detail below. As shown in fig. 4, the sensing circuit 12 includes a series connection circuit of resistors R1 and R2, and a connection point P1 of each resistor R1 and R2 is connected to an output terminal of the key Ky (i.e., the electrode Q2 shown in fig. 3). In fig. 4, 1 key Ky is described for each drive line M, but actually, as shown in fig. 1, j keys Ky are provided for 1 drive line M.

One end of the resistor R1 is connected to a terminal of the power supply voltage VB, and one end of the resistor R2 is connected to the ground. As described above, the series connection circuit is provided on each of the sense lines N, and the connection point P1 is connected to the multiplexer 31. The resistors R1 and R2 have the same resistance value. Therefore, the voltage at the connection point P1 is a voltage that is an intermediate value between the power supply voltage VB and the ground voltage supplied to the sensing circuit 12.

The multiplexer 31 selectively switches a voltage (voltage generated at the connection point P1) corresponding to a current flowing to the sense line N through each of the keys Ky (1, 1) to Ky (i, j)) at a predetermined period, and outputs the voltage to the peak hold circuit 32. Specifically, voltages are output in the order of the keys Ky (1, 1), ky (1, 2), ky (1, 3), …, ky (1, j), ky (2, 1), ky (2, 2), ky (2, 3), …, ky (2, j), ky (3, 1), …, ky (i, j).

The peak hold circuit 32 detects a peak value of the voltage generated at the connection point P1, and holds the detected peak value. When a reset signal is given by the control circuit 15, the held peak value is reset.

The a/D conversion circuit 33 digitizes the peak value of the voltage held by the peak holding circuit 32 when a conversion start signal is given by the control circuit 15, and outputs the digital data to the control circuit 15. The peak digital data is stored in the memory unit 44.

Then, the switch SW shown in fig. 4 is switched from OFF (OFF) to ON (ON) (i.e., the voltage of the driving line M is switched from L level to H level), and at this time, if the key Ky is pressed by the operation of the operator, the voltage of the connection point P1 increases because the electrostatic capacitance between the electrodes Q1, Q2 increases and a current flows. The voltage is supplied to the peak hold circuit 32 via the multiplexer 31, and is digitized by the a/D conversion circuit 33 in a state of being temporarily held in the peak hold circuit 32, and is output to the control circuit 15. That is, a voltage that varies as a linear function with respect to the amount of depression of the key Ky is detected.

The main control unit 41 determines whether or not the key Ky is pressed based on the read digitized voltage value. The amount of depression of the pressed key Ky is detected based on the peak value detected by the peak value holding circuit 32. The information on the pressing of each key Ky is converted into a key code, and transmitted to the host computer 16 via the output interface 43. The host computer 16 calculates the pressing speed based on the time-dependent change in the pressing amount of the key Ky.

[ description of method for detecting push-down speed ]

Next, a method for detecting the pressing speed when the key Ky is pressed will be described. Fig. 5 is a graph showing a change in the amount of depression with respect to time passage when the key Ky is depressed, wherein a straight line a1 shows a change in voltage at the key Ky when the key Ky is depressed with a relatively strong force, and a straight line a2 shows a change in voltage generated at the key Ky when the key Ky is depressed with a relatively weak force. In addition, the amount of depression of key Ky is not strictly proportional to the voltage that occurs at key Ky, but is labeled here for convenience. That is, the vertical axis of fig. 5 is denoted by "voltage (depression amount)".

In the straight line a1 shown in fig. 5, the amount of depression of the key Ky reaches the 1 st threshold Th1 at time t1, and reaches the 2 nd threshold Th2 at time t3. Therefore, the pressing speed can be calculated based on the time Δt21 from T1 to T3. On the other hand, in the straight line a2, the pushed-down amount reaches the 1 st threshold Th1 at time t2, and reaches the 2 nd threshold Th2 at time t 4. Therefore, the pressing speed can be calculated based on the time Δt22 from T2 to T4.

However, as described above with reference to fig. 11 and 12, if the scanning period of each key Ky is long, the time when the pushed-down amount reaches the 1 st threshold Th1 and the 2 nd threshold Th2 may not be accurately detected. In the present embodiment, a reference value Th0 lower than the 1 st threshold Th1 shown in fig. 5 is set, and when a key Ky whose depression amount reaches the reference value Th0 is detected, control is performed to shorten the scanning period of the key Ky. The following is a detailed description.

As described above, if the method of sequentially scanning all the keys Ky is adopted, 1 time is required to scan all the keys Ky in the time from the previous scan to the next scan for one key Ky. For example, when the number of keys is 100 as a whole, the next scan of one key Ky is performed after 99 scans other than the one key Ky from the previous scan of the one key Ky. In the present embodiment, the period of the key Ky whose depression amount has reached the reference value Th0 is set to be 1 time every 4 times of scanning in order to shorten the scanning period. That is, scanning is performed at intervals smaller than the total number of keys.

For example, when the amount of depression of the key Ky (1, 1) in the 1 st scan has reached the reference value Th0, the scans are performed in the order Ky (1, 1), ky (1, 2), ky (1, 3), ky (1, 1), ky (1, 4), ky (1, 5), ky (1, 6), ky (1, 1), ky (1, 7), ky (1, 8), ky (1, 9), ky (1, 1), …, ky (i, j). That is, with respect to the key Ky (1, 1), scanning is performed with a short period (1 scan every 4 scans). In addition, the present invention is not limited to 1 scan every 4 scans.

The main control unit 41 shown in fig. 4 controls the drive control signal to be outputted to the drive circuit 11 and the switch signal to be outputted to the multiplexer 31 so as to shorten the scanning period of the key Ky. When a plurality of (e.g., 2) keys Ky are pressed to reach the reference value Th0, the scanning period of all the pressed keys Ky is shortened.

[ description of the treatment Process ]

A specific processing method of the capacitive keyboard apparatus 10 according to the present embodiment will be described below with reference to flowcharts shown in fig. 6 and 7. Initially, in step S11 of fig. 6, the main control unit 41 initializes each parameter to be used in the calculation. The above-described reference value Th0, 1 st threshold Th1, and 2 nd threshold Th2 are set. This process can be set in advance by the main control unit 41 shown in fig. 4 or can be set by an initial input operation by the operator. Further, the values of the timer counter Tc (m, n) described later are all set to 0, the symbol m indicating the driving line (row number) and the symbol n indicating the sensing line (column number) shown in fig. 1 are each set to "1", and the symbol L indicating the number of scans (detailed later) in the interval between this and the next scan is further set to "0".

In step S12, the main control section 41 outputs a driving control signal to sequentially switch the voltages to be applied to the driving lines M-1 to M-i to the "H" level, and measures the voltages detected by the sensing circuit 12. Further, the measured voltage is associated with the key Ky and memorized in the memory unit 44. Specifically, the voltage Vk (m, n) detected at the key Ky (m, n) of the nth row and column of the mth row is memorized in the memory section 44. In the initial state, since m=1 and n=1, the voltage Vk (1, 1) detected at the key Ky (1, 1) is memorized in the memory area set in the memory section 44.

In step S13, the voltage Vk (m, n) is compared with the reference value Th 0. In the case of "Vk (m, n) < Th 0", it is determined that the key Ky (m, n) is not pressed, and in step S14, F0 (m, n) and F1 (m, n) are set to "0", respectively. F0 (m, n) is a parameter indicating that the pressing amount of the key Ky has reached the reference value Th0, and F1 (m, n) is a parameter indicating that the pressing amount of the key Ky has reached the 2 nd threshold Th2. On the other hand, when "Vk (m, n) > Th 0", it is determined that the key Ky (m, n) has been pressed, and F0 (m, n) is set to "1" in step S15.

In step S16, the main control unit 41 increases the parameter L indicating the number of scans in the section (l=l+1), and further determines in step S17 whether or not "l=3". In the case of "l=3", high-speed scanning is performed in step S18. If not "" L=3 "", the process proceeds to step S20 without performing high-speed scanning. The term "high-speed scanning" refers to the processing method of steps S51 to S63, that is, the processing inserted into the normal scanning in which all the keys Ky are scanned sequentially, and including the voltage measurement of the key Ky having reached the reference value Th 0.

The following describes a processing method of the high-speed scanning in step S18 in fig. 6 with reference to the flowchart in fig. 7. Initially, in S51 of fig. 7, a symbol m 'indicating the number of rows and a symbol n' indicating the number of columns are initialized. That is, "m '=1" and "n' =1" are set. In fig. 7, in order to distinguish m from n used in the flowchart of fig. 6, each symbol m and n is denoted by the symbol "n".

In step S52, the main control unit 41 determines whether or not "F0 (m ', n') =1" is associated with the key Ky to be the target. When the process of step S15 shown in fig. 6 is to be executed, that is, when the key Ky (m ', n') is pressed and the voltage reaches the reference value Th0, YES is determined in step S52, and the process proceeds to step S53. On the other hand, in the case of NO determination, scanning is not performed for the key Ky to be the object, and the process proceeds to step S60.

In step S53, main control unit 41 determines whether or not "F1 (m ', n') =1". As described above, F1 (m, n) becomes "1" when the amount of depression reaches the 2 nd threshold Th2, and therefore "0" in the initial state becomes NO determination, and the process proceeds to step S54.

In step S54, the main control unit 41 measures the voltage Vk (m ', n') generated at the key Ky (m ', n'). In this process, the voltage generated at each key Ky is measured sequentially as in the case of keys Ky (1, 1), ky (1, 2), …, but in practice, voltage detection is performed only for the key Ky whose depression has been detected in S13 of fig. 6, so that it can be performed in a short time. That is, the processing time of the processing shown in S54 of fig. 7 is extremely short compared to the processing shown in S12 of fig. 6.

In step S55, it is determined whether or not the voltage Vk (m ', n') detected at the key Ky (m ', n') is equal to or greater than the 1 st threshold Th1. If the 1 st threshold Th1 is not reached (NO in step S55), the process proceeds to step S60. That is, since the operation of the pressing speed is not required when the voltage does not reach the 1 st threshold Th1, the processing of steps S56 to S59 described later is not performed.

On the other hand, when the 1 st threshold Th1 or higher (YES in step S55, corresponding to t7 in fig. 9 described later), in step S56, the value of the timer counter Tc (m ', n') for the key Ky (m ', n') is increased. As described above, the initial state is "0" when the timer counter Tc (m ', n').

In step S57, the main control unit 41 determines whether or not the voltage Vk (m ', n') detected at the key Ky (m ', n') is equal to or greater than the 2 nd threshold Th2. If the 2 nd threshold Th2 is not reached (NO in step S57), the process proceeds to step S60. If the 2 nd threshold Th2 or higher (YES in step S57, corresponding to t22 in fig. 9 described later), the process proceeds to step S58.

In step S58, the main control unit 41 outputs the value of the timer counter Tc (m ', n') for the key Ky (m ', n') to the host computer 16 according to the output interface 43 shown in fig. 4. The host computer 16 calculates the pressing speed at which the key Ky (m ', n') is pressed based on the value of the timer counter Tc (m ', n'). That is, since the time from the 1 st threshold Th1 to the 2 nd threshold Th2 is detected by the voltage generated by the key Ky being pressed, the pressing speed at the time of pressing the key Ky can be calculated.

In step S59, the main control unit 41 sets the value of the timer counter Tc (m ', n') to "0", and sets the parameter F1 (m ', n') to "1". When the parameter F1 (m ', n') is set to "1", the next processing is YES determination in step S53 in fig. 7, and no voltage measurement is performed.

In step S60, the main controller 41 increments m'. In step S61, the main controller 41 determines whether m' is i+1 (i is the number of lines). That is, it is determined whether the final line has been reached. If m' =i+1 does not hold (NO in step S61), the process returns to step S52. If m' =i+1 is satisfied (YES in step S61), the process proceeds to step S62.

In step S62, the main control unit 41 sets m 'to "1", and increases n'. In step S63, the main controller 41 determines whether n' is j+1 (j is the column number). That is, it is determined whether the final column has been reached. If n' =j+1 does not hold (NO in step S63), the process returns to step S52. If n' =j+1 is satisfied (YES in step S63), the process proceeds to step S19 in fig. 6.

In step S19 of fig. 6, the main control unit 41 sets "l=0", and advances the process to step S20.

In step S20, the main control section 41 increments m, and further determines in step S21 whether m=i+1. If m=i+1 does not hold (NO in step S21), the process returns to step S12. If m=i+1 is satisfied (YES in step S21), the process proceeds to step S22.

In step S22, the main control unit 41 sets m to "1", and increases n. In step S23, the main controller 41 determines whether n is j+1. That is, it is determined whether the final column has been reached. If n=j+1 is not satisfied (NO in step S23), the process returns to step S12. If n=j+1 is satisfied (YES in step S23), n is incremented in step S24, and the process returns to step S12.

In this way, the driving line M and the sensing line N can be scanned, and the pressing amount of the key Ky whose voltage value has reached the reference value Th0 can be measured with a short period (1 time per 4 scans), and the pressing speed can be calculated.

Fig. 8 is a graph showing the relationship between the time elapsed and the voltage generated at the arbitrary key Ky, and the changes of the parameters F0 and F1 and the Timer counter (Tc).

As shown in fig. 8 (a), the following changes were made: if any key Ky is pressed, the voltage generated at the key Ky gradually increases, and then gradually decreases if the key is released. When the voltage reaches the reference value Th0 at time t31, the parameter F0 is switched from "0" to "1" as shown in fig. 8 (b). That is, the process of step S15 of fig. 6 is performed.

When the voltage reaches the 1 st threshold Th1 at time t32, the timer counter Tc starts counting as shown in fig. 8 (d). That is, the process of step S56 of fig. 7 is performed.

When the voltage reaches the 2 nd threshold Th2 at time t33, the parameter F1 is switched from "0" to "1" as shown in fig. 8 (c) and (d), and the timer counter Tc is further terminated. That is, the process of step S59 of fig. 7 is performed. The timer count value X1 at this time corresponds to the pressing speed of the key Ky because it indicates the time required for the pressing amount of the key Ky to reach the 2 nd threshold Th2 from the 1 st threshold Th1. The timer count value is transmitted to the host computer 16 according to the output interface 43 shown in fig. 4.

When the voltage decreases to less than the reference value Th0 at time t34, the parameters F0 and F1 are set to "0", respectively. That is, the process of step S14 of fig. 6 is performed. Then, when the parameter is maintained until the time t35, the key Ky is pressed again and the amount of pressing reaches the reference value Th 0. In this way, since the timer count value X1 is obtained and transmitted to the host computer 16, the host computer 16 can calculate the pressing speed when the key Ky is pressed.

Next, the timing of scanning the key Ky and the change in voltage caused by the execution of the above-described processing will be described with reference to the graph shown in fig. 9.

Fig. 9 is a characteristic diagram showing the scan timing when the key Ky (1, 1) is pressed and the voltage change caused by the pressing. In the process of step S17 in fig. 6, l=3 is set, whereby the scanning of the key Ky (1, 1) is performed after 3 intervals (i.e., every 4 scans). Therefore, as shown in fig. 9, scanning is performed at timings of t2, t3, …, t22, and t 23. Compared with the scanning period shown in fig. 5, it can be understood that the scanning period is shorter. Therefore, it can be detected that the voltage reaches the reference value Th0 at time t2 shown in fig. 9, reaches the 1 st threshold Th1 at time t7, and reaches the 2 nd threshold Th2 at time t 22.

Therefore, the time Δt from the time when the 1 st threshold Th1 is reached to the 2 nd threshold Th2 is accurately detected by the amount of depression of the key Ky (1, 1). Further, the pressing speed when the key Ky (1, 1) is pressed can be accurately calculated.

As described above, in the capacitive keyboard apparatus 10 according to embodiment 1, a plurality of keys Ky are scanned sequentially, and when it is detected that the amount of depression of one key Ky (in the above example, the key Ky (1, 1)) has reached the reference value Th0, the scanning cycle is shortened for that key Ky. Specifically, the key Ky is scanned every 4 times. Therefore, the resolution of the pressed amount detection can be improved, and the time when the pressed amount of the key Ky reaches the 1 st threshold Th1 and the time when the pressed amount reaches the 2 nd threshold Th2 can be accurately detected. As a result, the pressing speed can be accurately calculated, and the method is extremely useful when used as a MIDI keyboard.

When the pushed amount of the key Ky reaches the 2 nd threshold Th2, the voltage measurement in the high-speed scanning and the increase of the value of the timer counter are not performed on the key Ky. That is, when the amount of depression (voltage value) of the key Ky reaches the 2 nd threshold Th2, YES determination is made in step S57 of fig. 7, and then the parameter F1 is set to "1" in the process of step S59. Therefore, in the next scanning, YES determination is made in the processing of step S53, and the voltage measurement of step S54 and the increase of the value of the timer counter of step S56 are not performed. Therefore, unnecessary computation can be avoided, and the computation load can be reduced.

Then, even if the key Ky is released to reduce the amount of depression, the parameter F1 is set to "1", so that the above state is maintained. Further, the amount of depression of the key Ky is temporarily reduced to less than the reference value Th0, and the above state is maintained until reaching the reference value Th0 again.

[ description of embodiment 2 ]

Next, embodiment 2 of the present invention will be described. Since the device configuration is the same as that shown in fig. 1 and 4, the explanation of the configuration is omitted. In embodiment 2, the difference from embodiment 1 is that a 3 rd threshold value Th3 larger than the 2 nd threshold value Th2 is set in addition to the 1 st threshold value Th1 and the 2 nd threshold value Th2. That is, a threshold value of the depression amount of 3 or more keys Ky is set.

Fig. 10 is a graph showing a scanning sequence when the amount of depression of the key Ky (1, 1) reaches the reference value Th0 and further reaches the 1 st threshold Th1, 2 nd threshold Th2, and 3 rd threshold Th3. Specifically, the following is shown: the reference value Th0 is reached at time t2, the 1 st threshold Th1 is reached at time t7, the 2 nd threshold Th2 is reached at time t14, and the 3 rd threshold Th3 is reached at time t 22.

In this case, the time Δt1 from time T7 to T14, the time Δt2 from time T14 to T22, and the time Δt3 from time T7 to T22 can be detected. That is, the time required between the plurality of thresholds can be measured. Therefore, the pressing speed can be obtained by selecting any one of the times Δt1, Δt2, and Δt3.

According to embodiment 2 of the present invention, for example, the amount of pressing may be changed as follows: the number of increases in order of Th0, th1, th2, and Th3, and then returns to the amount of depression between Th1 and Th2, and then exceeds Th2, th3 again. In this case, the continuous key-pressing feeling of the conventional piano can be expressed by finding the pressing speed from the time between using Th2 and Th3, that is, Δt2.

As described above, in the capacitive keyboard device according to embodiment 2, the 3 rd threshold value Th3 is set in addition to the 1 st and 2 nd threshold values, so that the operation of the pressing speed that is more versatile can be performed. Therefore, when the keyboard is used as a keyboard for a MIDI machine, a tone color closer to the original sound source of the musical instrument can be output in accordance with the type of the musical instrument.

[ description of embodiment 3 ]

Next, embodiment 3 of the present invention will be described. Since the device configuration is the same as that shown in fig. 1 and 4, the explanation of the configuration is omitted. In embodiment 3, when one key Ky is pressed and the pressing speed is calculated, the scanning sequence is changed if another key Ky is pressed.

When 2 keys Ky (1, 1) and Ky (1, 2) are pressed and the amount of the pressing reaches the reference value Th0, the scanning sequence is as follows.

Ky(1,1)、Ky(1,2)、Ky(1,3)、Ky(1,1)、Ky(1,2)、Ky(1,4)、Ky(1,5)、Ky(1,6)、Ky(1,1)、Ky(1,2)、…、Ky(2,1)、Ky(1,1)、Ky(1,2)、Ky(2,2)、Ky(2,3)、Ky(2,4)、Ky(1,1)、Ky(1,2)、…、Ky(m,n)。

That is, when a plurality of keys Ky are pressed, each time a scan of keys Ky other than the pressed key Ky is performed 3 times, the pressed key Ky is scanned. Thus, even when a plurality of keys Ky are pressed, the scanning period of the pressed key Ky can be shortened, and accurate pressing speed calculation can be performed.

Although the capacitive keyboard of the present invention has been described above based on the embodiments of the drawings, the present invention is not limited to the embodiments, and the configuration of each part can be replaced with any configuration having the same function.

For example, in the above-described embodiment, the configuration in which the key Ky is arranged at the intersection of each drive line M and each sense line N has been described, but the present invention is not limited to this configuration, and there may be a position in which the key Ky is not arranged at the intersection. The number of driving lines M and sensing lines N may be the same, i.e., i=j.

Further, although the example in which the resistance values of the 2 resistors R1 and R2 provided in the sensing circuit 12 are the same has been described in the above embodiment, the present invention is not limited to such an example, and different resistance values may be made.

Claims (4)

1. An electrostatic capacity type keyboard device, comprising:

a plurality of driving lines and a plurality of sensing lines crossing the driving lines;

a key set provided at an intersection of each of the drive lines and each of the sense lines;

a capacitance element provided in each of the keys, the capacitance element changing capacitance between the drive line and the sense line in accordance with a pressed amount of the key;

a pressed amount detection unit for scanning each key and detecting the pressed amount of the key based on the change of the electrostatic capacitance element;

an input control unit for controlling the key so as to shorten the scanning period when the amount of depression detected by the depression amount detection unit reaches a preset reference value; and

a required time measuring unit for setting a1 st threshold value larger than the reference value and a2 nd threshold value larger than the 1 st threshold value, and measuring a required time from reaching the 1 st threshold value to reaching the 2 nd threshold value by a pressing amount

The input control part performs sequential scanning for sequentially scanning all keys when the pressing amount of all keys does not reach the reference value, and inserts high-speed scanning for scanning the keys reaching the reference value between the sequential scanning when the pressing amount of any key reaches the reference value,

the required time measuring unit measures the required time of the key to reach the reference value.

2. The electrostatic capacity type keyboard device according to claim 1, wherein in the sequential scanning, the high-speed scanning is inserted every time a predetermined number of times of pressing is detected.

3. The capacitive keyboard device according to claim 1, wherein the input control unit controls not to perform the high-speed scanning until the amount of depression of the key becomes smaller than the reference value after the amount of depression of the key reaches the 2 nd threshold.

4. The electrostatic capacity type keyboard apparatus according to claim 1, wherein a threshold value of a depression amount of 3 or more of the keys is set, and the required time measuring section measures a required time between a plurality of threshold values.