A preparation method of thermal print head and thermal print head

Abstract

Embodiments of the present invention disclose a method for preparing a thermal print head and a thermal print head. The thermal print head includes a heat dissipation substrate, a ceramic substrate, a heat storage layer, an electrode layer, and a resistor layer. The ceramic substrate is located on one side of the heat dissipation substrate, the heat storage layer is located on the side of the ceramic substrate away from the heat dissipation substrate, the electrode layer is located on the side of the ceramic substrate away from the heat dissipation substrate and covers the ceramic substrate, and the resistor layer is located on the side of the electrode layer away from the heat storage layer. The ceramic substrate also includes a cavity structure, and along the thickness direction of the thermal print head, the projection of the cavity structure overlaps with the projection of the resistor layer. The cavity structure includes a substrate and a filling material. The preparation method includes: obtaining a desired printing rate; and filling the cavity structure with the filling material according to the desired printing rate. By filling the cavity in the ceramic substrate with the filling material, the thermal conductivity and heat dissipation of the thermal print head can be adjusted based on the difference in physical properties between the filling material and the substrate, thereby ensuring the operating and printing performance of the thermal print head.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of thermal printing, and in particular to a method for preparing a thermal print head and a thermal print head. Background Art

[0002] As we all know, a thermal print head consists of a heat sink and a substrate made of insulating material. A base layer (heat storage layer glass) is formed on the substrate, and then wire electrodes are formed on the substrate and base layer surfaces. The wire electrodes are divided into individual electrodes and common electrodes. A heating resistor strip is formed on the wire electrodes along the main printing direction. One end of the individual electrode is connected to the heating resistor strip along the secondary printing direction, and the other end is connected to the control IC. One end of the common electrode is connected to the heating resistor strip along the secondary printing direction, and the other end is connected to the wire pattern. The electrical part of the thermal print head consists of the wire electrodes on the ceramic substrate, the heating resistor strip, the control IC, and the PCB. This electrical part is attached to the heat sink with double-sided tape or thermal conductive adhesive. The higher the printing speed and the greater the printing rate of the thermal print head, the higher the heat dissipation requirements. Conversely, the lower the speed and the smaller the printing rate, the higher the heat storage requirements. In general, the higher the thermal conductivity and heat storage capabilities of the thermal print head. Summary of the Invention

[0003] An embodiment of the present invention provides a method for preparing a thermal print head and a thermal print head. A cavity structure is set in a ceramic substrate according to the required printing rate and a filling material is filled therein, thereby meeting the high requirements of the thermal print head for heat dissipation and heat conduction, and ensuring the working performance and printing effect of the thermal print head.

[0004] In a first aspect, a method for preparing a thermal print head is provided, the method being applied to a thermal print head, the thermal print head comprising a heat dissipation substrate, a ceramic substrate, a heat storage layer, an electrode layer, and a resistor layer; the ceramic substrate being located on one side of the heat dissipation substrate, the heat storage layer being located on a side of the ceramic substrate away from the heat dissipation substrate, the electrode layer being located on a side of the ceramic substrate away from the heat dissipation substrate and covering the ceramic substrate, and the resistor layer being located on a side of the electrode layer away from the heat storage layer;

[0005] The ceramic substrate further includes a cavity structure, wherein a projection of the cavity structure overlaps with a projection of the resistance layer along a thickness direction of the thermal print head, and the cavity structure contacts the heat dissipation substrate; the cavity structure includes a base material and a filling material; and the preparation method includes:

[0006] Get the desired printing rate;

[0007] The cavity structure is filled with the filling material according to the required printing rate.

[0008] Optionally, filling the filling material in the cavity structure according to the required printing rate includes:

[0009] A first filling material is filled in the cavity structure, wherein the thermal conductivity of the first filling material can change with the current temperature.

[0010] Optionally, filling the filling material in the cavity structure according to the required printing rate includes:

[0011] Determining whether the required printing rate is less than a preset printing rate, wherein the preset printing rate is a printing rate at which the ceramic substrate is only filled with a base material;

[0012] If yes, filling the cavity structure with a second filling material;

[0013] If not, a third filling material is filled in the cavity structure, wherein the thermal conductivity of the second filling material is lower than that of the substrate, and the thermal conductivity of the substrate is lower than that of the third filling material.

[0014] Optionally, after the second filling material is filled in the cavity structure, the method further includes:

[0015] determining a thermal time constant of the cavity structure according to the required printing rate;

[0016] determining the thermal conductivity of the cavity structure according to the thermal constant;

[0017] determining a proportion of the second filling material according to the thermal conductivity;

[0018] After the cavity structure is filled with a third filling material, the method further includes:

[0019] determining the thermal time constant of the cavity structure according to the required printing rate;

[0020] determining the thermal conductivity of the cavity structure according to the thermal constant;

[0021] The proportion of the third filling material is determined according to the thermal conductivity.

[0022] Optionally, filling the filling material in the cavity structure according to the required printing rate includes:

[0023] Determining whether the required printing rate is less than a preset printing rate, wherein the preset printing rate is a printing rate at which the ceramic substrate is only filled with a base material;

[0024] If yes, filling the cavity structure with a fourth filling material;

[0025] If not, a fifth filling material is filled in the cavity structure, wherein the heat capacity of the fourth filling material is K1, the heat capacity of the substrate is K2, the heat capacity of the fifth filling material is K3, and K1<K2<K3, and K1, K2 and K3 are positive numbers.

[0026] Optionally, after the cavity structure is filled with a fourth filling material, the method further includes:

[0027] determining a thermal time constant of the cavity structure according to the required printing rate;

[0028] determining the heat capacity of the cavity structure according to the thermal time constant;

[0029] determining a proportion of the fourth filling material according to the heat capacity;

[0030] After the fifth filling material is filled in the cavity structure, the method further includes:

[0031] determining the thermal time constant of the cavity structure according to the required printing rate;

[0032] determining the heat capacity of the cavity structure according to the thermal time constant;

[0033] The proportion of the fifth filling material is determined according to the heat capacity.

[0034] In a second aspect, an embodiment of the present invention provides a thermal print head, which is prepared according to the method for preparing a thermal print head according to the first aspect, and is characterized by comprising:

[0035] heat dissipation substrate;

[0036] a ceramic substrate, located on one side of the heat dissipation substrate;

[0037] a heat storage layer, located on a side of the ceramic substrate away from the heat dissipation substrate;

[0038] an electrode layer, located on a side of the ceramic substrate away from the heat dissipation substrate and covering the ceramic substrate;

[0039] a resistance layer, located on a side of the resistance layer away from the heat storage layer;

[0040] The ceramic substrate further includes a cavity structure, wherein a projection of the cavity structure overlaps with a projection of the resistance layer along a thickness direction of the thermal print head, and the cavity structure contacts the heat dissipation substrate;

[0041] Wherein, the cavity structure includes a substrate and a filling material.

[0042] Optionally, there is a first angle a between an extension direction of the oblique side of the cavity structure and an extension direction of the heat dissipation substrate;

[0043] Among them, 20°≤a≤80°.

[0044] Optionally, the filling material includes metal particles and / or ceramic particles;

[0045] The metal particles include metal particles and / or metal alloy particles and / or metal compound particles;

[0046] The ceramic particles include solid ceramic particles and / or hollow ceramic particles.

[0047] Optionally, the base material and the filling material are evenly distributed.

[0048] An embodiment of the present invention provides a method for preparing a thermal print head, wherein the thermal print head includes a heat dissipation substrate, a ceramic substrate, a heat storage layer, an electrode layer, and a resistor layer. The ceramic substrate is located on one side of the heat dissipation substrate, the heat storage layer is located on the side of the ceramic substrate away from the heat dissipation substrate, the electrode layer is located on the side of the ceramic substrate away from the heat dissipation substrate and covers the ceramic substrate, and the resistor layer is located on the side of the electrode layer away from the heat storage layer. The ceramic substrate also includes a cavity structure, and along the thickness direction of the thermal print head, the projection of the cavity structure overlaps with the projection of the resistor layer. The cavity structure includes a substrate and a filling material, wherein the heat storage layer includes a substrate and a filling material. The preparation method first obtains the desired printing rate, and then fills the filling material into the cavity structure according to the desired printing rate. That is, the filling level of the filling material in the cavity structure is adjusted according to the desired printing rate to meet the high requirements of the overall heat dissipation and heat conductivity of the thermal print head, thereby ensuring the working performance and printing effect of the thermal print head. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings introduced here only illustrate some of the embodiments to be described by the present invention, and are not exhaustive. A person skilled in the art can derive other drawings based on these drawings without inventive effort.

[0050] Figure 1 This is a schematic flow chart of a method for preparing a thermal print head provided in Example 1 of the present invention;

[0051] Figure 2 1 is a schematic structural diagram of a thermal print head provided by an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the relationship between thermal timing and printing rate provided by an embodiment of the present invention;

[0053] Figure 4This is a schematic flow chart of a method for preparing a thermal print head provided in the second embodiment of the present invention;

[0054] Figure 5 1 is a schematic diagram of the relationship between thermal conductivity and time provided by an embodiment of the present invention;

[0055] Figure 6 This is a schematic flow chart of a method for preparing a thermal print head provided in the third embodiment of the present invention;

[0056] Figure 7 1 is a flow chart of a method for preparing a thermal print head provided in a fourth embodiment of the present invention;

[0057] Figure 8 This is a schematic structural diagram of a thermal print head provided by a fifth embodiment of the present invention;

[0058] Figure 9 This is a schematic structural diagram of another thermal print head provided by the fifth embodiment of the present invention;

[0059] Figure 10 This is a schematic structural diagram of another thermal print head provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a system, product, or device comprising a series of units is not necessarily limited to those steps or units explicitly listed, but may include other units that are not explicitly listed or that are inherent to these products or devices.

[0062] Example 1

[0063] Figure 1This is a flow chart of a method for preparing a thermal print head provided in Example 1 of the present invention. This embodiment is applicable to the preparation process of a thermal print head. The method can be executed by a control device for preparing a thermal print head in an embodiment of the present invention, wherein the device can be implemented by software and / or hardware. Specifically, the method for preparing a thermal print head includes:

[0064] S110: Obtain a required printing rate.

[0065] Among them, the thermal print head is generally composed of a row of heating elements. These elements have the same resistance. These elements are arranged closely and range from 200dpi to 600dpi. These elements will quickly generate high temperatures when a certain current passes through them. When the dielectric coating encounters these elements, the temperature will rise in a very short time, and the dielectric coating will undergo a chemical reaction and show color.

[0066] Furthermore, the heat storage layer in the thermal print head has the functions of heat storage and heat dissipation, and the heat storage and / or heat dissipation characteristics of the heat storage layer will affect its printing rate. Furthermore, a cavity structure is set in the ceramic substrate, that is, the bottom of the ceramic substrate corresponding to the heat storage layer is subjected to an oblique grinding process, and the side of the ceramic substrate bonded to the heat storage layer remains unchanged, thereby forming a cavity structure in the ceramic substrate. In addition to the base material, the cavity structure can also be filled with filling materials with different thermal conductivities and heat capacities. The difference in the performance of the filling materials can meet the printing rate requirements of the thermal print head in different occasions. The embodiment of the present invention can adjust the filling condition of the filling material in the cavity structure by pre-judging the printing rate of the thermal print head, thereby achieving adaptive adjustment of the actual printing rate of the thermal print head, thereby ensuring the printing effect and work efficiency of the thermal print head, and at the same time avoiding unnecessary waste when a lower printing rate is required.

[0067] Specifically, Figure 2 This is a schematic diagram of the structure of a thermal print head provided by an embodiment of the present invention, with reference to Figure 2As shown, the thermal print head 10 prepared by the preparation method includes a heat dissipation substrate 100, a ceramic substrate 200, a heat storage layer 300, an electrode layer 400, and a resistor layer 500. The heat dissipation substrate 100 facilitates heat dissipation from the thermal print head 10, ensuring the heat dissipation effect of the thermal print head 10. The ceramic substrate 200 is located on one side of the heat dissipation substrate 100, and the heat storage layer 300 is also provided on the ceramic substrate 200. This can prevent the heat generated by the resistor layer 600 prepared later from being dissipated too quickly through the heat dissipation substrate 100 and the ceramic substrate 200. In other words, the heat storage layer 300 has a certain heat preservation effect, ensuring the operating efficiency of the thermal print head 10. The electrode layer 400 can be formed into an electrode structure by patterned etching. The exemplary electrode structure generally includes a common electrode, a bonding electrode, and an extraction electrode, which is not described in detail in this embodiment of the present invention. By preparing the electrode layer 400, electrical connection with the driver chip can be ensured, thereby realizing the transmission of electrical signals and ensuring that the resistor layer 500 in contact with it generates heat. Furthermore, the ceramic substrate 200 includes a cavity structure 210. Along the thickness of the thermal print head 10, the projection of the cavity structure 210 overlaps with the thermal storage layer 300 and also overlaps with the resistor layer 500 on the thermal storage layer 300. The cavity structure 210 can be prepared by bevel grinding the ceramic substrate 200. Furthermore, the cavity structure 210 can be filled with a filler material based on the base material. Depending on the different physical properties of the filler material, different thermal conductivity and heat dissipation capabilities of the thermal print head 10 can be ensured, thereby achieving different operating efficiencies of the thermal print head 10.

[0068] Optionally, the thermal print head 10 may further include an insulating protective film 600 and a wear-resistant protective layer 700, and the ceramic substrate 200 and the heat dissipation substrate 100 may be connected by a connecting adhesive 800. For example, the connecting adhesive 800 may be a double-sided adhesive or a thermally conductive adhesive, which is not specifically limited in this embodiment of the present invention.

[0069] S120 , filling the cavity structure with a filling material according to a required printing rate.

[0070] Specifically, the materials in the cavity structure may include a base material and a filling material, wherein the base material is the main material in the cavity structure. The base material may be the same material as the ceramic substrate, while the filling material may be a material with different physical properties provided according to the actual printing rate. For example, when the thermal print head requires a higher printing rate, the filling material may be a material with higher thermal conductivity, thereby ensuring that the overall thermal conductivity and heat dissipation capabilities of the ceramic substrate are strong, thereby ensuring a higher printing rate of the thermal print head. Furthermore, based on further refined adjustments to the printing rate of the thermal print head, the filling condition of the filling material may also be adjusted. The filling condition may refer to the type of filling material, the physical properties of the filling material, and the proportion of the filling material.

[0071] For example, in the cavity structure, the base material can be composed of an organic adhesive material with low thermal conductivity and low density; the filling material can be made of high thermal conductivity and high density particles, and the particles can be metal or metal alloy or metal compound particles or ceramic particles. The metal or metal alloy or metal compound particles can be made of silver, aluminum, gold, iron, copper, zinc, etc. as the basic materials, and the ceramic material can be made of SIC and other materials. The filling ratio can be determined according to the required comprehensive thermal conductivity of the ceramic substrate. The higher the comprehensive thermal conductivity or comprehensive specific heat and density product of the filling material, the greater the filling ratio. The comprehensive thermal conductivity or comprehensive specific heat and density product is determined by the printing speed. The higher the printing speed, the higher the comprehensive thermal conductivity or comprehensive specific heat and density product.

[0072] Furthermore, when the required printing rate of the thermal print head is known, the filling condition of the filling material in the cavity structure can be adaptively adjusted according to actual conditions, thereby ensuring that the printing rate of the thermal print head finally prepared is the required printing rate, thereby better meeting actual production needs.

[0073] It needs to be explained that the reference Figure 3 As shown in the figure, the non-smooth connecting line segments represent the experimental tests conducted when the overall comprehensive thermal conductivity of the heat storage layer is large, and the smooth solid line in the figure can reflect the overall trend, that is, when the overall comprehensive thermal conductivity of the heat storage layer is large, that is, the thermal conductivity of the base glaze of the thermal print head (that is, the heat storage layer) is better, the thermal timing will be smaller in combination with the attached figure, and the printing rate will be faster.

[0074] In summary, the method for preparing a thermal print head provided by the embodiments of the present invention first determines the desired printing rate, and then fills the cavity structure with a filler material based on the desired printing rate. In other words, adjusting the filling level of the cavity structure based on the desired printing rate can meet the thermal print head's high heat storage requirements, improve its applicability, and ensure its operational and printing performance.

[0075] Example 2

[0076] Figure 4 This is a flow chart of a method for preparing a thermal print head provided by the second embodiment of the present invention, with reference to Figure 6 As shown, the method for preparing a thermal print head provided by an embodiment of the present invention further includes:

[0077] S210: Obtain a required printing rate.

[0078] S220 , filling the cavity structure with a first filling material.

[0079] Specifically, the first filling material may be a material whose thermal conductivity changes with the current temperature, that is, the higher the temperature, the higher the thermal conductivity of the filling material, and thus the first filling material in the cavity structure causes the overall thermal conductivity of the thermal print head to be greater. For example, Figure 5 This is a schematic diagram of the relationship between thermal conductivity and time provided by an embodiment of the present invention, with reference to Figure 5 As shown in the figure, the color temperature refers to the color change caused by the chemical reaction between the developer and the colorless dye at the current temperature where the thermal print head prints, forming the image. For example, the embodiment of the present invention does not limit the specific value of the color temperature. Further, Figure 5 There are also two curves in the figure. Curve a1 represents the case where the thermal conductivity can be changed when the cavity structure is filled with the first filling material. Curve a2 represents the case where the thermal conductivity is fixed without the cavity structure, or when the ceramic substrate is the base material. With the color development temperature - (20 ~ 40 ° C) as the turning point, the lower the thermal conductivity is when the heat storage layer temperature < the color development temperature - (20 ~ 40 ° C), the more conducive it is to increase the base temperature as soon as possible in the case of low base temperature (such as Figure 5 (t3-t2) < (t3-t1)), the purpose of saving energy can be achieved; when the temperature of the heat storage layer is greater than the color temperature - (20 ~ 40 ° C), the higher the thermal conductivity, the more conducive it is to reduce the temperature of the heating element as soon as possible in high temperature environments (such as Figure 5 (t4-t3)<(t5-t3)) can avoid tailing caused by high temperature time for too long.

[0080] For example, materials with temperature-dependent thermal conductivity, such as MgB2 polycrystalline samples, are prepared using solid-state reaction methods, such as hybrid physical and chemical vapor deposition, pulsed laser deposition, magnetron sputtering, molecular beam epitaxy, and electron beam evaporation. For example, when preparing MgB2 thin films using magnetron sputtering, direct current (DC) or radio frequency (RF) magnetron sputtering is employed, with the targets typically being dual targets of elemental Mg and B, or composite targets with B blocks embedded within the Mg target. Dual-target sputtering allows for the convenient adjustment of the amount of MgB atoms deposited on the substrate by adjusting the sputtering power of each target. However, for composite targets, the Mg and B contents within the effective sputtering region can only be determined during preparation. Dual-target sputtering can achieve better results if the ratio of Mg to B in the target is optimized. The Mg / B precursor film B uses a radio frequency magnetron source, and the Mg uses a direct current magnetron source. The precursor film is then in-situ annealed in an argon atmosphere at 500-700°C to obtain MgB2 with a smooth surface. The film obtained by in-situ annealing at 680°C has the best quality. Micron-sized particles are then produced by peeling and grinding and used as filler for the substrate.

[0081] In summary, the preparation method provided by the embodiment of the present invention can fill the cavity structure with a first filling material, that is, a filling material whose thermal conductivity can change with temperature, thereby better ensuring the working effect and efficiency of the thermal print head.

[0082] Example 3

[0083] Figure 6 This is a flow chart of a method for preparing a thermal print head provided by the third embodiment of the present invention, with reference to Figure 6 As shown, the method for preparing a thermal print head provided by an embodiment of the present invention further includes:

[0084] S310: Obtain the required printing rate.

[0085] S320: Determine whether the required printing rate is less than the preset printing rate. If so, execute S330; otherwise, execute S370.

[0086] The preset print rate is the print rate for a ceramic substrate filled only with base material. By determining the relationship between the desired print rate and the preset print rate, it is possible to determine whether the thermal print head's current print rate is higher or lower, with the preset print rate serving as the standard for comparison. Given that the distribution of filler material within the cavity structure affects the print rate, this criterion allows for more accurate and targeted adjustments to the filler material, and thus the thermal print head's print rate.

[0087] S330 , filling the cavity structure with a second filling material.

[0088] Specifically, when the desired printing rate is lower than the preset printing rate, a second filler material can be added to the cavity structure to adjust the thermal conductivity and heat dissipation performance of the ceramic substrate. The thermal conductivity of the second filler material is lower than that of the cavity structure's base material. This means that the cavity structure is filled with a filler material with even lower thermal conductivity, reducing the overall thermal conductivity. This integration of the second filler material and the base material ensures that the thermal conductivity of the cavity structure when filled with the second filler material is lower than that of the cavity structure without the second filler material, thereby reducing the thermal print head's printing rate.

[0089] S340, determining the thermal time constant of the cavity structure according to the required printing rate.

[0090] Furthermore, the cavity structure's thermal time constant can reflect the overall thermal conductivity and heat dissipation of the ceramic substrate. Specifically, when a higher printing rate is required, the cavity structure's thermal time constant should be shorter, while when a lower printing rate is required, the thermal time constant can be longer. In general, the thermal time constant of the cavity structure can be selected for different required printing rates, further ensuring that the prepared thermal printhead meets the desired parameter standards.

[0091] S350. Determine the thermal conductivity of the cavity structure according to the thermal constant.

[0092] S360: Determine the proportion of the second filling material according to the thermal conductivity.

[0093] Specifically, the cavity structure is filled with a second filler material on top of the substrate. Given that the thermal conductivity of the second filler material is lower than that of the substrate, the proportion of the second filler material in the entire cavity structure of the ceramic substrate can be adjusted to ensure that the ceramic substrate exhibits different thermal conductivities under the influence of the cavity structure. In thermal printheads, there is a specific numerical relationship between thermal conductivity and print rate. Based on the correlation formula between thermal conductivity and print rate, the thermal conductivity can be inferred at a known print rate.

[0094] If the cavity structure is known to be filled with a second filler material and the thermal conductivity is also known, the desired percentage of the second filler material in the cavity structure can be determined, and the thermal conductivity can be adjusted to achieve the desired thermal conductivity of the thermal print head. For example, if a relatively high thermal conductivity is required, a lower percentage of the second filler material can be used; if a relatively low thermal conductivity is required, a higher percentage of the second filler material can be used. This allows for precise adjustment of the thermal print head to ensure optimal performance.

[0095] S370 , filling the cavity structure with a third filling material.

[0096] Specifically, when the desired printing rate exceeds the preset printing rate, a third filler material can be added to the cavity structure to adjust the thermal conductivity and heat dissipation performance of the ceramic substrate. The thermal conductivity of the third filler material is greater than that of the cavity structure's base material. This means that the cavity structure is filled with a filler material with a higher thermal conductivity, increasing the overall thermal conductivity of the base material. This integration of the third filler material and the base material ensures that the thermal conductivity of the cavity structure when filled with the third filler material is greater than that of the cavity structure without the third filler material, thereby increasing the thermal printhead's printing rate.

[0097] S380, determining the thermal time constant of the cavity structure according to the required printing rate.

[0098] S390: Determine the thermal conductivity of the cavity structure according to the required printing rate.

[0099] S3100. Determine the proportion of the third filling material according to the thermal conductivity.

[0100] Specifically, the cavity structure is filled with a third filler material on top of the substrate. Given that the thermal conductivity of the third filler material is greater than that of the substrate, the proportion of the third filler material in the entire cavity structure of the ceramic substrate can be adjusted to ensure that the ceramic substrate exhibits different thermal conductivities under the influence of the cavity structure. In thermal printheads, there is a specific numerical relationship between thermal conductivity and print rate. Based on the correlation formula between thermal conductivity and print rate, the thermal conductivity can be inferred at a known print rate.

[0101] If the cavity structure is filled with a third filler material and the thermal conductivity is known, the appropriate percentage of the third filler material in the cavity structure can be determined, and the thermal conductivity can be adjusted to achieve the desired thermal conductivity of the thermal print head. For example, if the desired thermal conductivity is relatively low, a lower percentage of the third filler material can be used; if the desired thermal conductivity is relatively high, a higher percentage of the third filler material can be used. This allows for precise adjustment of the thermal print head to ensure optimal performance.

[0102] In summary, the method for preparing a thermal print head provided in an embodiment of the present invention compares the required printing rate with the preset printing rate, selects filling materials with different thermal conductivities to fill in the cavity structure, and selects the proportion of the filling materials, thereby ensuring that the actual printing rate of the prepared thermal print head is more in line with the required printing rate, thereby ensuring the working accuracy of the thermal print head.

[0103] Example 4

[0104] Figure 7 This is a flow chart of a method for preparing a thermal print head provided by the fourth embodiment of the present invention, with reference to Figure 7 As shown, the method for preparing a thermal print head provided by an embodiment of the present invention further includes:

[0105] S410: Obtain a required printing rate.

[0106] S420: Determine whether the required printing rate is less than the preset printing rate. If yes, execute S430; otherwise, execute S470.

[0107] S430: Fill the heat storage layer with a fourth filling material.

[0108] Specifically, when the required printing rate is lower than the preset printing rate, a fourth filler material can be added to the cavity structure to adjust the overall thermal conductivity of the thermal print head. The heat capacity of the fourth filler material is K1, and the heat capacity of the substrate is K2, with K1 less than K2. Thermal capacity is the product of density and specific heat capacity. The thermal capacity of the substrate can refer to the thermal capacity of the ceramic substrate without a cavity structure, or to the thermal capacity of the ceramic substrate with a cavity structure and only the substrate without any other filler material. The heat capacity of the fourth filler material is smaller than that of the substrate, and this heat capacity affects its thermal conductivity. If the heat capacity of the fourth filler material is smaller than that of the substrate, the cavity structure is filled with a filler material with a smaller heat capacity, rather than the original substrate, reducing the overall thermal conductivity. In other words, through the integration of the fourth filler material and the substrate, the thermal conductivity of the cavity structure filled with the fourth filler material is necessarily lower than that of the cavity structure without the fourth filler material, thereby reducing the printing rate of the thermal print head.

[0109] S440, determining the thermal time constant of the cavity structure according to the required printing rate.

[0110] S450. Determine the heat capacity of the cavity structure according to the thermal constant.

[0111] S450: Determine the proportion of the fourth filling material according to the heat capacity.

[0112] Specifically, the cavity structure is filled with a fourth filler material on top of the substrate. Given that the heat capacity of the fourth filler material is smaller than that of the substrate, adjusting the proportion of the fourth filler material in the cavity structure can ensure that the thermal print head ultimately exhibits different thermal conductivities and achieves different printing rates. In thermal print heads, there is a specific numerical relationship between heat capacity and printing rate. Based on the formula related to heat capacity and printing rate, the heat capacity can be inferred at a known printing rate.

[0113] If the cavity structure is known to be filled with a fourth filler material and the thermal capacity is also known, the percentage of the fourth filler material that should be filled in the cavity structure at this time can be determined to achieve the thermal capacity required by the thermal print head. For example, if the required thermal capacity is relatively large, a smaller amount of the fourth filler material is filled; if the required thermal capacity is relatively small, a larger amount of the fourth filler material is filled. This allows for precise adjustment of the thermal print head to ensure its performance.

[0114] S470: Fill the heat storage layer with a fifth filling material.

[0115] Specifically, when the required printing rate exceeds the preset printing rate, a fifth filler material can be added to the cavity structure to adjust the overall thermal conductivity of the thermal print head. The heat capacity of the fifth filler material is K3, the heat capacity of the substrate is K2, and K2 < K3. Thermal capacity is the product of density and specific heat capacity. The thermal capacity of the substrate can refer to the thermal capacity of the ceramic substrate without a cavity structure, or to the thermal capacity of the ceramic substrate with a cavity structure and only the substrate without any other filler material. The heat capacity of the fifth filler material is greater than that of the substrate, and this heat capacity affects its thermal conductivity. When the heat capacity of the fifth filler material is greater than that of the substrate, the cavity structure is filled with a filler material with a greater heat capacity in addition to the original substrate, thereby increasing the overall thermal conductivity. In other words, through the integration of the fifth filler material and the substrate, the thermal conductivity of the cavity structure when filled with the fifth filler material is greater than that when not filled with the fourth filler material, thereby reducing the printing rate of the thermal print head. By filling the material and increasing the heat capacity, it is possible to eliminate heat accumulation during rapid printing, avoid tailing caused by heat accumulation and damage to the resistance layer caused by excessive temperature.

[0116] S480, determining the thermal time constant of the cavity structure according to the required printing rate.

[0117] S490. Determine the heat capacity of the cavity structure according to the thermal constant.

[0118] S4100. Determine the proportion of the fifth filling material according to the heat capacity.

[0119] Specifically, the cavity structure is filled with a fifth filler material on top of the substrate. Given that the heat capacity of the fifth filler material is greater than that of the substrate, adjusting the proportion of the fifth filler material in the cavity structure can ensure that the thermal print head ultimately exhibits different thermal conductivities and achieves different printing rates. In thermal print heads, there is a specific numerical relationship between heat capacity and printing rate. Based on the formula relating heat capacity and printing rate, the heat capacity can be inferred at a known printing rate.

[0120] If the cavity structure is filled with a fifth filler material and the thermal capacity is known, the percentage of the fifth filler material that should be filled in the cavity structure to achieve the thermal capacity required by the thermal print head can be determined. For example, if the required thermal capacity is relatively large, a higher percentage of the fifth filler material is filled; if the required thermal capacity is relatively small, a lower percentage of the fifth filler material is filled. This allows for precise adjustment of the thermal print head to ensure optimal operation.

[0121] In summary, the method for preparing a thermal print head provided in an embodiment of the present invention compares the required printing rate with the preset printing rate, selects filling materials with different density and specific heat capacity products to fill the cavity structure, and selects the proportion of the filling materials, thereby ensuring that the actual printing rate of the prepared thermal print head is more in line with the required printing rate, thereby ensuring the working accuracy of the thermal print head.

[0122] Example 5

[0123] Based on the same inventive concept, an embodiment of the present invention further provides a thermal print head. Figure 8 is a schematic structural diagram of a thermal print head provided by Embodiment 5 of the present invention. Figure 9 is a schematic structural diagram of another thermal print head provided by the fifth embodiment of the present invention. Figure 10 This is a schematic diagram of the structure of another thermal print head provided by the fifth embodiment of the present invention, referring to Figure 2 、 Figures 8 to 10 As shown,

[0124] The thermal print head 10 provided in an embodiment of the present invention includes a heat dissipation substrate 100; a ceramic substrate 200, located on one side of the heat dissipation substrate 100; a heat storage layer 300, located on the side of the ceramic substrate 200 away from the heat dissipation substrate 100; an electrode layer 400, located on the side of the ceramic substrate 200 away from the heat dissipation substrate 100 and covering the ceramic substrate 200; and a resistor layer 500, located on the side of the electrode layer 400 away from the heat storage layer 300. The ceramic substrate 200 also includes a cavity structure 210. Along the thickness direction of the thermal print head 10, the projection of the cavity structure 210 overlaps with the projection of the resistor layer 500, and the cavity structure 210 is in contact with the heat dissipation substrate 100. The cavity structure 210 includes a base material and a filling material.

[0125] Among them, the thermal print head 10 is generally composed of a row of heating elements, which have the same resistance. These elements are arranged closely and range from 200dpi to 600dpi. These elements will quickly generate high temperatures when a certain current passes through them. When the dielectric coating encounters these elements, the temperature will rise in a very short time, and the dielectric coating will undergo a chemical reaction, showing color.

[0126] Among them, the heat dissipation substrate 100 facilitates the heat dissipation of the thermal print head 10 and ensures the heat dissipation effect of the thermal print head 10. The ceramic substrate 200 is located on one side of the heat dissipation substrate 100, and a heat storage layer 300 is also provided on the ceramic substrate 200, which can prevent the heat generated by the resistor layer 600 prepared subsequently from being lost too quickly through the heat dissipation substrate 100 and the ceramic substrate 200, that is, the heat storage layer 300 has a certain heat preservation effect, ensuring the working efficiency of the thermal print head 10. The electrode layer 400 can be formed into an electrode structure by patterned etching. The exemplary electrode structure generally includes a common electrode, a bonding electrode and an extraction electrode, which is not described in detail in this embodiment of the present invention. By preparing the electrode layer 400, the electrical connection with the driver chip can be guaranteed, thereby realizing the transmission of electrical signals and ensuring that the resistor layer 600 in contact with it generates heat.

[0127] Furthermore, a cavity structure 210 is provided in the ceramic substrate 200, and some filling materials can be filled in the cavity structure 210, that is, the cavity structure 210 is filled with filling materials with different physical properties under the base material of the ceramic substrate 200 to ensure different thermal conductivity of the thermal print head, etc., and realize different printing rates of the thermal print head.

[0128] Specifically, the ceramic substrate 200 is subjected to an oblique grinding process below the corresponding resistor layer 500. During the grinding process, the upper surface remains unchanged, and the lower surface is ground at an angle parallel to the main line of the resistor layer 500 in the direction of the resistor layer 500 to form a cavity structure 210. The angle between the cavity structure 210 and the horizontal line ranges from 20° to 80°, that is, Figure 2 、 Figures 8 to 10 The angle range of the first angle a between the extension direction of the hypotenuse of the hollow cavity structure 210 and the extension direction of the heat dissipation substrate 100 is defined. Adjustment of the first angle a ensures that the resistive layer 500 withstands mechanical pressure from the rubber roller, etc. Furthermore, the cavity structure 210 is filled with a filler material. This filler material must possess a certain mechanical strength to ensure the overall structural stability of the thermal print head 10, ensuring that the addition of the cavity structure 210 does not compromise the structural stability. The filler material in the cavity structure 210 can have different thermal conductivities and specific heat capacities depending on the application (speed, printing rate, etc.).

[0129] For further reference, Figure 2 、 Figure 8 and Figure 9 As shown, the smaller the first angle a is, the more parts are ground away and the larger the cavity is, which has a greater impact on heat storage and heat conduction. On the contrary, Figure 9 The larger the angle, the smaller the cavity and the smaller the impact. And the filling material of this cavity structure can be flexibly filled with different thermal conductivity and specific heat filling materials according to the customer's application (speed, printing rate, etc.) before leaving the factory. If you need to weaken the influence of the reinforcement material, you can Figure 10 As shown, the shape of the cavity structure 210 is adjusted to partially fill the cavity 210. That is, the shape and size of the cavity structure 210 can be adaptively adjusted according to actual needs.

[0130] For example, if the required printing speed of the thermal print head is relatively low, a material with a thermal conductivity lower than that of ceramics is used, that is, the thermal conductivity of the filling material filled in the cavity structure should be lower than that of the thermal wire not filled with the filling material. If the required printing speed of the thermal print head is relatively high, the opposite is true.

[0131] For example, in the cavity structure 210, the base material can be composed of an organic adhesive material with low thermal conductivity and low density; the filling material can be made of high thermal conductivity and high density particles, and the particles can be metal alloys or compound particles or ceramic particles. The metal particles can be made of silver, aluminum, gold, iron, copper, zinc, etc. as basic materials, and the ceramic material can be made of SIC and other materials. The filling ratio can be determined according to the required comprehensive thermal conductivity of the ceramic substrate. The higher the comprehensive thermal conductivity or comprehensive specific heat and density product of the filling material, the greater the filling ratio. The comprehensive thermal conductivity or comprehensive specific heat and density product is determined by the printing speed. The higher the printing speed, the higher the comprehensive thermal conductivity or comprehensive specific heat and density product.

[0132] Optionally, the thermal print head 10 may further include an insulating protective film 600 and a wear-resistant protective layer 700, and the ceramic substrate 200 and the heat dissipation substrate 100 may be connected by a connecting adhesive 800. For example, the connecting adhesive 800 may be a double-sided adhesive or a thermally conductive adhesive, which is not specifically limited in this embodiment of the present invention.

[0133] Optionally, the filling material in the cavity structure 210 includes metal particles, and the metal particles include metal particles and / or metal alloy particles and / or metal compound particles.

[0134] Optionally, the filling material in the cavity structure 210 may be solid ceramic particles and / or hollow ceramic particles.

[0135] Specifically, the filling material can be modified high-temperature resistant alloy particles or ceramic particles. The base metal of the alloy can be silver, aluminum, gold, iron, copper, zinc and other materials. The thermal conductivity of silver can reach up to 429W / mK, and the product of the density of silver (g / cm3) and the specific heat (J / g*k) can reach a maximum of 2.52. Ceramic particles can be Al2O3 (≈20w / mK) or SIC (≈270w / mK). Ceramic particles are of two types: solid and hollow. The solid comprehensive thermal conductivity is high, and the hollow comprehensive thermal conductivity is low. The filling material is adaptively adjusted according to the actual parameter requirements.

[0136] Furthermore, in some embodiments, the filling material in the heat storage layer may also include alloy particles and ceramic particles. Based on the specific configuration, the embodiments of the present invention do not limit this one by one.

[0137] Furthermore, the base material and the filling material can be evenly distributed in the cavity structure 210 .

[0138] Specifically, adding filling material to the cavity structure 210 can adjust the comprehensive thermal conductivity of the cavity structure 210, that is, adjust the overall thermal conductivity of the ceramic substrate 200. By evenly distributing the substrate and the filling material, the balance of the overall heat storage and heat dissipation effects of the cavity structure 210 can be ensured, which is beneficial to ensuring the working stability of the thermal print head 10.

[0139] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a thermal print head, the method being applied to a thermal print head, the thermal print head comprising a heat dissipation substrate, a ceramic substrate, a heat storage layer, an electrode layer, and a resistor layer; the ceramic substrate being located on one side of the heat dissipation substrate, the heat storage layer being located on a side of the ceramic substrate away from the heat dissipation substrate, the electrode layer being located on a side of the ceramic substrate away from the heat dissipation substrate and covering the ceramic substrate, and the resistor layer being located on a side of the electrode layer away from the heat storage layer; The ceramic substrate further includes a cavity structure, wherein a projection of the cavity structure overlaps with a projection of the resistance layer along a thickness direction of the thermal print head, and the cavity structure contacts the heat dissipation substrate; The cavity structure comprises a substrate and a filling material; and is characterized in that: The preparation method comprises: Get the desired printing rate; filling the filling material in the cavity structure according to the required printing rate; Wherein, filling the filling material in the cavity structure according to the required printing rate includes: Filling the cavity structure with a first filling material, wherein the thermal conductivity of the first filling material can change with the current temperature; the higher the temperature of the first filling material, the higher the thermal conductivity of the first filling material; Alternatively, determining whether the required printing rate is less than a preset printing rate, wherein the preset printing rate is a printing rate at which the ceramic substrate is only filled with a base material; If yes, filling the cavity structure with a second filling material; If not, filling the cavity structure with a third filling material, wherein the thermal conductivity of the second filling material is lower than the thermal conductivity of the substrate, and the thermal conductivity of the substrate is lower than the thermal conductivity of the third filling material; Alternatively, determining whether the required printing rate is less than a preset printing rate, wherein the preset printing rate is a printing rate at which the ceramic substrate is only filled with a base material; If yes, filling the cavity structure with a fourth filling material; If not, a fifth filling material is filled in the cavity structure, wherein the heat capacity of the fourth filling material is K1, the heat capacity of the substrate is K2, the heat capacity of the fifth filling material is K3, and K1<K2<K3, and K1, K2 and K3 are positive numbers.

2. The preparation method according to claim 1, characterized in that After the second filling material is filled in the cavity structure, the method further includes: determining a thermal time constant of the cavity structure according to the required printing rate; determining the thermal conductivity of the cavity structure according to the thermal constant; determining a proportion of the second filling material according to the thermal conductivity; After the cavity structure is filled with a third filling material, the method further includes: determining the thermal time constant of the cavity structure according to the required printing rate; determining the thermal conductivity of the cavity structure according to the thermal constant; The proportion of the third filling material is determined according to the thermal conductivity.

3. The preparation method according to claim 1, characterized in that After the cavity structure is filled with a fourth filling material, the method further includes: determining a thermal time constant of the cavity structure according to the required printing rate; determining the heat capacity of the cavity structure according to the thermal time constant; determining a proportion of the fourth filling material according to the heat capacity; After the fifth filling material is filled in the cavity structure, the method further includes: determining the thermal time constant of the cavity structure according to the required printing rate; determining the heat capacity of the cavity structure according to the thermal time constant; The proportion of the fifth filling material is determined according to the heat capacity.

4. A thermal print head, prepared according to the method for preparing a thermal print head according to claims 1-3, characterized in that: include: heat dissipation substrate; a ceramic substrate, located on one side of the heat dissipation substrate; a heat storage layer, located on a side of the ceramic substrate away from the heat dissipation substrate; an electrode layer, located on a side of the ceramic substrate away from the heat dissipation substrate and covering the ceramic substrate; a resistance layer, located on a side of the resistance layer away from the heat storage layer; The ceramic substrate further includes a cavity structure, wherein a projection of the cavity structure overlaps with a projection of the resistance layer along a thickness direction of the thermal print head, and the cavity structure contacts the heat dissipation substrate; Wherein, the cavity structure includes a substrate and a filling material.

5. The thermal print head according to claim 4, wherein: There is a first angle a between the extension direction of the hypotenuse of the cavity structure and the extension direction of the heat dissipation substrate; Among them, 20°≤a≤80°.

6. The thermal print head according to claim 4, wherein: The filling material includes metal particles and / or ceramic particles; The metal particles include metal particles and / or metal alloy particles and / or metal compound particles; The ceramic particles include solid ceramic particles and / or hollow ceramic particles.

7. The thermal print head according to claim 4, wherein: The base material and the filling material are evenly distributed.

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