JPS6255720A - Key scan system - Google Patents

Abstract

PURPOSE:To increase the number of keys without using any detector by sending successively the key scan signals to an output port that is used for designation of a visible display means in a turn-off period of the display means. CONSTITUTION:The key scan control is carried out for each 'L' period of the signal delivered to an output port (c). Therefore, the levels of output ports a1-a6 are kept at 'L' regardless of a turn-on or turn-off state of the light emitting diodes PD1-PD6 respectively in an 'L' period of the port (c) if no consideration is given to the key scan control. Thus the signals of 'H' are supplied successively to the signal lines l1-l6 in the column direction of a key matrix by changing the levels of the ports a1-a6 to 'H' for each 'H' period. Thus the lines l1-l6 are scanned successively. Furthermore, the diodes PD1-PD6 are never turned on even through the levels of the signals sent from the ports a1-a6 are set at 'H' for key scan control since the polarity relation between the ports a1-a6 and the port (c) is adverse to the polarities of the diodes PD1-PD6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a key scan method in a computer application system that is collectively controlled by a central processing unit.

(Prior art) A computer application system using a central processing unit (so-called CPU), such as electronic? The telephone terminal (hereinafter referred to as the telephone) of the tan telephone device has various keys.

- (line selection key, dial key, etc.) and visual display means (line display visual display means, etc.), and key depression detection and display control of the visual display means are performed by a central processing unit.

Visual display control means that each visual display means is controlled by each output of the central processing unit? - When the output port for outputting the visual display signal is selected, the visual display means to be displayed is selected by K.

In addition, key press detection is -, keys are arranged in a matrix to form a key matrix, and the corresponding key is +7.
For example, the signal line in the column direction of the TUX is connected to the output of the central processing unit.
At the same time, connect the signal lines in the row direction to, for example, the input ports of the central processing unit, output the J@ next scan signal to each output port, and detect the input of the scan signal to the input port at this time. This is done by identifying the pressed key by identifying the combination of the output port from which the scan signal was output and the input port from which the scan signal was input. This key press detection control is
This is usually called a key scan.

Conventionally, separate output states have been used for the visual display control and key scan control, so the number of visible display means and the number of keys have not been determined by the output of the central processing unit. Conventionally, in order to perform a number of visual displays and key scans that are limited by the number of data outputs and exceed the number determined by the number of output dates, for example, output for key scan? For example, the number of signal lines in the column direction was increased, thereby increasing the number of keys. According to this method, the key scan signal to the output date must be output in combination, which does not complicate control of signal transmission to the output port, and requires a new decoder.

(Problems to be Solved by the Invention) For example, in an electronic button telephone device, as the number of lines accommodated and the number of telephones installed increase, the number of visible displays and the number of keys on the telephones increase. , the number of output ports of the central control unit of the telephone is insufficient.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a key scanning method that can increase the number of keys without using a decoder as in the prior art.

(Means for Solving the Problems) For the above purpose, the present invention outputs a signal whose level is alternately switched from a central control device, dynamically drives the visual display means with this signal, and During the period when the display means is off, a key scan signal is sent out every time on an output date for specifying the visible display means. By doing this, the output port can be shared between visual display control and key scan control.
With a limited number of outputs, many visual displays and many keys can be controlled simultaneously.

(Configuration of Example) FIG. 1 is a circuit diagram showing an embodiment of the present invention.

Note that the following description will proceed assuming that the present invention is implemented in a telephone of an electronic butane telephone device.

As shown in FIG. 1, light emitting diodes PDl~PD are used as visible display means, and buttons □1~PD are pressed as keys.
0 is provided in the key matrix, and the key matrix has the above-mentioned key ``K4'' arranged at each cross point of the column direction signal lines t1 to t and the row direction signal lines m, to m. In the embodiment shown in FIG. 1, the number of light emitting diodes PDl-PD and the number of pushbutton keys Kis~ are 6 and 24, respectively, but these numbers themselves vary depending on the electronic butane telephone to be implemented. This is a design matter that is set depending on the scale of the device.

The anode sides of the light emitting diodes PD1 to FD are commonly connected (common connection line d), and the common connection line d is connected to the output of the central processing unit CPU via a light emitting diode drive circuit (hereinafter referred to as a drive circuit) DRV. f −) connected to c. In addition, the light emitting diodes PD1 to F
The cathode side of each of D, is separately connected to the central processing unit C.
It is connected to output ports a1 to a6 of the PU.

Further, the column direction signal lines t1 to t4 of the key matrix are provided with diodes D1 to D to prevent the signal from being recirculated.

respectively through the output ports of the central control unit CPU &1~
A, a row direction signal line ml of the key matrix, which is commonly connected to the light emitting diodes PD1 to PD, and a key matrix row direction signal line ml to
m, are connected to the inputs #-) b, ~b4 of the central control unit CPU, and further on the opposite side of the input ports b1 ~ b4,
After being terminated with resistors R1 to R4 that provide a logic state (low level), they are commonly connected (common connection line e).

The common connection line d (output/- of the central processing unit CPU) c) of the light emitting diodes PD, ~PD, is further connected to the pace of the switching transistor Q via an inverter IV and a resistor R. The common connection line e of R1 to R4 is connected to the collector of the transistor Q, and the emitter of this transistor Q is connected to ground.

This circuit consisting of inverter IV, resistor R, and transistor Q is connected to the central control unit CPU for key scan control.
output? (keep during the period when a low level signal is being output from tc to common signal line d) This is a circuit for setting the IJ sock row direction signal lines m1 to m4 to a low level state. The tank keys include various line selection keys, various function keys, dial keys, and the like.

In addition, in the embodiment, the output port of the central processing unit CPU)
a, to a are all kept in common with the visible display means) IJ Lux, but a part can be configured as common if necessary. For example, assuming that the visible display means is composed of four light emitting diodes PD, ~PD4, the output ports a and ~a4 are kept common to the visual display means and the IJ Lux. used for,
&, and a are used as key matrices alone (in Fig. 1, light emitting diodes PD and FD
, and the output capo) al and a6 may be removed. ).

Incidentally, the present invention is applicable to any computer system equipped with a visual display means for displaying various states and a key means for inputting various commands, data, etc. Needless to say, the present invention can be implemented not only with telephone devices.

(Operation of the embodiment) FIG. 2 is a time chart showing the operation of the embodiment of the present invention.

The output port C of the central processing unit CPU has a low level (hereinafter referred to as #Hn) and a low level (hereinafter referred to as #Hn).
A signal in which "L#" appears alternately at a constant period is output.

First, visual display control will be explained.

When lighting up the light emitting diodes PD, ~PD, a 0L'' signal is output to the corresponding output port a, ~a.

During the period when the signal output to output port C is "H", the output is ? -) a1~a and output capo -) c Since the mutual polarity is in the forward direction, during this period, the light emitting diodes PD, ~
During the period when PD is lit and the signal output to the output capacitor) is L'', the levels of the output ports a1 to a6 and the output capacitor)c are both L'', so the light emitting diode PD, ~PD, does not light up.

Therefore, each of the light emitting diodes PD to PD6 blinks in operation, but since the cycle is short, it visually turns on continuously. That is, in the present invention, visual display control is based on dynamic driving.

Also, when the light emitting diodes PD, ~PD, are turned off (not lit), the corresponding output! -) It is sufficient to output a "'H" signal to a, ~a, but in the embodiment of the present invention, output 1-)
The signal output to a, ~a, has a level of output/-
) 'H', 'L' with the same polarity and same period as the signal output to c
The signal changes alternately. In this case, in any period of the signal output to output port C, the output? -a1~&, f) V health & output $-) C level is the same and both are 1H" or 1L"
), the light emitting diodes FD, ~PD, do not light up.

Regarding visible display control, the operation shown in FIG. 2 is that the light emitting diodes FD and PD light up,
, and FD go out, and the light emitting diode PD goes off at time 1.
An example is shown in which the light is turned off at time t, and the light emitting diode PD is turned off at time t.

Next, key scan control will be explained.

The key scan control is performed every time a period in which the level of the signal output to the output port C is "L" (hereinafter referred to as "L" period) arrives. That is, the output, 1f)(
! During the "L" period, the levels of the outputs I-a and a to a6 are all the same regardless of whether the light-emitting diodes PD1 to PD are turned on or off, unless key scan control is taken into account.
Since the current level is "L", each time the corresponding "L" period arrives, the capo is sequentially applied. sequential′″
H” signal is supplied, which causes the column direction signal line t
1 to t will be sequentially scanned. In addition, during the above output port 70'''L'' period, even if the level of the signal from the output ports &1~a is set to ``H'' for key scan control, the output ports at this time are J~a. , and output port C are light emitting diodes PD, ~P
Since the polarity is opposite to that of D, the light emitting diodes PD, ~PD, do not light up.

Regarding key scan control, the operation shown in FIG. 2 is to sequentially output key scan signals to output ports a, ~a6 in this order, scan column direction signal lines t, ~t6 in this order,
An example of this operation in which nb is returned cyclically is shown.

By the way, during the "L" period of the above output capacitor (c), the level of the common connection line d is 'L', and this is the
The level of the common connection line e becomes "L", and the row direction signal lines m1 to m4 of the key matrix all become "L". ”, and for input #-)bt-b, press the key Kl□~4. j9"L" unless is pressed
has been entered.

Here, for example, if 11 is pressed on the depress key, at the time when the key scan signal is output to the output port a1, the key scan signal "I (
”The level is input, the above output port a, and input yt?
-)b, the central control unit CPU detects the depression of the push-and-release key Kll.

Note that during the period when the output port C is "H", the transistor Q is off and the row direction signal lines m, to m4 are
. . . I impedance and shi, neither logic is given 4. Therefore, during this period, part of the logic cannot be obtained in inputs/-)b and ~b4, but the central processing unit CPU is programmed so as not to read data from input ports b1 to b4 during this period. is configured, there is no problem with key scan control, and the diode D
1 ” The existence of D@ does not cause any problem in visual display control during the relevant period.

(Effects of the Invention) As described above in detail, the present invention outputs a signal whose level alternates to an output port common to a plurality of visual display means, and dynamically controls the visual display means using the signal. At the same time, a key scan signal is sequentially outputted to individual output ports that designate lighting of the visual display means during the off period of the visual display means, and one of the individual output ports is Since part or all of the key matrix can be shared with the visual display means and the key matrix, the number of keys can be increased without requiring means such as a decoder, which is extremely useful for increasing the size of computer application systems such as electronic button telephone devices. It is effective.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a time chart showing the operation of the embodiment. (Main symbols) CPU...Central processing unit, K11-KU...Press key, PD1-p5...Light-emitting diode, e, al-a,...Output port, b1-b4...
・Input I-to. Figure 1: 1 shaku 1-l? 4----Written Amendment to Printing Procedures September 7, 1939 Director-General of the Patent Office Kuro 11.1 Meishi JL 3. Relationship with the case of the person making the amendment Applicant II - Name Akira 〃, Denki Co., Ltd. 4, Agent address: 3305 Marunouchi Shigesu Building, 2-6-2 Marunouchi, Chiyoda-ku, Tokyo, Date of amendment order: Whitening, ``7, Subject of amendment: 1 side 3b::H': □H, C4. o2rr) = + supplement
We will amend the text in the main specification of the application. Note 1, page 7, line 3, ``Push button 10'' is corrected to ``Push button 10 Kll''''K411''. 2. On page 9, line 8, "ports a1-a2 J" should be corrected to "port &+-ail."

Claims (1)

[Claims] Outputting a signal whose level alternately switches from the central processing unit, dynamically driving the visual display means with this signal, and outputting for specifying the visual display means during the off period of the visual display means. A key scan method in which a signal with a polarity opposite to the polarity of the output port during the above-mentioned off period is sequentially output to the port, and the signal with the opposite polarity is guided to the key matrix to perform key scanning. .