JPH06328739A - Temperature control method for print head - Google Patents

Abstract

PURPOSE:To print stably near a critical temperature by limiting printing when a forecasting temperature of an electric element based on a detected data is higher than an alarm temperature, in a print head having a temperature detecting element for detecting data corresponding to the temperature of the electric element. CONSTITUTION:At a print head 8, for example, of a wire dot impact type, a magnetic flux in an opposite direction of an exciting circuit generates when a coil 35 is excited. As a result, a force for attracting an armature 34 reduces and a plate spring 30 for bias is restored, so that a print wire 33 protrudes from a nose 22a of a guide frame 33 so as to push an ink ribbon and a print medium to a platen. Thus, printing is carried out. At this time, heating of the coil 35 is detected by a temperature detecting element 8a through a filler 38. In this case, a forecasting temperature of the coil 35 is calculated based on the detected data of the temperature detecting element 8a. When the forecasting temperature is higher than an alarm temperature, printing is restricted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control method for a print head of a printer which is an output device of information equipment.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of a main part of a conventional printer. In FIG. 7, this printer is a wire dot impact printer, and an interface (I / F) for inputting print data to this printer.
1 and a control circuit 2 as a control means for controlling the operation of the entire printer, and the control circuit 2 includes an interface LSI 2a and an interface LSI 2b.
And CPU (central processing unit) 2c, RAM 2d which is a read / write memory, and RO which is a read-only memory
It is composed of M2e.

In addition, the control circuit 2 includes a line feed motor driver 3, a line feed motor 4, and a space motor driver 5.
A space motor 6, a head driver 7, a print head 8, a temperature detection element 8a provided in the print head 8, an operation switch 9, and a temperature detected by the temperature detection element 8a to a set temperature. An alarm detection circuit 10 is connected to detect whether or not it has reached.

FIG. 8 is a schematic sectional view showing an example of the print head 8. The print head 8 is a spring-charged wire dot print head, and is provided between the guide frame 22 and the cap 23 with a spacer 24 on the back surface of the substrate 2.
5, the permanent magnet 27, the pedestal 28, and the spacer 2 in a state of being stacked on the base 26.
9, bias leaf spring 30 and armature yoke 31
Are sequentially stacked and arranged, and these are fixed integrally by a clamp 32.

Further in detail, the leaf spring 30 for bias is used.
Is made as a ring-shaped flat plate,
A metal having integrally a plurality of flexible portions 30b protruding from the ring-shaped main body portion toward the center at substantially equal intervals in the circumferential direction, and the printing wires 33 being fixed to the respective flexible portions 30b. An armature 34 made of steel is attached. Further, a core 36 around which a coil 35 is wound is attached to the base 26 at a position corresponding to each flexible portion 30b of the bias leaf spring 30.
The lead terminals 5 are connected to a circuit such as the head driver 7 on the substrate 25. In addition, the temperature detecting element 8a such as a thermistor for temperature detection is mounted on the substrate 25, and the temperature detecting element 8a is covered with the coil 35 and the filler 38 such as epoxy resin having good heat conductivity. There is.

Next, the operation of the wire dot print head 8 will be described. First, in the wire dot print head 8, the magnetic flux of the permanent magnet 27 causes the base 28, the spacer 29, the bias leaf spring 30, and the armature yoke 3 to move.
1, the permanent magnet 2 again through the core 36 and the base 26
It flows on the route returning to 7.

When the coil 35 is not energized, the armature 34 causes the flexible portion 30b of the bias leaf spring 30 to move.
While being biased, the core 36 is attracted, the strain energy is accumulated in the bias leaf spring 30, and the bias wire spring 30 is in a biased state, and the printing wire 33 is drawn into the nose portion 22a of the guide frame 22. FIG. 8 shows this state.

On the other hand, when a current is passed through the coil 35 to excite it, a magnetic flux in the direction opposite to the exciting circuit is generated.
Then, the force of attracting the armature 34 decreases, the strain energy accumulated in the bias leaf spring 30 is released, and the bias leaf spring 30 returns. Further, upon this return, the print wire 33 fixedly attached to the tip of the armature 34 protrudes from the nose portion 22a of the guide frame 22, and presses the ink ribbon (not shown) and the print medium against the platen. As a result, characters and graphic patterns can be printed.

Thus, after the armature 34 is once opened, the coil 35 is de-energized again. Then,
The armature 34 is again attracted to and held by the core 36 together with the print wire 33 returning after impacting the print medium.

In the structure of the print head 8, when a large number of coils 35 are simultaneously energized during printing, magnetic interference occurs between the adjacent cores 36 and heat is generated. The generated heat is transferred to the temperature detecting element 8a by the filler 38, and is input into the control circuit 2 via the alarm detecting circuit 10. Further, the control circuit 2 controls the energization to the coil 35 based on the temperature data to limit the printing, and keep the temperature of the electric element (coil 35) below the limit temperature.

FIG. 9 shows a procedure for restricting printing by controlling the operation of the print head 8, that is, the energization of the coil 35 on the control circuit 2 side based on the temperature data obtained by the temperature detecting element 8a. It is a thing. In the control procedure shown in FIG. 9, when temperature data is input to the alarm detection circuit 10 from the temperature detection element 8a, the temperature in the print head 8 detected by the alarm detection circuit 10 (hereinafter referred to as "detection temperature"). Is above the preset alarm temperature (step S1), and this is input to the CPU 2c via the interface LSI 2b.
Then, the CPU 2c arithmetically processes it and designates normal printing when the alarm detection circuit 10 determines that the detected temperature is lower than the alarm temperature (step S2), and designates printing stop when it determines that the detected temperature is higher than the alarm temperature. Then, the processing is performed (step S3). Therefore, the temperature rise of the print head 8 is prevented by repeating this process.

However, the temperature detecting element 8a is used for the print head 8
The temperature Td detected by the temperature detecting element 8a and the plurality of coils (heat generating electric elements) are provided at a predetermined position (in this example, the center surrounded by the plurality of cores 36 on the substrate 25). ) The temperature T of the coil, which is the highest temperature of 35
Generally, there is a temperature difference with c. Further, this temperature difference is usually different between low density printing and high density printing.

FIG. 10 shows a temperature detecting element 8a for low density printing.
Detected temperature Td detected in step 3 and the actual temperature T of the coil 35
11 shows a characteristic curve of c, and FIG. 11 shows a characteristic curve showing the detected temperature Td detected by the temperature detecting element 8a during high density printing and the actual temperature Tc of the coil 35, respectively. Figure 1
0 and FIG. 11, since there is little heat generation in low density printing (FIG. 10), the coil temperature Tc and the temperature detection element 8a
The temperature difference from the detection temperature Td of the
In 1), the temperature difference between the coil temperature Tc and the detection temperature Td of the temperature detection element 8a is large due to the sudden heat generation. Moreover, this temperature difference may be several tens of degrees. The alarm temperature T1 is set in both low density printing and high density printing.
Printing is stopped when the detection temperature Td is applied. 10 and 11, the Y axis is temperature,
The X-axis represents time, and the symbol T3 represents the coil 35.
Represents the limit temperature of the heat generating electric element such as.

[0014]

As described above, since heat generation is low in low density printing, the temperature difference between the coil temperature Tc and the detection temperature Td of the temperature detecting element 8a is small, but in high density printing, abrupt heat generation occurs. Therefore, the temperature difference between the coil temperature Tc and the detection temperature Td of the temperature detection element 8a becomes large. As described above, the coil temperature Tc and the detection temperature Td depend on the print density.
Since the temperature difference between the alarm temperature T1 and the temperature difference between the alarm temperature T1 and the alarm temperature T1 is high, the alarm temperature T1 may be overshot to exceed the limit temperature of the heat-generating electric element and may be burned and damaged.
If is set low, overshoot of the limit temperature can be prevented, but the printing speed cannot be increased in the low density printing and the printing speed cannot be increased. Further, in the future, it is expected that the temperature will further increase in order to increase the printing speed, but there is a problem that the printing control according to the temperature characteristic of the electric element cannot be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a temperature control method for a print head capable of performing stable print control in the vicinity of the limit temperature of a mounted electric element. is there.

[0016]

In order to achieve the above object, a temperature control method for a print head according to the present invention is a printing method having a temperature sensing element capable of obtaining output data according to the temperature of an electric element mounted on the printing head. In a printer equipped with a head, the expected temperature T of the electric element is calculated from the output data
F is calculated, and printing is limited when the predicted temperature TF is higher than the alarm temperature T2. Further, in addition to the condition of limiting printing when the predicted temperature TF is higher than the alarm temperature T2, the height of the temperature gradient K obtained by the ratio of the previously detected temperature Td ₀ to the currently detected temperature Td The printing may be limited when the temperature gradient KS is higher than the reference temperature gradient KS. Furthermore, as a method of obtaining the expected temperature TF of the electric element, the previously obtained expected temperature TF ₀ , the temperature gradient K, the detected temperature Td, the constants c and e, and the time from the previous detection to the current detection You may make it calculate by the following formula | equation with the elapsed time t. TF = TF ₀ × c + Td × (1-c) + K × t × e where 0 <c <1, e> c.

[0017]

According to this method, the expected temperature of the mounted electric element can be calculated, and the printing can be controlled under the condition that the predicted temperature is equal to or lower than the limit temperature of the electric element.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing a main configuration of a printer to which an embodiment of the present invention is applied. In FIG. 2, components corresponding to those in FIGS. 7 and 8 are described with the same reference numerals as those in FIGS. 7 and 8. It should be noted that the point of great difference between the configuration shown in FIG. 7 and the configuration of the present embodiment shown in FIG. 2 is that the alarm detection circuit 10 shown in FIG.
The point is that an A / D converter 11 is provided instead of.

That is, the printer shown in FIG. 2 is provided with an interface 1 for inputting print data to the printer, a control circuit 2 as control means for controlling the operation of the entire printer, and the control circuit 2. Is the interface LSI 2a and the interface LSI
2b, CPU 2c, RAM 2d, and ROM 2e, and the control circuit 2 further includes a line feed motor driver 3 and
A line feed motor 4, a space motor driver 5, a space motor 6, a head driver 7, a print head 8,
A temperature detecting element 8a provided in the print head 8;
The temperature data of the operation switch 9 and the temperature detection element 8a is set to A
An A / D converter 11 for performing / D conversion and inputting to the control circuit 2 is connected.

The temperature data detected by the temperature detecting element 8a is A / D converted by the A / D converter 11 and input to the control circuit 2. Further, in the control circuit 2, this data is calculated by the CPU 2c, and the coil 35
The electric current to the electric element (coil 35) is controlled to be controlled, and the temperature of the electric element (coil 35) is maintained below the limit temperature.

FIG. 1 is a flow chart showing an example of a processing procedure in the CPU 2c as an embodiment of the temperature control method for the print head 8 according to the present invention. Therefore, this processing procedure will be described below. First, when temperature data is input from the temperature detecting element 8a to the CPU 2c via the A / D converter 11 and the interface LSI 2b, the temperature detecting element 8a recognizes the detected temperature Td and the detected temperature T
Based on d, the temperature gradient K and the expected temperature TF of the mounted electric element such as the coil 35 are calculated.

Here, the temperature gradient K is obtained from the ratio of the previously detected temperature Td ₀ and the present detected temperature Td stored in the RAM 2d, and the predicted temperature TF is obtained from the following equation (1).

[0023]

TF = TF ₀ × c + Td × (1-c) + K × t × e (1) However, 0 <c <1, e> c, and TF ₀ is the previous predicted temperature (initial value is This time it should be the same as the detected temperature Td),
c and e are constants, and t is the time elapsed from the previous detection to the current detection.

That is, in the above equation (1), the constants c and e are set in accordance with the electric elements mounted on the print head 8 so that the expected temperature TF rises according to the constants c and e when the temperature rises. The curve shows a curve that approaches the detected temperature Td when the temperature is stable, and shows a curve according to the constants c and e when the temperature drops. Therefore, by using the above equation (1), it is possible to know the expected temperature of the pseudo-mounted electric element. In addition, each detected temperature Td is not converted into temperature,
The output that has passed through the A / D converter 11 may be processed by setting an equivalent constant.

When the limit temperature of the electric element such as the coil 35 is set to T3, several degrees to several tens of degrees Celsius from the limit temperature T3.
The alarm temperature T2 is set so as to be a low temperature, and the reference temperature gradient KS is set so that RO is set in advance.
It is stored in M2e or the like.

Then, in step S11, the detection temperature Td is recognized, the temperature gradient K is calculated, and the expected temperature TF is calculated. Next, in step S12, the detection temperature Td is compared with the alarm temperature T2. If the detected temperature Td exceeds the alarm temperature T2, the process proceeds to step S16, and print stop is designated. On the other hand, the detected temperature Td
Is above the alarm temperature T2, step S
Move to 13.

In step S13, the detected temperature gradient K and the reference temperature gradient KS are compared, and if the detected temperature gradient K exceeds a certain value of the reference temperature gradient KS, then step S13.
In step 16, the print stop is designated and the print is stopped. On the other hand, the detected temperature gradient K is the reference temperature gradient KS
If it does not exceed the constant value of, the process proceeds to step S14.

In step S14, the estimated temperature TF is compared with the alarm temperature T2. If the estimated temperature TF exceeds the alarm temperature T2, the process proceeds to step S16 to designate printing stop. On the other hand, when the predicted temperature TF does not exceed the alarm temperature T2, step S15
Move to and specify normal printing. By repeating this, the temperature rise of the print head 8 can be suppressed below the limit temperature of the mounted electric element.

FIG. 3 shows the detected temperature Td detected by the temperature detecting element 8a during low density printing and the actual temperature Tc of the coil 35.
4 shows a characteristic curve of the expected temperature TF of the coil 35, and FIG. 4 shows a characteristic curve showing the detected temperature Td detected by the temperature detecting element 8a during high-density printing, the actual temperature Tc of the coil 35, and the expected temperature TF of the coil 35. Respectively,
In the present embodiment, the energization of the coil 35 is controlled by the predicted temperature TF, so that in the low density printing (FIG. 3), the limit temperature T3.
Printing speed can be increased by continuing the printing operation up to a high temperature close to the above, and in high density printing (FIG. 4), it is possible to prevent overshoot of the limit temperature T3 of the electric elements such as the mounted coil 35. it can. 3 and 4, the Y axis represents temperature and the X axis represents time.

Therefore, according to the temperature control method of this embodiment, the temperature gradient K and the expected temperature TF of the mounted electric elements such as the coil 35 are calculated from the temperature data detected by the temperature detecting element 8a, and the expected temperature TF is calculated. Since the printing is controlled by the above, it is possible to perform the temperature alarm control according to the temperature characteristic of the mounted electric element in a stable state near the upper limit (limit temperature) of the mounted electric element. In addition, in order to improve printing quality and speed up printing in the future, it is expected that electronic components such as sensors with strict upper limit values will be mounted on the print head, but even when these electronic components are mounted, It becomes possible to perform print control under the condition where the temperature becomes lower than the limit temperature of the electric component.

FIG. 5 is a flow chart showing a processing control procedure in the CPU 2c as another embodiment of the print head temperature control method according to the present invention. In this processing procedure, the temperature data from the temperature detecting element 8a is sent to the CPU via the A / D converter 11 and the interface LSI 2b.
2c, the temperature T detected by the temperature detecting element 8a is the same as in the processing procedure shown in FIG. 1 in step S21.
The recognition of d and the calculation of the temperature gradient K and the predicted temperature TF of the mounted electric elements such as the coil 35 are performed based on the detected temperature Td.

The temperature gradient K here and the expected temperature TF
Are obtained in the same manner as the processing procedure shown in FIG. Even in the case of this processing, when the limit temperature of the electric element is set to T3, the alarm temperature T2 is set so that the temperature is lower than the limit temperature T3 by about several degrees Celsius to several tens of degrees Celsius, and further standard. KS indicating the lower limit of temperature gradient
a and KSb indicating the upper limit are set and stored in the ROM 2e or the like. In addition, the caution temperature T4 is set between the limit temperature T3 and the alarm temperature T2 and stored in advance in the ROM 2e or the like.

Then, in step S21, the detection temperature Td is recognized, the temperature gradient K is calculated, and the predicted temperature TF is calculated. Next, in step S23, the detection temperature Td and the limit temperature T3 are compared. If the detected temperature Td exceeds the limit temperature T3, the process proceeds to step S30, the print stop is designated, and the print is stopped. On the other hand, when the detected temperature Td does not exceed the limit temperature T3, the process proceeds to step S24.

In step S24, the estimated temperature TF and the alarm temperature T2 are compared. If the estimated temperature TF exceeds the alarm temperature T2, the process proceeds to step S25.
In step S25, the predicted temperature TF and the caution temperature T4 are compared. Then, in step S25, the estimated temperature T
If F exceeds the caution temperature T4, step S30
Move to and specify print stop. On the other hand, if the predicted temperature TF does not exceed the caution temperature T4, the process proceeds to step S29 to specify the limited printing. When the limited print designation is performed, control is performed to reduce the number of prints per unit time as compared with the normal print, whereby the temperature rise of the coil 35 also becomes gentle.

If the predicted temperature TF does not exceed the alarm temperature T2 in step S24, the process proceeds to step S26. In this step S26, the detected temperature gradient K is compared with the lower limit gradient KSa of the reference temperature, and if the detected temperature gradient K exceeds the lower limit temperature gradient KSa constant value, the process proceeds to step S27, and in this step S27. The detected temperature gradient K and the upper limit gradient KSb of the reference temperature are compared.
Then, in step S27, the detected gradient K is the upper limit gradient KSb.
If it is above, the process proceeds to step S30 and print stop is designated. On the other hand, the detected gradient K is the upper limit gradient K
If it does not exceed Sb, the process proceeds to step S29 to specify the limited printing.

On the other hand, if the detected temperature gradient K does not exceed the lower limit temperature gradient KSa in step S26, the process proceeds to step S28 to specify normal printing. By repeating this, the temperature rise of the print head 8 is prevented.

FIG. 6 shows the detected temperature Td detected by the temperature detecting element 8a during high density printing and the actual temperature Tc of the coil 35.
And characteristic curves showing the expected temperature TF of the coil 35 are shown respectively. In FIG. 6, the Y axis represents temperature and the X axis represents time.

Therefore, in the control according to the procedure shown in FIG. 5, the limit printing designated area is provided to bring the limit temperature T3 of the electric element (coil 35) closer to the limit temperature without overshooting. It is possible to speed up printing. Further, since the limited print designation and the print stop designation are controlled also by the temperature gradient, it is possible to reliably prevent the overshoot.

In each of the above-described embodiments, the case where the invention is applied to the wire dot print head has been described, but the invention is not limited to the wire dot print head and can be similarly applied to other types of print heads.

[0040]

As described above, according to the method of controlling the temperature of the print head according to the present invention, the expected temperature of the mounted electric element is calculated, and the predicted temperature becomes equal to or lower than the limit temperature of the electric element. Print control can be performed under. Therefore, in the future, in order to improve the printing quality and speed up printing, it is expected that electronic components such as sensors with strict upper limit values will be installed in the print head, but even if this sensor is installed, the same applies. Applicable.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a main configuration of a printer to which the invention is applied.

FIG. 3 is a diagram showing temperature characteristics during low-density printing.

FIG. 4 is a diagram showing temperature characteristics during high-density printing.

FIG. 5 is a flowchart showing another embodiment of the present invention.

FIG. 6 is a diagram showing temperature characteristics during high-density printing.

FIG. 7 is a block diagram showing a main configuration of a conventional printer.

FIG. 8 is a schematic cross-sectional view showing an example of a print head.

FIG. 9 is a flowchart showing a conventional print head temperature control method.

FIG. 10 is a diagram showing temperature characteristics during low density printing.

FIG. 11 is a diagram showing temperature characteristics during high-density printing.

[Explanation of symbols]

 2 control circuit 8 print head 8a temperature detection element 35 coil (heating element)

 ─────────────────────────────────────────────────── --Continued front page (72) Inventor Noboru Oishi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (3)

[Claims] 1. A printer including a print head having a temperature detection element capable of obtaining output data according to the temperature of an electric element mounted on the printer, the expected temperature TF of the electric element being calculated from the output data, A print head temperature control method, wherein printing is restricted when the expected temperature TF is higher than the alarm temperature T2. 2. In addition to the printing restriction condition, the height of the temperature gradient K obtained by the ratio of the previously obtained detected temperature Td ₀ and the presently obtained detected temperature Td is higher than the reference temperature gradient KS. The temperature control method for a print head according to claim 1, wherein printing is restricted even under the condition. 3. The predicted temperature TF of the electric element, the predicted temperature TF ₀ obtained last time, the temperature gradient K, the detection temperature Td, constants c, e, from the previous detection to the current detection 3. The print head temperature control method according to claim 1, wherein the temperature is calculated by the following equation based on the elapsed time t. TF = TF ₀ × c + Td × (1-c) + K × t × e where 0 <c <1, e> c.