JP2000326529A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of printable sheets when a printer is being carried, by prolonging the lifetime of a battery without sacrifice of print quality. SOLUTION: At lest two high and low energy application modes are provided between applying energies P1-P4 producing ink ejection speeds V1-V4 in a range for sustaining the quality of a print image. Printing is carried out in high energy application mode when an AC adapter is used and high or low energy application mode can be selected when a battery is used. When the battery voltage is lower than a specified level, for example, printing is carried out in low energy application mode forcibly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a printing device selected and supplied from a power supply or a battery.

[0002]

2. Description of the Related Art In recent years, various types of portable devices have been increasing along with miniaturization of electronic devices. In general, many of such portable devices are configured such that an AC adapter and a battery can be used as an energy supply source. And A
When the C adapter is mounted, the battery circuit is shut off by the insertion detection switch provided in the jack of the AC adapter, and power is exclusively supplied from the AC adapter.

As described above, even when a battery is mounted, power is supplied from the AC adapter when the AC adapter is mounted. In many cases, the drive control when using the AC adapter and the drive control when using the battery for the device main body are performed in the same manner.

For example, in a printing apparatus, that is, a printer, the same control (the same applied energy to the print head) is performed to make the print quality the same regardless of whether an AC adapter is used or a battery is used. I was

[0005]

In the case where the printer is a portable type, a battery is mainly used as a power source. However, not only the printer but also a battery of a portable device, if the battery is too large, the weight of the entire device becomes heavy, and the portable device becomes portable. It is difficult to increase the size because it impairs the performance. Since the size of the battery to be mounted cannot be increased in this way, as a result, the remaining amount of the battery in the portable device becomes insufficient at an early stage, and a case where a desired number of printed sheets cannot be obtained occurs, which is a cause of frustration. Was.

Further, the battery has a characteristic that the life is more rapidly reduced when the current used is large and when the current is small. Since the operating current of the printer is relatively large as compared with other electronic devices, there is also a problem that the life of the battery is extremely short.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional circumstances,
An object of the present invention is to provide a printing apparatus that prolongs battery life without deteriorating printing quality.

[0008]

SUMMARY OF THE INVENTION A printing apparatus according to the present invention is configured to be capable of receiving energy by selecting energy from an AC power supply or a battery, and having a print head having different printing characteristics by changing applied energy. Determining means for determining whether the energy is supplied from the AC power supply or the battery; and at least a high energy application mode and a low energy application mode for applying the applied energy to the print head. Control means for changing between two application modes, wherein the control means applies a high-energy application mode to the print head when the determination means determines that the energy is supplied from the AC power supply. When energy is supplied, while it is determined that the battery is supplying the energy. Configured to allow selection and the high energy application mode and the low energy application mode.

Further, for example, the voltage application time to the print head in the high energy application mode is longer than the voltage application time to the print head in the low energy application mode. The voltage applied to the print head in the high energy application mode is higher than the voltage applied to the print head in the low energy mode.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating an overall configuration of a thermal inkjet printer as a printing device according to an embodiment. As shown in the figure,
The thermal inkjet printer 1 is connected to an MPU 2, an interface 4 connected to the MPU 2 via a bus 3, a memory 5, a thermal head controller 6, and to the thermal head controller 6 via a flexible signal cable 7. It comprises a thermal head 8.

The interface 4, the memory 5, and the thermal head controller 6 are connected in series by buses 9 and 11, separately from the connection with the MPU 2. The interface 4 is connected to a host device 13 via a connection cord 12. The thermal head 8 is a thermal inkjet head that performs printing by ejecting ink droplets from an ink ejection nozzle onto a paper surface, and the host device 13 is, for example, a personal computer, a digital camera, a television, a video device, or the like.

The basic operation of the above configuration will be described. First, the MPU 2 controls the entire thermal inkjet printer 1. The interface 4 stores print data (including character data and image data, hereinafter referred to as print data) and control codes transmitted from the host device 13 to the thermal inkjet printer 1 via the connection code 12 in the memory 5. The memory 5 functions as an interface buffer, and the thermal head control unit 6 sequentially reads out the print data from the memory 5 and transfers the read out print data to the thermal head 8 while generating a control signal to the thermal head 8. . The thermal head 8 performs printing in accordance with the print data on a sheet surface (not shown) that moves relatively to the thermal head 8 in synchronization with the transfer of the print data.

In this printing, energy is selectively applied to a heating element in a fine ink pressurizing chamber in accordance with print data to cause the heating element to generate heat, and this heat generation causes film bubbles to be generated in the ink on the heating element surface. This is performed by causing ink droplets to be ejected from the ink ejection nozzles by instantaneous expansion of the film bubbles.

FIG. 2 is a diagram schematically showing a configuration of a power supply in the thermal ink jet printer 1 described above.
As shown in FIG. 1, the thermal inkjet printer 1 is configured to be able to receive power from both the AC adapter 14 and the battery 15. Then, the AC adapter 14 or the battery 15 is connected to the backflow prevention diode 16 or 1.
7 directly to the thermal head 8 shown in FIG.
The logic circuit system is supplied with electric power after the DC / DC converter 18 converts the voltage to a desired voltage VDD19. When power is supplied by the AC adapter 14, the connection between the battery 15 and the backflow prevention diode 17 is disconnected by a power cutoff circuit (not shown).

In this power supply configuration, the thermal ink jet printer 1 according to the present invention has two modes of a high energy application mode and a low energy application mode when printing.
There are two application modes. The setting of these two application modes is obtained from a general relationship between the applied energy applied to the heating element and the ejection speed of the ink droplet. The characteristics will be described below.

FIG. 3 is a characteristic diagram of a general thermal head 8 showing the relationship between the energy applied to the heating element and the ejection speed of ink droplets. In the figure, the horizontal axis indicates the applied energy P.
And the vertical axis indicates the ejection speed V of the ink droplet. As shown in the figure, when the applied energy is gradually increased from the applied energy P0 to P3, the ejection speed is proportionally increased from the ejection speed V0 to V3.
When the applied energy is further increased from P3 to P4, the ejection speed slightly increases from the ejection speed V3 to V4, and the ejection speed V4 at the applied energy P4 is obtained.
As a result, the discharge speed saturates.

This saturated state is maintained even after the applied energy is increased from the applied energy P4 to the applied energy P5. When the applied energy is further increased beyond the applied energy P5, the ejection speed starts to decrease, and when the applied energy exceeds the applied energy P6, the ejection speed sharply decreases, and finally, the ejection stops.

The fact that the ejection speed V is high means that the energy of the ink droplet at the time of ejection is large and is strong against disturbance. Therefore, printing with the largest possible ejection energy has a larger margin for disturbance.

In experiments, the applied energy P of various magnitudes
When printing was performed by giving the print quality, it was found that a discharge speed of 12 m / s or more was necessary as a discharge speed in order to perform printing while maintaining high image quality. Here, assuming that the ejection speed V1 is 12 m / s, the applied energy P only needs to be in the range of the applied energies P1 to P6.

The relationship between the applied energy and the discharge speed varies depending on the structure of the thermal head.
× 25μm heater, orifice diameter 20μm,
When a thermal head having a thickness of the orifice plate of 17 μm and a distance from the heater to the lower surface of the orifice plate of 10 μm is used, P1 = 0.72 μJ, P4 = 0.8 μJ, P5
= 1.0 μJ, P6 = 1.1 μJ, V4 = 14 m / s.

In this embodiment, the method of applying the applied energy P of various magnitudes to the heating element depends on the length of the voltage application time. That is, when a larger applied energy P is applied, the voltage application time is made longer,
When a smaller applied energy P is applied, the magnitude of the applied energy is changed by shortening the voltage application time.

The applied energies P2 and P2 shown in FIG.
3 and P4 are the above required ejection speeds V1
The applied energies P1 to P corresponding to the above ejection speeds
6, the applied energy P2 to P4
Is higher than the discharge speed V1, which is the lowest discharge speed. That is, high quality printing can be performed without any problem in the normal printing as long as the applied energy is within the range of P2 to P4. In this case, the only difference depending on the level of the applied energy is only the margin for disturbance.

Referring now to FIG. 3, the applied energy for maximizing the discharge speed V is sufficient at the applied energy P4. Even if a larger applied energy is applied, there is no change in the discharge speed. It is clear from the figure that if the energy is too large, the ejection speed will be reduced, which will have the opposite effect.

In the present embodiment, based on the results of the above-described experiments, the application mode of the applied energy to the print head, that is, the thermal head 8 is changed to at least two application modes of a high energy application mode and a low energy application mode. The printing is variably controlled. The high energy application mode is, for example, a printing mode in which printing is performed at an ejection speed V4 using the application energy P4 shown in FIG. 3, and the low energy application mode is an application energy P lower than the application energy P4 shown in FIG.
2 is a print mode in which printing is performed at an ejection speed V2.

When printing is performed with power supplied from the AC adapter 14, printing is performed in the high energy application mode, and when printing is performed using the battery 15 as power,
The battery life priority mode for printing in the low energy application mode and the print quality priority mode for printing in the high energy application mode can be selected.

FIGS. 4 (a), 4 (b) and 4 (c) are timing charts showing specific ways of changing the applied energy for switching the application mode between the high energy application mode and the low energy application mode. Figure (a) shows the AC adapter 1
4 shows a method of applying a voltage in a high energy application mode which is a print quality priority mode when using the battery 15 or when using the battery 15. FIG. 4B shows a low energy application mode which is a battery life priority mode when the battery 15 is used. 2 shows a voltage application method. FIG. 4C shows the printing cycle T of the heating element.
The order of application of the individual heating elements at w is shown.

First, when the applied energy P is V, the resistance value of the heating element is R, and the application time is t, P = (V ＾ 2 / R) · t. . . . . . . (1) It is shown by. Here, the voltage V supplied to the thermal head 8 indicates a voltage supplied from the AC adapter 14 or the battery 15 via the backflow prevention diode 16 or 17, and the voltage of the AC adapter 14 is unchanged and the voltage of the battery 15 Is also unchanged in the short term. Further, since the same heating element is always used for the thermal head 8, the resistance value R of the heating element does not change.

Therefore, in this embodiment, the applied energy P is changed by changing the applied time t as shown in FIGS. Although not particularly shown, the thermal head 8 shown in FIG. 1 of the present example has 100 heating elements and 100 ink ejection nozzles corresponding to the heating elements arranged in a horizontal line. In this example, 10 heating elements can be simultaneously applied to these 100 heating elements.

Therefore, during one printing cycle Tw, 10 (the number of heating elements / the number of simultaneous application) each voltage application cycle D
By applying the applied energy P to a maximum of 10 (the maximum number of simultaneously applied) heating elements at t, printing is performed with all the ink discharge nozzles. The voltage application period Dt is a time required for printing one dot.

During the period of the voltage application cycle Dt, in the high energy application mode shown in FIG.
Each of the heating elements is driven to generate heat (application of applied energy) only during 0, and in the low energy application mode shown in FIG. 4B, each heating element is driven to generate heat only during a period S1 shorter than the period S0.

That is, by substituting the above-mentioned period S0 or S1 for the time t of the above-mentioned equation (1), the applied energy P4 in the high-energy application mode is expressed as “P4 = (V ＾ 2 /
R) · S0 ”, and the applied energy P2 in the low energy application mode is“ P2 = (V ＾ 2 / R)
.S1 ".

According to the present invention, the MPU shown in FIG.
Reference numeral 2 controls printing in the inkjet printer 1 by switching between a high energy application mode and a low energy application mode according to the state of the power supply.

FIG. 5 is a flowchart of control for switching between the high energy application mode and the low energy application mode according to the state of the power supply. Hereinafter, using FIG.
The operation of control by PU2 will be described. First, it is determined whether or not the AC adapter 14 is used (Step S)
1). When the AC adapter 14 is used (S1 is Y), the connection of the battery 15 is electrically disconnected (step S2), and then the voltage application time in the voltage application cycle Dt is set to S0 to increase the energy consumption. After the application mode is set (step S3), printing is executed (step S4).

On the other hand, when the AC adapter 14 is not used in step S1 (N in S1), it is determined whether or not a mode that prioritizes battery life is set (step S5). In this process, for example, it is determined whether or not the battery life priority mode has been designated by the user in advance, or an inquiry message as to whether to give priority to battery life is displayed on a display device (not shown) to determine whether or not the battery life priority mode is possible. This is a process of determining a key input from the selected user.

When the battery life priority mode is designated or selected in advance (Y in S5), the voltage application time in the voltage application cycle Dt is set to S1 to switch to the low energy application mode. (Step S6) The above step S4 is executed.

If the battery life priority mode has not been designated or selected in advance (S5: N), since this is the print quality priority mode, the process goes to step S3 to set the high energy application mode. The process proceeds to step S4 to execute printing.

As described above, the print head thermal head 8
The application mode of the applied energy P to the power supply is changed to at least two application modes of a high energy application mode and a low energy application mode,
Judge whether it is the adapter 14 or the battery 15,
If the energy is supplied from the AC adapter 14, the applied energy in the high energy application mode is supplied to the thermal head 8. On the other hand, if it is determined that the energy is supplied from the battery 15, the high energy application mode and the low energy application mode are used. And are selectable.

FIG. 6 is a flowchart showing another example of control for switching between the high energy application mode and the low energy application mode in accordance with the state of the power supply. In the figure, steps S11, S12, S13, S14, S16
The processing of S17 is the same as the processing of steps S1, S2, S3, S4, S5 and S6 in the flowchart of FIG. In FIG. 6, the process of step S15 different from the process of FIG. 5 will be described below.

First, when it is determined in step S11 in FIG. 6 that the AC adapter 14 is not used (Y in S11), it is determined whether the voltage of the battery 15 is higher than a predetermined voltage Vs. It is determined (step S15). The setting of the predetermined voltage Vs in this processing is performed by, for example, the battery 15
90% of the new voltage.

When the voltage of the battery 15 reaches a predetermined voltage Vs
If it is higher than (S15 is Y), step S1 is immediately executed.
On the other hand, when the voltage of the battery 15 is equal to or lower than the predetermined voltage Vs (N in S15), in this case, the process proceeds to the low energy application mode setting process of step S17. As described above, the voltage of the battery 15 becomes the predetermined voltage V
By setting the battery life priority mode forcibly when it is equal to or less than s, it is possible to secure a larger number of printed sheets even when the voltage of the battery 15 drops.

FIG. 7 is a flowchart showing still another example of control for switching between the high energy application mode and the low energy application mode in accordance with the state of the power supply. In the figure, steps S21 to S24, S25, S27 and S
The processing in step S11 in the flowchart in FIG.
To S14, S15, S16, and S17. In FIG. 7, the process of step S26 different from the process of FIG. 6 will be described below.

First, at step S25 in FIG.
Is higher than the predetermined voltage Vs (Y in S25), the process immediately proceeds to step S27 for determining whether or not the battery life priority mode is designated or selected.
On the other hand, when the voltage of the battery 15 is equal to or lower than the predetermined voltage Vs (N in S25), in this case, a warning is issued that the remaining battery level is "small" (step S26), and the above-described step S27 is performed. Move to the processing of. Thus, even if the battery level is low, the user can designate the print quality priority mode when the user wants to give priority to the print quality over the number of prints, so that the print function is always selectable and easy to use. Will be better.

In the embodiment shown in FIGS. 6 and 7,
In each case, the high energy application mode and the low energy application mode are switched by changing the voltage application time. In this way, instead of the voltage application time, the applied voltage itself is switched between high and low, and the high energy application mode and the low energy application mode are switched. The mode may be switched.

FIG. 8 is a flowchart showing an example of control for switching between the high energy application mode and the low energy application mode by the applied voltage according to the state of the power supply.
Note that, in the figure, steps S31, S32 and S34
The processing of steps S21 and S21 in the flowchart of FIG.
22 is the same as the processing of S24.

If it is determined in step S31 in FIG. 8 that the AC adapter 14 is being used (YES in S31), the connection of the battery 15 is electrically disconnected in step S32. Then, the application voltage VH in the voltage application cycle Dt is set to VH1 to set the high energy application mode (step S33), and step S33
At 34, printing is executed.

On the other hand, when the AC adapter 14 is not used in step S31 (N in S31), the applied voltage VH in the voltage application cycle Dt is set to VH2 to set the low energy application mode (step S35). Proceed to step S34.

As described above, the voltage V applied to the thermal head 8 is
H is VH1 when the AC adapter 14 is used, and VH2 when the battery 15 is used. At this time, VH1> V
H2, and the voltage application time in the voltage application cycle Dt is equal to Sx in both application modes. P4 (when the AC adapter 14 is used) = (VH1 ＾ 2 / R1) · Sx. . . (4) P2 (when battery 15 is used) = (VH2 ＾ 2 / R1) · Sx. . . . . . . (5) holds.

When the output of the battery 15 is used as the power source of the thermal head 8 immediately as shown in FIG. 2, the terminal voltage (VH2) of the battery 15 is changed to the output (VH1) of the AC adapter 14.
You only need to set it lower. Even if the battery 15 is exhausted, printing can be performed while the energy exceeds the minimum energy P1 required for printing.

Alternatively, a DC / DC converter may be inserted into one or both of the AC adapter 14 and the battery 15 so as to obtain the above voltage relationship. DC / D after battery 15
When the C converter is inserted, the voltage is changed to VH1 in the print quality priority mode and to VH2 in the battery life priority mode as in the embodiment of FIG. Good.

In the above-described embodiment, a thermal ink jet printer has been described as an example. However, the printer is not limited to this, and may be an ink jet printer that discharges ink droplets by a piezo element. It may be a printer or the like. These print characteristics change depending on the energy applied to the print head. For example, in a hot-melt printer, when the applied energy is small, the ink on the ink ribbon is not sufficiently melted, but it is possible to read a printed image by applying a small amount of predetermined energy. Similarly, in the case of a thermal sublimation printer, a sufficient sublimation of the coloring agent cannot be performed, but similarly, a low applied energy can be set so that an image can be read.

Therefore, the present invention is not limited to a thermal ink jet printer, but can be applied to any printer that can use both an AC adapter and a battery.

[0052]

As described above in detail, according to the present invention, since at least two voltage application modes, a high energy application mode and a low energy application mode, are provided, the applied energy for printing is reduced when the battery is used. This makes it possible to cope with both the case of printing a high-quality image and the case of giving priority to the number of prints when carrying the camera, thereby improving the usability.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a thermal inkjet printer as a printing device according to an embodiment.

FIG. 2 is a diagram schematically illustrating a configuration of a power supply in the thermal inkjet printer according to one embodiment.

FIG. 3 is a characteristic diagram of a thermal inkjet head showing the relationship between the energy applied to a heating element and the ejection speed of ink droplets obtained as a result of an experiment.

FIGS. 4 (a), (b), and (c) are timing charts showing a specific method of changing applied energy for switching an application mode to a high energy application mode or a low energy application mode.

FIG. 5 is a flowchart (part 1) of control for switching between a high energy application mode and a low energy application mode according to the state of a power supply.

FIG. 6 is a flowchart (part 2) of control for switching between a high energy application mode and a low energy application mode according to the state of a power supply.

FIG. 7 is a flowchart (part 3) of control for switching between a high energy application mode and a low energy application mode according to the state of a power supply.

FIG. 8 is a flowchart illustrating an example of control for switching between a high energy application mode and a low energy application mode by an applied voltage according to a state of a power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal inkjet printer 2 MPU 3 Bus 4 Interface 5 Memory 6 Thermal head control part 7 Flexible signal cable 8 Thermal head 9, 11 Bus 12 Connection code 13 Host device 14 AC adapter 15 Battery 16, 17 Backflow prevention diode 18 DC / DC converter 19 Voltage VDD to logic circuit

Claims (3)

[Claims] 1. A printing apparatus comprising a print head configured to receive energy by selecting energy from an AC power supply or a battery, and having a printing characteristic that varies by changing applied energy, wherein the energy is the AC power supply or the battery. Determining means for determining from which of the batteries the battery is supplied; control means for varying the application mode of the applied energy to the print head to at least two application modes of a high energy application mode and a low energy application mode; The control means, when it is determined by the determination means that the energy is supplied from the AC power supply, supplies the applied energy to the print head in a high energy application mode, while the energy from the battery Is determined to be supplied, the high energy application mode and the previous Printing apparatus, characterized by a selectable and low energy application mode. 2. The printing apparatus according to claim 1, wherein a voltage application time to the print head in the high energy application mode is longer than a voltage application time to the print head in the low energy application mode. 3. The printing apparatus according to claim 1, wherein a voltage applied to the print head in the high energy application mode is higher than a voltage applied to the print head in the low energy mode.