JP3278271B2 - Printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus suitable for portable electronic information equipment driven by a rechargeable battery.

[0002]

2. Description of the Related Art In recent years, there has been an increasing number of cases in which a portable information device is brought to a site where the information is generated in order to perform information processing for information generation in the outdoors and processing is performed on the site. This type of device is made lightweight so as to be easy to hold while having an information processing unit, a display unit such as a liquid crystal, an input unit such as a key and a touch panel, a printer unit, and the like.

[0003] Paper transport in this type of equipment generally uses a stepping motor to control the printing position with high accuracy, and the driving method employs a 1-2 phase excitation method. An efficient constant current control circuit is used as the driving circuit.

[0004] The printing recording system of the printer is thermal recording, in which 500 to 1000 known heating elements (dots) are arranged in a line. The printing is performed by coloring the heat-sensitive paper which is the print paper sent to a predetermined position by the step motor. It has been confirmed that this heating element adheres to the thermal paper after the thermal paper is colored, and the adhesive strength often has a bad influence on the motor drive.

[0005] Therefore, in the related art, after the printing of half of the total number of the heating elements is completed, the printing is performed in half steps of one step. As a means for feeding paper in this half step, there is a method of driving a motor which rotates once in 24 steps in 2-2 phase excitation by 1-2 phase excitation. That is, when printing the left half of the total number of dots, printing is performed when excitation is performed in two phases, and when printing the right half, printing is performed when excitation is performed in one phase.

[0006]

However, since the damping characteristics of the motor differ between the case of exciting in one phase and the case of exciting in two phases, when the heating element is heated after the motor phase is switched, the excitation is performed in two phases. The print quality on the left side and the print quality on the right side excited in one phase are different, which is a problem. Specifically, there is a difference in the transition time between the case where the two-phase excitation state is shifted to the one-phase excitation state and the case where the one-phase excitation state is shifted to the two-phase excitation state. This difference in transition appears as a difference in print quality.

An object of the present invention is to solve the above-mentioned drawbacks, and an object of the present invention is to provide a printing apparatus capable of obtaining high-quality printing.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a conveying means for conveying a sheet by driving a stepping motor by one-two phase excitation, and printing on a sheet conveyed by the conveying means. When the stepping motor is switched from the one-phase excitation state to the two-phase excitation state and printing is performed, printing is performed by the printing means t1 hours after switching the motor phase,
When printing is performed by switching the stepping motor from the two-phase excitation state to the one-phase excitation state, in a printing apparatus in which printing is performed by the printing unit after a time t2 longer than the time t1 after switching the phase of the motor, When the number of steps of the stepping motor for conveying the sheet from the position where the printing is completed to the position where the next printing is performed is equal to or more than a predetermined amount, the stepping motor is switched from the two-phase excitation state to the one-phase excitation state and printed. When printing is performed, printing is performed by the printing unit after the time t1 since the phase of the motor is switched.

[0009]

[0010]

FIG. 1 shows a portable information apparatus to which the present invention is applied. 1 is a main unit, 2 is a thermal line printer for printing information processed by the main unit 1, and 3 is an input for inputting data to the main unit 1. Keys 4 are liquid crystal displays for displaying information.

FIG. 2 is a view of the main body 1 as viewed from the back, and FIG.
Is a secondary battery for driving the main body 1. The battery 5 is a series connection of five Ni-Cd batteries having a nominal voltage of 1.2 V. The nominal voltage is 6 V, and the discharge end voltage is 4.8 V when no load is applied.

(Basic Structure of Printer) FIGS. 3A and 3B show the printer 2 of FIG. 1, 6 is a housing of the printer, 7 is a platen roller, and 8 is a thermal head having 512 heating elements. Reference numeral 9 denotes a head mounting plate for pressing the thermal head 8 against the platen roller 7, reference numeral 10 denotes a mounting plate shaft for fixing the head mounting plate 9 to the housing 6, reference numeral 11 denotes a manual knob attached to one end of the platen, and reference numeral 12 denotes a pinch. Roller.

The sheet conveying means of the printer is constructed by pressing a pinch roller 12 which is driven by a platen roller 7 which is a conveyed rotary member by a leaf spring (not shown) or the like. A manual knob 11 is attached to one of the platen roller shafts, and a stepping motor 15 is connected to the other via gears 16 and 17. When the thermal paper 18 is inserted, the sheet sensor 14 determines the presence or absence of the paper and rotates the stepping motor 15. When the platen roller 7 rotates, the pinch roller 12 also rotates, and the thermal paper 18 is conveyed along the peripheral surface of the platen roller between both rollers.
When the thermal paper 18 passes over the registration sensor 13, it is sensed and the motor is rotated for a predetermined number of steps. Thus, the thermal paper 18 is transported to the head 8 along the peripheral surface of the platen roller.

(Explanation of Electric Block Diagram of Portable Electronic Information Device) FIG. 4 shows an electric block diagram of the portable electronic information device having the above configuration. The portable electronic information device is the information processing unit 2
8 performs all controls. The information processing unit 28 is controlled by a main CPU 30 and a sub CPU 29. The main CPU 30 controls an OS, an application, and the like.
4, the printer 4, the LCD controller 32, and the like. 33 is a ROM in which a character font exists;
Is a RAM for developing character fonts and is a main CPU 3
0 and are shared by the sub CPU 29. 37 is a ROM built in the sub CPU 29 in which a program and a heat table are present. Reference numeral 38 denotes a built-in RAM of the sub CPU 29 for storing the character font. When printing characters, the main CPU 30 prepares two buffers and stores them in the ROM.
The character font is developed from 33 to the RAM 31. Next, the occupation right of the bus is transferred to the sub CPU 29, and the sub CPU 29 transfers the data of one dot row (512 bits) of the character font from the RAM 31 to the RAM 38 in a block manner. Further, the sub CPU 29 shifts the data written in the RAM 38 to the 512-bit shift register 25. During this time, the main CPU 30 changes the right to occupy the bus again to the sub CPU.
The character font is developed in an empty buffer of the two buffers from the buffer 29 so that the buffer can be stored in the RAM 31 at any time.

The sub CPU 29 outputs the print data (512 bits) block-transferred to the RAM 38 and the motor feed data as a print data transmission signal (PDA).

The 8-bit shift register 27 shifts the data of the transmission signal (PDA) of the print data. The motor feed data included in the transmission signal (PDA) is shifted to the 8-bit shift register 27 and the motor latch is shifted. By activating the signal (MLA), the motor feed data is latched by the 8-bit shift register 27 and the feed data is output. FIG. 5 shows a print data transmission signal (PDA) and a motor latch signal (ML).
A) shows the relationship between the print latch signal (PLA).

The stepping motor driver 39 with a built-in output current adjusting function is a driver capable of adjusting the phase current flowing to the stepping motor 15 and is, for example, M54670.
P (Mitsubishi). The current adjustment method is M54670P
In the case of (2), it is possible to drive with two phase signals (PHa, PHb) and four current amount adjustment signals (I0a, I1a, I0b, I1b). Accordingly, driving is performed by six signals from the 8-bit shift register 27. FIG. 6 shows each signal and the amount of current.

Reference numeral 25 denotes a 512-bit shift register which shifts print data included in a print data transmission signal (PDA), and a 512-bit latch register 26 corresponds to one dot = 1 bit by a print latch signal (PLA). The print data to be heated is stored for one hour.
Reference numeral 8 denotes a 512-dot thermal line head including 512 heating elements, which performs printing by a strobe signal (STB) for controlling the heating of the heating elements by latch data. The strobe signal (STB) is 512
It is connected to all the gates, and can control the heating of all 512 heating elements. The print data transmission signal (PDA), motor latch signal (MLA), print latch signal (PLA), and strobe signal (STB) are all connected to and controlled by the sub CPU 29.

In this embodiment, the number of dots to be heated simultaneously is 36.

Reference numeral 5 denotes a set of five Ni-Cd batteries as secondary batteries, which have a nominal voltage of 1.2 V per cell, 7.5 V in a fully charged state, and 4.8 V in a state of reduced capacity. Output.

Reference numeral 24 denotes a 512 dot thermal head 27
And a step-up DC / DC converter for generating a driving voltage 17V for the stepping motor 15. The output of the secondary battery 5 is 17V with respect to an input that fluctuates from 7.5V to 4.8V, and the output current is 2A. Step-up DC / DC converter 2
4 is controlled on / off by a signal line 19 (PDC) from the sub CPU 29. Reference numeral 20 denotes a regulator, which is 4.8 V while the input fluctuates from 7.5 V to 4.8 V.
Is output. The regulator 20 has an output of 4.8 V and is connected to VCC. VCC is a power source of the information processing unit 28 and requires a maximum output of 100 mA. 2
Reference numeral 2 denotes an interrupt generation circuit, and the secondary battery voltage is 4.8 V
When the battery voltage becomes lower than the predetermined value, the interrupt controller 35 is notified through the signal line LBAT that the battery voltage has become lower than 4.8V. Upon receiving the signal, the interrupt controller 35 notifies the sub CPU 29 and the main CPU 30 that the voltage has become less than 4.8V . Sub CPU 29 and main CPU
The signal 30 interrupts the process being executed in response to the signal, saves necessary data and the like in a memory, and requests the operator to replace the battery.

The presence / absence of paper is determined by the sheet sensor 14. When the paper is inserted, automatic loading is performed and the registration sensor 13 performs positioning. Both sensors are sub CPU
29 and is controlled.

The flow of control of printout of the portable electronic information device having the above configuration will be described with reference to FIG.

The outline of the print sequence in the present embodiment will be described on the assumption that H patterns of 1632 fonts are printed. When the main CPU 30 finds a print process in the application software, it sends a print start command to the sub CPU 29. Main CPU 30
While the sub CPU 29 executes the command, it operates in parallel to develop the first character string into the font on the RAM, and sends a one character string print command after the sub CPU 29 completes the printing process. The main CPU 30
While the sub CPU 29 is executing one character string printing, which will be described later, it operates in parallel in the same manner as described above to develop the next character string font. FIG. 8 shows an example of a bit image that has been subjected to font development.

In FIG. 8, the thermal head used in this embodiment has 512 dots as described above.
With 32 fonts, 32 digits of "H" can be printed in 512 dots. In the bit image of FIG. 8, the first to third dots from the top of one dot line composed of 512 dots are shown in FIGS.
It is shown in (c).

FIG. 10 is a timing chart for printing "H" of 32 digits in a 1632 font. In this embodiment, the time required for heating and the time for rotating the motor by one step are 1 msec.

Sub C receiving print start command
The PU 29 activates the signal line 19 (PDC) to supply 17 V which is a driving voltage of the head and the motor,
Transmit the DC / DC converter 24 (S7-0)
1). Next, assuming that the paper is to be fed, the paper feed counter is initialized to 0 (S7-02).

First, the 512 bits at the top of FIG. 8 (FIG. 9A) are block-transferred to the RAM 38 built in the sub CPU 29 (S7-03). It is determined whether there is data to be heated in the transferred data (S7-04). However, since there is no data to be heated, the paper feed counter is incremented (S7-0).
5) Then, the second 512 bits from the top ((b) in FIG. 9) are transferred to the RAM 38 in the sub CPU 29 again. However, since there is no data to be heated, the paper feed counter is incremented again, and the third 51
The two bits ((c) of FIG. 9) are again block-transferred to the RAM 38 built in the sub CPU 29. Here is the data to be heated. Therefore, it is necessary to feed the paper by the number of steps set in the paper feed counter (S7).
-06).

(Paper feed sequence) A phase signal for one step is output as a print data transmission signal (PDA). For example, at point a in FIG. 10, PHa is 1, PHb is 0, I
0a is 1, I1a is 1, I0b is 1, and I1b is 1, so that an 8-bit signal of (11111100) is output. Here, the last two 00s are dummy for using only 6 bits out of 8 bits. When this signal is set in the 8-bit shift register 27, the latch signal (MLA) is activated. Thus, the 8-bit shift register 27 stores (11111)
1) is output and the motor moves one step. Here, when printing 512 dots, half-step feeding after printing 256 dots is as described above, and one dot line is composed of two steps. Therefore, from the top
Since there was no print data up to the dot line, the paper feed counter was set to four. Therefore, by repeating four times, the second 512 bits of paper from the top are fed.

The stepping motor driver 39 used in this embodiment is a current controllable driver.
Since the two-phase excitation method is used, the feed data to be sent next is (11001100) in order to set the current value of the phase A to zero.

(1 dot line printing sequence)
Printing of one dot line is performed (S7-06).

First, when printing 256 dots on the left side, excitation is performed by two-phase excitation, and when printing 256 dots on the right side, excitation is performed by one-phase excitation, as described above. In the paper feed sequence, since the paper feed has been completed to the second bit position from the top, one-step paper is fed to the third bit position from the top. This corresponds to the point b in FIG. 10, and the feed data is (00111100), which indicates a two-phase excitation state.

The sub CPU 29 transfers the print data transmission signal (P) while counting the number of bits for heating the third 512-bit data from the top, which has been block-transferred to the built-in RAM.
DA). In this embodiment, since the number of dots to be heated simultaneously is 36, when the number of dots becomes 36, the remaining data is output as white data. When this is input to the 512-bit shift register 25, the print latch signal (PLA) is activated, so that the data is latched in the 512-bit latch register 26.

After switching the phase of the motor, the timer is started and the state is maintained for t1 time, and the heating element is heated after t1 time. That is, the heat signal (STB) is activated, and the heating of 36 dots out of 256 dots in the left half is completed.

For example, the third 51 from the top in FIG.
This will be described using 2-bit data (FIG. 9C).

In the case of the 16 32 font, FIG.
Heat data is 4 dots per "H" character. The heat data is output to the PDA while counting.
When the heat data reaches 36 dots, that is, "H"
When nine characters (36/4 = 9) are output, the remaining two characters are output.
Output empty data for three characters (32 characters-9 characters = 23) and activate STB. Thereby, the heat of 36 dots is executed. When the heat is completed, this time, while counting the heat data from the 10th character, PD
Output to A. By repeating this twice, printing of the left half of one dot line is completed. The two times are 1
As mentioned above, there are 4 bits of heat data per character, but 32 bits of "H" are contained in 512 bits, and 16 characters of "H" are contained in 256 dots in the left half of 512 dots. So the total heat data is 4/16 =
64 dots, and the maximum number of simultaneous heat dots is 36 dots, so 64/36 = once more, 28 dots,
Two heats are needed.

When printing of the left half is completed, 25 of the right half is printed.
One-step paper feed is performed to print 6 dots. The feed data at this time is (00001100) to make the current of the phase A zero.

After the phase of the motor is switched, the timer is started and the state is maintained for t2, and the heating element is heated after t2. That is, the heat signal (STB) is activated, and the heating of 36 dots out of 256 dots in the right half is completed. After that, printing is performed in the same manner as the left half,
One dot line printing sequence is completed (S7-0)
7).

Printing is performed by repeating the above-described paper feed sequence and the one-dot line printing sequence.

The above processing is repeated for one character (S7-0)
8) The print processing ends.

At the same time when the printing process ends, the sub CP
U29 makes the signal line 19 (PDC) non-active,
Stop the DC / DC converter 24 (S7-0)
9). This completes the print sequence.

Next, t1 and t2 used in this embodiment will be described.

The time that the motor actually moves after the phase signal is given to the motor and the platen roller moves and moves to the predetermined position is determined from the one-phase excitation state to the two-phase excitation state based on the damping characteristics after the phase switching shown in FIG. About 1ms to become
Approximately 1.5 ms from two-phase excitation to one-phase excitation
Take it. This is presumably because two-phase excitation gives twice as much energy to the motor as one-phase excitation, resulting in a difference in transition time. Therefore, the time from the application of the phase signal to the activation of the strobe as in the prior art is 1 ms.
12, the dots are elongated only on the right side as shown in FIG. 12, and the character quality differs between the left side and the right side. Thus when the time to become two-phase excitation state from the one-phase excitation state as in the present embodiment is composed of t1 = 1 ms, 2-phase excitation state to the one-phase excitation state to t2 = 1.5 ms, the heating element immediately When the heat is executed, dots are formed as shown in FIG. FIGS. 12 and 13 show dots printed on paper when one dot line, that is, all 512 dots are data to be heated. In particular, 256 dots which are the intermediate point between the left and right sides are shown. The left and right 10 dots are shown at the boundary. The thermal line head used in this embodiment has a dot pitch of 0.1.
25 mm, and the paper feed amount by one step after printing 256 dots is completed is 0.125 / 2 = 0.0625 mm. It can be seen that the right half of the dots in FIG. 12 are trailing in comparison with FIG. 13, which causes print unevenness.

Therefore, by changing the waiting time between the one-phase excitation state and the two-phase excitation state as in the present embodiment and the two-phase excitation state and the one-phase excitation state, the print quality is improved. Can be kept constant.

Further, a means for controlling the time from switching the motor phase to printing according to the number of steps fed before starting printing is added.

If the number of steps for feeding the paper between the end of printing and the next printing is large, the rotation speed of the motor, that is, the rotation speed of the paper transport platen approaches a constant speed.
Then, the transition time from the one-phase excitation state to the two-phase excitation state,
There is almost no difference in the transition time from the two-phase excitation state to the one-phase excitation state, and the character quality becomes uniform even if there is no difference in the time from when the motor phase is switched to when printing is performed.

When the value of the paper feed count becomes 8 or more, the time from switching the motor phase to printing is changed from the one-phase excitation state to the two-phase excitation state, from the two-phase excitation state to the one-phase excitation state. And 1 ms for both. By doing so, the character quality can be kept uniform even if the number of paper feed steps is large before printing.

FIG. 14 is a timing chart of normal printing when the paper feed counter becomes 8 or more.
Shows a control flowchart.

In FIG. 15, (S7-05) is a diagram
The same control as 7 is performed. Next, it is determined whether the paper feed counter is 8 or more (S15-01). If it is less than 8, the time t1 from switching from the one-phase excitation state to the two-phase excitation state to starting printing is set to 1 ms. The time t2 from when the two-phase excitation state is switched to the one-phase excitation state to when printing is started is set to 1.5 ms (S15-
02). If the paper feed counter is 8 or more, t1 = t2
= 1 ms (S15-03). The following control is the same as FIG. This makes it possible to make character quality more uniform.

[0050]

As described above, when the number of steps of the stepping motor for transporting the sheet from the position where the previous printing is completed to the position where the next printing is performed is equal to or more than the predetermined amount, the stepping motor is set to two. When printing is performed by switching from the phase excitation state to the one-phase excitation state, printing is performed by the printing means at time t1 after the phase of the motor is switched. Therefore, printing unevenness can be eliminated and character quality can be kept constant.

[Brief description of the drawings]

FIG. 1 is an external view of a portable electronic information device including a printing device according to an embodiment of the present invention.

FIG. 2 is a rear view of the information device shown in FIG. 1 as viewed from the back side.

FIG. 3A is an exploded perspective view of a printing unit shown in FIG. b
FIG. 2 is a cross-sectional configuration diagram of a printing unit shown in FIG.

4 is an electrical block diagram of a portable electronic information device provided with the printing device shown in FIG.

FIG. 5 is a relation diagram of control signals of a printing unit shown in FIG.

FIG. 6 is a waveform diagram of a current signal of the stepping motor shown in FIG.

FIG. 7 is a flowchart of a control operation of the printing unit shown in FIG.

8 is a bit image of a 32-digit H pattern by the printing unit shown in FIG. 4;

FIG. 9 is a bit image of three dot lines from the top in FIG.

FIG. 10 is a timing chart of the printing unit shown in FIG.

FIG. 11 is a damping characteristic diagram of the stepping motor shown in FIG.

FIG. 12 is a printed dot diagram when the time from the start of excitation to the start of heat is fixed at 1 msec in the printing unit shown in FIG. 4;

FIG. 13 shows the printing unit shown in FIG. 4 in which the time from the start of excitation to the start of heat is 1 msec for one-phase to two-phase excitation,
FIG. 7 is a dot diagram printed when 1.5 msec is set for one-phase excitation from one phase.

FIG. 14 is a timing chart when the paper feed counter of the printing unit shown in FIG . 4 becomes 8 or more.

FIG. 15 is a flowchart illustrating a control operation of the printing unit illustrated in FIG . 4 ;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 portable electronic information device main body 2 thermal line printer 3 input key 4 liquid crystal display 5 rechargeable battery 6 printer housing 7 platen roller 8 thermal line head 9 head mounting plate 10 mounting plate shaft 11 manual knob 12 pinch roller 13 resist sensor 14 Sheet sensor 15 Stepping motor 16 Gear 17 Gear 18 Thermal paper 19 DC / DC converter control signal 20 Regulator 22 Interrupt generation circuit 1 24 Boost DC / DC converter 25 512-bit shift register 26 512-bit latch register 27 8-bit shift register 28 Information processing Unit 29 Sub CPU 30 Main CPU 31 RAM 32 LCD controller 33 ROM 34 Touch panel 35 Interrupt controller 37 ROM with built-in sub CPU 8 sub CPU internal RAM 39 stepping motor driver

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 19/30 B41J 11/42

Claims (1)

(57) [Claims] 1. A stepping motor comprising: a conveying means for conveying a sheet by driving a stepping motor by one-two-phase excitation; and a printing means for printing on a sheet conveyed by the conveying means. When printing is performed by switching from the excitation state to the two-phase excitation state, printing is performed by the printing unit after time t1 after switching the motor phase,
When printing is performed by switching the stepping motor from the two-phase excitation state to the one-phase excitation state, in a printing apparatus in which printing is performed by the printing unit after a time t2 longer than the time t1 after switching the phase of the motor, When the number of steps of the stepping motor for conveying the sheet from the position where the printing is completed to the position where the next printing is performed is equal to or more than a predetermined amount, the stepping motor is switched from the two-phase excitation state to the one-phase excitation state and printed. A printing device for performing printing by the printing means after the time t1 after switching the phase of the motor.