EP0458691A1 - Improvement in thermal printheads - Google Patents
Improvement in thermal printheads Download PDFInfo
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- EP0458691A1 EP0458691A1 EP91401300A EP91401300A EP0458691A1 EP 0458691 A1 EP0458691 A1 EP 0458691A1 EP 91401300 A EP91401300 A EP 91401300A EP 91401300 A EP91401300 A EP 91401300A EP 0458691 A1 EP0458691 A1 EP 0458691A1
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- European Patent Office
- Prior art keywords
- line
- points
- heating
- film
- substrate
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/335—Structure of thermal heads
- B41J2/33555—Structure of thermal heads characterised by type
- B41J2/3357—Surface type resistors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
- B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
- B41J2/375—Protection arrangements against overheating
Definitions
- the present invention relates to thermal printers.
- a thermal printer head comprises, on a support plate, a line of heating points, each of them consisting of an electrically resistant element capable of heating by Joule effect, inserted in a supply conductor in current which includes an electronic switch.
- the operating principle of such a device is simple. On the one hand, it involves scrolling under the line of points, in contact with it, a ribbon of paper sensitive to temperature and successively supplying series of heating points so as to bring their temperature for a short time to a value greater than that of the paper reaction.
- Each point thus heated will create a trace on the paper whose dimensions depend on a number of factors such as the width of the heating point (taken transversely to the direction of travel of the paper), the speed of the paper, the holding time at the prescribed point temperature ....
- other points are heated while the previous ones cool, the trace resulting from the succession of these sequences forming the desired impression.
- a temperature sensor which is in the form of a component of the thermistor type. This component is placed on the substrate relatively far from the line of points so that the response time of this component is of an order of magnitude (ten seconds) which is not acceptable, taking into account the rates of change d thermal state of a line of points resulting from the increasingly high rates of excitation.
- values of the order of a millisecond will be given with regard to the period of the pulses to be compared to ten or twenty seconds of response time from the temperature sensor, which leads to regulation with 10 or 20 000 lines of delay printing dots.
- the object of the present invention is to remedy this drawback by proposing a thermal printer head comprising means for having a temperature measurement of the heating points in an extremely short response time allowing fine regulation of the quantity of energy to bring to each heating point guaranteeing the constant quality of the print on the one hand along the line and on the other hand over time.
- the invention relates to a thermal printer head comprising on an insulating substrate, a layer of glass having an upper support surface the line of heating points and their supply conductors, the conductors being oriented perpendicular to the line of points, a protective layer covering the upper surface of glass provided with the line of points and conductors, which thermal head comprising at the plumb with the line of heating points and under the latter, a film of heat-resistant material electrically insulated from the line of heating points.
- Heat dissipation from the heating points takes place on the one hand towards the paper and on the other hand towards the substrate.
- the substrate is equipped on its rear face with a heat dissipation radiator, the heat flow flows in the substrate in a preferred manner transversely thereto. It is therefore optimal to place the thermo-resistive material directly above this line of points because it is in this zone that it is subjected to the most intense heat flow.
- the primary function of this film is therefore that of temperature sensor by measuring its resistance.
- the reaction time of this sensor will be all the faster as it is close to the line of points.
- thermoresistive in between. It is not outside the scope of the invention to have this sensor, directly above the line of points on the other face of the substrate. This solution, although less efficient, is however much more interesting than the devices known to date.
- Another characteristic arrangement of the invention resides in the fact that the heat dissipation radiator is attached to the face of the substrate opposite to that provided with the heating points, by means of a layer of a thermally conductive material.
- This arrangement has a double advantage. Firstly, it establishes a thermal bridge which distributes the heat received, through the substrate through the heated points of the line. There is therefore a certain distribution of heat at this bridge which promotes the exchange of heat between the hot spots and the cold spots. The homogenization of the point line temperature is favored.
- the intimacy of the contact between the substrate and the radiator is very significantly improved, which makes it possible to improve the heat flow from the line of points to the radiator. This heat flow, previously, presented a certain heterogeneity since with the plumb of a heated point could be a point of bad contact between substrate and radiator. Under these conditions, the flow had to take a longer path to circumvent this discontinuity.
- This arrangement of the invention is particularly advantageous when the heating points of the line are not physically separated from each other as it is now more and more the case, because it makes it possible to equalize the cooling conditions for each heating point of a line.
- the thermal printer head shown conventionally comprises an insulating ceramic substrate (based on alumina) which constitutes the structure of the head in the form of a plate about half a millimeter thick, its width being of the order of ten centimeters.
- an insulating ceramic substrate based on alumina
- thermoresistive material such as platinum is deposited on this substrate.
- the deposition techniques are known. This is, for example, a screen printing of an organometallic paste which undergoes cooking at around 1000 ° C.
- the shape of this film 2 is determined by experience as a function of the ohmic values required. It can be either a simple rectangle over the entire width of the substrate, or a frieze of a longer conductor.
- This film can be electrically continuous or comprise several sections.
- thermo-resistive material The upper surface of the substrate comprising this film of thermo-resistive material is then covered, in a known manner, with a layer of glass 3 (coating), also by screen printing and baking, with the necessary reserves to allow access to suitable locations, film 2 for electrical interconnections.
- a resistant material 5 is deposited which forms the line of heating points.
- this material arranged in a line is either physically divided into separate points, each of them being inserted in a supply circuit (conductors 4), or continuous and is heated in sections according to the connections made electronically. between conductors 4 and a power source.
- a layer of protective material 6 covers at least the zone of the line of heating points to electrically isolate the circuits thus produced from the outside and to constitute a lining for protecting the line of heating points against abrasion of the paper. who walks past her.
- the resistance of the film 2 which is made of a material whose resistance varies with temperature, is a variable directly proportional to its temperature
- the measurement of this resistance gives an indication of its temperature and consequently an indication of the temperature of the line of heating points. Given the very short distance between them, the temperature variations of the heating points immediately influence the temperature of the sensor film.
- the resistance of the film therefore varies very quickly and a signal relating to it can be used as a control parameter for controlling the energy to be supplied to the heating points, for example to keep the maximum temperature at which each is brought substantially constant. heating point.
- the measurement readings which will necessarily be average values, concern several points which, in reality, are at different temperatures.
- the data collected can be processed in conjunction with the parameters relating to the frequency of supply of the dots which can be extracted from the print management unit. it will then be possible to refine the regulation.
- Another arrangement consists in seeking to reduce the thermal gradient which may exist between each point so as to reduce the temperature range in which the regulation must be exerted. To do this, it is necessary to favor on the one hand the speed of cooling of the hot spots and on the other hand the heat exchange along the line of points.
- the invention proposes to have between the substrate 1 and a radiator 7 which is known in itself and present on the other face of the ceramic plate 1, a layer 8 of a material which is very thermally conductive (for example silver) which has the effect, on the one hand, of improving the contact between radiator 7 and plate 1 therefore of promoting the transfer of heat in the thickness of the head towards the dissipation radiator and, d 'on the other hand to form a heat distributor under the line of heating points and thus to promote a heat exchange between hot and cold points.
- a radiator 7 which is known in itself and present on the other face of the ceramic plate 1
- a layer 8 of a material which is very thermally conductive (for example silver) which has the effect, on the one hand, of improving the contact between radiator 7 and plate 1 therefore of promoting the transfer of heat in the thickness of the head towards the dissipation radiator and, d 'on the other hand to form a heat distributor under the line of heating points and thus to promote a heat exchange between hot and cold points.
- the print head according to the invention thus equipped with this heat-resistant film (in any suitable material) has an additional advantage. It is indeed possible to use this film as a heating resistor of the line of points. It should indeed be noted that such thermal printers are subject to extremely severe conditions of use because they can be fitted to external devices subjected to the most severe climates.
- this film 2 It is therefore possible to connect to this film 2 a source of electrical energy, for determined time spaces (prior to editing, and during editing) in the form of pulses or train of pulses, interspersed between the times. monitoring and measurement, the film then being connected to another energy source.
- the interconnections of the film to the measurement supply or to that of the power supply (heating) can be managed by a control device of the kind comprising a multiplexing function if necessary.
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Abstract
Description
La présente invention concerne les imprimantes thermiques.The present invention relates to thermal printers.
On rappellera qu'une tête d'imprimante thermique comporte, sur une plaque support, une ligne de points chauffants, chacun d'eux étant constitué par un élément électriquement résistant capable de s'échauffer par effet Joule, inséré dans un conducteur d'alimentation en courant qui comporte un interrupteur électronique.It will be recalled that a thermal printer head comprises, on a support plate, a line of heating points, each of them consisting of an electrically resistant element capable of heating by Joule effect, inserted in a supply conductor in current which includes an electronic switch.
Le principe de fonctionnement d'un tel appareil est simple. Il consiste d'une part à faire défiler sous la ligne de points, au contact de celle-ci, un ruban de papier sensible à la température et à alimenter successivement des séries de points chauffants de manière à porter leur température pendant un temps bref à une valeur supérieure à celle de réaction du papier. Chaque point ainsi échauffé créera une trace sur le papier dont les dimensions dépendent d'un certain nombre de facteurs tels que la largeur du point chauffant (prise transversalement au sens de défilement du papier), la vitesse du papier, le temps de maintien à la température prescrite du point.... A la séquence suivante, ce sont d'autres points qui sont échauffés tandis que les précédents se refroidissent, la trace résultant de la succession de ces séquences formant l'impression désirée.The operating principle of such a device is simple. On the one hand, it involves scrolling under the line of points, in contact with it, a ribbon of paper sensitive to temperature and successively supplying series of heating points so as to bring their temperature for a short time to a value greater than that of the paper reaction. Each point thus heated will create a trace on the paper whose dimensions depend on a number of factors such as the width of the heating point (taken transversely to the direction of travel of the paper), the speed of the paper, the holding time at the prescribed point temperature .... At the next sequence, other points are heated while the previous ones cool, the trace resulting from the succession of these sequences forming the desired impression.
Dans la pratique, les problèmes à résoudre sont nombreux compte tenu des performances de plus en plus élevées qui sont demandées à ces imprimantes.In practice, the problems to be solved are numerous in view of the increasingly high performances which are demanded of these printers.
L'un d'eux réside dans la régulation de la température de chaque point chauffant. En effet, il faut apporter une énergie déterminée au point pour lui faire atteindre la température nécessaire au marquage du papier. Cette énergie lui est apportée sous forme d'une impulsion électrique (rectangulaire) dont la surface dépend de l'inertie thermique du matériau résistif pour atteindre cette température et de la température de départ du point à échauffer. Or cette température de départ est fonction de facteurs indépendants les uns des autres tels notamment que le temps qui sépare deux impulsions de chauffe et la température ambiante. Ces deux facteurs pour un point sont tout à fait aléatoires et variables, l'un dépendant de l'impression à réaliser et l'autre des conditions climatiques et atmosphériques du lieu d'utilisation de l'imprimante. Il y a donc lieu de connaître cette température de départ pour pouvoir ajuster la quantité d'énergie à fournir au point afin de l'échauffer suffisamment pour obtenir le résultat souhaité. Un échauffement insuffisant se traduit par une absence de marquage ou un marquage trop peu contrasté. Un échauffement trop élevé force le marquage et détruit la finesse de l'impression.One of them is the regulation of the temperature of each heating point. Indeed, it is necessary to bring a determined energy to the point to make it reach the temperature necessary for the marking of the paper. This energy is brought to it in the form of an electric pulse (rectangular) whose surface depends on the thermal inertia of the resistive material to reach this temperature and on the starting temperature of the point to be heated. However, this starting temperature is a function of factors independent of each other such as in particular the time which separates two heating pulses and the ambient temperature. These two factors for a point are completely random and variable, one depending on the impression to be made and the other on the climatic and atmospheric conditions of the place of use of the printer. It is therefore necessary to know this starting temperature in order to be able to adjust the amount of energy to be supplied to the point in order to heat it sufficiently to obtain the desired result. Insufficient heating results in an absence of marking or too little contrasting marking. Too much heating forces the marking and destroys the fineness of the print.
Les imprimantes actuelles sont équipées d'un capteur de température qui se présente sous la forme d'un composant du genre thermistance. Ce composant est disposé sur le substrat relativement loin de la ligne de points si bien que le temps de réponse de ce composant est d'un ordre de grandeur (dizaine de secondes) qui n'est pas acceptable, compte tenu des vitesses de changement d'état thermique d'une ligne de points résultant des cadences de plus en plus élevées d'excitation. On donnera à titre d'exemple des valeurs de l'ordre de la milliseconde en ce qui concerne la période des impulsions à comparer à dix ou vingt secondes de temps de réponse du capteur de température, ce qui conduit à une régulation avec 10 ou 20 000 lignes de points d'impression de retard.Current printers are equipped with a temperature sensor which is in the form of a component of the thermistor type. This component is placed on the substrate relatively far from the line of points so that the response time of this component is of an order of magnitude (ten seconds) which is not acceptable, taking into account the rates of change d thermal state of a line of points resulting from the increasingly high rates of excitation. By way of example, values of the order of a millisecond will be given with regard to the period of the pulses to be compared to ten or twenty seconds of response time from the temperature sensor, which leads to regulation with 10 or 20 000 lines of delay printing dots.
La présente invention a pour but de remédier à cet inconvénient en proposant une tête d'imprimante thermique comportant des moyens pour disposer d'une mesure de température des points de chauffe dans un temps de réponse extrêmement bref permettant une régulation fine de la quantité d'énergie à apporter à chaque point de chauffe garantissant la qualité constante de l'impression d'une part tout au long de la ligne et d'autre part dans le temps.The object of the present invention is to remedy this drawback by proposing a thermal printer head comprising means for having a temperature measurement of the heating points in an extremely short response time allowing fine regulation of the quantity of energy to bring to each heating point guaranteeing the constant quality of the print on the one hand along the line and on the other hand over time.
Il apparaît aujourd'hui vain et surtout économiquement prohibitif de vouloir capter directement la température (donc l'énergie à apporter) de chaque point à chaque impulsion de chauffe. Il est cependant très avantageux de pouvoir connaître rapidement la température moyenne de la ligne de points ou les températures moyennes de quelques tronçons de ligne de points chauffants En effet une première régulation doit permettre de maintenir cette température moyenne dans un rapport déterminé avec la température de réaction du papier. On améliore ainsi la régularité de l'impression. En plus, la connaissance rapide de cette température moyenne permet d'associer sa valeur à d'autres paramètres de fonctionnement de la ligne de points, comme par exemple la fréquence d'excitation de chacun des points pour en tirer des conclusions permettant de "personnaliser" l'apport d'énergie au point considéré et donc d'affiner la régulation.Today it seems futile and above all economically prohibitive to want to capture the temperature (therefore the energy to be supplied) of each point at each heating pulse. It is however very advantageous to be able to quickly know the average temperature of the line of points or the average temperatures of a few sections of line of heating points. In fact, a first regulation must make it possible to maintain this average temperature in a determined relationship with the reaction temperature. paper. This improves the regularity of printing. In addition, the rapid knowledge of this average temperature makes it possible to associate its value with other operating parameters of the line of points, such as for example the excitation frequency of each of the points to draw conclusions making it possible to "personalize "the energy supply at the point considered and therefore to refine the regulation.
Afin donc d'améliorer la qualité de l'impression par une régulation efficace de la température des points chauffants, l'invention a pour objet une tête d'imprimante thermique comprenant sur un substrat isolant, une couche de verre présentant une surface supérieure de support de la ligne de points chauffants et de leurs conducteurs d'alimentation, les conducteurs étant orientés perpendiculairement à la ligne de points, une couche protectrice recouvrant la surface supérieure de verre pourvue de la ligne de points et des conducteurs, laquelle tête thermique comprenant à l'aplomb de la ligne de points chauffants et sous cette dernière, un film de matériau thermorésistif isolé électriquement de la ligne de points chauffants.In order therefore to improve the quality of printing by effective regulation of the temperature of the heating points, the invention relates to a thermal printer head comprising on an insulating substrate, a layer of glass having an upper support surface the line of heating points and their supply conductors, the conductors being oriented perpendicular to the line of points, a protective layer covering the upper surface of glass provided with the line of points and conductors, which thermal head comprising at the plumb with the line of heating points and under the latter, a film of heat-resistant material electrically insulated from the line of heating points.
La dissipation de chaleur à partir des points chauffants s'effectue d'une part en direction du papier et d'autre part en direction du substrat. Comme, en général, le substrat est équipé sur sa face arrière d'un radiateur de dissipation des calories, le flux thermique s'écoule dans le substrat de manière privilégiée transversalement à celui-ci. Il est donc optimal de placer le matériau thermo-résistif à l'aplomb de cette ligne de points car c'est dans cette zone qu'il est soumis au flux thermique le plus intenseHeat dissipation from the heating points takes place on the one hand towards the paper and on the other hand towards the substrate. As, in general, the substrate is equipped on its rear face with a heat dissipation radiator, the heat flow flows in the substrate in a preferred manner transversely thereto. It is therefore optimal to place the thermo-resistive material directly above this line of points because it is in this zone that it is subjected to the most intense heat flow.
Ce film a donc pour première fonction celle de capteur de température par mesure de sa résistance. Le temps de réaction de ce capteur sera d'autant plus rapide qu'il est proche de la ligne de points.The primary function of this film is therefore that of temperature sensor by measuring its resistance. The reaction time of this sensor will be all the faster as it is close to the line of points.
C'est ainsi que dans un mode préféré de réalisation, il est placé entre le substrat et la couche de verre, voire au milieu de la couche de verre qui, dans ce cas, sera appliquée en deux fois sur le substrat avec interposition du matériau thermo-résistif entre les deux. Ce n'est pas sortir du cadre de l'invention que de disposer ce capteur, à l'aplomb de la ligne de points sur l'autre face du substrat. Cette solution, bien que moins performante est cependant beaucoup plus intéressante que les dispositifs connus à ce jour.Thus in a preferred embodiment, it is placed between the substrate and the glass layer, or even in the middle of the glass layer which, in this case, will be applied twice on the substrate with interposition of the material. thermoresistive in between. It is not outside the scope of the invention to have this sensor, directly above the line of points on the other face of the substrate. This solution, although less efficient, is however much more interesting than the devices known to date.
Une autre disposition caractéristique de l'invention réside dans le fait que le radiateur de dissipation de chaleur est rapporté sur la face du substrat opposée à celle pourvue des points chauffants, par l'intermédiaire d'une couche d'un matériau thermiquement conducteur. Cette disposition présente un double avantage. En premier lieu elle établit un pont thermique qui répartit la chaleur reçue, au travers du substrat par les points échauffés de la ligne. Il se produit donc une certaine répartition de la chaleur au niveau de ce pont qui favorise l'échange de chaleur entre les points chauds et les points froids. On favorise l'homogénéisation de la température de la ligne de points. En second lieu on améliore très sensiblement l'intimité du contact entre substrat et radiateur, ce qui permet d'améliorer le flux de chaleur de la ligne de points vers le radiateur. Ce flux de chaleur, auparavant,présentait une certaine hétérogénéité puisqu'à l'aplomb d'un point chauffé pouvait se trouver un point de mauvais contact entre substrat et radiateur. Dans ces conditions, le flux devait emprunter un chemin plus long pour contourner cette discontinuité.Another characteristic arrangement of the invention resides in the fact that the heat dissipation radiator is attached to the face of the substrate opposite to that provided with the heating points, by means of a layer of a thermally conductive material. This arrangement has a double advantage. Firstly, it establishes a thermal bridge which distributes the heat received, through the substrate through the heated points of the line. There is therefore a certain distribution of heat at this bridge which promotes the exchange of heat between the hot spots and the cold spots. The homogenization of the point line temperature is favored. Secondly, the intimacy of the contact between the substrate and the radiator is very significantly improved, which makes it possible to improve the heat flow from the line of points to the radiator. This heat flow, previously, presented a certain heterogeneity since with the plumb of a heated point could be a point of bad contact between substrate and radiator. Under these conditions, the flow had to take a longer path to circumvent this discontinuity.
Cette disposition de l'invention est notamment intéressante lorsque les points chauffants de la ligne ne sont pas physiquement séparés les uns des autres comme c'est maintenant de plus en plus le cas, car elle permet d'égaliser les conditions de refroidissement pour chaque point chauffant d'une ligne.This arrangement of the invention is particularly advantageous when the heating points of the line are not physically separated from each other as it is now more and more the case, because it makes it possible to equalize the cooling conditions for each heating point of a line.
D'autres caractéristiques et avantages ressortiront de la description d'un mode de réalisation de l'invention donnée ci-après à titre d'exemple.Other characteristics and advantages will emerge from the description of an embodiment of the invention given below by way of example.
Il sera fait référence au dessin annexé représentant par une figure unique une tête d'imprimante selon l'invention vue en coupe partielle transversalement à la ligne de points chauffants.Reference will be made to the appended drawing representing, by a single figure, a printer head according to the invention seen in partial section transversely to the line of heating points.
La tête d'imprimante thermique représentée comporte de manière classique un substrat 1 en céramique (à base d'alumine) isolant qui constitue la structure de la tête sous forme d'une plaque d'environ un demi-millimètre d'épaisseur, sa largeur étant de l'ordre de la dizaine de centimètres.The thermal printer head shown conventionally comprises an insulating ceramic substrate (based on alumina) which constitutes the structure of the head in the form of a plate about half a millimeter thick, its width being of the order of ten centimeters.
Selon l'invention, on dépose sur ce substrat un film 2 de matériau thermo-résistif comme par exemple du platine. Les techniques de dépôt sont connues. Il s'agit, par exemple, d'une sérigraphie d'une pâte organométallique qui subit une cuisson aux environs de 1000°C. La forme de ce film 2 est déterminée par l'expérience en fonction des valeurs ohmiques requises. Elle peut être soit un simple rectangle sur toute la largeur du substrat, soit une frise d'un conducteur plus long. Ce film peut être continu électriquement ou comporter plusieurs tronçons.According to the invention, a film 2 of thermoresistive material such as platinum is deposited on this substrate. The deposition techniques are known. This is, for example, a screen printing of an organometallic paste which undergoes cooking at around 1000 ° C. The shape of this film 2 is determined by experience as a function of the ohmic values required. It can be either a simple rectangle over the entire width of the substrate, or a frieze of a longer conductor. This film can be electrically continuous or comprise several sections.
La surface supérieure du substrat comportant ce film de matériau thermo-résistif est ensuite recouverte, de manière connue, d'une couche de verre 3 (enverrage), également par sérigraphie et cuissons, avec les réserves qui s'imposent pour laisser accessible, aux endroits appropriés, le film 2 pour des inter-connexions électriques.The upper surface of the substrate comprising this film of thermo-resistive material is then covered, in a known manner, with a layer of glass 3 (coating), also by screen printing and baking, with the necessary reserves to allow access to suitable locations, film 2 for electrical interconnections.
Sur la couche de verre 3, on procède à la réalisation de couches conductrices en or, que l'on divise ensuite en conducteurs 4 par photogravure (ou tout autre procédé connu).On the
Transversalement à ces conducteurs et sur ceux-ci, on dépose un matériau résistant 5 qui forme la ligne de points chauffants.Crosswise to these conductors and on them, a resistant material 5 is deposited which forms the line of heating points.
De manière également connue, ce matériau disposé en une ligne est, soit physiquement divisé en points distincts, chacun d'eux étant inséré dans un circuit d'alimentation (conducteurs 4), soit continue et est chauffée par tronçons en fonction des connexions réalisées électroniquement entre les conducteurs 4 et une source d'alimentation.In a manner also known, this material arranged in a line is either physically divided into separate points, each of them being inserted in a supply circuit (conductors 4), or continuous and is heated in sections according to the connections made electronically. between conductors 4 and a power source.
Enfin, une couche de matériau de protection 6 recouvre au moins la zone de la ligne de points chauffants pour isoler électriquement les circuits ainsi réalisés de l'extérieur et pour constituer une garniture de protection de la ligne de points chauffants contre l'abrasion du papier qui défile devant elle.Finally, a layer of protective material 6 covers at least the zone of the line of heating points to electrically isolate the circuits thus produced from the outside and to constitute a lining for protecting the line of heating points against abrasion of the paper. who walks past her.
Comme la résistance du film 2 qui est en matériau dont la résistance varie avec la température, est une variable directement proportionnelle à sa température, la mesure de cette résistance donne une indication de sa température et par voie de conséquence une indication sur la température de la ligne de points chauffants. Compte tenu de la très faible distance qui les sépare, les variations de température des points chauffants influencent immédiatement la température du film du capteur.As the resistance of the film 2 which is made of a material whose resistance varies with temperature, is a variable directly proportional to its temperature, the measurement of this resistance gives an indication of its temperature and consequently an indication of the temperature of the line of heating points. Given the very short distance between them, the temperature variations of the heating points immediately influence the temperature of the sensor film.
La résistance du film varie donc très rapidement et un signal qui lui est relatif peut être utilisé comme paramètre de commande d'un asservissement de l'énergie à apporter aux points chauffants, pour par exemple maintenir sensiblement constante la température maximale à laquelle est porté chaque point chauffant.The resistance of the film therefore varies very quickly and a signal relating to it can be used as a control parameter for controlling the energy to be supplied to the heating points, for example to keep the maximum temperature at which each is brought substantially constant. heating point.
Bien entendu, on pourra diviser le film du capteur en plusieurs tronçons pour obtenir un nombre de mesures plus important et réguler séparément plusieurs groupes de points chauffants car, en fonction de l'impression à réaliser les points chauffants ne sont pas uniformément sollicités.Of course, it will be possible to divide the sensor film into several sections in order to obtain a larger number of measurements and to regulate several groups of heating points separately because, depending on the impression to be made, the heating points are not uniformly stressed.
Les relevés de mesure, qui seront nécessairement des valeurs moyennes intéressent plusieurs points qui, en réalité sont à des températures différentes. Les données relevées peuvent être traitées en liaison avec les paramètres relatifs à la fréquence d'alimentation des points qui, eux, peuvent être extraits de l'unité de gestion de l'impression. il sera alors possible d'affiner la régulation.The measurement readings, which will necessarily be average values, concern several points which, in reality, are at different temperatures. The data collected can be processed in conjunction with the parameters relating to the frequency of supply of the dots which can be extracted from the print management unit. it will then be possible to refine the regulation.
Une autre disposition consiste à chercher de réduire le gradient thermique qui peut exister entre chaque point de manière à réduire la plage de températures dans laquelle doit s'exercer la régulation. Pour ce faire, il faut favoriser d'une part la vitesse de refroidissement des points chauds et d'autre part l'échange thermique le long de la ligne de points. Pour ce faire, l'invention propose de disposer entre le substrat 1 et un radiateur 7 qui est connu en lui-même et présent sur l'autre face de la plaque 1 en céramique, une couche 8 d'un matériau très conducteur thermiquement (par exemple de l'argent) qui a pour effet, d'une part d'améliorer le contact entre radiateur 7 et plaque 1 donc de favoriser le transfert de chaleur dans l'épaisseur de la tête en direction du radiateur de dissipation et, d'autre part de former un répartiteur de chaleur sous la ligne de points chauffants et donc de promouvoir un échange de chaleur entre points chauds et froids.Another arrangement consists in seeking to reduce the thermal gradient which may exist between each point so as to reduce the temperature range in which the regulation must be exerted. To do this, it is necessary to favor on the one hand the speed of cooling of the hot spots and on the other hand the heat exchange along the line of points. To do this, the invention proposes to have between the
La tête d'impression selon l'invention ainsi équipée de ce film thermo-résistif (en toute matière appropriée) possède un avantage supplémentaire. Il est en effet possible de se servir de ce film comme d'une résistance de réchauffage de la ligne de points. Il faut en effet noter que de telles imprimantes thermiques sont soumises à des conditions d'emploi extrêmement sévères car elles peuvent équiper des appareils extérieurs soumis aux climats les plus rigoureux.The print head according to the invention thus equipped with this heat-resistant film (in any suitable material) has an additional advantage. It is indeed possible to use this film as a heating resistor of the line of points. It should indeed be noted that such thermal printers are subject to extremely severe conditions of use because they can be fitted to external devices subjected to the most severe climates.
On peut donc connecter à ce film 2 une source d'énergie électrique, pendant des espaces de temps déterminés (en préalable à l'édition, et pendant l'édition) sous forme d'impulsions ou train d'impulsions, intercalés entre les temps de surveillance et de mesure, le film étant alors connecté à une autre source d'énergie. Les interconnexions du film à l'alimentation de mesure ou à celle de puissance (chauffage) peuvent être gérées par un dispositif de commande du genre comportant une fonction de multiplexage si nécessaire.It is therefore possible to connect to this film 2 a source of electrical energy, for determined time spaces (prior to editing, and during editing) in the form of pulses or train of pulses, interspersed between the times. monitoring and measurement, the film then being connected to another energy source. The interconnections of the film to the measurement supply or to that of the power supply (heating) can be managed by a control device of the kind comprising a multiplexing function if necessary.
Claims (6)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9006444 | 1990-05-23 | ||
| FR9006444A FR2662395A1 (en) | 1990-05-23 | 1990-05-23 | IMPROVEMENT TO THERMAL PRINTER HEADS. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0458691A1 true EP0458691A1 (en) | 1991-11-27 |
Family
ID=9396888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91401300A Withdrawn EP0458691A1 (en) | 1990-05-23 | 1991-05-21 | Improvement in thermal printheads |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5196865A (en) |
| EP (1) | EP0458691A1 (en) |
| FR (1) | FR2662395A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1431045A1 (en) * | 2002-12-17 | 2004-06-23 | Agfa-Gevaert | A modeling method for taking into account thermal head and ambient temperature. |
| CN101730448A (en) * | 2008-10-24 | 2010-06-09 | 鸿富锦精密工业（深圳）有限公司 | Heat dissipating device with function of monitoring temperature |
| JP7093226B2 (en) * | 2018-05-22 | 2022-06-29 | ローム株式会社 | Thermal print head |
| JP7228428B2 (en) * | 2019-03-20 | 2023-02-24 | ローム株式会社 | thermal print head |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4837586A (en) * | 1988-01-28 | 1989-06-06 | Eastman Kodak Company | Image contrast by thermal printers |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55144178A (en) * | 1979-04-27 | 1980-11-10 | Toshiba Corp | Thermal head |
| JPS56142081A (en) * | 1980-04-09 | 1981-11-06 | Ricoh Co Ltd | Thermal head |
| US4449033A (en) * | 1982-12-27 | 1984-05-15 | International Business Machines Corporation | Thermal print head temperature sensing and control |
| JP2568492B2 (en) * | 1985-05-09 | 1997-01-08 | 松下電器産業株式会社 | Thermal head |
| JPS61291156A (en) * | 1985-06-19 | 1986-12-20 | Yokogawa Electric Corp | Method for driving thermal head |
| JPS62199471A (en) * | 1986-02-27 | 1987-09-03 | Mitsubishi Electric Corp | Thermal printer |
| US5036337A (en) * | 1990-06-22 | 1991-07-30 | Xerox Corporation | Thermal ink jet printhead with droplet volume control |
-
1990
- 1990-05-23 FR FR9006444A patent/FR2662395A1/en active Granted
-
1991
- 1991-05-20 US US07/703,261 patent/US5196865A/en not_active Expired - Fee Related
- 1991-05-21 EP EP91401300A patent/EP0458691A1/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4837586A (en) * | 1988-01-28 | 1989-06-06 | Eastman Kodak Company | Image contrast by thermal printers |
| US4837586B1 (en) * | 1988-01-28 | 1992-06-30 | Eastman Kodak Co |
Non-Patent Citations (4)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN vol. 11, no. 111 (M-578)(2558), 8 avril 1987; & JP - A - 61255872 (MATSUSHITA ELECTRIC IND. CO. LTD.) 13.11.1986 * |
| PATENT ABSTRACTS OF JAPAN vol. 12, no. 52 (M-668)(2899), 17 février 1988; & JP - A - 62199471 (MITSUBISHI ELECTRIC CORP.) 03.09.1987 * |
| PATENT ABSTRACTS OF JAPAN vol. 5, no. 14 (M-52)(686), 28 janvier 1981; & JP - A - 55144178 (TOKYO SHIBAURA DENKI K.K.) 10.11.1980 * |
| PATENT ABSTRACTS OF JAPAN vol. 6, no. 23 (M-111)(901), 10 février 1982; & JP - A - 56142081 (RICOH K.K.) 06.11.1981 * |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2662395A1 (en) | 1991-11-29 |
| US5196865A (en) | 1993-03-23 |
| FR2662395B1 (en) | 1995-01-13 |
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