JP3298925B2 - Power control device for heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control device for a heater, and more particularly to a heater for controlling the total power consumption of a plurality of heaters above a set value and controlling the heater with power within the set value. The present invention relates to a power control device for use.

[0002]

2. Description of the Related Art Conventionally, in an apparatus having a plurality of heaters, the power that can be output from a power supply or the current that can be used is limited to a certain set value or less due to restrictions on price, volume, and specifications. May be done. If this current is defined as the constraint current,
When a plurality of heaters are operated at the same time, the sum of the current consumption of each heater may exceed the limit current. In such a case, the power supply may be destroyed.

Therefore, when the sum of the current consumption of each heater exceeds the restriction current, each heater is time-divisionally controlled so that the sum of the current consumption does not exceed the restriction current. Here, the current consumption of each heater is represented by Ohm's law (power consumption =
Since the calculation is performed according to (supply voltage / heater resistance), when the voltage supplied to each heater is fixed, it is determined by the resistance value of the heater.

[0004] However, the resistance value of the heater varies during manufacturing and changes with time. For this reason, the current consumption of each heater has been calculated using the minimum resistance value that takes these changes into account. This is because if a resistance value other than the minimum resistance value, such as a design value, is used for calculating the current consumption, the actual current consumption becomes larger than the calculated current consumption, and the sum of the current consumption of each heater exceeds the constraint current. This is because the possibility increases.

For example, the voltage supplied to the heater is V, and the design values of the resistances of the heaters A, B, and C are R _A ,
Assuming that the rate of change of R _B , R _C , and the resistance value of the heater during manufacture and over time is ± 20%, the minimum resistance value of each heater used in the calculation of current consumption is 0.8R _A , 0.8R _B , 0. .8R _C
And the sum of the consumption currents is V / (0.8R _A + 0.8R _B
+ 0.8R _C ).

If the design value of the resistance of the heater is used in the calculation of the current consumption, the sum of the current consumption becomes V / (R _A + R _B + R
_C ). At this time, if the actual resistance value of the heater is 20% smaller than the set value, the sum of the actual current consumption is 1.2 times the sum of the current consumption calculated based on the set value.
If the restriction current is determined based on the set value, the sum of the actual current consumption exceeds the restriction current.

[0007]

However, when the current consumption of each heater is calculated based on the minimum resistance value and the restriction current is determined based on the calculated value, the restriction current is V / (0.8R _A + 0.8R _B + 0.8R _C )
In addition, the actual sum of the current consumption is V / (0.8R _A + 0.8R _B + 0.8R) according to the change in the resistance value of each heater.
_C ) to V / (1.2R _A + 1.2R _B + 1.2R _C )
, The sum of the actual current consumption is always smaller than the limit current.

As described above, since the control current is set with a margin, there is no possibility that the sum of the actual current consumption exceeds the limit current. However, a large power supply must be used as the power supply, and There is a problem that the device becomes large and expensive. Also, the difference between the limited current and the actual current consumption cannot be used, and the power within the constraint cannot be used effectively.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to control the power of each heater by effectively using a limited current, and to use a small and inexpensive power source. It is an object of the present invention to provide a heater power control device that can be used.

[0010]

In order to achieve the above object, a heater power control device according to the present invention comprises a plurality of heaters and a temperature measuring means for measuring each heater temperature of the plurality of heaters. In the power control device, counting means for counting the operation time of each heater of the plurality of heaters, and a current value flowing through each heater of the plurality of heaters from a temperature measured before and after the heater operation time measured by the temperature measurement means a first storage means stored in advance guidance output Sutame data, stores the current value flowing to the each heater
Rewritable second storage means for storing the first storage means
Based on the data stored in the
Flow from the temperature before and after to each heater of the plurality of heaters
Is derived and stored in the second storage means.
In each case, the current of each heater stored in the second storage means
The sum of the current consumption of each heater exceeds the current limit based on the value
And control means for controlling the energization of each heater so as not to cause a problem.

[0011]

The heater power control device of the present invention having the above-described structure measures each heater temperature of a plurality of heaters by using the temperature measuring means, and measures each heater temperature of the plurality of heaters by using the counting means. counts the operating time, to exit guide the current flowing from the heater operating time counted by the temperature and the counting means measured by said temperature measuring means to each heater of the plurality of heaters. The control means controls energization of each heater based on the derived current value.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a hot-melt ink jet printer (hereinafter abbreviated as a printer) 10 of the present embodiment. Below the printer 10, a paper cassette 12 for stacking and storing sheets P for printing is detachably provided. A paper feed roller 14 for contacting the uppermost sheet P in the paper cassette 12 and feeding the sheet P toward a platen 16 described later is provided above the paper cassette 12. .

[0014] the center of the printer 10, the printer head 18 and the platen 16 for supporting the sheet P which ejects melted ink toward the sheet P is disposed to face at a predetermined interval. The platen 16 is provided with a platen heater 20 and a platen heater temperature sensor 21, and the print head 18 is provided with a head heater 22 and a head heater temperature sensor 23, respectively.

A lower paper feed roller 24 and an upper paper feed roller 26 are arranged below and above the platen 16 so that the fed paper P is fed while contacting the platen 16. . Below the lower paper feed roller 24, a paper sensor 28 for determining whether the fed paper is an OHP film or plain paper is provided. The paper sensor 28 is a well-known transmissive sensor including a light emitting unit and a light receiving unit that face each other at a predetermined interval, and determines whether the fed paper is an OHP film or plain paper based on the amount of transmitted light. I do.

The paper P is placed above the upper paper feed roller 26 based on the determination result of the paper sensor 28.
A switching gate 30 for switching between feeding to the HP processing unit and discharging to the outside of the printer 10 is provided. The OHP processing unit is provided with OHP transport rollers 32, 34, and 36 for transporting the OHP film in the OHP processing unit. Further, between the OHP conveying roller 34 and the OHP conveying roller 36, OHP heater motor 3 8 and OHP heater temperature sensor 39 and cooling the platen 40 for cooling the OHP film for reheating the OHP film is installed ing.

The front of the printer 10 (left side in FIG. 1)
Is provided with an ink tank 42 for replenishing the print head 18 with ink.
And the ink tank 42 are connected by a supply tube 44. The ink tank 42 is provided with an ink tank heater 46 and an ink tank heater temperature sensor 47.

Next, a control section for controlling the printer 10 will be described with reference to FIG.

As shown in FIG. 2, the control section comprises a CPU 50 constituting the control means of the present invention, a ROM 52, a timer 53 constituting the counting means of the present invention, and a RAM 54 constituting the storage means of the present invention. And each is connected via a bus.

The CPU 50 has a driver circuit 58 for controlling a motor 56 for driving each roller, and an OH
A paper sensor 28 for determining whether the film is a P film is connected. The CPU 50 includes the platen heater 20,
A heater driver circuit 60 for driving the head heater 22, the OHP heater 38, and the ink tank heater 46;
The temperature sensors 21, 23, 39, 47 of the respective heaters constituting the temperature measuring means of the present invention are also connected. Further, C
An external interface (I / F) 62 for receiving commands and image data from a host computer (not shown) is connected to the PU 50.

The ROM 52 stores a control program for controlling the entire ink jet printer 10 and a data table 5 for storing data for deriving current consumption of each heater constituting the first storage means of the present invention.
2a is stored.

Further, the RAM 54 has a second memory of the present invention .
A current value memory 54a that stores current consumption of each heater, which is a storage unit, an image data memory that stores image data, a control data memory that temporarily stores data necessary for controlling the printer, a register, a flag, and the like. Is provided.

Next, the heater control operation of the ink jet printer 10 thus configured will be described with reference to the flowchart of FIG.

After the power is turned on, the CPU 50 performs initialization (S1). After the initialization is completed, the CPU 50 first reads the temperature of the platen heater 20 from the temperature sensor 21 and stores this temperature as T0 (S2). Next, the unit time Δt is set in the timer 53 (S3), the timer 53 is started (S4), and the platen heater 20 is energized (S5). The unit time set by the timer 53 in S3Ｓ
It waits until the time measurement of t ends (S6: NO), and after the time measurement ends (S6: YES), reads the temperature of the platen heater 20 from the temperature sensor 21 and stores it as T1 (S7).

Next, the temperature rise ΔT of the platen heater 20 per unit time Δt is determined by ΔT = T1−T0 (S8). Using this ΔT, the current consumption I of the platen heater 20 is determined from the data table 52a stored in the ROM 52 (S9), and stored in the current value memory 54a of the RAM 54 (S10).

Here, as shown in FIG. 4, the current consumption is determined by the temperature rise (.DELTA.T) of the heater per unit time (.DELTA.t). It was done.

In accordance with the above flow chart, each of the head heaters 22 other than the platen heater 20 and the OHP heater 3
8, the consumption current of the ink tank heater 46 is determined in the same manner, and the consumption current of the platen heater is I ₂₀ , the consumption current of the head heater is I ₂₂ , the consumption current of the OHP heater is I ₃₈ , and the consumption current of the ink tank heater is I ₄₆ . This is stored in the current value memory 54a.

When it is necessary to energize all the heaters after the power is turned on, the heaters are energized in descending order of priority.
The priority of each heater is determined by the head heater 22, the platen heater 20, the OHP heater 38, and the ink tank heater 4.
The order is 6. The constraint current of the printer 10 is I
_MAX .

At this time, if I ₂₂ + I ₂₀ <I _MAX , it is further confirmed whether or not the OHP heater can be energized. At this time I ₂₂
If + I ₂₀ + I ₃₈ > I _MAX , it is checked whether or not the ink tank heater can be energized instead of the OHP heater. In this case _{I 22 + I 20 + I 46} < energizing the Inkutan click arsenide <br /> over data if I _MAX. In this manner, as the sum of the current consumption of the heater to be energized it does not exceed the constraint current, also performs heater control for better use of constraint current.

It is also effective to determine each heater consumption current from the ON / OFF ratio (duty ratio) of the heater when the temperature of the heater is maintained at a constant temperature. This is because when the heater is maintained at a constant temperature, the ON / OFF ratio of the heater decreases as the current consumption of the heater increases,
Smaller current consumption of the heater by utilizing the ON / OFF ratio of the heater ing large, by measuring the conduction time of the heater when maintaining the heater per unit time period at a constant temperature, the current consumption of the heater Is a way to derive

As described above, in the printer of this embodiment, each time the power is turned on, the current consumption of each of the platen heater 20, the head heater 22, the OHP heater 38, and the ink tank heater 46 is calculated, and the current value is calculated. The energization of each heater is controlled based on the current consumption stored in the memory 54a and the current consumption stored in the current value memory 54a. Since a large margin is not given to the set value, a small power source can be used, the size and cost of the device can be reduced, and the power can be used effectively.

[0032]

As is apparent from the above description, the heater power control device of the present invention calculates the current consumption of each heater in use and controls the heater by effectively using the limited current. it can. In addition, a small power source can be used, and the size and cost of the device can be reduced. Only
The temperature is measured by the temperature measurement
From the temperature around the heater operation time to each heater of multiple heaters
Because we try to derive the value of the flowing current,
For example, a separate means for directly measuring the current value
No need to do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an ink jet printer according to an embodiment.

FIG. 2 is a block diagram of a control unit of the inkjet printer.

FIG. 3 is a flowchart relating to heater control.

FIG. 4 is a graph for calculating a heater current consumption from a heater temperature rise value per unit time.

[Explanation of symbols]

Reference Signs List 20 platen heater 21 platen heater temperature sensor 22 head heater 23 head heater temperature sensor 38 OH P heater 39 OH P heater temperature sensor 46 ink tank heater 47 ink tank heater temperature sensor 50 CPU 53 timer 54 RAM

Claims (1)

(57) [Claims] 1. A heater power control device comprising: a plurality of heaters ; and a temperature measuring means for measuring a temperature of each heater of the plurality of heaters , wherein a counting operation of each heater of the plurality of heaters is counted. means and said temperature measuring means and the heater operation the plurality of <br/> first data of Sutame out guide the current flowing through each heater is stored in advance in the heater from the temperature around the time measured by the Storage means, rewritable for storing a current value flowing through each heater
A second storage means which ability, on the basis of the data stored in said first storage means,
From the temperatures before and after the heater operation time, the plurality of heaters
Of the current flowing through each heater of the second memory
And store it in the second storage means.
Of the current consumption of each heater based on the current value of each heater
And a control means for controlling energization of each heater so that the current does not exceed the limit current .