JPH01271820A - Key input device - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution and to obtain a compact and light-weight key input device by securing an exclusive OR between a 1st key information obtained with the present key scan and a 2nd key information obtained with the preceding key scan. CONSTITUTION:A key input device which inputs the information after scanning plural keys secures an exclusive OR between the 1st key information obtained with the present key scan and the 2nd key information obtained with the preceding key scan. For the result of said exclusive OR, only the bit having the difference between the present key input and the preceding key input is set at HI. Thus the new key input can be decided by securing an AND of key input between the result of the exclusive OR and the present key input. In such a way, the decision of the new key input is possible in a simple way for a multi-push function with use of a software technique only. Thus it is possible to simplify the circuit constitution and to obtain a compact and light-weight key input device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a key input device that detects a newly input key even if a plurality of keys are pressed simultaneously.

Currently, a wide variety of key input devices are used, such as personal computers, cash registers, and familiar calculators and Quibwriters. These key input devices are used for f! ll type creates a need for multiple press functions. Here, the multiple press function is a function that detects the newly pressed key even if two or more keys are pressed. etc., the multiple press function is required to speed up printing and improve ease of use.This is because if the key input device prohibits multiple presses, when a key is pressed, the next key is pressed until the key is released. Since the key is not input, the puncher must release the key and press the next key.
Human cassbees fall off and are also very difficult to handle. However, with a key input device that has a multiple press function (=I), the next key can be input without taking the trouble of taking your finger off the key, making it easier to handle even large keys. In order to do this, it is necessary to distinguish between the previous key input and the new key input. Conventionally, mechanical systems use a combination of gears, cams, etc. The device was configured to ignore the fact that the key was pressed and prepare to accept the next key.However, with this method, it was difficult to make the product compact, lightweight, and simple.This is when electronic technology appeared. It is a type key input device.

This is a method that outputs a signal corresponding to the key pressed.
Small size, light weight, and simplification are possible. The biggest problem in realizing the multiple press function with this type of key input device is how to distinguish the signal of a new key from the duplicate signals that appear when two or more keys are pressed. In other words, when you press only one key, only the signal corresponding to that key is output, so there is no problem, but when you press two or more keys, the signals corresponding to each key overlap and become one signal. Therefore, we need to extract only the signal corresponding to the newly pressed key. If this detection is not done well,
The circuit becomes complicated and costs increase.

The present invention solves these problems and is an effective means for making products smaller, lighter, simpler, and cost-effective. Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a specific embodiment of an electronic circuit for implementing the invention. Microprocessor 1, read-only memory (ROM) with built-in program 2, read/write memory (RAM) that can read and write data
3. DATA bus, ADD centered around decoder circuit 4
5. Input/output port to RESS bus, C0NTR0L bus.
6.7.9 are combined and connected to a 4×16 matrix type keyboard 8. Output port 5 performs key input control by driving rows of the keyboard, and input port 7 detects keys in each column by 8 bits. Key input control is performed by sequentially outputting signals to COM1-C0M4, and key detection for each sequence is performed.

At this time, each wire is connected to ground through a resistor to ensure that COM and the rows in which no keys are pressed are LOW when no signal is flowing. Furthermore, a diode is inserted in each COM to prevent the signal from flowing backward through the COMs other than the C0M outputting the signal to the output port 5 when keys in the same row are pressed at the same time. Furthermore, rows with shift keys and repeat keys are input directly to the microprocessor 1 without passing through the input port 7, so that when only the key is pressed, it is not judged as a new key input. make a judgment. The result of key detection in this way is the RA of 3.
The data are sequentially stored in M. The output port 9 is provided for outputting the key input code converted by the microprocessor 1 to the outside. In addition, the ROM 2 stores a program for detecting key inputs and identifying new key inputs, as well as other necessary programs, but since various operations can be processed simultaneously by simply changing the program, this The method is very effective.

FIG. 2 shows how detected keystrokes are stored in RAM. First, a signal is output to COMI, and the 8-bit segment signal detected by the input port is stored in the first column, and then the 8-bit segment signal detected by the input port is stored in the second column. This operation is performed sequentially for 00M1 to C0M4 to obtain the memory contents as shown in FIG.

FIG. 3 is a schematic overall flowchart of an embodiment of the present invention. In this example, three or more presses are not allowed. This is a structural problem with the keyboard.
Explanation will be added using an example in Figure 4. Now, in FIG. 3, when the circuit is first powered on, the output ports, registers, and other counters are initialized at 31.

Next, at 32, the driving of the row of the keyboard is carried out through the output port 5 (FIG. 1), and along with this, the detection of the column of the keyboard is carried out through the input port 7, and the result is stored in the RAM 3. Then at 34 32
The key input data detected in is called from the RAM 3, and it is determined whether the number of input keys is three or more. As a result, if the number of inputs is not three or more, it is determined in step 35 whether or not the input is a new input. Since this method is the object of the present invention, a specific example will be shown in FIG. 6 and a separate explanation will be added. If the key is determined to be a new key, the code is converted for output and output. In addition, RAM3 has a place to store 1iii key inputs, and has 38
, the current key input and the previous key input are exchanged and the current key input is stored in that location. Its storage style is
This is the same as in FIG. 2, and the data before code conversion is exchanged between new and old data. 39 timers are provided for timing purposes.

FIG. 4 does not show a part of the matrix type keyboard. A black circle indicates that a key is pressed. The reason why three or more presses were not allowed in the embodiment of FIG. 3 will be explained below. For example, assume that three keys are pressed to cause a current (signal) to flow through COMI as shown in (a). Tracing the path of the signal at this time, first a signal is detected at A because the IA key is pressed, and then a signal is detected at C because the Ic key is pressed.

Also, since 3C is pressed, the signal tries to flow into C0M3, but since a diode is inserted as shown in FIG. 1, the signal stops here. Therefore, COM
When a signal is sent to I, signals are detected at △ and C, and the key that is actually being pressed is detected, so there is no problem. However, when the signal comes from C0M3, the 3C1IC1IA key is pressed, so the signal is C0M3→3C-, C→IC-IC0M1-IIA→
The signal flows along the path A, and signals are detected at A and C as well. For this reason, it appears that the 3A key is being pressed. Therefore, in this type of keyboard, triple pressing or more must be prohibited. However, if the keyboard itself is modified to some extent by inserting a diode between each row as shown in (b), this problem can be solved and multiple presses will be possible.

FIG. 5 shows an example of the code conversion of FIG. 36. The 1st and 2nd bits contain the repeat and shift codes detected by the microprocessor itself, respectively.
The third and fourth bits are used for the four COM conversion codes. Then, the remaining four pits are used for the conversion code of the key segment input data. If code conversion is performed in this way, all key inputs can be covered with 8 bits, which is very convenient and improves efficiency.

FIG. 6 is a detailed view of FIG. 35 and is a specific example of the present invention. First, in 61, the corresponding bytes of the previous key input data and the current key input data stored in the memory are respectively read out, and in 62, the exclusive OR of the two is calculated. The result of the exclusive OR is determined at step 63, and if the value is all O's, there is no change in the 8 bits between the current key input and the previous key input. In other words, it indicates that no new key has been pressed within those 8 bits. Then 64 to all pies 1,
In this case, it is determined whether 8 bytes have been processed. Here, if the determination is YES, it goes without saying that the current key input is the same as the previous key input. If the determination is No, the address containing the new and old key data is not indicated at 65 and the counter is incremented by one in order to proceed to the next byte check, and the process returns to 61 and the above-described operation is repeated. Further, if the determination at 63 is NO, this indicates that a new key has been pressed within the 8 bits. As a result of exclusive OR, only the bits that differ between the previous key input and the current key input will be "■"I, so
A new keystroke can be detected by ANDing the result with the current keystroke at 66. Also, 2
By releasing one of the keys that was pressed heavily, the previous key input and the current key input will be different, but they will be canceled out by taking the logical product, and the current key input will not be judged as a new key input. Zumo.

As described above, according to the present invention, it is possible to easily detect a new key input in the multiple press function using only a software method, so the circuit does not become complicated and various operations can be performed simply by adding a program. Therefore, there are advantages such as a wide range of applications, and it is also possible to reduce the size and weight. Further, the present invention can also be implemented in terms of hardware using logic circuits and the like. The present invention can be particularly effective for electronic typewriters.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention. FIG. 2 is a diagram showing a method of storing key inputs in memory in the embodiment of the present invention. FIG. 3 is a schematic overall flowchart of an embodiment of the present invention. FIG. 4 is a diagram showing a part of a matrix type keyboard. FIG. 5 is a diagram showing an example of code conversion in FIG. 36. FIG. 6 is a detailed view of FIG. 35 illustrating a specific example of the present invention. 1... Microprocessor 2... Read-only memory (ROM) 3... Readable/writable memory (RAM) 4... Decoder circuit 5.9/Output port]/6.7/Input port 8 ...4x16 matrix type keyboard or above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (and 1 other person) 61 N Shima ν
SuQ+-lri'J (J (J) Procedural amendment (voluntary) Key input device 3, relationship with the person making the amendment Applicant Seiko Epson Co., Ltd. 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (236) Company Representative Director Tsuneya Nakamura 4, Agent 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 163 Seiko Epson Corporation (9338) Patent Attorney Kizobe Suzuki (1 other person) Contact information 6
348-8531 Extensions 300 to 3025, Description subject to amendment (Claims) Claim: “In a key input device that inputs information by scanning a plurality of keys, ;) -- Using the information and the second key information from the previous key scan, calculate the exclusive OR of the first and second key information.

Claims (1)

[Claims] In a key input device that inputs information by scanning a plurality of keys, the first and second keys are A key input device characterized by calculating an exclusive OR of information and detecting a newly input key based on the result of ANDing the exclusive OR and first key information.