JPH06201486A - Temperature detector - Google Patents

Abstract

PURPOSE:To always detect a correct temperature even if there is unevenness in resistance values due to difference among individuals by providing a resistance value selecting means to make voltage applied between terminals of a detecting resistor approximately constant at a predetermined temperature. CONSTITUTION:A resistance value selecting means 5 for example is connected through a connection cable 10 to an input of a microprocessor 12 of a control substrate 9 on a main body side, while an input terminal is connected through a group 11 of pull-up resistors 11A, 11B, 11C to a power source Vcc. With combination information of ON-OFF of switch means 8A, 8B, 8C of the resistance value selecting means 5, the microprocessor 12 controls so that a constant current source 13 is at a predetermined constant current by combination of 3 bits. Thus an output of voltage according to a change in temperature can be obtained between terminals D and E of a temperature detecting resistor 3 irrespective of unevenness in the resistance values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device,
More specifically, the present invention relates to a temperature detecting device provided in an ink ejection recording head having an electrothermal converter as an ejection energy generating element.

[0002]

2. Description of the Related Art Conventionally, in a recording apparatus having an ink discharge recording head of this type, an electrothermal converter provided in a liquid path is driven to generate thermal energy, and the energy is used to discharge the ink. Recording is performed by ejecting ink from. Therefore, in the electrothermal converter that is often driven, the resulting heat raises the ambient temperature,
Since the temperature of the recording head itself is increased, the ejection characteristics may be deteriorated due to fluctuations in the viscosity of the ink, which may affect the ink dots, leading to deterioration in the quality of the recorded image.

In order to prevent such a situation, the recording head has been provided with temperature detecting means so far to suppress the electric energy supplied to the electrothermal converter according to the detected temperature,
Control has been performed such that the recording operation is stopped and further heating is performed using a heater. In many cases, a resistance pattern (hereinafter referred to as a resistor) formed by a thin film forming technique on the same substrate as the electrothermal converter has been used for such temperature detecting means.

[0004]

By the way, in the conventional resistor for the temperature detecting device provided on the substrate of the recording head as described above, the resistance value is changed due to the subtle difference in the thickness and width of the metal film. It is difficult to accurately detect the temperature because there is individual variation in the ink. Therefore, this affects the ink ejection control, and high-precision control cannot be expected.
Therefore, so far, the resistance of the resistor is kept at a predetermined temperature, for example, 25 ° C., the resistance value at this temperature is measured, and ranks are classified based on the height of the resistance to deal with variations in the resistance value. It was

However, the above-mentioned problems cannot be solved by only the above-mentioned measures for ranking the resistors of the temperature detecting device. That is, as described above, the resistance value of the resistor changes with temperature,
Now, assuming that the resistance value is R and the change amount of the resistance value is ΔR, ΔR / R is constant. However, due to the reasons described above, the individual resistances have individual differences in resistance even under the same temperature, and thus they vary. Due to such individual differences, the amount of change ΔR also differs, and thus it has been difficult to accurately detect the temperature in the recording head so far.

An object of the present invention is to pay attention to such a conventional problem, and in order to solve the problem, a recording head which can always expect accurate temperature detection even if the resistance value of the temperature detecting resistor has variations due to individual differences. An object of the present invention is to provide a temperature detection device suitable for temperature control of the above.

[0007]

In order to achieve the above object, the present invention provides a temperature detecting device for detecting the temperature of a recording head having an electrothermal converter for generating ejection energy in ink. The voltage applied between the terminals of the resistor is made substantially constant at a predetermined temperature by the information of the resistance selecting means set based on the resistance value of the resistor provided for detection at a predetermined temperature. It is a thing.

Further, a resistor is connected in series with the resistor by using the resistance value selecting means so that a substantially constant voltage can be obtained by a simple method. It is a thing.

[0009]

According to the present invention, even if the resistance value of the temperature detecting resistor varies, it is appropriate to deal with the variation among the plurality of thin film resistor pieces provided for voltage adjustment by the resistance value selecting means. Since the combination of resistance pieces can be selected so that the resistance value can be obtained, this makes it possible to obtain a voltage output according to the temperature change between the terminals of the temperature detecting resistor regardless of the variation in the resistance value. it can.

[0010]

Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

The resistance value selecting means 5 is a control board 9 on the main body side.
Connection cable 10 to the input of the microprocessor 12 of
, And each input terminal is connected to the power supply Vcc through 11A, 11B and 11C of the pull-up resistor group 11. Switch means 8 of resistance value selecting means 5
The microprocessor 12 controls the constant current source 13 to have a predetermined constant current by the combination of 3 bits according to the on / off combination information of A, 8B, and 8C (eight ways in this embodiment).

At a predetermined temperature, in order to fix the voltage across the resistor 3 (between DE) to 1V, the resistor 3 has a voltage of 10V.
When it is 0Ω, the output i _A of the constant current source 12 may be 10 mA. When the resistors 3 of the other heads fluctuate and become 112Ω at a predetermined temperature, the constant current source may be controlled so that i _A flows at 8.93 mA. As a specific example, Table 1 shows the current and voltage values when R _A changes. When the voltage is set in this way, the resistance value of the resistor 3 changes linearly with a change in temperature. Therefore, the accurate temperature can be known by detecting the deviation from the set value 1V at the predetermined temperature. For example, the voltage between the DEs can be sent to the AD conversion unit of the microprocessor 12, the temperature of the head can be detected, and ejection control can be performed.

[0014]

[Table 1]

FIG. 2 shows an embodiment of the present invention, in which only the portion of the ink discharge recording head relating to the present invention is shown. Reference numeral 1 denotes an electrothermal converter for ejecting ink (hereinafter simply referred to as a heating element), 2 denotes a heating substrate on which a plurality of heating elements 1 arranged in the same direction and a temperature detecting resistor 3 are formed, and 4 denotes A wiring board having resistance adjusting means (resistance value selecting means) 5 according to the present invention together with a circuit (not shown) for driving the heating element 1, and 6 of both terminals C and B of the temperature detecting resistor 3. It is a wiring that is connected to one terminal B and leads this to the external extraction terminal D.

Next, the circuit configuration of the resistance adjusting means 5 will be described with reference to FIG. Here, 7A, 7B, 7C and 7D are adjusting resistors (thin film resistance pieces) connected in series in the resistance adjusting means 5, and 8A, 8B and 8C are switch means that can be turned on and off. The resistance values of the temperature detecting resistor 3 and the adjusting resistors 7A, 7B, 7C and 7D at predetermined temperatures (for example, 25 ° C.) are R _A , R ₁ , R ₂ , R ₃ and R ₄ , respectively. .

Therefore, in the resistance adjusting means 5 configured as described above, the combination of the adjusting resistors 7A to 7D interposed between the terminals A to C is freely selected by the switch means 8A to 8C. It can be changed at will.

The adjusting operation relating to the temperature detecting resistor 3 according to the present embodiment will be described below with reference to a specific example.

As a basic principle of the present invention, the resistance value R _A of the temperature detecting resistor 3 is wide even if variations due to individual differences of about ± 15% are matched for the reason described above. It is designed to maintain a constant voltage between the terminals of the detection device within the temperature range under the same temperature.
As a result, even if the resistance value of the resistor 3 varies, it is guaranteed that the temperature change can always be normally detected and the recording head is controlled to perform recording by ejecting the ink as set.

When the temperature detecting resistor 3 is formed of an aluminum pattern, the temperature coefficient of resistance T _CR is about 4.2 × 10 ^-3 / ° C. In the case of this example, a voltage of 1 is applied between both terminals CB of the temperature detecting resistor 3 at a temperature of 25 ° C.
V is output, and a voltage 5 is applied between terminals A and B in a state in which adjustment detectors 7A to 7D are connected in series to V.
V is applied. In this case, assuming that the resistance R _A has a value of 100Ω at a temperature of 25 ° C., the adjustment resistor 7
Resistance value to keep A to 7D (R ₁ + R ₂ + R ₃ + R ₄ )
Should be 400Ω. Also, such resistance values R _{1 to} R
_When setting ₄ , for example, R _{1 to} R _{3
1: R 2: R 3 =} 1: 2: it is possible to adjust by rank for Years set as described below by keeping as 4 relationship is maintained.

Thus, according to the present embodiment, the resistance value R of about ± 15% of the temperature detecting resistor 3 is shown in Table 2 depending on the resistance value selecting means only by the combination of the heat generating board and the wiring board.
_For the variation of _A , that is, 84Ω to 112Ω,
By performing "OFF" of the switch means 8A to 8C with the combination shown in the second column, the temperature rise is + 10 ° C and +.
In the case of 20 ° C, as shown in Table 2, 1.03 between terminals C and B (or between E and D) in any combination.
A stable linear voltage change relationship of 3 V and 1.066 V could be obtained.

[0022]

[Table 2]

The set values of R ₁ , R ₂ , R ₃ and R ₄ in this example are 16Ω, 32Ω, 64Ω and 336Ω, respectively.
Resistance values of 336Ω, 352Ω, ...
It becomes 448Ω. As described above, according to this example, by providing the three switch means between the adjusting resistors, it is possible to perform 2 ³ = 8 ways of adjusting by rank.

Thus, as shown in this example, the voltage between the terminals B and C is kept at 1 V when the temperature is 25 ° C.,
For example, when the temperature change increases by + 10 ° C, the voltage between terminals A and B increases by 33 mV as shown in Table 1 to 1.033V.
In addition, when the temperature rises by + 20 ° C, it changes to 1.066V, which changes linearly by 3.3mV with respect to the change of the temperature of 1 ° C.
By detecting this voltage via an A / D converter or the like, the ink ejection operation by the recording head can be controlled normally.

FIG. 4 shows a configuration according to another embodiment of the present invention. In this example, the resistance adjusting means 5 is separately arranged on the wiring board 4 on the recording head side and the control board 9 on the recording apparatus main body side. Reference numeral 10 is a connection cable for electrically connecting the wiring board 4 and the control board 9 to the temperature detecting device according to the present invention, which is used to supply an electric signal or the like to the recording head from the recording device main body side. It may be incorporated into a flexible cable.

According to this embodiment, the adjusting resistors 7A to 7A are provided.
Since C and its wiring are provided by being transferred to the main body side control board 9, the circuit board on the head side is omitted and the wiring board 4 is provided.
Can be formed so small that it can contribute to downsizing of the recording head.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the structure of the recording head, in addition to the combination structure of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection to the main body of the apparatus or the ink from the main body of the apparatus by being attached to the main body of the apparatus The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus according to the present invention, besides the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile having a transmitting / receiving function. It may be a device or the like.

[0035]

As described above, according to the present invention, each of the resistors provided for temperature detection has a resistance value set based on the resistance value at a predetermined temperature. A plurality of thin film resistor pieces for adjusting the voltage applied between the terminals, and resistance selecting means capable of freely selecting a combination of the resistor pieces energized from among the plurality of thin film resistor pieces, Since a substantially constant voltage can be obtained between the terminals of the resistor through the combination of the resistance pieces selected by the resistance selecting means, even if the resistance value of the temperature detecting resistor varies, By adjusting the voltage between the terminals of the measuring device via the resistance adjusting means, the relationship between the temperature change and the voltage change can be kept linear and stable without high cost. Note by temperature detection Control of the head has become possible. Further, the rank division for the adjustment can be set freely.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is a circuit diagram schematically showing another configuration example according to the present invention.

FIG. 3 is a circuit diagram showing a configuration example of resistance adjusting means according to the present invention.

FIG. 4 is a circuit diagram schematically showing a configuration according to still another embodiment of the present invention.

[Explanation of symbols]

1 electrothermal transducer 2 heating substrate 3 temperature detecting resistor 4 the wiring board 5 resistance adjusting means 7A, 7B, 7C, 7D trimmer resistor (film resistor _{pieces) R A, R 1, R} 2, R 3, R ₄ Resistance value 8A, 8B, 8C Switch means 9 Control board 10 Connection cable

Claims (6)

[Claims] 1. A temperature detection device for detecting the temperature of a recording head having an electrothermal converter for generating ejection energy in ink, comprising: a resistor provided for temperature detection; and a resistance of the resistor at a predetermined temperature. A resistance value selecting means set on the basis of a value, and a substantially constant voltage can be obtained between the terminals of the resistor at a predetermined temperature according to the information selected by the resistance value selecting means. And temperature detection device. 2. The temperature detecting device according to claim 1, wherein the temperature detecting resistor is formed of an aluminum thin film. 3. The temperature detecting device according to claim 1, wherein the resistor and the resistance value selecting means are connected in series. 4. The temperature detecting device according to claim 1, wherein the resistance value selecting means is a switch means capable of selecting a resistance by cutting a substrate pattern. 5. A resistor is connected between the terminals of the resistance value selecting means, and the resistance values of the resistors are 1, 2, 4, ... 2, respectively.
The temperature detecting device according to claim 1, wherein the temperature detecting device is set to be ⁿ . 6. The electrothermal converter is an element that generates thermal energy that causes film boiling in the ink as energy for ejecting the ink. The temperature detection device according to item.