JP2008257951A - Light source for scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source for a scanner capable of preventing change of luminance of a light-emitting part, even when the temperature of the light-emitting part changes, and capable of extending own lifetime. <P>SOLUTION: This light source 11 for a scanner is provided with the elongated light emitting part 17, having an organic EL layer 15 formed between a positive electrode 14 and a negative electrode 16; terminal parts 19 for the positive electrode electrically connected to an external drive circuit; terminal parts 20 for the negative electrode electrically connected to the negative electrode 16; and resistance parts 22, arranged in parts other than the light emitting part 17 and having a positive temperature coefficient. The resistance parts 22 are arranged throughout the total length in the longitudinal direction of the positive electrode 14. The light source for a scanner is also provided with a power feed part 18 electrically connected to all of the resistance parts 22, and supplying a current to the positive electrode 14 via the resistance parts 22. The organic EL layer 15 and the resistance parts 22 are structured, such that the sum of the voltage applied to the light-emitting part 17 and the voltage applied to the resistance part 22 is set to be a constant, regardless of the temperature variations of the light-emitting part 17 and the resistance parts 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source for a scanner.

  An organic EL element is configured by providing an organic EL layer between an anode and a cathode. For example, a scanner light source that emits irradiation light on a document using the organic EL element as a light emitting unit is considered. .

In addition, in a self-luminous display panel composed of a plurality of pixels, a temperature compensation functional layer having a temperature resistance characteristic that has the same tendency as the light emission luminance characteristic of the light emission functional layer is provided for each pixel, thereby reducing the temperature dependence of the light emission luminance. Have been proposed (see, for example, Patent Document 1). The self-luminous display panel described in Patent Document 1 includes a first electrode, at least one or more light emitting functional layers formed on the first electrode, and a second electrode formed on the light emitting functional layer. The self-light-emitting element consisting of is provided for each pixel. Since the temperature compensation functional layer has a temperature resistance characteristic in which the resistance value is relatively increased with respect to the temperature rise, as the temperature of the light emitting functional layer rises, the temperature of the temperature compensation functional layer also rises. The resistance value increases. Since the temperature compensation function layer is laminated in series with the voltage supply path applied between the first electrode and the second electrode, the change in the voltage characteristic due to the temperature change of the light emitting function layer is the temperature compensation function. The change in brightness is offset by the resistance change of the layer, and the change in luminance is suppressed.
JP 2006-269284 A

  When the temperature of the organic EL element changes due to the influence of the ambient temperature or the like, the forward voltage changes and the luminance changes. Therefore, when the organic EL element is used as the light emitting part of the light source for the scanner, the luminance of the light emitting part may change with a change in ambient temperature. If the light emitting part has an elongated shape, the temperature in the light emitting part may vary due to the thermal effect of the ambient temperature. In this case, the applied voltage varies for each part of the light emitting part, and the brightness is high at the part where the temperature is high. Therefore, there is a characteristic that the luminance is low at a part where the temperature is low. Therefore, when the organic EL element is used as the light emitting part of the light source for the scanner, the luminance distribution of the light emitting part may change due to the thermal influence of the ambient temperature.

  The self-luminous display panel described in Patent Document 1 is a display panel including a plurality of pixels, and a light-emitting unit including an EL element is provided for each pixel. Is different. In the self-luminous display panel, no consideration is given to a problem that occurs when the area of the light emitting portion is increased by using it as a light source for a scanner.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to suppress the change in luminance of the light emitting section even when it is affected by the thermal effect of the ambient temperature and to extend the lifetime. An object of the present invention is to provide a scanner light source.

  The invention according to claim 1 is an elongated light emitting part in which an organic EL layer is provided between an anode and a cathode, an anode terminal part configured to allow an external current to be input, the cathode, An electrically connected cathode terminal portion, a resistor portion provided over the entire length in the longitudinal direction of the anode and provided in a portion other than the light emitting portion, and having a positive temperature coefficient, and the anode terminal And a power supply unit that is electrically connected to the whole and the resistor unit and supplies current to the anode through the resistor unit, and a voltage applied to the light emitting unit and a voltage applied to the resistor unit The gist of the invention is that the sum is constant regardless of the temperature change of the light emitting portion and the resistance portion.

  Note that “provided over the entire length in the longitudinal direction of the anode” is not limited to being provided so as to correspond to 100% of the total length in the longitudinal direction of the anode, but in the target luminance distribution in the longitudinal direction. On the other hand, it means that the brightness deviation is provided at an interval that is within ± 5%. In addition, “the sum of the voltage applied to the light emitting portion and the voltage applied to the resistance portion is constant regardless of the temperature change of the light emitting portion and the resistance portion” means that the voltage applied to the light emitting portion and the resistance portion are applied. It means that the fluctuation of the sum with the applied voltage is within ± 5%.

  In the present invention, even when the light emitting part and the resistance part change in temperature under the influence of the ambient temperature, and the forward voltage of the light emitting part changes, the voltage applied to the resistance part is a change in the forward voltage of the light emitting part. It changes according to. Therefore, the sum of the voltage applied to the light emitting part and the voltage applied to the resistance part is constant and the amount of current flowing through the light emitting part does not change regardless of the temperature change of the light emitting part and the resistor part. Even if changes, it can suppress that the brightness | luminance of a light emission part changes.

  In addition, if the light emitting part has an elongated shape, a temperature difference may occur for each part of the light emitting part and the resistance part. For this reason, the voltage applied to the light emitting part and the voltage applied to the resistance part are different for each part. However, the sum of the voltage applied to the light emitting portion and the voltage applied to the resistance portion is constant at any part. Therefore, it can suppress that the electric current amount which flows into a light emission part changes with the site | parts of a light emission part, and can suppress that the luminance distribution of a light emission part changes even if it receives to the thermal influence of ambient temperature.

  In addition, when there is a temperature difference for each part of the light emitting part, the current value of the part with high temperature becomes high and the brightness of that part becomes high, so the brightness deterioration is compared with other parts. Get faster. However, in the present invention, the value of the current flowing through the light emitting unit does not change with respect to the partial temperature change of the light emitting unit, so that the life of the scanner light source can be extended.

The invention according to claim 2 is summarized in that, in the invention according to claim 1, the resistance portion is made of metal.
In this invention, even if the resistance portion is made of metal, an EL material whose resistance value of the light emitting portion changes in response to a change in the resistance value of the resistance portion due to temperature is applied to the light emitting portion. The sum of the applied voltage and the voltage applied to the resistance portion can be made constant.

  ADVANTAGE OF THE INVENTION According to this invention, even when it receives to the thermal influence of ambient temperature, while changing the brightness | luminance of a light emission part, a lifetime can be extended.

  Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. FIGS. 1A and 1B schematically show the structure of the organic EL element. For convenience of illustration, some dimensions are exaggerated for easy understanding. The ratio of dimensions such as the width, length, and thickness of the portion is different from the actual ratio.

  As shown in FIG. 1A, the scanner light source 11 is configured by an organic EL element 12 which is mounted on a mounting substrate (not shown) and has a strip shape (elongated shape) and a rectangular shape in plan view. Yes. As shown in FIG. 1B, in the organic EL element 12, an anode 14, an organic EL layer 15, and a cathode 16 are sequentially laminated on a substrate 13, and light from the organic EL layer 15 is extracted from the substrate 13 side. It is configured as a so-called bottom emission type that is mounted (emitted), and is mounted on a mounting board (not shown) in a state where the surface opposite to the board 13 faces a mounting board (not shown).

  As the substrate 13, a substrate having visible light transmittance is used, and for example, a glass substrate is used. The anode 14 is made of a known transparent conductive material (for example, ITO (indium tin oxide)) and is larger than the organic EL layer 15. The organic EL layer 15 is formed using a known organic EL material, and the organic EL element 12 is configured to emit monochromatic light. The organic EL layer 15 is made of a known EL material, and has a characteristic that the resistance value decreases as the temperature increases, and generally has a negative temperature coefficient. The cathode 16 is made of a known cathode material, such as aluminum, and has reflectivity. The organic EL element in which the organic EL layer 15 is provided between the cathode 16 and the anode 14 is used as the light emitting unit 17. The light emitting unit 17 has an elongated shape and is formed so that the total length is at least longer than the region to be irradiated (reading region). For example, when irradiating an A4 size document, the total length is A4 size. It is formed to be longer than the vertical length.

  As shown in FIG. 1A, a power supply portion 18 having a rectangular shape in plan view extending along the long side of the anode 14 is provided outside the one long side of the anode 14. The power feeding unit 18 is formed of the same member as the anode 14 with a constant width, and is configured to supply current to the anode 14 via a resistance unit 22 described later. The “width of the power supply unit 18” means the length of the organic EL element 12 in the short direction. The power feeding portion 18 is provided with anode terminal portions 19 for electrical connection with an external drive circuit (not shown) at both ends in the longitudinal direction. The anode terminal portion 19 is formed of the same member as the anode 14 and the power feeding portion 18 and is formed integrally with the power feeding portion 18.

  Further, cathode terminal portions 20 are formed on the outer sides of the sides located at both ends of the cathode 16 in the longitudinal direction. The cathode terminal portion 20 is formed of the same material as the anode 14 and the anode terminal portion 19, and as shown in FIGS. 1A and 1B, a cathode extension in which a part of the cathode 16 extends outward. It is connected to the part 16a.

  As shown in FIG. 1A, the anode terminal portion 19 and the cathode terminal portion 20 are longitudinal in the longitudinal end portion (the left end portion or the right end portion in FIG. 1A) of the substrate 13. Are arranged in a direction orthogonal to the direction.

  Further, in the region outside the organic EL layer 15, it extends continuously on a part of the anode terminal portion 19 and on the power feeding portion 18, and on the power feeding portion 18, it extends along the long side of the anode 14. An electrode 21 is provided. The auxiliary electrode 21 is formed so as to be narrower than the power supply unit 18 with a constant width, and has a volume resistivity lower than that of the anode 14 and is formed of the same material as the cathode 16.

  Between the power supply unit 18 and the anode 14, a plurality of resistance units 22 that electrically connect the power supply unit 18 to the anode 14 are provided over the entire length in the longitudinal direction of the anode 14, and other than the light emitting unit 17. It is provided in the part. The plurality of resistance portions 22 are all formed on the same plane as the anode 14 and the power feeding portion 18 in a state of being arranged in parallel along the longitudinal direction of the anode 14. The plurality of resistance portions 22 are all connected to the long side of the anode 14 and the long side of the power feeding portion 18. The resistance value of each resistance unit 22 is adjusted for each width and part so that the luminance distribution in the longitudinal direction of the light emitting unit 17 becomes a predetermined luminance distribution. Moreover, the distance between the adjacent resistance parts 22 is constant. The resistance portion 22 is made of a material different from the material of the power feeding portion 18 and the anode 14 and has a positive temperature coefficient. In this embodiment, the resistance portion 22 is made of polysafety (registered trademark) manufactured by Daito Tsushinki Co., Ltd. Yes. Here, the polysafety constituting the resistance portion 22 is formed by kneading a crystalline polymer that is an insulator and conductive carbon. The temperature coefficient of the resistance unit 22 is positive, and the absolute value thereof is substantially equal to the absolute value of the temperature coefficient of the light emitting unit 17. Here, “the absolute value of the temperature coefficient of the resistance portion 22 is substantially equal to the absolute value of the temperature coefficient of the light emitting portion 17” means that the absolute value of the temperature coefficient of the resistance portion 22 and the absolute temperature coefficient of the light emitting portion 17 are absolute. This means that the error range from the value is within 10%.

  In order to prevent the organic EL layer 15 from being adversely affected by moisture (water vapor) and oxygen, the anode 14, the organic EL layer 15, the cathode 16, the cathode extension portion 16a, the power feeding portion 18, the resistance portion 22, and the auxiliary electrode 21 are It is covered with a protective film (not shown). The protective film (not shown) is a known passivation film, for example, a ceramic film such as silicon nitride.

Next, the electrical configuration of the organic EL element 12 will be described.
FIG. 2 is an equivalent circuit diagram showing an electrical configuration of the organic EL element 12, and the resistance of the light emitting unit 17 configured by providing the organic EL layer 15 between the anode 14 and the cathode 16 is changed to that of the diode. Shown with circuit diagram symbols.

  In the organic EL element 12, the anode terminal portion 19 and the cathode terminal portion 20 are electrically connected by the resistor portion 22 and the light emitting portion 17, and the resistor portion 22 and the light emitting portion 17 are connected in series. .

  The forward voltage of the light emitting unit 17 is determined by the product of the resistance value of the light emitting unit 17 and the current value flowing through the light emitting unit 17, and the light emitting unit 17 has an ambient temperature-forward voltage characteristic in which the forward voltage drops as the temperature increases. . For example, when a current of 80 [mA] flows at an ambient temperature of 20 ° C., the light emitting unit 17 has a forward voltage of 5.4 [V] and a current of 80 [mA] at an ambient temperature of 60 ° C. When the current flows, the forward voltage of the light emitting unit 17 is 4.9 [V]. Further, in other words, the ambient temperature-forward voltage characteristic of the light emitting unit 17 in which the forward voltage of the light emitting unit 17 decreases as the temperature increases when the flowing current value is constant, in other words, the characteristic that the resistance value decreases as the temperature increases ( That is, the light emitting unit 17 has a negative temperature coefficient. When the ambient temperature-forward voltage characteristic of the light emitting unit 17 is converted into a temperature coefficient, the temperature coefficient is about −12.5 × 10E−3 [1 / ° C.].

  On the other hand, the resistor 22 has a characteristic (positive temperature coefficient) in which the resistance value increases as the temperature increases, and a resistor having a temperature coefficient of about + 12.5 × 10E-3 [1 / ° C.] is selected. Has been. When a voltage is applied between the anode terminal unit 19 and the cathode terminal unit 20, the current flows from the power supply unit 18 through the resistance unit 22 and the light emitting unit 17 into the cathode terminal unit 20, and the cathode Is output from the terminal section 20 to the outside. At this time, when a current flows through the resistance unit 22 and the light emitting unit 17, the voltage Vr is applied to the resistance unit 22, and the voltage Vdi is applied to the light emitting unit 17.

Next, an operation when the scanner light source 11 configured as described above is mounted on a scanner illumination device will be described.
As shown in FIG. 3, the scanner 23 includes a glass plate 24 on which a document or the like is placed, an illumination device 25 provided below the glass plate 24, and an illumination device 25 that emits light on the glass plate 24. And a sensor device 26 that receives light reflected by the placed document P. The sensor device 26 is equipped with a control circuit (not shown) for driving and controlling a photoelectric conversion element such as a CCD. The scanner light source 11 is used by being incorporated in the illumination device 25. When the scanner 23 operates, the voltage Vr is applied to the light emitting unit 17 to emit light, whereby the scanner light source 11 emits irradiation light.

  Here, the ambient temperature of the scanner 23 is not always constant and may change. In such a case, the temperature of the entire scanner light source 11 also changes, and accordingly, the temperature of the light emitting unit 17 and the resistance unit 22 also changes. Since the resistance value of the light emitting unit 17 changes when the temperature of the light emitting unit 17 changes, the voltage applied to the light emitting unit 17 with the temperature change of the light emitting unit 17 and the resistance unit 22 as shown in FIG. Vdi and the voltage Vr applied to the resistance portion 22 change. Therefore, the sum Vdi + Vr of the voltage Vdi applied to the light emitting portion 17 and the voltage Vr applied to the resistance portion 22 is constant regardless of the temperature change of the scanner light source 11. Since the amount of current flowing through the light emitting unit 17 does not change, the luminance of the light emitting unit 17 is suppressed from changing even if the temperature of the scanner light source 11 changes. Note that “the sum Vdi + Vr of the voltage Vdi applied to the light emitting unit 17 and the voltage Vr applied to the resistor unit is constant regardless of temperature changes of the light emitting unit 17 and the resistor unit 22” is applied to the light emitting unit 17. This means that the variation of the sum Vdi + Vr of the voltage Vdi and the voltage Vr applied to the resistor 22 is within a range of ± 5%.

  Further, when the temperature of the scanner light source 11 is increased due to an increase in the ambient temperature, the current is supplied to the anode 14 by supplying a current to a resistance portion made of a metal such as aluminum, for example. Partial current concentration is unlikely to occur due to temperature changes. Therefore, it is possible to avoid a situation in which the light emitting unit 17 deteriorates early due to the thermal influence of the ambient temperature, and the life of the scanner light source 11 can be extended.

  Further, when the scanner 23 is operated for a long time, a control circuit (not shown) arranged in the central portion of the light emitting unit 17 of the scanner light source 11 generates heat, and the thermal effect is given to the scanner light source 11. The temperature distribution was such that the temperature T1 at the central portion of the light emitting portion 17 was the highest, and the temperatures T2 to T5 were lowered as approaching the terminal side. At this time, as shown in FIG. 4, the voltages Vdi <b> 1 to Vdi <b> 5 applied to each part of the light emitting unit 17 in order from the central part of the light emitting unit 17 to the terminal side end are far from the terminal side end of the light emitting unit 17. Accordingly, the voltages Vr1 to Vr5 applied to the respective portions of the resistor portion 22 in order from the central portion of the light emitting portion 17 to the terminal side end portion increase as the distance from the terminal side increases. The sum Vdi + Vr of the voltage Vr applied to the resistance unit 22 and the voltage Vdi applied to the organic EL element 12 is constant in any part between the power supply unit 18 and the cathode terminal unit 20, and the light emitting unit The value of the current flowing through each part 17 is the same. Therefore, even if the temperature varies for each portion of the scanner light source 11 due to the thermal effect of the ambient temperature, the change in the luminance distribution of the light emitting unit 17 is suppressed.

According to this embodiment, the following effects can be obtained.
(1) The organic EL layer 15 and the resistance unit 22 have a sum Vdi + Vr of the voltage Vdi applied to the light emitting unit 17 and the voltage Vr applied to the resistance unit 22 regardless of temperature changes of the light emitting unit 17 and the resistance unit 22. It is configured to be constant. Therefore, even when the temperature of the light source 11 for scanner changes, it can suppress that the luminance distribution of the light emission part 17 changes.

  (2) Even if the temperature of the light source 11 for the scanner partially increases, the amount of current flowing through the corresponding portion of the light emitting unit 17 is smaller than that of the conventional light source for the scanner, so the light emitting unit 17 deteriorates early. It is possible to avoid the occurrence of such a situation, and the life of the scanner light source 11 can be extended.

  (3) Even if the temperature varies for each portion of the scanner light source 11 due to the thermal effect of the ambient temperature, the sum of the voltage at each portion of the light emitting portion 17 and the voltage at each portion of the resistance portion 22 is constant. The luminance distribution of the light emitting unit 17 can be prevented from changing.

  (4) The plurality of resistance portions 22 are provided over the entire length in the longitudinal direction of the anode 14, and the power supply portions 18 that are electrically connected to all of the plurality of resistance portions 22 are provided. Current is supplied. For example, the scanner light source 11 includes the elongated light-emitting unit 17 having a larger area than one pixel, and even if the temperature of each portion of the scanner light source 11 varies, one position of the resistor unit 22 The amount of current supplied to each resistance unit 22 can be made the same as compared with the case where current is supplied from. Therefore, the light source 17 is a scanner light source formed in an elongated shape, and the luminance distribution of the light emitter 17 can be prevented from changing even if the scanner light source 11 is affected by the influence of the ambient temperature.

  (5) The resistance unit 22 is made of a material having a negative temperature coefficient, an absolute value of the temperature coefficient being substantially equal to the absolute value of the temperature coefficient of the light emitting unit 17, and a voltage Vdi applied between the light emitting units 17. And the voltage Vr applied to the resistor 22 is constant. Therefore, even if the material used for the organic EL layer 15 is a known EL material, the change in the luminance distribution of the light emitting unit 17 can be suppressed regardless of the temperature change of the light emitting unit 17 and the resistance unit 22.

The embodiment is not limited to the above, and may be configured as follows, for example.
The resistance portions 22 may be provided at intervals at which the luminance deviation is within ± 5% with respect to the target luminance distribution in the longitudinal direction at least in the longitudinal direction of the anode 14. Instead of providing, for example, a resistance portion that extends continuously along the long side of the anode 14 and is connected to the entire long side of the anode 14 may be provided.

  O As long as the material has a positive temperature coefficient, the material constituting the resistance portion 22 may be changed. When the organic EL layer 15 is made of a known EL material, the temperature coefficient of the light emitting part 17 has the same absolute value, and the resistor part 22 may be made of a material having a negative temperature coefficient. The resistance portion 22 may be made of a polymer composite material in which titanium carbide is dispersed in maleic acid-modified polyethylene, polypropylene, or the like. For example, the resistance portion 22 may be formed of a metal such as aluminum, gold, silver, copper, or chromium. However, in this case, the temperature coefficient of the material constituting the resistance unit 22 is the same as the absolute value and a negative temperature coefficient so that the change in the resistance value of the resistance unit 22 due to the temperature change can be invalidated. It is necessary to form an organic EL layer from a certain EL material.

The resistor 22 may be connected in series with materials having different temperature coefficients. In this case, one material may be made of a material having a small absolute value of the temperature coefficient, and the other material may be made to have a negative temperature coefficient.

○ The members constituting the resistance portion 22 are not limited. For example, the resistance portion 22 may be formed of a film or a member including a mounting lead.
○ An external resistor may be used as the resistor. In this case, for example, on the substrate 13, the light emitting portion 17 in which the anode 14, the organic EL layer 15, and the cathode 16 are sequentially laminated is manufactured, and a connection terminal portion connected to the long side of the anode 14 is formed. At this time, when forming the anode 14, the power supply unit 18 is simultaneously formed on the substrate 13 separately from the light emitting unit 17, and when the cathode 16 is formed, the auxiliary electrode 21 is simultaneously formed with the power supply unit 18. A film is formed on top. Thereafter, an ACF (anisotropic conductive film) is interposed between the power supply unit 18 and the external resistor terminal, and between the connection terminal unit and the external resistor terminal. Are electrically connected through an external resistor. At this time, a plurality of external resistors are provided so as to extend over the entire length of the anode 14 in the longitudinal direction.

  As shown in FIG. 5, the light emitting unit 17 and an external resistor 28 as a resistor unit may be mounted on the printed circuit board 27. In this case, the light emitting unit 17 is mounted on the printed circuit board 27, and thereafter, the input side terminal of the external resistor 28 is connected to the first wiring pattern 29 as a power feeding unit, and the output side terminal of the external resistor 28 emits light. Connected to the second wiring pattern 30 located near the portion 17. A plurality of external resistors 28 connected in this way are provided so as to extend over the entire length of the anode 14 in the longitudinal direction (the direction perpendicular to the paper surface in FIG. 5), and the second wiring is provided via a flexible printed circuit board (FPC) 31. By connecting the pattern 30 to the connection terminal portion 32 connected to the long side of the anode 14, current flows from the first wiring pattern 29 through the external resistor 28 and is supplied to the anode 14.

  The organic EL element 12 is not limited to the configuration in which the anode terminal portion 19 and the cathode terminal portion 20 are formed at both ends in the longitudinal direction. For example, either one of the cathode terminal portions 20 may be omitted, and only the anode terminal portion 19 may be formed at both ends of the organic EL element 12. Alternatively, each of the anode terminal portion 19 and the cathode terminal portion 20 may be omitted, and the anode terminal portion 19 and the cathode terminal portion 20 may be provided only on one side of the organic EL element 12.

  The number of organic EL elements 12 included in the scanner light source 11 is not particularly limited. For example, the scanner light source may be configured by mounting a plurality of organic EL elements on a mounting substrate. And when comprising the light source for scanners from a some organic EL element, you may connect a some organic EL element in series. For example, when two organic EL elements are connected in series, the anode terminal of one organic EL element is connected to an external drive circuit, and the cathode terminal is connected to the anode terminal of the other organic EL element. If the cathode terminal of the other organic EL element is connected to an external drive circuit, the two organic EL elements can be connected in series.

  The organic EL element 12 is not limited to the bottom emission type, but may be a top emission type that emits light emitted from the organic EL layer 15 from the side opposite to the substrate 13. In this case, in the organic EL element 12, the cathode 16 may be formed of a transparent electrode, and the anode 14 may be formed of a transparent electrode or an opaque electrode. The substrate 13 is not limited to a transparent substrate, and may be an opaque substrate.

The organic EL element 12 may not be mounted on the mounting substrate, and the scanner light source 11 may be configured by only the organic EL element 12 and mounted on the illumination device 25.
The organic EL layer 15 is not limited to a configuration that emits monochromatic light of red, blue, or green, but may be changed to a configuration that emits white light by combining monochromatic light such as red, blue, green, or yellow.

  The materials of the anode 14, the organic EL layer 15 and the cathode 16 constituting the organic EL element 12 are not limited to those described above, and other materials used in known organic EL elements may be used.

(A) is a top view of this embodiment, (b) is the AA line partial side sectional view of (a). The electrical block diagram of an organic EL element. The partial schematic diagram of a scanner. Explanatory drawing explaining the relationship between the voltage applied to a light emission part, the voltage applied to a resistance part, and temperature. The sectional side view of the light source for scanners in another embodiment.

Explanation of symbols

  Vdi: voltage applied to the light emitting unit, Vr: voltage applied to the resistor unit, 11: light source for scanner, 12 ... organic EL element, 14 ... anode, 15 ... organic EL layer, 16 ... cathode, 17 ... light emitting unit , 18... Power supply section, 19... Anode terminal section, 20... Cathode terminal section, 22... Resistance section, 28... External resistor as resistance section, 29.

Claims (2)

An elongated light emitting part in which an organic EL layer is provided between an anode and a cathode;
An anode terminal portion configured to allow input of an external current; and
A cathode terminal electrically connected to the cathode;
A resistance portion that is provided over the entire length of the anode in the longitudinal direction, is provided in a portion other than the light emitting portion, and has a positive temperature coefficient;
A power supply section that is electrically connected to the anode terminal section and the entire resistance section and supplies current to the anode through the resistance section;
A scanner light source configured such that a sum of a voltage applied to the light emitting unit and a voltage applied to the resistor unit is constant regardless of a temperature change of the light emitting unit and the resistor unit. The scanner light source according to claim 1, wherein the resistance portion is made of metal.

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