JP6789161B2 - Capacitive keyboard device - Google Patents

Description

The present invention relates to a keyboard having a plurality of keys, and in particular, a capacitive keyboard device that detects a change in capacitance when a key is pressed and a key pressing time to detect a key pressing speed. Regarding.

A capacitive keyboard device that detects a key operation based on a change in capacitance due to pressing a key has been proposed and put into practical use. On the other hand, it has been proposed to use a keyboard device having a plurality of keys such as an ASCII keyboard as a MIDI (musical instrument digital interface) keyboard or as an operator of a game machine. Therefore, it is desired 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 at at least two points. The pressing speed is detected based on the time difference between two points when the key is pressed. Specifically, the first pressing amount and the second pressing amount deeper than the first pressing amount are set for each key, and the time required from the first pressing amount to the second pressing amount is calculated, and this is calculated. Detects the pressing speed when a key is pressed based on the required time.

Capacitive keyboard devices scan each key in sequence to detect the amount of key presses. For example, when n keys Ky1, Ky2, Ky3, ... Kyn exist, each key is scanned in order, for example, "Ky1 → Ky2 → ... Kyn → Ky1 → ...". When it is detected that the pressing amount has reached the first threshold Th1 with the key Ky1, and it is detected that the pressing amount has reached the second threshold Th2 in the subsequent scans of the key Ky1, the first threshold Th1 is set. The pressing speed is calculated based on the required time from the detected time to the time when the second threshold Th2 is detected.

However, in the above method, since a plurality of keys are scanned in sequence, the scan cycle becomes long, and it takes a long time from this scan to the next scan. Therefore, there is a possibility that an accurate pressing speed cannot be detected. This will be described in detail below.
In FIG. 11, the horizontal axis is time and the vertical axis is voltage. In the capacitance type keyboard device, the capacitance changes with the pressing of the key, and the voltage generated in the key changes. Therefore, the amount of pressing the key is detected by measuring the voltage. Therefore, the vertical axis can also be referred to as the "pressing amount". The straight line q1 shown in FIG. 11 indicates the voltage generated when an arbitrary key (this is referred to as “key Ky1”) is pressed, and the timing for scanning the key Ky1.

As described above, since n keys are scanned in sequence, the scan timing of the key Ky1 is set to time t1, t2, and t3. That is, the time of t1 to t2 and the time of t2 to t3 are the keyboard scan cycle (the time required from the previous scan to the current scan). Since the amount of key Ky1 pressed increases with the passage of time, the straight line q1 increases linearly. The first threshold value of the amount of pressing the key Ky1 is indicated by Th1, and the second threshold value is indicated by Th2.

Now, as shown in FIG. 11, when it is detected that the pressing amount of the key Ky1 reaches the first threshold Th1 at time t1, and then it is detected that the second threshold Th2 is reached at time t3. It is detected that it takes time ΔT11 of t1 to t3 from reaching the first threshold value Th1 to reaching the second threshold value Th2. Therefore, the pressing speed at the time of pressing the key Ky1 can be obtained based on the time ΔT11.

On the other hand, in the straight line q2 shown in FIG. 12, the pressing amount does not reach the first threshold Th1 at time t1. After that, it is detected that the first threshold value Th1 is reached at time t2, and further, it is detected that the second threshold value Th2 is reached at time t3. In this case, it is detected that it takes time ΔT12 of t2 to t3 from the detection of the first threshold value Th1 to the detection of the second threshold value Th2. In this case, although the pressing amount actually reaches the first threshold Th1 immediately after the time t1, this is not detected until the time t2. Therefore, after the pressing amount reaches the first threshold Th1, the second threshold Th2 There will be a large error in the time it takes to reach. Therefore, there arises a problem that the calculation accuracy of the pressing speed is lowered.

Therefore, as a keyboard for the purpose of improving the calculation accuracy of the pressing speed, for example, the one disclosed in Patent Document 1 is known. Patent Document 1 discloses an electronic musical instrument having a two-point switch type key (keyboard) having a first switch and a second switch, periodically scans the first switch, and the second switch is the first switch. It is shown to scan only the keys (keys) that contain the keys that are on. By not scanning the key group in which the first switch is not turned on, the scan cycle of the second switch can be shortened.

Japanese Unexamined Patent Publication No. 5-165471

However, since the conventional example disclosed in Patent Document 1 described above employs a method of dividing each key into a plurality of key groups, the key group including the key in which the first switch is turned on is the first. The scan of the second switch will be performed even if the first switch is not turned on, and there is an increasing demand for shortening the scan cycle and detecting the pressing speed with high accuracy.

The present invention has been made to solve such a conventional problem, and an object of the present invention is a capacitive keyboard device capable of detecting the pressing speed of a pressed key with high accuracy. Is to provide.

In order to achieve the above object, the present invention is provided at a plurality of drive lines (M), a plurality of sensing lines (N) intersecting the drive lines, and at the intersection of each drive line and each sensing line. A key (Ky), a capacitance element provided on each key and whose capacitance between the drive line and the sensing line changes according to the amount of pressing the key, and each key are scanned and described. The pressing amount detection unit that detects the pressing amount of the key and the pressing amount detected by the pressing amount detecting unit based on the change in the capacitance of the capacitance element reach a preset reference value (Th0). In this case, an input control unit that controls to perform a high-speed scan that shortens the scan cycle of this key, a first threshold value that is larger than the reference value, and a second threshold value that is larger than the first threshold value are set. The input control unit includes a required time measuring unit for measuring the required time from when the key pressing amount reaches the first threshold value to reaching the second threshold value, and the input control unit has the first key pressing amount. When the two threshold values are reached, it is characterized in that the execution of the high-speed scan by the one key is stopped until the pressing amount of the one key becomes less than the reference value .

In the capacitive keyboard device according to the present invention, it is possible to detect the pressing speed of the pressed key with high accuracy.

FIG. 1 is an explanatory diagram schematically showing a 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 a detailed configuration of keys 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 the two electrodes and the coil spring of the key used in the capacitive keyboard device according to the embodiment of the present invention. FIG. 4 is a block diagram showing a detailed configuration of a drive circuit, a sensing circuit, and a control circuit of 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 pressing with respect to the passage of time. The straight line a1 shows a case where the key pressing speed is high, and the straight line a2 shows a case where the key pressing speed is slow. FIG. 6 is a flowchart showing a processing procedure of the capacitive keyboard device according to the embodiment of the present invention. FIG. 7 is a flowchart showing a processing procedure of the capacitive keyboard device according to the embodiment of the present invention. FIG. 8 is a graph showing a change in the pressing amount with the passage of time, a change in the parameters F0 and F1, and a change in the timer counter Tc. FIG. 9 is a graph showing changes in scan timing and pressing amount when the scanning cycle of pressed keys is shortened according to the first embodiment of the present invention. FIG. 10 is a graph showing changes in the scan timing and the pressing amount when the scanning cycle of the pressed key is shortened according to the second embodiment of the present invention. FIG. 11 is a graph showing the timing of measuring the amount of pressing an arbitrary key with a conventional capacitive keyboard device. FIG. 12 is a graph showing the timing of measuring the pressing amount of an arbitrary key with a conventional capacitive keyboard device, and shows a case where the timing at which the pressing amount reaches Th1 is slightly delayed from the time t1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing a configuration of a capacitive keyboard device according to an embodiment of the present invention. As shown in FIG. 1, the capacitive keyboard device 10 according to the present embodiment has a plurality of drive lines M (M-1, M-2, M-3, ..., M) (number i in the figure). -i) and a plurality of sensing lines N (N-1, N-2, N-3, ..., N-j) (the number j in the figure) are arranged so as to intersect each other. In the following, when the drive line is not specified, the symbol "M" is added, and when the individual drive line is specified, the suffix is added as "M-1". I will show it. Similarly, when the sensing line is indicated without specifying the individual, the symbol "N" is added, and when the individual is specified and indicated, a suffix such as "N-1" is added.

As shown in FIG. 1, each drive line M is connected to the drive circuit 11, and each sensing line N is connected to the sensing circuit 12. The drive circuit 11 and the sensing circuit 12 are connected to the control circuit 15, and the drive of the drive circuit 11 and the sensing circuit 12 is controlled by the control of the control circuit 15.
The control circuit 15, the drive circuit 11, and the sensing circuit 12 can be configured as, for example, an integrated computer including a central processing unit (CPU) and storage means such as a RAM, a ROM, and a hard disk.

Each drive line M and each sensing line N are connected by a key Ky at each intersection, and in normal times (when the key Ky is not pressed), both lines M and N are electrically connected at each intersection. Not conducting. As will be described later, since the key Ky includes a variable capacitance capacitor (capacitance element), each key Ky is indicated by a symbol of the variable capacitance capacitor in the figure.

As shown in FIG. 2, the key Ky includes a substrate 21 having a pair of electrodes Q1 and Q2, and a housing 22, and a conical coil spring 23 and flexibility are provided between the substrate 21 and the housing 22. A rubber 24 having a property and a plunger 25 are provided. Since the electrodes Q1 and Q2 and the coil spring 23 are electrically insulated by an insulating layer (not shown), they form a capacitor. Further, a key top 26 is provided above the housing 22, and when the operator presses the key top 26, the coil spring 23 is urged and the capacitance between the electrodes Q1 and Q2 changes. .. That is, the key Ky is configured so that the capacitance between the electrodes Q1 and Q2 increases according to the pressing amount when the key top 26 is pressed.

The key Ky shown in FIG. 2 does not particularly define the structure, and may be configured so that the capacitance between the electrodes increases according to the pressing amount when the key top 26 is pressed. Just do it. Further, the voltage may be monotonously increased according to the amount of key pressing. Those that increase linearly are preferable.
In the following, when a plurality of key Kys are not specified, the code "Ky" is added, and when each key is specified, the number of the drive line M and the number of the sensing line N, which are intersections, are shown in parentheses. I will show it with. For example, the key provided at the intersection of the drive line M-4 and the sensing line N-5 is indicated by "key Ky (4,5)".

Then, of the two electrodes Q1 and Q2 provided on the key Ky described above, one electrode Q1 is connected to the drive line M and the other electrode Q2 is connected to the sensing line N. Specifically, as shown in the schematic diagram of FIG. 3, the electrode Q1 and the electrode Q2 are arranged to face each other at a certain distance, the electrode Q1 is connected to the drive line M, and the electrode Q2 is connected to the sensing line N. ing. Then, the capacitance between the electrodes Q1 and Q2 changes according to the expansion / contraction state of the coil spring 23 provided between the two electrodes Q1 and Q2 (that is, the pressing amount of the key top 26 shown in FIG. 2). Along with this, the current flowing from the electrode Q1 to the electrode Q2 changes. Therefore, the voltage detected by the sensing circuit 12 (see FIG. 1) changes.

Hereinafter, the details of the drive circuit 11, the sensing circuit 12, and the control circuit 15 will be described with reference to the block diagram shown in FIG. The control circuit 15 includes a main control unit 41, a storage control unit 42, a storage unit 44, and an output interface 43.

The main control unit 41 comprehensively controls the control circuit 15 and outputs various control signals to the drive circuit 11 and the sensing circuit 12. Specifically, a drive control signal for selectively setting each drive line M to H level is output to the drive circuit 11. Further, the switching control signal of the multiplexer 31 (described later) is output to the sensing circuit 12, the reset signal of the peak hold circuit 32 (described later) is output, and the conversion start signal of the A / D conversion circuit 33 (described later) is output. Output.

Further, the main control unit 41 calculates the pressing amount of the key Ky based on the voltage generated in each key Ky output from the A / D conversion circuit 33. That is, the main control unit 41 has a function as a pressing amount detecting unit that scans each key Ky and detects the pressing amount of the key Ky based on the change in the capacitance of the variable capacitance capacitor (capacitive element). ..
Further, the main control unit 41 has a function as an input control unit that controls to shorten the scan cycle of the key Ky when there is a key Ky whose pressing amount reaches the reference value Th0 described later.

The storage unit 44 has a storage area for each key Ky. Specifically, each of the m-th drive line M and the n-th sensing line N has a storage area, and the voltage detected by the sensing circuit 12 corresponds to the key Ky (m, n). It is stored as the voltage Vk (m, n). Further, the storage unit 44 is set with a timer counter Tc (m, n) for calculating the pressing speed of the key Ky as described later.

The storage control unit 42 acquires a voltage corresponding to a key Ky provided at each intersection based on the voltage generated in the drive line M set to H level and each sensing line N, and stores the acquired voltage in the storage unit 44. Write to the storage area corresponding to each set key Ky. Further, it controls to read out the voltage stored in the storage area. Further, based on the count value stored in the timer counter Tc (m, n) described above, the time from when the key Ky pressing amount reaches the first threshold value Th1 described later to when the second threshold value Th2 is reached is measured. To do. That is, the memory control unit 42 has a function as a required time measurement unit.

The reference value Th0, the first threshold value Th1, and the second threshold value Th2 can be arbitrarily set. Further, if there is a variation between the pressing amount and the generated voltage for each key Ky, in order to correct this variation, the above reference values Th0, the first threshold value Th1, and the second threshold value are used for each key. It is also possible to set Th2 to a different numerical value.

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

The drive circuit 11 selectively has an H level (high level) for a certain period of time for each drive line M (M-1 to Mi) based on a control command (drive control signal) output from the control circuit 15. ) Is applied. Specifically, the voltage of each drive line M is set to H level in the order of M-1, M-2, ..., M-i, M-1 ... The voltage of the other drive line M is L level (low level). The order of applying the voltage is not limited to the above, and the voltage of the drive line M may be selectively set to the H level at regular intervals.

As described above, the H level and the L level of each drive line M can be switched by the control of the drive circuit 11. Therefore, in FIG. 4, this switching is indicated by the switch SW and the arrow indicating the drive control signal for convenience. ing. That is, when a command to set the drive line M to the H level is supplied by the drive control signal output from the control circuit 15, the switch SW is switched from "L" to "H", and the key Ky is set to the H level. Voltage will be applied.

Further, as will be described later, when a pressing amount at which the generated voltage reaches the reference value Th0 is detected by an arbitrary key Ky, the control circuit 15 sets the scanning order so that the scan cycle of the key Ky is shortened. Implement control to change. For example, the key Ky of the pressing amount that reaches the reference value Th0 is controlled to be scanned every four times.

The sensing circuit 12 detects a voltage corresponding to the current flowing through each sensing line N. The details will be described below. As shown in FIG. 4, the sensing circuit 12 includes a series connection circuit of resistors R1 and R2, and the connection point P1 of each of the resistors R1 and R2 is connected to the output end of the key Ky (that is, the electrode Q2 shown in FIG. 3). Has been done. Although one key Ky is shown for each drive line M in FIG. 4, in reality, as shown in FIG. 1, j key Ky are provided for one drive line M. Has been done.

One end of the resistor R1 is connected to the terminal of the power supply voltage VB, and one end of the resistor R2 is connected to the ground. The series connection circuit is provided for each sensing line N as described above, 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 an intermediate value between the power supply voltage VB supplied to the sensing circuit 12 and the ground voltage.

The multiplexer 31 selects a voltage (voltage generated at the connection point P1) according to the current flowing through the sensing line N via each key Ky (Ky (1,1) to Ky (i, j)) at a constant cycle. It is switched uniformly and output to the peak hold circuit 32. Specifically, the keys Ky (1,1), Ky (1,2), Ky (1,3), ... Ky (1, j), Ky (2,1), Ky (2,2), The voltage is output in the order of Ky (2,3), ... Ky (2, j), Ky (3,1), ... Ky (i, j).

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

When the conversion start signal is given by the control circuit 15, the A / D conversion circuit 33 digitizes the peak value of the voltage held by the peak hold circuit 32 and outputs this digital data to the control circuit 15. The peak value digital data is stored in the storage unit 44.

Therefore, when the switch SW shown in FIG. 4 is switched from off to on (that is, the voltage of the drive line M is switched from the L level to the H level), and the key Ky is pressed by the operator's operation at this time. Since the capacitance between the electrodes Q1 and Q2 increases and a current flows, the voltage at the connection point P1 increases. This voltage is supplied to the peak hold circuit 32 via the multiplexer 31, and while being temporarily held by the peak hold circuit 32, it is digitized by the A / D conversion circuit 33 and output to the control circuit 15. To. That is, a voltage that changes linearly with the amount of key Ky pressed is detected.

The main control unit 41 determines whether or not the key Ky is pressed by reading the digitized voltage value. Further, the pressing amount of the pressed key Ky is detected based on the peak value detected by the peak hold circuit 32. Then, the pressing information for 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 temporal change in the pressing amount of the key Ky.

[Explanation of pressing speed detection method]
Next, a method of detecting the pressing speed when the key Ky is pressed will be described. FIG. 5 is a graph showing the change in the pressing amount with respect to the passage of time when the key Ky is pressed. The straight line a1 is pressed with a relatively weak force when the key Ky is pressed with a strong force. It shows the change in voltage that occurs in the key Ky at the time. The amount of key Ky pressed and the voltage generated by the key Ky are not strictly proportional, but here, for convenience, they are proportional. That is, the vertical axis of FIG. 5 is "voltage (pressing amount)".

In the straight line a1 shown in FIG. 5, the amount of pressing the key Ky reaches the first threshold value Th1 at time t1 and reaches the second threshold value Th2 at time t3. Therefore, the pressing speed can be calculated based on the time ΔT21 of t1 to t3. On the other hand, in the straight line a2, the pressing amount reaches the first threshold value Th1 at time t2 and reaches the second threshold value Th2 at time t4. Therefore, the pressing speed can be calculated based on the time ΔT22 of t2 to t4.

However, as described with reference to FIGS. 11 and 12 described above, if the scan cycle of each key Ky is long, the time when the pressing amount reaches the first threshold Th1 and the second threshold Th2 may not be detected with high accuracy. .. In the present embodiment, a reference value Th0 lower than the first threshold value Th1 shown in FIG. 5 is set, and when a key Ky whose pressing amount reaches the reference value Th0 is detected, the scan cycle of this key Ky is shortened. Control to do. The details will be described below.

As described above, if the method of scanning all key ky in sequence is adopted, one scan of all key ky is performed for one key ky during the time from this scan to the next scan. Therefore, it takes a long time. For example, when the total number of keys is 100, the next scan of one key Ky will be performed after the other 99 scans from this scan of one key Ky. In the present embodiment, in order to shorten the scan cycle for the key Ky whose pressing amount has reached the reference value Th0, the scan cycle is set to every four times. That is, scanning is performed at intervals smaller than the total number of keys.

For example, if the amount of key Ky (1,1) pressed reaches the reference value Th0 in the first scan, 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 Scan in the order of (1,9), Ky (1,1), ... Ky (i, j). That is, the key Ky (1,1) is scanned in a short cycle (every 4 times). The present invention is not limited to scanning every four times.

The main control unit 41 shown in FIG. 4 controls the drive control signal output to the drive circuit 11 and the switching control signal output to the multiplexer 31 so that the scan cycle of the key Ky is shortened. Further, when a plurality of (for example, two) key Kys are pressed and the reference value Th0 is reached, the scan cycle of all the pressed keys Ky is shortened.

[Explanation of processing procedure]
Hereinafter, a specific processing procedure of the capacitive keyboard device 10 according to the present embodiment will be described with reference to the flowcharts shown in FIGS. 6 and 7. First, in step S11 of FIG. 6, the main control unit 41 initializes each parameter used in the calculation. Further, the above-mentioned reference value Th0, the first threshold value Th1 and the second threshold value Th2 are set. This process is preset in the main control unit 41 shown in FIG. 4, or can be set by the operator by an initial input operation. Further, all the values of the timer counters Tc (m, n) described later are set to 0, and the code m indicating the drive line (number of rows) and the code n indicating the sensing line (number of columns) shown in FIG. 1 are set to “1”, respectively. Further, the code L indicating the number of scans (details will be described later) between the current scan and the next scan is set to “0”.

In step S12, the main control unit 41 outputs a drive control signal, sequentially switches the voltage applied to each drive line M-1 to Mi to the "H" level, and measures the voltage detected by the sensing circuit 12. To do. Further, the measured voltage is stored in the storage unit 44 in correspondence with the key Ky. Specifically, the voltage Vk (m, n) detected by the key Ky (m, n) in rows m and columns n is stored in the storage unit 44. Initially, since m = 1 and n = 1, the voltage Vk (1,1) detected by the key Ky (1,1) is stored in the storage area set in the storage unit 44.

In step S13, the voltage Vk (m, n) is compared with the reference value Th0. When "Vk (m, n) <Th0", 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 amount of key Ky pressed has reached the reference value Th0, and F1 (m, n) is a parameter indicating that the amount of key Ky pressed has reached the second threshold Th2. Is. On the other hand, when "Vk (m, n) ≥ Th0", it is determined that the key Ky (m, n) has been pressed, and F0 (m, n) is set to "1" in step S15. To do.

In step S16, the main control unit 41 increments the parameter L indicating the number of scans of the interval (L = L + 1), and further determines in step S17 whether or not “L = 3”. If “L = 3”, a high-speed scan is performed in step S18. If it is not “L = 3”, the process proceeds to step S20 without performing the high-speed scan. The “high-speed scan” refers to the processing procedure from step S51 to step S63, and includes voltage measurement for the key ky that has reached the reference value Th0 by interrupting the normal scan that scans all the key ky in sequence. It is a process.

Hereinafter, the high-speed scan processing procedure shown in step S18 of FIG. 6 will be described with reference to the flowchart shown in FIG. 7. First, in step S51 of FIG. 7, the code m'indicating the number of rows and the code n'indicating the number of columns are initialized. That is, "m'= 1" and "n'= 1". In FIG. 7, "'" is added to each of the reference numerals m and n in order to distinguish them from m and n used in the flowchart of FIG.

In step S52, the main control unit 41 determines whether or not “F0 (m', n') = 1” is set for the target key Ky. When the process of step S15 shown in FIG. 6 is executed, that is, when the key Ky (m', n') is pressed and the voltage reaches the reference value Th0, a YES determination is made in step S52. The process proceeds to step S53. On the other hand, in the case of NO determination, the target key Ky is not scanned, and the process proceeds to step S60.

In step S53, the main control unit 41 determines whether or not "F1 (m', n') = 1". As described above, F1 (m, n) becomes "1" when the pressing amount reaches the second threshold Th2, so that it is initially "0", and a NO determination is made, and step S54 is performed. Proceed with processing.

In step S54, the main control unit 41 measures the voltage Vk (m', n') generated in the key Ky (m', n'). In this process, the voltage generated in each key Ky is measured in sequence like the keys Ky (1,1), Ky (1,2), ..., But in reality, in S13 of FIG. Since voltage detection is executed only for the key Ky for which pressing is detected, 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 as compared with the processing shown in S12 of FIG.

In step S55, it is determined whether or not the voltage Vk (m', n') detected by the key Ky (m', n') is equal to or higher than the first threshold value Th1. If the first threshold Th1 has not been reached (NO in step S55), the process proceeds to step S60. That is, when the voltage does not reach the first threshold value Th1, it is not necessary to calculate the pressing speed, so the processes of steps S56 to S59 described later are not performed.

On the other hand, when the first threshold value is Th1 or more (YES in step S55, corresponding to t7 in FIG. 9 described later), in step S56, the timer counter Tc (m', n') for the key Ky (m', n') Increment n'). As described above, the timer counter Tc (m', n') is initially "0".

In step S57, the main control unit 41 determines whether or not the voltage Vk (m', n') detected by the key Ky (m', n') is equal to or higher than the second threshold value Th2. If the second threshold Th2 has not been reached (NO in step S57), the process proceeds to step S60. If the second threshold value is Th2 or more (YES in step S57, corresponding to t22 in FIG. 9), the process proceeds to step S58.

In step S58, the main control unit 41 outputs the timer counter Tc (m', n') for the key Ky (m', n') to the host computer 16 from the output interface 43 shown in FIG. The host computer 16 calculates the pressing speed when the key Ky (m', n') is pressed based on the timer counter Tc (m', n'). That is, since the time from the first threshold Th1 to the second threshold Th2 for the voltage generated by pressing the key Ky is detected, the pressing speed when the key Ky is pressed can be calculated.

In step S59, the main control unit 41 sets the timer counter Tc (m', n') to "0" and the parameter F1 (m', n') to "1". By setting the parameter F1 (m', n') to "1", in the next process, a YES determination is made in step S53 of FIG. 7, and the voltage is not measured.

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

In step S62, the main control unit 41 sets m'to be "1" and increments n'. In step S63, the main control unit 41 determines whether or not n'is j + 1 (j is the number of columns). That is, it is determined whether or not the last row has been reached. If n'= j + 1 is not satisfied (NO in step S63), the process returns to step S52. If n'= j + 1 (YES in step S63), the process proceeds to step S19 in FIG.

In step S19 of FIG. 6, the main control unit 41 sets “L = 0” and proceeds to step S20.
In step S20, the main control unit 41 increments m, and in step S21, determines whether or not m = i + 1. If m = i + 1 (NO in step S21), the process returns to step S12, and if m = i + 1 (YES in step S21), the process proceeds to step S22.

In step S22, the main control unit 41 sets m to "1" and increments n. In step S23, the main control unit 41 determines whether or not n has become j + 1. That is, it is determined whether or not the last row has been reached. If n = j + 1 (NO in step S23), the process returns to step S12. If n = j + 1 (YES in step S23), n is incremented in step S24 and the process is returned to step S12.
In this way, each drive line M and sensing line N can be scanned, the amount of key Ky pressed when the voltage value reaches the reference value Th0 is measured in a short cycle (every four scans), and the pressing speed can be calculated. it can.

FIG. 8 is a graph showing the relationship between the passage of time and the voltage generated in an arbitrary key Ky, and changes in the parameters F0 and F1 and the timer counter Tc described above.
As shown in FIG. 8A, when an arbitrary key Ky is pressed, the voltage generated in this key Ky gradually increases, and then when the key is released, the voltage gradually decreases. When the voltage reaches the reference value Th0 at time t31, the parameter F0 is switched from "0" to "1" as shown in FIG. 8B. That is, the process of step S15 of FIG. 6 is executed.

When the voltage reaches the first threshold Th1 at time t32, the timer counter Tc starts counting as shown in FIG. 8D. That is, the process of step S56 of FIG. 7 is executed.
When the voltage reaches the second threshold value Th2 at time t33, the parameter F1 is switched from "0" to "1" as shown in FIGS. 8C and 8D. Further, the timer counter Tc ends the count. That is, the process of step S59 in FIG. 7 is executed. Since the timer count value X1 at this time indicates the time required for the key pressing amount to reach the first threshold Th1 to the second threshold Th2, it corresponds to the pressing speed of the key Ky. This timer count value is output to the host computer 16 from the output interface 43 shown in FIG.

When the voltage drops below 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 executed. Next, at time t35, the key Ky is pressed again and the pressing amount is maintained until the reference value Th0 is reached. In this way, the timer count value X1 is obtained and transmitted to the host computer 16, so that the host computer 16 can calculate the pressing speed when the key Ky is pressed.

Next, the scan timing of the key Ky and the change in voltage due to the above processing will be described with reference to the graph shown in FIG.
FIG. 9 is a characteristic diagram showing the scanning timing when the key Ky (1,1) is pressed and the change in voltage caused by the pressing. By setting L = 3 in the process of step S17 of FIG. 6, the key Ky (1,1) is scanned at three intervals (that is, every four times). Therefore, as shown in FIG. 9, the scan is performed at the timings t2, t3, ... T22, and t23. It is understood that the scan cycle is shorter than the scan cycle shown in FIG. 5 described above. Therefore, it is detected that the voltage reaches the reference value Th0 at the time t2 shown in FIG. 9, the voltage reaches the first threshold value Th1 at the time t7, and the voltage reaches the second threshold value Th2 at the time t22. it can.

Therefore, it is possible to detect with high accuracy the time ΔT from when the pressing amount of the key Ky (1,1) reaches the first threshold value Th1 to when it reaches the second threshold value Th2. As a result, it is possible to calculate the pressing speed when the key Ky (1,1) is pressed with high accuracy.

In this way, in the capacitive keyboard device 10 according to the first embodiment, a plurality of key Kys are scanned in sequence, and one key Ky (in the above example, the key Ky (1,1)) is pressed. When it is detected that the amount has reached the reference value Th0, the scan cycle is shortened for this key Ky. Specifically, this key Ky scan is performed every four scans. Therefore, the resolution of pressing amount detection is improved, and the time when the pressing amount of the key Ky reaches the first threshold value Th1 and the time when the pressing amount reaches the second threshold value Th2 can be detected with high accuracy. As a result, the pressing speed can be calculated with high accuracy, which is extremely useful when used as a MIDI keyboard.

Further, when the pressing amount of the key Ky reaches the second threshold value Th2, the voltage in the high-speed scan and the counter timer are not incremented thereafter for this key Ky. That is, when the pressing amount (voltage value) of the key Ky reaches the second threshold value Th2, a 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 scan, a YES determination is made in the process of step S53, and the voltage measurement in step S54 and the count timer in step S56 are not incremented. Therefore, it is possible to prevent unnecessary calculation from being performed and reduce the calculation load.
Next, even if the key Ky is released and the pressing amount is reduced, the parameter F1 is set to "1", so that the above state is maintained. Further, the amount of key Ky pressed is once reduced to less than the reference value Th0, and is maintained until the reference value Th0 is reached again.

[Explanation of the second embodiment]
Next, the second embodiment of the present invention will be described. Since the apparatus configuration is the same as that shown in FIGS. 1 and 4, the description of the configuration will be omitted. The second embodiment is different from the first embodiment described above in that a third threshold value Th3 larger than the second threshold value Th2 is set in addition to the first threshold value Th1 and the second threshold value Th2 described above. That is, the threshold value of the pressing amount of the key Ky is set to 3 or more.

FIG. 10 is a graph showing the scan timing when the pressing amount of the key Ky (1,1) reaches the reference value Th0 and further reaches the first threshold Th1, the second threshold Th2, and the third threshold Th3. .. Specifically, when the reference value Th0 is reached at time t2, the first threshold value Th1 is reached at time t7, the second threshold value Th2 is reached at time t14, and the third threshold value Th3 is reached at time t22. Shown.

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 a plurality of threshold values can be measured. Therefore, the pressing speed can be obtained by selecting any one of the times ΔT1, ΔT2, and ΔT3.

According to the second embodiment of the present invention, for example, the pressing amount increases in the order of Th0 → Th1 → Th2 → Th3, then is returned to the pressing amount between Th1 and Th2, and changes so as to exceed Th2 → Th3 again. There are times. In such a case, it is possible to express the feeling of repeated striking of an acoustic piano by obtaining the pressing speed using ΔT2, which is the time between Th2 and Th3.

As described above, in the capacitive keyboard device according to the second embodiment, by setting the third threshold value Th3 in addition to the first and second threshold values, it is possible to calculate the pressing speed more versatilely. Become. Therefore, when used as a keyboard for a MIDI device, it is possible to output a timbre closer to the sound source of the musical instrument itself according to the type of the musical instrument.

[Explanation of Third Embodiment]
Next, a third embodiment of the present invention will be described. Since the apparatus configuration is the same as that shown in FIGS. 1 and 4, the description of the configuration will be omitted. In the third embodiment, the scanning order is changed when another key Ky is pressed while one key Ky is pressed and the pressing speed is calculated.

When the two keys Ky (1,1) and Ky (1,2) are pressed and the pressing amount reaches the reference value Th0, the scanning order 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 key Kys are pressed, the pressed key Ky is scanned every time the other keys Ky are scanned three times. By doing so, even when a plurality of key Kys are pressed, the scan cycle of the pressed keys Ky can be shortened, and highly accurate pressing speed calculation can be performed.

Although the capacitive keyboard device of the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is an arbitrary configuration having the same function. Can be replaced with.

For example, in the above-described embodiment, the key Ky is arranged at the intersection of each drive line M and each sensing line N, but the present invention is not limited to this, and the key Ky is not limited to this. There may be a place where is not arranged. Further, the number of drive lines M and the number of sensing lines N may be the same. That is, i = j can also be set.

Further, in the above-described embodiment, an example in which the resistance values of the two resistors R1 and R2 provided in the sensing circuit 12 are the same has been described, but the present invention is not limited to this, and different resistance values may be used.

10 Capacitive keyboard device 11 Drive circuit 12 Sensing circuit 15 Control circuit 16 Host computer 21 Board 22 Housing 23 Coil spring 24 Rubber 25 Plunger 26 Key top 31 multiplexer 32 Peak hold circuit 33 A / D conversion circuit 41 Main control unit 42 Memory control unit 43 Output interface 44 Storage unit Q1, Q2 Electrode R1 Resistance R2 Resistance SW switch

Claims (4)

A plurality of drive lines and a plurality of sensing lines intersecting the drive lines,
Keys provided at the intersection of each drive line and each sensing line,
A capacitance element provided on each of the keys and whose capacitance between the drive line and the sensing line changes according to the amount of pressing the key.
A pressing amount detection unit that scans each key and detects the pressing amount of the key based on the change in capacitance of the capacitance element.
An input control unit that controls to perform a high-speed scan that shortens the scan cycle of this key when the pressing amount detected by the pressing amount detection unit reaches a preset reference value.
A first threshold value larger than the reference value and a second threshold value larger than the first threshold value are set, and the time required from when the key press amount reaches the first threshold value to when the second threshold value is reached is measured. Equipped with a required time measurement unit
The input control unit
When the amount of pressing one key reaches the second threshold value, control is performed so that the execution of the high-speed scan by the one key is stopped until the amount of pressing one key becomes less than the reference value. capacitive keyboard apparatus characterized by. The input control unit scans all the keys in order when the pressing amount of all the keys does not reach the reference value, and when the pressing amount of one key reaches the reference value, the input control unit scans all the keys in order. The capacitive keyboard device according to claim 1 , wherein the high-speed scanning is performed on the one key. The capacitance according to claim 2, wherein when there are a plurality of keys whose pressing amount reaches the reference value, the input control unit performs the high-speed scan on all of the plurality of keys. Type keyboard device. The capacitance according to any one of claims 1 to 3 , wherein a threshold value for the amount of pressing the key is set to 3 or more, and the required time measuring unit measures the required time between a plurality of threshold values. Capacitive keyboard device.

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