JPH0550614A - Control of multi-head printer - Google Patents

Abstract

PURPOSE:To prevent the lowering of throughput while extending life and improving printing quality by reducing the unbalance of the load between the heads of a multi-head in a multi-head printer. CONSTITUTION:The divided printing regions allotted to the respective heads 1-3 of a multi-head are partially overlapped with each other to be used in common by the adjacent heads 1-3 to perform control correcting the unbalance of load quantities by a method transferring the allotment of the common regions from the heads 1-3 of large load to the heads 1-3 of small load corresponding to the magnitudes of the loads of the heads 1-3. The load quantities of the heads 1-3 are detected by the temps. of the heads, duties at every heads 1-3 and the cumulated striking number of pins.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended for a multi-head printer to prevent the deterioration of the throughput due to the concentration of the print load, prevent the bias of the deterioration of the head, and reduce the variation of the print quality between the heads. Control method

In the conventional single-head printer, the printing speed is limited because it takes a long time to scan one line. Therefore, a multi-head printer has been developed in which the print area is divided and shared by a plurality of heads, and printing is performed in parallel. In the multi-head printer, the printing speed is high, but the imbalance of the load between the heads causes a difference in deterioration, resulting in variations in printing quality and life. Further, the throughput may be reduced due to the temperature rise of the head caused by the deviation of the printing load.

According to the present invention, control is performed to balance the loads between the heads as much as possible, the print quality and the life of the heads are equalized, and the division printing due to the temperature rise of the heads is prevented. This prevents a decrease in throughput.

[0004]

2. Description of the Related Art FIG. 5 shows a print area of a conventional multi-head printer. The illustrated example is of a three-head type, and heads 1 to 3 are attached to a carrier 4 at equal intervals l. By moving the carrier 4 left and right by 1 as shown by the arrow, each head 1
In Nos. 3 to 3, a 1-line printing area having a length of 3 liters is divided into 3 by 1 and scanned, so that printing for 1 line can be performed at a moving distance of 1/3 as compared with a single head printer.

Divided printing areas are fixedly allocated to the heads 1 to 3, and each head is
The print data belonging to the divided print area assigned to itself is driven in parallel. Head is 2
It is composed of 4 pins and has several built-in thermal sensors to detect abnormal temperature rise. The heat resistance limit of the head is designed to be 180 ° C., for example, and there is a risk of burning out at a temperature higher than this. The head temperature changes depending on the dot rate (hereinafter referred to as duty). The duty of general print data is 10 to 30%, and when it exceeds that, the head is gradually heated. Therefore, the temperature of the head is monitored by the thermal sensor in the head, and when the temperature exceeds a certain level, the temperature rise prevention control is performed so as to reduce the duty.

[0006]

In the conventional multi-head printer, when the print data or high duty deviates to a specific head and the temperature of the head rises rapidly, the temperature rise prevention control is activated and the printing speed becomes slow. Then, the throughput was significantly reduced.

The head is managed as a life component due to pin tip wear, and the life is generally 200 to 400 million strokes. If the pin tip wear of a specific head is significant due to the imbalance of the load amount between the heads of the multi-head, the service life will be exhausted quickly, so it is desirable to make the pin tip wear as uniform as possible between the heads. Further, if there is a difference in the pin tip wear of the head, there is a problem in that there is a difference in the impact force, which causes variations in the print quality.

It is an object of the present invention to reduce the imbalance of the load between the heads of a multi-head to prevent a decrease in throughput, extend the life and improve the print quality.

[0009]

SUMMARY OF THE INVENTION According to the present invention, divided print areas allocated to each head of a multi-head are partially overlapped and shared by adjacent heads, and the shared area is determined according to the magnitude of the load on the heads. The control for correcting the imbalance of the load amount is performed by the method of moving the allocation of (1) to the head with the smaller load.

FIG. 1 is a diagram for explaining the principle of the present invention. Figure 1
1, heads 1, 2 and 3 are arranged at equal intervals l, respectively, and 4 is a carrier for mounting the heads and driving them left and right. The driving distance is indicated by l + α. As a result, the maximum printable range of each head is l + α, and the print area of one line is 3l + γ, and between head 1 and head 2,
Between the head 2 and the head 3, a shared area having a length of α is formed. Depending on which of the adjacent heads this shared area is distributed to, several divided print areas can be combined. 1 to 3 show the types of the combination states.

Is the length of the divided print area of the head 1 is l
+ Α, and heads 2 and 3 are l. In the case of, head 2 is l + α and heads 1 and 3 are 1, in the case of head 3, head 3 is l + α and heads 1 and 2 are 1, and in the case of head 1 is l + α, head 2 is l−α, head 3 Is 1 + α. By switching the states of these to, it is possible to increase or decrease the load of a specific head.

In the present invention, the load amount of each head is evaluated based on the temperature inside the head, the duty, the cumulative number of shots, etc., and based on this, a narrow print area excluding the common area is assigned to the overloaded head, Try to reduce the imbalance.

[0013]

FIG. 2 is a flow chart of the allocation control of the divided print areas of the multi-head according to the present invention. In this example, the load of the head is determined by the temperature of the head.

In FIG. 2, T _{1 to} T ₃ are the temperatures of the heads 1 to 3, respectively, and a is the temperature rise detection slice level corresponding to the overload condition. Further, ~ corresponds to each combination state of the divided print areas in FIG. The control logic is to overload a head whose head temperature exceeds a and change the allocation of the shared area so that the print area of the head is as narrow as possible.

For example, if only T _{1 of} head 1 exceeds a, then the state is selected and only T _{2 of} head 2 is a.
If T ₁ and T 2 of both head 1 and head 2 exceed a, the state is selected. When only T _{3 of the} head 3 exceeds a, when both T ₁ to T ₃ exceed a, and T ₁
When both ~ T ₃ do not exceed a, all are in the state.

In the case of a 3-head multi-head, there are four states (1) to (3), so the control logic is as shown in FIG.
In the case of other multi-heads such as 2 heads and 4 heads, control may be performed by a similar method so that the print area of the overloaded head is narrowed, that is, the shared area is allocated to the remaining heads.

[0017]

1 is a block diagram of a multi-head printer according to an embodiment of the present invention. In FIG. 3, 1 to 3 are heads, 5 is an MPU for control, 6 is a program memory of a ROM in which a control program is stored, 7 is a DMA controller that controls transfer of print data, and 8 is management regarding the load on the head. It is a non-volatile memory that holds data and the like. Reference numeral 9 is a line buffer in which dot pattern data of print data for one line is developed, 10 is a print head control unit that controls driving of the heads 1 to 3 based on the dot pattern data of the line buffer 9, 11 is heads 1 to 3. Print duty control unit that detects the overload (abnormal temperature rise in this case) and controls the print duty and the range of the print area. Reference numeral 12 indicates the temperature based on the output of the thermal sensor built in the heads 1 to 3. It is a head temperature detecting unit for detecting.

The print duty control unit 11 monitors the temperature detected by the head temperature detection unit 12, and as described with reference to FIG. 2, the head temperatures T _{1 to} T ₃ of the heads _{1 to 3} have the temperature rise detection slice level a. It is checked whether or not the temperature has exceeded the limit, and the combination state of the divided print areas is switched depending on the contents of the temperatures T _{1 to} T ₃ that have exceeded a.

FIG. 4 is a diagram for explaining the operation of the embodiment shown in FIG.
It is based on the control management of FIG. The initial state is, for example, T _{1 to} T ₃ are all in the normal operating state where they do not exceed a. Here, when T ₁ of the head 1 exceeds a,
, And change the print area size of head 1 to l + α
Reduce the load from 1 to l. The print area of the head 2 is changed from 1 to 1 + α by adding a common area.
And the load becomes heavier. Next, after T ₁ of the head 1 and T 2 of the head ₂ also exceed a, the state is switched to. In this state, the size of the print area of the head 1 and the head 2 is 1, and only the print area of the head 3 is 1 + α, and the load on the head 1 and the head 2 is lightened.

After that, when T _{1 of} the head falls below a, the state is switched to. At this time, the print areas of the head 1 and the head 3 have a size of l + α, and the print area of the head 2 is further reduced to 1−α, so that the load on the head 2 is further reduced.

The above control is sequentially executed as the temperature of each head rises and falls. by the way,
In the embodiment of FIG. 3, the load state of each head is detected by whether or not the head temperature exceeds the temperature rise detection slice level a. However, as another method, the duty of each head is changed for each printing of each line. The range of the print area can be switched using the control logic similar to that of FIG. 2 by calculating based on the number of dots of the dot pattern in the print area currently assigned and applying an appropriate slice level to the result. ..

As yet another method, the dot hit counts for each head are accumulated and stored in the non-volatile memory of FIG. 3, and the prints of each head are printed at appropriate time intervals in the direction in which the dot hit counts of each head are averaged. It is possible to control to switch the range of the region. As a result, it is possible to prevent the deterioration of the print quality and the shortening of the life due to the imbalance of the pin tip wear of the head.

Furthermore, it is possible to execute the above methods in combination.

[0024]

As described above, according to the present invention, the imbalance of the load amount of each head in the multi-head printer can be easily reduced by changing the size of the print area, so that the load can be reduced at a low cost. Throughput can be prevented from lowering due to deviation, the life of the head can be extended, and print quality can be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a flow chart of allocation control of divided print areas of a multi-head according to the present invention.

FIG. 3 is a block diagram of a multi-head printer according to an embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 5 is a diagram illustrating a print area of a conventional multi-head printer.

[Explanation of symbols]

 1-3: Head 4: Carrier

Claims (4)

[Claims] 1. A plurality of heads mounted on a single carrier are each divided into a plurality of print areas for one line, and each divided print area is allocated, and the plurality of divided print areas are arranged in parallel. In a multi-head printer that performs printing by using a plurality of divided print areas, a part of each boundary of the divided print areas is shared by two adjacent heads, and the print load of each of the plurality of heads is increased. Check the
A method for controlling a multi-head printer, characterized in that allocation of the shared printing area of the boundary to the head is designated so that the load of the head having a large load is reduced. 2. The control method for a multi-head printer according to claim 1, wherein the size of the print load of each of the plurality of heads is determined by the temperature of each head. 3. The control method for a multi-head printer according to claim 1, wherein the size of the print load of each of the plurality of heads is determined by the print duty of each head. 4. The control method for a multi-head printer according to claim 1, wherein the magnitude of the print load of the plurality of heads is determined by the past cumulative dot hit count for each head.