Digital piano tuning device

Abstract

The present invention provides a tuning device for a digital piano, the device including: a support that forms a key or the underside of the key; and a base plate that faces the support and is arranged on the underside at a predetermined distance; the underside of the support plate is provided with a first moving section, a second moving section that is arranged at a predetermined distance from the first moving section and aligned with the first moving section, and a counter moving section that is arranged at a predetermined distance from the second moving section and aligned with the second moving section; the base plate is provided with a first sensor, a second sensor and a counter sensor that detect the first moving section, the second moving section and the counter moving section, respectively, and is provided with slots through which the first moving section, the second moving section and the counter moving section can pass as they move downward; when the key is pressed, the counter sensor detects the degree of pressure of the key by the downward movement of the counter moving section.

Description

[Technical field]

[0001] The present invention relates to a tuning device for a digital piano. [Background technology]

[0002] A digital piano is a type of keyboard designed as an alternative to the playing style and sound of a traditional piano. It provides an accurate simulation of an acoustic piano (analog piano). Digital pianos are designed to look like a regular piano, such as an upright or grand piano. Digital piano sounds are created by using synthetic emulation or real piano samples to match stored sounds with the touched key positions, and then transmitting the stored sounds through speakers. Digital pianos come in three types: 88 keys, 76 keys, and 61 keys, but 88 keys are the most commonly used.

[0003] Digital pianos have the advantages of being less expensive to maintain than acoustic pianos, having MIDI sound, built-in functions to help with learning and composing, not needing a microphone, and being easy to carry. Digital piano keys are made to feel similar to acoustic pianos and are speed-responsive, so the volume and timbre of the played sound depend on the speed of the key. Digital pianos have hammers to give the feel of an actual piano touch. They differ from ordinary electronic keyboards and synthesizers in that they have analog sensors to detect key pressure. Some digital pianos have built-in pedals, but those that have the function of adjusting the damper by pressing the pedals for resonance like acoustic pianos are very expensive.

[0004] Korean Patent Publication No. 10-1014809 discloses the structure of a digital piano key. As shown in Fig. 7, the structure of the digital piano key includes a frame 120' that accommodates a key 130', a hammer 140' that is rotatably attached to the key 130', and a rubber switch 150' that is attached adjacent to the pivot point of the hammer 140'. The key modules are arranged at regular intervals, with one octave being one module, to form seven octaves.

[0005] By providing the storage space 122' of a fixed size, the keys 130' consisting of the white keys 130a' and the black keys 130b' are stored without error while maintaining a predetermined interval. A locking portion 124' is provided to prevent the keys 130' from falling out.

[0006] The key 130' includes a body 132' which forms the part touched by the player, and an extension 134' extending from the body 132'. A locking protrusion 133a' is provided at a predetermined position on the bottom of the body 132', which engages with the locking part 124' to prevent the key 130' from coming off the frame 120'. The extension 134' extends from one side of the body 132', and is provided with a vibration adjustment part 134a' which penetrates vertically at a certain position so that an elastic member 170' can be inserted therein.

[0007] The hammer 140' includes a weight portion 142' having a weight body 142a' and a pivot coupling portion 144' provided on one side of the weight portion 142' and pivotally coupled to the key 130'. The pivot coupling portion 144' includes a fixing protrusion 146' pivotally fastened to one side of the key 130'.

[0008] The rubber switch 150' is installed at a position adjacent to the pivot point of the hammer 140'. In more detail with reference to Fig. 8, a rubber cap 152' made of a rubber material is installed at a position facing a contact part 162' provided on a printed circuit board 160', and a relief protrusion 154' is provided at the bottom of the rubber cap 152', which is grounded and electrically connected to the contact part 162'. When the key 10' is pressed, the rubber cap 152' comes into contact with the contact part 162' provided on the printed circuit board 160' and is electrically connected to be turned on / off. The insertion protrusion 155' is inserted into a coupling hole 166' provided through the printed circuit board 160'.

[0009] Currently, in the tuning of a digital piano, as shown in Fig. 9, a rubber dome 100' corresponding to a relief protrusion 154' has a first rubber dome 102' inserted in a long column and a second rubber dome 104' arranged in a relatively short column on the underside of the rubber dome 100', and a first contact portion 102a' and a second contact portion 104a' are provided on a PCB board 106' facing them. Even if the underside of a key 100k' is kept parallel when the rubber dome 100' is pressed, the first rubber dome 102' contacts the first contact portion 102a' first, and the second rubber dome 104' contacts the second contact portion 104a' second, due to the difference in height.

[0010] Here, when the player presses the key 100k', as shown in Fig. 10, the smaller the time difference (T) between the first rubber dome 102' and the first contact portion 102a', and between the second rubber dome 104' and the second contact portion 104a', the smaller the volume of the sound that is output, and vice versa. In other words, the faster the player presses the key, the louder the volume becomes, and the slower the player presses the key, the quieter the volume becomes.

[0011] However, this method cannot realize the effect of an acoustic piano, where a loud sound is output when the key is pressed hard, i.e., deeply, and a soft sound is output when the key is pressed softly, i.e., only lightly. Depending on how deeply the key is pressed, effects such as tone, strength, and softness as well as the volume change, but current digital pianos are limited in that they cannot reflect this function.

[0012] The present invention has been devised to solve all of the problems of the prior art and prior patents described above at once. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Korean Patent No. 10-1014809 Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, the present invention aims to provide a new type of tuning device for a digital piano that can adjust the velocity so as to adjust the sound depending on the amount of pressure, i.e., the distance traveled, of the key of the digital piano, from a perspective completely different from that of the prior art. [Means for solving the problem]

[0015] In order to achieve the above-mentioned object, the present invention provides a tuning device for a digital piano, the device including: a support that forms a key or the underside of the key; and a base plate that faces the support and is arranged on the underside at a predetermined distance; the underside of the support plate is provided with a first moving part, a second moving part that is arranged at a predetermined distance from the first moving part and aligned with the first moving part, and a counter moving part that is arranged at a predetermined distance from the second moving part and aligned with the second moving part; the base plate is provided with a first sensor, a second sensor and a counter sensor that detect the first moving part, the second moving part and the counter moving part, respectively, and is provided with slots through which the first moving part, the second moving part and the counter moving part can pass when they move downward; and when the key is pressed, the counter sensor detects the degree of pressure of the key by the downward movement of the counter moving part.

[0016] The first sensor can detect the time when the first moving part passes the first sensor when the key is pressed, and the second sensor can detect the time when the second moving part passes the second sensor when the key is pressed.

[0017] The tuning device includes a control unit that adjusts the sound of the digital piano, and the control unit can determine a primary velocity based on the time difference between the passing time of a first moving part measured by the first sensor and the passing time measured by the second sensor.

[0018] The control unit may increase or decrease the first velocity according to the downward movement amount of the counter movement unit measured by the counter sensor, thereby determining the final velocity.

[0019] The counter movement part has light-shielding parts and light-transmitting parts alternately arranged in multiple rows from the bottom along the height direction, and the counter sensor can detect the amount of downward movement of the counter movement part by counting the passing digits of the light-shielding parts or light-transmitting parts when a key is pressed.

[0020] Each of the first sensor, the second sensor and the counter sensor may be a color sensor, a light sensor, an infrared sensor or a photointerrupter.

[0021] The present invention also provides a tuning device for a digital piano, comprising: an MCU on a main board; and a plurality of keyboards communicating in series with the MCU, the MCU further comprising a key lighting system connected to a wireless or wired device, the keyboards being provided with a plurality of LED lights, the wireless or wired device incorporating an app or program for adjusting the hue and intensity of the LED lights of the keys, and allowing a user to actively set and input the color of the LED lights and the intensity of the color.

[0022] The present invention also provides a tuning device for a digital piano, comprising: an MCU on a main board; and a plurality of keyboards communicating in series with the MCU, the MCU further comprising a key lighting system connected to a wireless or wired device, the keyboard being provided with a plurality of LED lights, the wireless or wired device incorporating an app or program for selecting the hue of the LED lights of the keys, the user actively setting and inputting the color of the LED lights, and the intensity of the color being automatically adjusted according to the final velocity.

[0023] The present invention also provides a tuning device for a digital piano, the device including a support forming a key or an underside of the key, and a base plate facing the support and disposed below at a predetermined distance, the underside of the support being provided with a counter movement portion, The present invention provides a tuning device for a digital piano, in which a counter sensor is provided on the substrate to detect the amount of pressure applied to the counter moving part, the counter moving part being arranged in multiple rows with light-shielding parts and light-transmitting parts alternately arranged from the bottom along the height direction, and the counter sensor counts the number of times the light-shielding parts or light-transmitting parts pass when a key is pressed to detect the amount of downward movement of the counter moving part.

[0024] The present invention also provides a tuning device for a digital piano, the device including a support forming a key or an underside of the key, and a base plate facing the support and disposed below at a predetermined distance, the support having a counter movement portion disposed on the underside thereof, A counter sensor is provided on the substrate to detect the amount of pressure applied to the counter moving part, the counter moving part being arranged in multiple rows with first and second color parts repeated from the bottom along the height direction, and the counter sensor counts the passing digits of the first or second color part when a key is pressed to detect the amount of downward movement of the counter moving part, thereby providing a tuning device for a digital piano. Effect of the Invention

[0025] The present invention controls the sound, including the increase and decrease in volume, according to the distance the digital piano keys are moved, i.e., the degree of pressing, so that the same effect as pressing the keys on an analog piano can be achieved, and realistic music can be played by making the most of the player's skill.

[0026] To improve marketability of a digital piano by focusing the attention of an audience and improving the atmosphere by displaying various hues by keys and varying the brightness of the hues by the degree of pressing of the keys when the digital piano is played.

[0027] The present invention allows a performer or user to actively set the hue and hue intensity in advance using a wireless device before a performance, thereby producing a variety of atmospheres. [Brief description of the drawings]

[0028] [Figure 1] 1 is a configuration diagram of a tuning device for a digital piano according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing a case where a user presses a key in the tuning device of the digital piano according to the embodiment of the present invention. [Diagram 3] FIG. 11 is a configuration diagram of a tuning device for a digital piano according to another embodiment of the present invention. [Figure 4]4 is a diagram showing a case where a user presses a key in the tuning device of the digital piano according to the embodiment of FIG. 3. FIG. [Diagram 5] FIG. 1 illustrates a key lighting system of the present invention. [Figure 6] FIG. 13 is a diagram illustrating an example of an LED adjustment guide provided by an app on a wireless device. [Figure 7] FIG. 1 illustrates the structure of a key of a prior art digital piano. [Figure 8] FIG. 2 is a diagram showing a rubber part of the key structure of FIG. 1. [Figure 9] FIG. 1 is a diagram for explaining a volume adjustment method for a digital piano according to currently common technology. [Figure 10] FIG. 4 is a diagram for explaining a volume control method based on a time difference in the prior art of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Each embodiment of the present invention is merely an example for aiding in understanding the present invention, and the present invention is not limited to such an embodiment. The present invention may be configured by combining at least one or more of the individual configurations and individual functions included in each embodiment.

[0030] The present invention is characterized in that, in order to adjust the sound of a digital piano, the volume is adjusted by taking into consideration a parameter according to the depth of key depression in addition to the velocity according to the speed difference.

[0031] FIG. 1 is a configuration diagram of a tuning device 1 for a digital piano according to an embodiment of the present invention. The sound adjustment device 1 of the present invention includes an upper support 100 and a substrate 200 provided below and facing the support 100.

[0032] The support 100 may be the key itself or a part of the key. Alternatively, it may be realized by a base separately attached to the lower surface of the key. The support 100 has a rectangular key shape, but is not limited thereto. The support 100 must reflect the pressing depth and movement trajectory of the key when the key is pressed.

[0033] The underside of the support 100 includes a first moving portion 104, a second moving portion 106 arranged at a predetermined distance from the first moving portion 104 and aligned with the first moving portion 104, and a counter moving portion 108 arranged at a predetermined distance from the second moving portion 106 and aligned with the second moving portion 106.

[0034] The first moving part 104, the second moving part 106 and the counter moving part 108 are aligned on the same line in the left-right direction of the drawing, i.e., along the longitudinal direction of the support 100, preferably along the center line of the lower surface. These are manufactured to a height that allows the support 100 to pass sufficiently through the substrate 200 when pressed.

[0035] Although the first moving part 104 and the second moving part 106 are shown as being in the shape of a rectangular bar with a narrow width and a tall height, they can be embodied in various shapes such as a circular column, etc. Also, they can be made of various materials such as rubber, plastic, metal, etc.

[0036] The overall shape of the counter moving part 108 is similar to that of the first moving part 104, but is different in that horizontal bar-shaped light-shielding parts 108a, ..., 108a are arranged at predetermined intervals from the bottom along the height direction, and light-transmitting parts 108b, ..., 108b are formed between them. The material of the light-shielding parts 108a, ..., 108a is the same as that of the first moving part 104, but the material of the light-transmitting parts 108b, ..., 108b may be made of a light-transmitting material or transparent glass, or may be provided as space.

[0037] The substrate 200 has slots 202 for the first moving part 104, the second moving part 106, and the counter moving part 108 to pass through, facing the lower surfaces of these members. A first sensor 304, a second sensor 306, and a counter sensor 308 are provided on the upper side of the substrate 200 adjacent to the slot 202. These sensors are preferably member detection sensors that use light or wavelengths, such as color sensors, optical sensors, infrared sensors, or photointerrupters. In FIG. 1, a U-shaped photointerrupter is shown as an example. A transmission type photointerrupter is an optical switch in which a light emitting element and a light receiving element are arranged facing each other in a single package, and when a detection object passes between them, the light is blocked, thereby detecting the presence or absence of an object.

[0038] 2 is a diagram showing a case where a user presses a key on the tuning device 1 of a digital piano according to an embodiment of the present invention. It is assumed that the right side of the drawing is the part where the user sits and presses keys.

[0039] When a user presses a key in FIG. 1, the support 100 follows the movement trajectory of the key, and as shown in FIG. 2, the right end of the support 100 is pushed to an inclination that tries to maintain the original center position as much as possible.

[0040] In terms of time, the counter mover 108 passes through the slot 202 first, then the second mover 106 passes through the slot 202, and finally the first mover 104 passes through the slot 202. However, due to its function, the counter mover 108 does not need to pass through the substrate 200 first. Also, the first mover 104 does not necessarily have to pass through the slot 202 after the second mover 106, and it is important to measure the time difference.

[0041] For convenience, the process of adjusting the velocity for adjusting the sound of the digital piano of the present invention will be described below based on the sequence illustrated in Fig. 2. "Velocity" means speed, but in the present invention, it means a tuning variable that takes into account the depth of key depression in addition to the speed (time difference), and should be interpreted broadly.

[0042] The velocity adjustment of the present invention described below is preferably performed by the control unit of the main board of the digital piano. The main board is provided with a communication line and an input / output interface for transmitting and receiving data to and from the volume adjustment members of each key, which are connected to the control unit together with a memory.

[0043] First, the time taken for the second moving part 106 to pass the measurement level L2 of the second sensor 306 is measured. Next, the time taken for the first moving part 104 to pass the measurement level L1 of the first sensor 304 is measured. Then, based on these data, the time difference (Td) between the two times is calculated. The result is the same even if the time of the measurement level L1 is measured first and the time of the measurement level L2 is measured later, and the order is not limited. The measurement levels L1, L2, and L3 are set at the midpoint where the transmitter and receiver of the sensor face each other, but they can be set at other positions according to the sensor specifications as long as they provide the same reference line.

[0044] The time difference (Td) is the first variable for adjusting the volume of a piano. The faster the player presses the key, the smaller the time difference (Td) will be, and the slower the player presses the key, the larger the time difference (Td) will be. The smaller the time difference (Td), the faster the key speed will be, and the louder the volume will be. This principle is similar to the speed response method of the prior art, but the present invention differs in that it uses an optical detection sensor instead of a rubber dome and contact part. Therefore, more precise volume control is possible compared to the prior art, and design and manufacture are simpler since there is no need to add physical structures such as a rubber dome and contact part. In particular, the accuracy of the sensor can be improved since each sensor only needs to measure the time when each moving part passes through a reference level.

[0045] Furthermore, in the present invention, the depression depth of the key is measured by the counter movement portion 108 and the counter sensor 308 .

[0046] When a key is pressed, the counter movement unit 108 moves downward, and the numbers of the light-shielding units 108a, ..., 108a passing through the measurement level L3 of the counter sensor 308 change. When pressed lightly, the number is "0" and can reach a maximum of "9." As the light-shielding units 108a, ..., 108a and the light-transmitting units 108b, ..., 108b pass through the reference level L3 in sequence, values ​​such as "0" (low) and "1" (high) are repeatedly detected, so it is easy to accumulate and count the number "0", and therefore the sensor design is also easy.

[0047] In the present invention, when a key is pressed normally, that is, when a user presses a key with what he or she thinks is a normal volume, the number at which the light-transmitting portion passes the measurement level L3 is assumed to be the reference state (for example, reference counter N=3), and if the counter is higher than this number, it is determined that the key is pressed deeper than normal, and the predetermined value of the first velocity (V1) is increased by a predetermined value (α) based on the time difference (Td). Conversely, if the counter is lower than this, it is determined that the key is pressed a little more than normal, and the predetermined value of the first velocity (V1) is decreased by a predetermined value (α) based on the time difference (Td). The predetermined value, as a matter of course, differs depending on the number on the counter, and the further it is from the reference value, the larger its absolute value becomes.

[0048] The second velocity (V2) as the final value thus determined is determined as in Equation 1 below.

[0049]

number

[0050] The primary velocity (V1) value can be calculated using data on the contact time difference using a conventional rubber dome, but the digital piano volume control device of the present invention has a different structure from conventional devices, so calibration or initialization by repeated keystrokes may be necessary. The predetermined value (α) can be determined so that V2 is in the range of half to twice V1, for example, and varies depending on the counter numbers of the light-shielding parts 108a, ..., 108a.

[0051] In the above, the cumulative counting of the passing numbers of the light-shielding portions 108a, . . . , 108a has been described. However, it goes without saying that the cumulative counting of the passing numbers of the light-transmitting portions 108b, .

[0052] Structurally, the smaller the height of each of the light blocking portions 108a, ..., 108a and the more rows the horizontal pattern of the light blocking portions 108a, ..., 108a is formed in, the more accurately the key pressing depth can be reflected in the velocity calculation.

[0053] FIG. 3 is a configuration diagram of a tuning device 1 of a digital piano according to another embodiment of the present invention, and FIG. 4 is a diagram showing a case where a user presses a key on the tuning device 1 of a digital piano according to the embodiment of FIG.

[0054] Another embodiment of the present invention is different in that, instead of a U-shaped photointerrupter, the first sensor 304, the second sensor 306 and the counter sensor 308 are arranged as a pair of optical transmitter and receiver facing each other with the slot 202 in between. The measurement levels L1, L2, and L3 are set at the midpoint of the dotted line where the optical transmitter and receiver face each other.

[0055] Even in such a case, the functions described in FIG. 1 and FIG. 2 can be achieved, so a detailed description will be omitted.

[0056] When using a color sensor, the counter moving part is formed with two different hues, and the color sensor is used to count the numbers that the same hue passes through.

[0057] Next, a key lighting system 500 of the present invention will be described. As shown in Fig. 5, the key lighting system includes a main board MCU 502 and a plurality of keyboards K that serially communicate with the MCU. The MCU 502 can be wirelessly connected to a wireless device 504 such as a mobile phone, and can also be connected to an external terminal 506. A plurality of LED lights L, ..., L are provided on the upper part of the keyboard K. The lighting control of the LED lights L, ..., L is performed by an LED control unit C that receives a signal from the MCU 502 via serial communication.

[0058] An app or program for adjusting the hue and intensity of the LED light of the lock is installed in the wireless device 504. The user can run the app or program to set the color (red, pink, blue, green, etc.) that the LED lights L, ..., L emit and the intensity (density) of the color. For example, even if the color is the same pink, a light pink and a dark pink have different intensities, and therefore give different impressions and aesthetic sensations to people around them.

[0059] FIG. 6 shows an example of an LED adjustment guide provided by an app of the wireless device 504, in which a table is displayed showing representative colors and sub-colors corresponding to their respective intensities, allowing the user to easily input the sub-colors by touching them.

[0060] The advantage of the present invention is that when the player presses the key deeply to output a loud sound, the color intensity is increased, and when the player presses the key deeply to output a loud sound, the color intensity is set to be weak, and this is transmitted to the MCU 502 so that the LED lights L, ..., L are illuminated in a variety of ways.

[0061] Alternatively, the performer may preset only the color, and the hue intensity according to the key pressing may be automatically adjusted by the MCU 502 or the LED control unit C according to the velocity value finally determined.

[0062] When using the key lighting system 500 of the present invention, a method can be used in which a signal is received via the MCU 502 on the main board and the LED control unit C of the keyboard K directly controls the LED lights L, ..., L (block piano), or a method can be used in which the MCU 502 on the main board controls the LED lights L, ..., L without the intervention of the LED control unit C (general digital piano).

[0063] The external terminal 506 can be connected to the MCU 502 via a wired connection and can perform the same functions as the wireless device 504 .

[0064] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and alterations of the present invention are possible. For example, the present invention can be applied to the existing structure of a digital piano, such as adjusting the velocity according to the pressing distance of the key by providing a counter movement part and a counter sensor while using the existing rubber dome method.

[0065] It is obvious that the scope of the present invention extends to the same or equivalent scope as the claims described below.

Claims

1. A tuning device for a digital piano, comprising: The device includes a support forming a key or a lower surface of the key, and a substrate arranged on the lower side opposite the support at a predetermined distance, A first moving part, a second moving part provided at a predetermined interval from the first moving part and aligned with the first moving part, and a counter moving part provided at a predetermined interval from the second moving part and aligned with the second moving part are provided on a lower surface of the support; the base plate is provided with a first sensor, a second sensor and a counter sensor for detecting the first moving part, the second moving part and the counter moving part, respectively, and is also provided with slots through which the first moving part, the second moving part and the counter moving part can pass when moving downward; When the key is pressed, the counter sensor detects the degree of key pressing by the downward movement of the counter moving part, the first sensor detects the time when the first moving part passes the first sensor when the key is pressed, and the second sensor detects the time when the second moving part passes the second sensor when the key is pressed; The tuning device for a digital piano includes a control unit that adjusts the sound of the digital piano, and the control unit determines a primary velocity based on the time difference between the passing time of a first moving part measured by the first sensor and the passing time measured by the second sensor.

2. 2. The tuning device for a digital piano according to claim 1, wherein the control unit determines a final velocity by increasing or decreasing a primary velocity according to a downward movement amount of the counter movement unit measured by a counter sensor.

3. 5. The tuning device for a digital piano according to claim 4, wherein the counter movement section has a plurality of rows in which light-shielding sections and light-transmitting sections are alternately arranged from bottom to top along the height direction, and the counter sensor detects the amount of downward movement of the counter movement section by counting the numbers passing through the light-shielding sections or the light-transmitting sections when a key is pressed.

4. 2. The toning device for a digital piano according to claim 1, wherein each of the first sensor, the second sensor and the counter sensor is a color sensor, a light sensor, an infrared sensor or a photointerrupter.

5. The keyboard further includes a key lighting system including an MCU on a main board and a plurality of keyboards that serially communicate with the MCU, the MCU being connected to a wireless or wired device; The keyboard is provided with a plurality of LED lights, 2. The tuning device for a digital piano as described in claim 1, wherein the wireless or wired device is equipped with an app or program for adjusting the hue and intensity of the LED lights of the keys, and the user is allowed to actively set and input the color of the LED lights and the intensity of said color.

6. The keyboard further includes a key lighting system including an MCU on a main board and a plurality of keyboards that serially communicate with the MCU, the MCU being connected to a wireless or wired device; The keyboard is equipped with multiple LED lights.

2. The tuning device for a digital piano according to claim 1, wherein the wireless or wired device is equipped with an app or program for selecting the hue of the LED light of the key, the user actively sets and inputs the color that the LED light will emit, and the intensity of the color is automatically adjusted according to the final velocity.

7. 2. The tuning device for a digital piano according to claim 1, wherein the counter movement section has a plurality of rows in which light-shielding sections and light-transmitting sections are alternately arranged from bottom to top along a height direction, and the counter sensor detects an amount of downward movement of the counter movement section by counting the number of times the light-shielding sections or light-transmitting sections pass when a key is pressed.

8. 2. The tuning device for a digital piano according to claim 1, wherein the counter movement section is arranged in a plurality of rows in which first and second color sections are repeated from bottom to top along the height direction, and the counter sensor detects the amount of downward movement of the counter movement section by counting the passing digits of the first or second color section when a key is pressed.

Images