CN2376011Y - Calculator - Google Patents

Abstract

The utility model discloses a calculator, comprising buttons (42, 44, 46, 48) for inputting instructions into the calculator so as to calculate a calculation result using a central processing unit (14); and a liquid crystal display (31, 38, 40) for displaying the instructions input into the calculator and the calculation result. When each instruction is input into the calculator, the calculator executes the instructions and the intermediate result is displayed on the liquid crystal display (40).

Description

calculator

The utility model relates to a calculator, in particular to a calculator with a liquid crystal display (LCD).

In an ordinary calculator having an LCD, the LCD is a one-line LCD that can only display the last numerical value input to the calculator or the calculation result obtained after executing an instruction input to the calculator. When mathematical operations such as "+", "-", "×", "÷" are entered into the calculator, these mathematical operations will not be displayed on the LCD. Once subsequent values are entered into the calculator, the previous value displayed on the LCD is replaced by the last entered value. Take the operation "6+2" as an example. When the button "6" is pressed, the LCD will display the number "6". The display of the number "6" does not change when the "+" button is pressed. When the button "2" is pressed, the LCD will only display the number "2". When the button "=" is pressed, the number "8" will be displayed, which is the result of the operation "6+2". It can be seen that such an ordinary calculator is not capable of displaying the sequence of instructions input to it and the result.

In another general calculator, only the last input value and the last mathematical operation are displayed on the LCD, although the mathematical operation input thereto is also displayed. The entire command sequence is also not displayed on the LCD.

The main disadvantage of these two common calculators is that the user cannot check whether he has entered the correct commands into the calculator and therefore cannot check whether the results are correct. Also, in both calculators, in the event of only one wrong command being entered, re-entry is required unless the last value was entered (which can usually be corrected by pressing the key "C" and then keying in the correct value) entire instruction sequence.

It is therefore an object of the present invention to provide a calculator which overcomes the aforementioned disadvantages, or at least to provide a useful alternative to calculators of the prior art.

According to the utility model, there is provided a calculator comprising an input device and an output device, the input device inputs instructions to the calculator, so that a calculation result can be calculated by a central processing unit, and the output device includes a liquid crystal display (LCD) device, capable of displaying the instructions and calculation results input to the calculator, when each instruction is input to the calculator, the calculator executes these instructions, and uses the output device to display intermediate results, wherein the The LCD device includes at least a first row and a second row of LCD elements, the instructions input to the calculator are displayed on the first row of LCD elements, the calculation results are displayed on the second row of LCD elements, and the second row of LCD elements is displayed. A row of LCD elements is located above the second row of LCD elements, and the calculator is characterized in that each of the first row of LCD elements is arranged in a dot matrix.

Now refer to the accompanying drawings to describe an embodiment of the utility model by way of example, in the figure:

Fig. 1 represents the circuit diagram of the utility model calculator;

Fig. 2 A represents the front view of the layout of the printed circuit board (PCB) used in the utility model 12 calculators;

Figure 2B shows a rear view of the PCB shown in Figure 2A;

Fig. 3 A represents the front view of the layout of the printed circuit board (PCB) used in the 10-digit calculator of the present invention;

Figure 3B shows a rear view of the PCB shown in Figure 3A;

Fig. 4 represents the block diagram of the central processing unit used in the utility model calculator;

Fig. 5 shows the pad arrangement of the central processing unit shown in Fig. 4;

Fig. 6 is a table showing the positions of the pads of the central processing unit shown in Fig. 4;

Fig. 7 is a table showing pin descriptions of the central processing unit shown in Fig. 4;

Fig. 8 A represents the front view of the 12 liquid crystal displays used in the utility model calculator;

Figure 8B shows a side view of the LCD shown in Figure 8A;

Fig. 9 shows a "segment" schematic circuit diagram design of the LCD shown in Fig. 8A;

Fig. 10 shows a "shared" schematic circuit diagram design of the LCD shown in Fig. 8A;

Fig. 11 briefly represents the keyboard arrangement of the utility model calculator;

Fig. 12 represents the first operation sequence of the calculator of the present utility model;

Fig. 13 shows the second operation sequence of the utility model calculator.

Since the appearance of the calculator is not important to the present invention, only the internal circuit structure of the calculator will be discussed here. Referring to Fig. 1 at first, this figure represents the block diagram of calculator of the present utility model. The calculator includes a liquid crystal display (LCD) 12 electrically connected to and interfaces with a central processing unit (CPU) 14 . It can be seen that both the LCD 12 and the CPU 14 are connected to several switches (SW1-SW60) that control the operation of the calculator.

Calculators can be 8-digit, 10-digit or 12-digit calculators, at the option of the manufacturer. 2A and 2B show the layout of a printed circuit board (PCB) 16 suitable for use in the 12 digit calculator of the present invention. 3A and 3B illustrate the layout of a printed circuit board (PCB) 18 suitable for use in the 10-digit calculator of the present invention.

The central processing unit that can be used for the utility model is a single-chip 4-bit microcomputer 14' (seeing figure 4). Microcomputer 14' includes random access memory (RAM) 20 for data storage, liquid crystal display (LCD) driver 22, key input circuit 24 and buzzer port 26. By connecting the microcomputer 14' to an external crystal (not shown), the clock function can be easily implemented with a 1 Hz time signal. Although the microcomputer 14' is capable of performing many functions, only the functions relevant to the calculator of the present invention are described here. The display size of the LCD driver 22 is 60 segments x 8 columns. Fig. 5 shows the pad arrangement of the microcomputer 14', and Fig. 6 is a table showing the pad positions of the microcomputer 14'. While the pad size of the microcomputer 14' is 93 mm x 93 mm, the chip size is 4.28 mm (in the X direction shown in FIG. 5) x 4.00 mm (in the Y direction shown in FIG. 5).

Turning to Fig. 7, this figure is a table showing the description of the pins of the microcomputer 14'. For K16 and K17, use the mask option to select between key input and switch input (parallel). Use the Shield option to set the following leads as follows:

-Key input: input is allowed only when the strobe signal is output, which can be used as a wait release

-Switch input: input is allowed only when the strobe signal is output, but cannot be used as a wait release

When used as a switch input lead, the input signal cannot be used as a wait release. K16 and K17 can be set independently of each other. For XCR, it can be fixed to Vcc or GND level by shield selection. Since the "TEST" lead is always connected to Vcc, this lead has no user function.

8A and 8B are front and side views, respectively, of the liquid crystal display (LCD) 12 shown schematically in FIG. 1 . The LCD 12 includes a front transmissive polarizer 28 and a rear reflective polarizer 30. As can be seen from FIG. 8A , there are mainly three rows of LCD elements 31 , 38 , 40 . The upper row LCD element 31 is used to display the letters "AM", "PM", "F" and "K", the numbers "4", "2" and "0", the combination "Add2", the bell icon 32, the right arrow icon "→" 34 and left arrow icon "←" 36 . The middle row of LCD elements 38 is arranged in twelve (12) groups of 5x5 LCD elements. The reason for this arrangement is to be able to display mathematical symbols such as "+", "-", "×" and "÷" on the line. This line also shows the commands entered into the calculator. When each command is input to the calculator, the lower LCD element 40 displays the calculation result obtained by executing the calculation according to the input command, and also displays "GT" (referring to the total), "E" (referring to the error) or "M" (referring to the memory ).

9 and 10 show a "segmented" schematic circuit design for LCD 12 and a "common" schematic circuit design for LCD 12, respectively. Lead assignments are shown in the lower part of each figure. Figure 11 shows a possible arrangement of a keyboard that may be used in the calculator of the present invention.

The symbols/numbers "F", "4", "2", "0" and "Add2" indicate the decimal place the calculator is in. If "F" is displayed, it means that the floating decimal point function is in use, and the displayed calculation result is not rounded. When the number "4", "2" or "0" is displayed, it is rounded to the selected decimal place. When the symbol "Add2" is displayed, a decimal point and two decimal places are automatically added even if no decimal point is entered. For example, when in the "Add2" function, if only "12" is entered, "12.00" will also be displayed.

The main feature of this calculator is that the input instructions can not only be edited and modified when all the instructions have not been completed (that is, the button "=" is not pressed), but also can be calculated and displayed after the final result (that is, the key has been pressed) Press the key "=") to edit and modify. The "←" button 42 can be pressed to move the cursor displayed on the LCD 12 to the middle row LCD element 38. Pressing the "←" button 42 will display the left arrow icon "←" 36. If you want to delete the numbers, you can press the "←" button 42 and/or the "→" button 44 to move the cursor until it reaches the number to be deleted. Pressing the "→" button 44 will display the right arrow icon "→" 34. The relevant digit can then be deleted by pressing the "DEL/CE" key 46. If you want to insert a number, you can press the "←" button 42 and or "→" button 44 to move the cursor until it reaches the position just after the position where the number will be inserted, and then press the relevant number button to enter the number. The "=" button can then be pressed to obtain a new result. A similar sequence of operations may be used to alter one or more instructions related to the mathematical operation input to the calculator.

The first step sequence of the calculator operation is shown in FIG. 12 . The operation to be input is "1+2-6×4÷7". It should be pointed out that, for the calculator of the present utility model, the calculation does not follow the rule that "×" and "÷" operations take precedence over "+" and "-" operations. In step 1, the calculator is powered on, the symbol "F" indicates that it is in the "floating decimal point" mode, and the number "0" is displayed in the lower LCD element 40 . Press the "mode" button 48 to change the decimal place function to "4", that is, the calculation result is rounded to four decimal places. The number "1" will be displayed in the lower LCD element 40 as soon as the "1" button is pressed. When the "+" button is pressed, the display of the lower LCD element 40 does not change. However, the number "1" will be displayed at the leftmost position of the middle row of LCD elements 38, indicating that a command sequence is being entered. When the "2" button is pressed, the symbol "+" appears after the number "1" in the middle row of LCD elements 38, and the number "2" will replace the number "1" in the lower row of LCD elements 40.

In step 6, press the "-" button. While the number “2” appears after the symbol “+” in the middle row of LCD elements 38 , the intermediate result of the “1+2” operation, namely 3, is displayed in the lower row of LCD elements 40 . In step 7, the number "6" is entered, and the number "6" is displayed in the lower row of LCD elements 40, and the symbol "-" appears after the number "2" in the middle row of LCD elements 38. The operation continues to step 12, when the "=" key is pressed, the final result "-0.4286" is obtained, which is displayed in the lower LCD element 40.

If it is now found that the number "6" should actually be "8", the subsequent operation steps are as follows. The "←" button 42 should be pressed to move the cursor along the middle row of LCD elements 38. The position of the cursor is indicated by the flashing of the relevant symbol or number. Once the "←" button 42 is pressed, the symbol "=" in the second row of LCD elements 38 starts to blink. Press the "←" button five times to move the cursor to the number "6", and the number displayed in the middle row LCD element 38 will start to flash. When the "8" button is pressed, the blinking number "8" will appear in front of the number "6" displayed on the LCD element 38 in the middle row. Pressing the "→" button 44 will cause the number "6" to start blinking. When the "DEL/CE" button 46 is pressed, the number "6" will disappear, and the symbol "×" will start to flash at the same time. At this time, the "=" symbol can be pressed to obtain a new result "-4".

Although the above operation sequence shows that the numerical value input to the calculator can be changed, the mathematical operation input to the calculator can also be changed. As shown in Figure 13, in step 1, the instruction sequence "1+2-6× 4÷5=", showing the result "-2.4000" because the answer has been rounded to four decimal places as indicated by the number "4" displayed in the LCD element 31 on the upper row. If it is later found that the mathematical operation "÷" should be "-", it can be corrected as follows: first press the "←" button 42 three times, so "÷" starts to flash, indicating that a cursor exists. Once the "DEL/CE" key 46 is pressed, the mathematical symbol "÷" will disappear and the number "5" will start to flash. The "-" button can then be pressed and the "-" symbol will appear in front of the number "5" in the middle row of LCD elements 38. At this time, the "=" button can be pressed to obtain a new result "-17.0000", which will be displayed in the lower LCD element 40 to replace the previous result "-2.4000", as shown in step 5 of FIG. 13 .

It can be seen that the utility model provides an easy-to-use multipurpose calculator. In particular, the utility model allows the calculator user to check whether the instructions he inputs are correct, and to edit and modify the instructions.

It should be recognized that the above only describes an embodiment of the utility model, and various improvements can be made to the utility model without departing from the essence of the utility model.

Claims (6)

1. A calculator, comprising an input device and an output device, the input device inputs instructions into the calculator, so that a calculation result is calculated by a central processing unit, the output device includes a liquid crystal display (LCD) device, which can display input to Instructions and calculation results of the calculator, when the various instructions are input to the calculator, the calculator executes these instructions, and uses the output device to display intermediate results, wherein the LCD device includes at least the first One row and second row of LCD elements, the instructions input to the calculator are displayed on the first row of LCD elements, the calculation results are displayed on the second row of LCD elements, and the first row of LCD elements is located at the On the second row of LCD elements, the calculator is characterized in that each of the first row of LCD elements is arranged in a dot matrix. 2. The calculator according to claim 1, further characterized in that each of said first row of LCD elements is arranged in a 5*5 dot matrix. 3. The calculator according to claim 1 or 2, further characterized in that the instructions displayed by said LCD device are changeable. 4. The calculator according to claim 3, further characterized in that the calculation result displayed by the LCD device changes with the change of the instruction, and the changed calculation result is displayed by the LCD device. 5. A calculator according to claim 3 or 4, further characterized in that at least one value input to said calculator is changeable to a different value. 6. A calculator according to claim 3 or 4, further characterized in that at least one mathematical operation input to said calculator is changeable to a different mathematical operation.

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