JP2000211194A - Portable printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a printing quality constant irrespective of a battery or an external power source as a power supply source. SOLUTION: In the portable printer for printing by a thermal head driven by a power from either a battery or an external power source, a driving voltage is measured (step S2), which power of the battery and the external power source is supplied is decided by the measured value (steps S3 to S5), a printing operation is differentiated in response to the decided result (steps S7 to S9), thereby control conditions adapted to the battery and the power source having a difference at an obtained voltage value can be selected, and hence stable printing quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable printer which is driven by power supply from a battery or an external power supply and prints characters, bar codes, and the like on paper by a thermal head.

[0002]

2. Description of the Related Art A portable printer is driven by electric power supplied from a battery when used in a portable manner.
When used indoors in a stationary state, it is driven by being supplied with power from an external power supply.

[0003] However, in a printer for printing using a thermal head, printing is performed by energizing a heating element provided in the thermal head. Therefore,
Printing quality depends on the voltage and current capacity of the power supply.

When a battery is used, the output voltage tends to be low, and during printing, a voltage drop may occur depending on the printing rate. Therefore, when the printing rate is high, the printing becomes thin. Occurs. When the printing becomes thin, for example, in the case of a bar code, there is an inconvenience that scanning cannot be performed.

[0005] Further, the output voltage of the battery gradually decreases as the charged amount decreases. For this reason, when the portable printer is driven by power supply from the battery, the printing conditions cannot always be kept constant.

In order to cope with this problem, the voltage application time of the thermal head is set in consideration of the voltage drop at the time of printing in the case of battery driving. Since a sufficiently high voltage can be obtained, the printing becomes too dark, causing problems such as crushed characters.

Therefore, it is desirable to specify a power source and to perform printing by energizing the heating element within a range corresponding to the capability of the power source.

In order to meet such a demand, a printer is provided with a control condition when driven by a battery and a control condition when driven by an external power supply. The user manually switches the changeover switch depending on which one of the power supplies is used. By reading the signal from the changeover switch, it is determined which power supply source is being used, and the one that matches the result is determined. The printer which selects the control condition of (1) is conceivable.

[0009]

However, it is troublesome for the user to manually switch the changeover switch according to the power supply as in the conventional printer, and the user may forget to change the switch. If the user forgets to switch the switch, printing is performed under the control condition suitable for the external power supply even though the battery is used, so that the printing becomes thinner and the battery consumption becomes faster.

An object of the present invention is to maintain a constant print quality regardless of whether a power supply source is a battery or an external power supply.

[0011]

According to a first aspect of the present invention, there is provided a portable printer including a battery mounting portion and an external power supply connector, wherein the battery is mounted on the battery mounting portion or connected to the external power supply connector. In a portable printer which is driven by power supply from one of an external power supply and prints predetermined contents by a thermal head, a voltage measuring means for measuring a voltage of the battery or the external power supply, and a voltage measured by the voltage measuring means. A power supply determining unit that determines whether power is supplied from the battery or the external power supply; and a differentiating unit that differentiates a printing operation according to a determination result of the power supply determining unit.

The present invention is based on the premise that there is a difference between the voltage value obtained from the battery and the voltage value obtained from the external power supply. Therefore, it is possible to determine whether the power supply source is a battery or an external power source by measuring the drive voltage, and if a control condition suitable for the result is selected, stable printing quality can be obtained.

According to a second aspect of the present invention, in the portable printer according to the first aspect of the present invention, the differentiating unit is configured to output the thermal head when the determination result of the power determining unit is a power supply from the battery. The voltage application time to the thermal head is shortened when the result of the determination by the power supply determination means is power supply from the external power supply.

Therefore, by applying a longer voltage application time when the battery is supplied with power and the voltage is low, and by shortening the voltage application time when an external power supply is used and the voltage is high, stable printing quality can be obtained. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a portable printer according to the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view showing the appearance of a portable printer 1 according to the present embodiment. The portable printer 1 includes a paper storage unit (not shown) for storing rolled paper wound with long paper in a main body case 2,
The opening / closing cover 3 for opening and closing the paper storage unit is attached
The front of the.

When the opening / closing cover 3 is closed, a paper transport path is formed between the opening / closing cover 3 and the main body case 2 for transporting the paper drawn from the roll paper stored in the paper storage unit. .

A thermal head 1 for printing on paper conveyed in a paper conveyance path is provided on a surface of the opening / closing cover 3 on the paper storage section side.
6 (see FIG. 2). Further, a platen (not shown) that presses against the thermal head 16 with the sheet transporting path interposed therebetween while the cover 3 is closed is rotatably mounted in the main body case 2.

The open / close cover 3 also includes a thermal head 1
A discharge port 4 for discharging the sheet printed at 6 is formed.

The portable printer 1 includes a battery mounting section 5 and an external power supply connector (not shown). The portable printer 1 has a battery 22 (see FIG. 2) or an external power supply 21 (see FIG. 2) mounted on the battery mounting section 5. It is driven by power supply from either one.

FIG. 2 is a block diagram of a control system provided in the portable printer 1.

First, the portable printer 1 includes a CPU 6 for executing various arithmetic processes and centrally controlling each unit. The CPU 6 has a flash ROM 7 and an SRA
M8 is connected by a bus line.

Various programs are stored in the flash ROM 7, and the CPU 6 follows these programs. A predetermined area of the SRAM 8 is used as a print buffer.

The CPU 6 is connected to an LED 9, various switches 10, a label sensor 11, a motor driver 12, a thermal head controller 13, and a selector 14 via a bus.

The LED 9 is a light-emitting element for display. Although only one LED 9 is shown in FIG. 2, a plurality of LEDs 9 are actually provided for error display, battery exhaustion display, print-in-progress display, and the like. .

The various switches 10 include a power switch, a feed switch, and a thermal head open switch.

A pulse motor 15 for feeding a sheet is connected to the motor driver 12.

A thermal head 16 is connected to the thermal head controller 13. Label sensor 11
Detects whether there is a sheet in a printable position.
Further, the selector 14 has an infrared sensor controller 18 to which an infrared sensor 17 is connected, and an RF sensor for wireless communication.
A module 19 and an I / F 20 used for communication with a personal computer are connected, and one of these three is used by selection by the selector 14.

The printing process of the portable printer 1 is as follows.
First, the infrared sensor 17 or the RF module 19 or the I / F
When print data is received from any one of the SRAMs 20, the print data is temporarily stored in the SRAM 8 and then stored in the SRAM 8.
The data is developed as image data assigned to each line in a print buffer provided in M8.

The portable printer 1 is, as described above,
An external power supply 21 and a battery 22 are provided as power supply sources, and either of them is selectively used.

The voltage value between the external power supply 21 and the battery 22 has a certain difference. In the present embodiment, the voltage of the battery 22 is approximately 8.4 V to 7.2 V, and the voltage of the external power supply 21 is set to approximately 9 V (± 0.4 V).

A voltage detection circuit 23 for measuring a voltage supplied to a power supply path is connected to the CPU 6 by a bus.
In this embodiment, since the battery 22 is 8.4 V even when fully charged and the external power supply 21 is at least 8.6 V, the reference value for the determination is set to 8.5 V. If the voltage value measured by the voltage detection circuit 23 is 8.5 V or more, it is determined that power is being supplied from the external power supply 21. If the voltage value is less than 8.5 V, power is being supplied from the battery 22. Judge.

FIG. 3 is a flowchart showing a flow of processing for differentiating a printing operation according to a power supply source.

First, when a power switch is turned on and energized, predetermined initial processing is performed (step S).
1). Next, the voltage of the power supply is read by the voltage detection circuit 23 (step S2), and it is determined whether the voltage value is 8.5 V or more (step S3).

Here, if the voltage value is 8.5 V or more (Y in step S3), a flag indicating that power is being supplied from the external power supply 21 is set (step S4).
If the voltage value is less than 8.5 V (N in step S3), a flag indicating that power is being supplied from the battery 22 is set (step S5).

Thereafter, the apparatus is in a standby state until a print request is made (N in step S6). If there is a print request (Y in step S6), first, it is determined which power supply the set flag indicates. (Step S7).

If the flag indicates that power is being supplied from the external power supply 21, the process proceeds to step S8, where the thermal power set to be shorter in accordance with the case where power is supplied from the external power supply 21 is set. The voltage application time to the head is set (step S8). If the flag indicates that the power is being supplied from the battery 22, the process proceeds to step S9, and the voltage to the thermal head set longer in accordance with the case where the power of the battery 22 is supplied. The application time is set (step S9).

Then, the process proceeds to step S10 to perform a printing process (step S10).

Here, in the present embodiment, step S2
Represents voltage measuring means, steps S3 to S5 represent power source determining means,
Steps S7 to S9 correspond to differentiating means.

As described above, according to the present embodiment, by measuring the voltage of the power supply, it can be determined whether the power of the battery is supplied or the power is supplied from the external power supply. The printing operation can be changed, for example, by changing the voltage application time to the thermal head and printing in accordance with the characteristics of the power supply.

In this embodiment, the voltage application time to the thermal head is changed depending on the type of power supply.
Implementation is not particularly limited to this. For example, when a battery is used, reducing power consumption is important to improve battery life, but when an external power supply is used, power saving is not so significant. Therefore, if there is a process that is postponed for power saving, change the control conditions related to various printing operations depending on the type of power supply, such as giving priority to that process over power saving and increasing the processing speed. Can be considered.

[0042]

According to the first aspect of the present invention, whether the power is supplied from the battery or the external power supply is determined by measuring the voltage, and the printing operation is differentiated according to the determination result. If a control condition suitable for the power supply source is selected, stable printing quality can be obtained, and each process can be efficiently performed by performing control suitable for each power supply source.

According to the second aspect of the present invention, when power is supplied from a battery, the voltage application time to the thermal head is lengthened, and when power is supplied from an external power supply, the voltage application time to the thermal head is increased. When power is supplied from a battery and the voltage is low, the voltage application time is lengthened.When an external power supply is used and the voltage is high, the voltage application time is shortened, so that stable printing quality can be obtained. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a portable printer according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an electrical connection of each unit included in the portable printer.

FIG. 3 is a flowchart illustrating a flow of processing for differentiating a printing operation according to a power supply source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable printer 5 Battery mounting part 16 Thermal head 21 External power supply 22 Battery Step S2 Voltage measuring means Step S3 to S5 Power discriminating means Step S7 to S9 Differentiating means

Claims (2)

[Claims] An external power supply connector provided with a battery mounting portion and an external power supply connector. The thermal power supply device is driven by power supply from either a battery mounted on the battery mounting portion or an external power supply connected to the external power supply connector. In a portable printer for printing predetermined contents by a head, voltage measurement means for measuring a voltage of the battery or the external power supply, and power supply from either the battery or the external power supply based on a measured value of the voltage measurement means. A portable printer, comprising: a power source determining unit for determining whether the printing operation is different from the power source determining unit; 2. The method according to claim 1, wherein the differentiating means increases a voltage application time to the thermal head when the result of the determination by the power source determining means is the power supply from the battery. 2. The portable printer according to claim 1, wherein a voltage application time to the thermal head is shortened when the power is supplied from the external power supply.