JP3096546B2 - Touch detection device for electronic musical instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch detection device using an optical switch for detecting a key touch state in a keyboard device of an electronic musical instrument such as a synthesizer, an electronic piano, an electronic organ and a single keyboard. About.

[0002]

2. Description of the Related Art In recent years, electronic musical instruments having various functions have become widespread and widely used. In particular, FIG. 5 shows a typical main configuration of many electronic musical instruments having many sound sources built in one housing.

That is, a central processing unit (CPU), a read-only memory (ROM), and a random access memory (RA)
M), sound source (SG), etc., as well as MIDI (Musical Instrument Digital Interfa
Various inputs and outputs are possible through terminals, and a wide variety of usages are developed and widely used.

Normally, in the keyboard device KBD used for such an electronic musical instrument, it is not enough to detect the presence or absence of a key depression in terms of music expression, and it depends on the velocity, acceleration, pressure and the like of the key depression. Differences, ie key touches, must also be considered.

[0005] For this purpose, a touch detection device TD that generates different touch data according to the state of key depression.
It has. The touch data generated by the touch detection device TD is converted into, for example, velocity data or the like and given to a sound source in order to generate a musical sound having a volume or tone corresponding to a key touch.

By employing such a touch detection device TD, it is possible to express subtle changes in timbre, volume and the like in accordance with the strength of key depression, thereby enabling emotional performance.

The touch detection device TD includes a first switch that operates at an early point in time after the start of key depression and a second switch that operates at a point in time when the key depression operation proceeds. Open / close signal time difference (see Fig. 6)
In many cases, touch data is generated on the basis of touch data.

[0008] As the touch detection device conventionally used, there have been many touch detection devices formed of a two-pole spring switch for electrically opening and closing the first switch and the second switch, and a rubber switch.

In the method of opening and closing the spring switch,
For example, switches that are mechanically opened and closed two by two for each of the 88 keys are used, and there is a possibility that an erroneous signal may be generated due to a defective contact or a deteriorated spring. The problem in the point was pointed out.

Although the rubber switch does not use a spring or a metal contact which is liable to be deteriorated, it has a drawback that the electric resistance at the time of forming the closed circuit is large, and the voltage drop and the power consumption are large. Furthermore, rubber and springs also have an effect on the key touch feeling.

In consideration of such circumstances, a system using an optical switch combining a light emitting diode (LED) and a phototransistor whose output is turned on / off according to the presence or absence of incident light has been adopted.

The touch detection device TD using such an optical switch has switches S1 and S2 as shown in the waveform of FIG.
In addition to the fact that the timing of the generated signal is accurate, there is an advantage that it has no contact point, has a long life, has no effect on key touch, and is also effective in reducing the size and weight of the electronic musical instrument. .

However, when an optical switch is used, FIG.
Two light emitting diodes per key (LE
D) 1 and 2 are always lit, and switches S1 and S2
The optical path to the phototransistors 3 and 4, which are the signal generating units, is blocked by a shutter 6 attached to the key 5.

In this case, the shutter 6 has switches S1,
The height of the light shielding portion differs depending on S2. Therefore, there is a time difference in the light passing through the phototransistors 3 and 4 according to the key touch, and the touch data is often detected from this value.

Since two light emitting diodes (LEDs) 1, 2 of such an optical switch are required for each key, for example, in an 88-key electronic musical instrument, the number becomes 176.

Normally, four light emitting diodes having a rated capacity of about 25 mA are connected in series and light is applied by applying a voltage + V. Therefore, in order to always light all the light emitting diodes, 176 ÷ 4 × 25 = 1100 mA Requires a large current capacity and therefore a large power consumption.

When the power consumption is large,
The power supply device is large, which is contrary to the demand for miniaturization and portable convenience. In addition, the heat generated inside the electronic musical instrument increases, and the usable time of the portable electronic musical instrument, which sometimes uses a battery as a power source, is reduced.

In an electronic musical instrument having a built-in secondary battery,
There is a disadvantage that the battery capacity needs to be increased, and the required charging time becomes longer.

FIG. 8 shows a touch detection device T according to the prior art.
3 shows a configuration example of D.

The touch detecting device TD includes a light emitting diode group (88 × 2 to provide two keys for each key of a keyboard).
= 176) LED and 176 phototransistors as light receiving elements (8 × 11 blocks × 2 = 176)
And a phototransistor matrix circuit PTM.

The optical path between the light emitting diode group LED and the phototransistor matrix circuit PTM is configured to be opened and closed by a shutter SH linked to each key.

In such a circuit configuration, when the scanning signals SC4 to SC1 to the touch detection device TD are input via the decoder DC, the outputs SWAX0 to SWAX7 of the switch S1 are output.
The output SWBX 0-7 of the switch S2 is generated.

In the conventional touch detection device TD using such an optical switch, all the LEDs of the light emitting diode group are used.
Has a drawback that power consumption and voltage drop are large because it is always lit.

[0024]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has improved a touch detection device using an optical switch having excellent responsiveness and long life so as to achieve excellent performance with low power consumption. It is an object of the present invention to provide a touch detection device for an electronic musical instrument exhibiting the following.

[0025]

SUMMARY OF THE INVENTION According to the present invention, a first switch which is activated at an early time after the start of a key depression operation and a second switch which is activated at a time when the key depression operation is advanced are provided for each key. , And each of these switches is a touch detection device for a keyboard of an electronic musical instrument constituted by an optical switch composed of a light emitting diode and a phototransistor, wherein an operation circuit of a light emitting diode forming the first switch is integrated. The light emitting diodes of the first switch group (S1) are always lit, and when the operation of at least one switch in the first optical switch group is detected, the light emitting diodes of the second switch group are formed. Key-pressing operation state at the point in time when key-pressing operation is advanced by starting light emission of the light-emitting diodes of the second switch group (S2) integrated with the operation circuit Allows the detection, further wherein the first
If all of the switch groups (S1) are not detected, that is, if all keys are released, the electronic control unit includes a switching unit for turning off the light-emitting diode of the second switch group (S2). It is a touch detection device for musical instruments.

Further, the first and second switch groups are divided into blocks each having an appropriate number of keys, and according to the operation of the first optical switch, the first and second switches belong to the block to which the first switch belongs. This is more advantageously solved by a touch detection device for an electronic musical instrument, comprising a switching means for selectively illuminating a light emitting diode block of a corresponding second optical switch group.

[0027]

The touch detection device for an electronic musical instrument according to the present invention comprises:
Normally, only the light emitting diode group of the first optical switch S1 is turned on, and the light emitting diode group of the second optical switch S2 is not turned on.

When one of the keys is depressed and the central processing unit CPU detects that the first optical switch S1 has been operated, it generates a signal CS2, and the second optical switch is operated by the switching means operated by this signal. Control is performed so that the light emitting diode group of S2 is turned on.

Therefore, when no key is depressed, the power consumption is halved, and significant power saving is achieved.

Here, the minimum required time from the activation of the first optical switch S1 to the lighting of the second optical switch is 1 to 3.
Since the time is 2 msec, the above configuration can sufficiently cope with the case where the key operation is performed at the highest speed.

The light emitting diode L of the second optical switch S2
The condition for turning off the ED is when the first optical switches S1 are all turned off or when the light reception of the phototransistors corresponding to all the second optical switches is extinguished.

This is when it is detected that all the keys are in the released state or that at least all of the second optical switches are not depressed until the conditions for activating them.

[0033]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a touch detection device for an electronic musical instrument according to the present invention.

FIG. 1 shows a first example of the configuration of a touch detection device 10 for an electronic musical instrument according to the present invention.
Lighting circuits for the light emitting diode groups corresponding to the number of times are formed separately in the first LED group 12 and the second LED group 14.

The electronic musical instrument touch detection device 10 shown here
Is formed in the same manner as in the conventional case with respect to the light receiving transistor matrix 16.

Here, the first LED group 12 is always lit while the power switch is on, but the second LED group 12 is turned on.
Group 14 does not light at this stage.

At least one of the keys is depressed to operate a shutter (not shown), and the operation of the first switch S1 is detected by the output signal SWAX7-0 of the phototransistor. .

A CPU (not shown) outputs a signal CS.
2. Output a low level here. Upon receiving this output, the transistor 22 serving as the switching means is activated,
+ V is applied to the second LED group 14 to emit light.

The scanning signals SC 4-1 are applied to the light receiving transistor matrix 16 via the decoder 18,
SWB which is the output signal of the phototransistor belonging to each of the optical switch S1 and the second optical switch S2 of FIG.
X7-0 are obtained.

With this configuration, when no key is depressed, the second LED group 14 is not turned on, so that the power consumption is reduced.

FIG. 2 is a flowchart showing these operations. With the start of the flow, it is determined whether or not any of the first switches has been operated, and the process waits until the operation is detected (step S1).

Output SW when the first switch is operated
The CPU receiving AX7-0 generates a signal CS2 and transmits it to the switching means (step S2). This output CS2
This causes the second LED group to emit light (step S3).

Thereafter, the light is emitted until all the keys are released (step S4). When the release of all keys is confirmed, the second LED group is turned off (step S5), and the routine returns.

FIG. 3 shows another embodiment of the touch detection device, in which the first LED group 26 and the second LED group 24 are appropriately divided into blocks B1, B2, B3,. It was done.

A signal SWAX from the light receiving transistor matrix indicates that one of the first switches S1 has been activated.
Upon detection by 7 to 0, a CPU (not shown) outputs a signal corresponding to the second LED block among the signals CS21 to CS2n.

Any of the transistors 32 corresponding to the signals CS21 to CS2n causes only the LEDs of the corresponding blocks B1, B2, B3,... Bn to emit light.

During this time, the second LED group 24 of the block in which the switch S1 is not operated is not lit, so that low power consumption is achieved. For example, even when two or three blocks are turned on, power saving of about 1/4 to 1/3 can be achieved.

In this case, the block division of the light emitting diode can be appropriately divided, but may be related to the scanning signal or irrelevant.

The entire keyboard can be equally divided, or the center can be subdivided in consideration of the frequency of key depression, and a large number of keys can be divided into blocks near both ends. Also,
It can be appropriately selected according to the form and type of the electronic musical instrument.

FIG. 4 is a flowchart showing the operation state of the second embodiment. With the start of the flow, it is determined whether or not any of the first switches S1 has been operated, and the process waits until the operation is detected (step S11).

Next, the block to which the activated switch S1 belongs determines one of B1, B2,..., Bn (step S12).

In response to this determination, the CPU sends the signal CS2 1
~ N are generated and transmitted to the corresponding block switching means (step S13). As a result, the second LED group of the corresponding block emits light (step S14).

The light emission of the LED operating in this manner is as follows.
It is determined whether all the keys belonging to the block have been released (step S15). If the keys have been released, the second LED group is turned off (step S16), and the process returns.

[0054]

As described above in detail, according to the present invention, the touch detection device in an electronic musical instrument having a keyboard is constituted by an optical switch, and the power consumption of a light emitting diode as a light source of the optical switch is reduced as much as possible. Can be reduced.

If all keys are not pressed, the power consumption is at least １ ／. Therefore,
The required power supply capacity for achieving the same performance is reduced, miniaturization and weight reduction are achieved, and portability is improved. Since a small battery can be adopted, it can contribute to cost reduction.

In the case of a type using a secondary battery, the required charging time can be shortened, the size of the replacement battery pack can be reduced, and an electronic musical instrument suitable for outdoor use can be obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment of a touch detection device according to the present invention.

FIG. 2 is a flowchart showing a processing flow in the touch detection device of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a second embodiment of the touch detection device according to the present invention.

FIG. 4 is a flowchart showing a processing flow in the touch detection device of FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of an electronic musical instrument including a keyboard device.

FIG. 6 is a waveform diagram showing a relationship between switch output signals for touch detection.

FIG. 7 is an explanatory diagram of a key touch detection mechanism using an optical switch.

FIG. 8 is a diagram illustrating a configuration of a touch detection device using an optical switch according to the related art.

[Explanation of symbols]

10 Touch detection device (TD) 12, 26 First light emitting diode group (switch S
1) 14, 24 Second light emitting diode group (switch S
2) 16 light receiving transistor matrix 18 decoder 22, 32 transistor (switching means)

Claims (2)

(57) [Claims] 1. A first switch that operates at an early point in time after the start of a key press operation, and a second switch that operates at a point in time when the key press operation proceeds.
And a switch for each key, wherein each of the switches is a light emitting diode forming the first switch in a keyboard touch detection device of an electronic musical instrument constituted by an optical switch including a light emitting diode and a phototransistor. The light emitting diodes of the first switch group (S1) integrated with the operation circuit of (1) are constantly lit, and when the operation of at least one switch in the first optical switch group is detected, the second The light emitting diode of the second switch group (S2), in which the operation circuit of the light emitting diode forming the above switch is integrated, starts emitting light to enable detection of the key pressing operation state at the time when the key pressing operation proceeds. If not all of the first switch group (S1) is detected, the second switch group (S2) is not detected.
A touch detection device for an electronic musical instrument, comprising: switching means for turning off light emission of the light emitting diode. 2. The first switch group (S1) and the second switch group (S2) are appropriately divided into blocks each having the number of keys, and each of the first switch group (S1) and the second switch group (S2) is divided into blocks each having an appropriate number of keys. 2. The electronic musical instrument according to claim 1, further comprising: means for selectively causing only the light emitting diodes of the blocks of the second switch group corresponding to the block to which the activated first switch belongs to to emit light. Touch detection device.