JP2005212185A - Exposure device and electrophotographic device using the exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize the amount of light by regulating, initially and over time, the amount of light of each light emitting element of an exposure device which uses the light emitting element such as an electroluminescence element (an EL element). <P>SOLUTION: In the exposure device, a means is provided which has a train of the light emitting elements linearly disposed; a first wave directing path 2 for directing each of luminescent lights from the light emitting elements individually in the direction of photosensors; and a second wave directing path 4 for directing each of the luminescent lights from the light emitting elements in common. In addition, the means regulates the amount of light of each light emitting element based on the amount of light detected by a first and a second light receiving sensor 5 and 6 arranged at the end parts of the second wave directing path 4. Also, the electrophotographic device using the exposure device is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus including a light emitting element array configured by arranging a large number of light emitting elements in a line, and a technique of an electrophotographic apparatus using the exposure apparatus.

  An electrostatic latent image is formed on a pre-charged photoconductor by exposure according to image information, and this is developed with a toner to which a predetermined charge is applied, and the toner image developed on the photoconductor is applied to a recording paper. As an exposure device of an electrophotographic apparatus that obtains an image by applying pressure and heat to the recording paper on which the toner image has been transferred and then transferred by a fixing device, a beam using a laser diode as a light source, for example, an optical device such as a rotating polygon mirror A system that scans the photosensitive member using a scanning means to form an electrostatic latent image and a large number of light emitting elements formed using light emitting diodes and organic materials are arranged in a line, and each light emitting element is individually turned on. There is known a system in which an electrostatic latent image is formed on a photoreceptor by controlling (on / off).

  In general, in an electrophotographic apparatus using an exposure apparatus composed of a light-emitting element array such as an LED printer, the rotary polygon mirror in the laser beam printer is used to selectively illuminate each light-emitting element and irradiate light onto a photoconductor. There is no moving part like, and it is excellent in reliability and silence. Further, a large space for scanning light in the main scanning direction is unnecessary, and there is an advantage of downsizing the apparatus.

  However, in the exposure apparatus composed of these light emitting element arrays, the amount of light for each light emitting element varies due to the manufacturing process and the like, causing the image density to change. As a countermeasure for this, for example, a method is known in which the variation in the light amount of each light emitting element is measured in advance, and the final image density is made uniform by controlling the light amount and the light emission time of each light emitting element based on this measurement data. Yes.

  However, even if the light intensity and the light emission time of each light emitting element in the initial state are adjusted by the above method and it can be used within a range where the image density does not change, there is a difference in the total lighting time of each light emitting element as the number of recordings advances. In response to this, the light quantity deterioration proceeds independently for each light emitting element. This phenomenon is particularly noticeable in so-called organic electroluminescence elements using organic materials as light emitting elements. However, since the characteristics of light quantity deterioration change depending on the driving conditions of the elements and the ambient temperature, the organic electroluminescence elements simply have a light emission time. The method of controlling the light amount and the light emission time based on the accumulated value has a limit in correspondence, and is a big problem in realizing an exposure apparatus using an organic electroluminescence element.

As a countermeasure for the above problem, there has been proposed an exposure apparatus that corrects variations in the light amount of each light emitting element by detecting the light amount of each light emitting element with a light receiving sensor.
JP 2002-1227489 A

  The above document discloses a configuration in which one light receiving sensor is provided corresponding to the number of light emitting elements, or one for every two adjacent light emitting elements. In this case, the number of light receiving sensors becomes enormous. Furthermore, since each light emitting element and each light receiving sensor must be arranged at an equal distance, the actual accuracy of each light emitting element depends on the positional accuracy of each light emitting element and each light receiving sensor, variation in light receiving characteristics of each light receiving sensor, and the like. It is difficult to correct the amount of light uniformly.

In addition, there are a large number of light receiving sensors, the cost increases due to the increase in the number of terminals of the processing unit for processing the signals of each light receiving sensor, the arrangement space of each light receiving sensor, the securing of the wiring area of each light receiving sensor, etc. Also, there arises a problem of increasing the size of the exposure apparatus.

  The present invention has been made in order to solve the conventional problems as described above, and its purpose is to effectively and inexpensively correct light intensity variations including deterioration of each light emitting element with a simple configuration. It is an object to provide an exposure apparatus capable of performing the above, or an electrophotographic apparatus using the exposure apparatus.

  In order to achieve the above object, a feature of the invention of claim 1 is that a light emitting element array in which a plurality of light emitting elements are arranged in a line and light output from each of the light emitting elements are individually guided in a first direction. And having a first waveguide and a second waveguide for commonly guiding the light output from each of the light emitting elements in the second direction.

  A feature of the invention of claim 2 is that the first waveguide is an aggregate of a plurality of minute waveguides. As a result, the light emitted from each light emitting element can be guided to an object (photoconductor) to be exposed.

  A feature of the invention of claim 3 is that the second waveguide is arranged in the same direction as the arrangement direction of the light emitting element rows. By this second waveguide, the light emitted from the light emitting element is guided in a direction different from the object to be exposed (photosensitive member), that is, the same direction as the arrangement direction of the light emitting element array. Thereby, the internal space of the exposure apparatus can be used effectively and the size can be reduced.

  A feature of the invention of claim 4 is that the second waveguide is substantially equal to or longer than the arrangement length of the light emitting element rows, and guides light emitted from all the light emitting elements in the same direction. By this second waveguide, light emitted from all the light emitting elements can be guided in a direction different from the object (photosensitive member) to be exposed, that is, in the same direction as the arrangement direction of the light emitting element arrays. This makes it possible to detect the light amounts of all the light emitting elements using a single waveguide.

  A feature of the invention of claim 5 is that a part of light emitted from the light emitting element is directly incident on the second waveguide. By adopting a structure in which a part of light of the light emitting element is directly taken, light emitted from each issuing element can be effectively guided to the second waveguide.

  A feature of the invention of claim 6 is that a part of light emitted from the light emitting element is directly incident on the first waveguide, and the amount of light incident on the first waveguide is incident on the second waveguide. That is, it is larger than the amount of incident light. As a result, it is possible to secure a light amount toward the target (photosensitive member) to be exposed.

  The feature of the invention of claim 7 is that the first waveguide and the second waveguide are disposed on the same plane, and the height of the first waveguide from the plane is the second waveguide. That is, the height of the waveguide is made substantially equal. As a result, the control electrode (anode) for controlling ON / OFF of the light emitting element can be easily arranged.

  A feature of the invention of claim 8 is that light shielding means is provided between the first waveguide and the second waveguide along the second waveguide. As a result, the so-called crosstalk in which the light guided through the second waveguide leaks to the first waveguide side can be prevented.

  A feature of the invention of claim 9 is that light intensity detection means for detecting the light intensity of the light guided by the second waveguide is provided at the end of the second waveguide. Since the light amount detecting means detects the light of each light emitting element guided through the second waveguide, the number of light receiving sensors can be dramatically reduced.

  A feature of the invention of claim 10 is that light intensity detecting means for detecting the light intensity of the light guided by the second waveguide is provided at both ends of the second waveguide. Generally, when light propagates through the waveguide, it gradually attenuates. However, by providing light receiving sensors at both ends of the second waveguide, the influence of light attenuation can be reduced.

  The feature of the invention of claim 11 is that a light emitting element array in which a plurality of light emitting elements are arranged in a line, a first waveguide for individually guiding light output from each of the light emitting elements in a first direction, and A second waveguide for commonly guiding the light output from each of the light emitting elements in the second direction, exposing the photoconductor with the light guided by the first waveguide, and The driving condition of the plurality of light emitting elements is controlled based on the result of detecting the light guided through the waveguide by the light detecting means. This makes it possible to easily correct variations in light emitting elements and deterioration over time with high term accuracy.

  According to the exposure apparatus of the present invention, the light emitted from each light emitting element can be guided through the second waveguide and detected by the light receiving sensor provided at the end of the second waveguide. It is possible to effectively correct variations and changes with time of each light emitting element while reducing the number of the light emitting elements. Further, as the number of light receiving sensors decreases, problems such as an increase in space required for wiring the light receiving sensors and difficulty in connection can be solved. As a result, a small exposure apparatus can be realized at low cost.

  The exposure apparatus according to the present invention aims at effectively adjusting the light quantity of each light emitting element, more precisely, the light energy to be irradiated with respect to the initial time and time, and a light receiving sensor at one waveguide and at the end of the waveguide. This is realized by detecting the light amount of each light emitting element and controlling the driving conditions of the individual light emitting elements with a simple configuration.

  FIG. 1 is a schematic top view of the exposure apparatus of the present invention. In FIG. 1, reference numeral 1 denotes the entire exposure apparatus. Reference numeral 2 denotes a first waveguide. The first waveguide 2 is an aggregate of fine cores and clads made of a transparent resin material arranged alternately. An organic electroluminescence element, which is a light emitting element, is formed on at least the core of the first waveguide 2 (not shown; details will be described later). The first waveguide 2 emits light emitted from each light emitting element (not shown). Are guided in the direction A (first direction) independently of the light emitting element unit. Reference numeral 3 denotes a fiber lens array. The fiber lens array 3 is formed by bundling a large number of fine transparent resins having a lens action, and forms the light guided through the first waveguide 2 as an equal-magnification erect image on a photosensitive member (not shown). . Reference numeral 4 denotes a second waveguide configured along the arrangement direction of the organic electroluminescence elements as the light emitting elements. The second waveguide 4 propagates the light emitted from each light emitting element in the direction B and the direction C, that is, the direction perpendicular to the direction A in which the first waveguide 2 propagates the light (second direction). is there. The core (not shown) of the first waveguide 2 is provided in a one-to-one relationship with each light emitting element, whereas the second waveguide 4 guides the light of all the light emitting elements in common. Since the second waveguide 4 guides the light of all the light emitting elements in common, it is at least equal to or longer than the length of the light emitting element array.

  Reference numeral 5 denotes a first light receiving sensor, and reference numeral 6 denotes a second light receiving sensor. The first light receiving sensor 5 and the second light receiving sensor 6 detect the amount of light guided by the second waveguide 4. Reference numeral 7 denotes a light shielding plate, which optically blocks the first waveguide and the second waveguide. Reference numeral 8 denotes a drive circuit for driving the light emitting element. Reference numeral 9 denotes a base material made of, for example, ceramic or glass. On the base material 9, the first waveguide 2, the fiber lens array 3, the second waveguide 4, the drive circuit 8, and the like are arranged and formed. Yes. Note that these components are covered with a sealing material (not shown), and cannot be visually observed in practice.

  2 is a view showing a section A of the exposure apparatus 1 shown in FIG. 1, and FIG. 3 is a view showing a section B of the exposure apparatus 1 shown in FIG.

  Hereinafter, the structure of the exposure apparatus 1 will be described in detail with reference to FIGS.

  2 and 3, a drive circuit 8 is formed on a substrate 9 by a TFT (Thin Film Transistor) using a silicon-based material such as polysilicon or amorphous silicon.

  Reference numeral 20 denotes a planarizing film formed using, for example, a resin, and the driving circuit 8 is covered with the planarizing film 20 so that the upper part thereof is flat. On the planarizing film 20, the first waveguide 2 made of a transparent resin is formed. The first waveguide 2 is formed by alternately arranging minute cores 21 and claddings 22 using a so-called photo bleaching method in which a cladding layer is formed by changing the refractive index of a resin by, for example, ultraviolet irradiation.

A control electrode (anode) 23, which is an electrode for injecting holes, made of a transparent conductive film formed by a sputtering method, a resistance heating vapor deposition method, or the like is formed on the core 21. As the material of the control electrode (anode 23), ITO (indium tin oxide), IZO (indium zinc oxide), ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO), or the like is used.

  Reference numeral 24 denotes a light emitting layer. In this embodiment, an organic electroluminescence element is used as the light source of the exposure apparatus 1. In this embodiment, a thin film layer made of an organic material is formed only by the light emitting layer 24. In addition to such a structure, a two-layer structure of a light emitting layer 24 and a hole transport layer (not shown), a light emitting layer 24 and an electron transport layer (not shown), a three-layer structure of a hole transport layer (not shown), a light emitting layer 24, and an electron transport layer (not shown) can be used. As the light emitting layer 24, not only a fluorescent material but also a phosphorescent material may be used. Further, in order to block holes and increase the efficiency, a positive electrode is formed at the interface between the light emitting layer 24 and the electron transport layer (not shown). A hole blocking layer (not shown) may be provided. The effect in the present invention is not particularly affected by the element structure of organic electroluminescence.

  The light emitting layer 24 covers the entire surface of the first waveguide 2 regardless of the presence or absence of the control electrode (anode) 23, and electrons such as aluminum formed by resistance heating vapor deposition are injected into the upper surface of the light emitting layer 24. A common electrode (cathode) 25 as an electrode is formed. Aluminum used for the common electrode (cathode) 25 has a function as a reflective film in addition to a function as an electrode.

  A sealing material 26 made of glass or the like is formed on the common electrode (cathode) 25.

  The control electrode (anode) 23 is connected to the drive circuit 8 through the through hole 30 (see FIG. 3), and the drive circuit 8 is controlled by a control means (not shown) to control the control electrode (anode) of the organic electroluminescence element. When a DC voltage is applied with the positive electrode 23 and the common electrode (cathode) 25 as the negative electrode, holes are injected into the light emitting layer 24 from the control electrode (anode) 23 and from the common electrode (cathode) 25. Are injected with electrons. The holes and electrons injected in this way are recombined inside the light emitting layer 24, and a light emission phenomenon occurs in the light emitting region 27 when excitons generated thereby shift from the excited state to the ground state. Happens. In such an organic electroluminescence element, light emitted from the light emitting region 27 in the light emitting layer 24 is emitted in all directions around the phosphor.

The light thus generated is directly incident on the core 21 formed in the first waveguide 2, and the core 2
1 is guided in a direction A (direction of a photoreceptor not shown). Since the clad 22 is provided on both sides of the core 21 and the refractive index of the core 21 is larger than the refractive index of the clad 22, the light incident on the core 21 does not leak out of the clad 22, and the direction A (not shown) It is efficiently propagated in the direction of the photoreceptor.

  The light emission luminance of the organic electroluminescence element itself at the present time is not sufficient for forming a latent image on a photoconductor (not shown). However, as described above, a large area of light is condensed by the first waveguide 2. By guiding to the photoconductor side, a light spot having a luminance necessary for forming an electrostatic latent image can be obtained on the photoconductor.

  The greatest feature of the present invention is that, apart from the first waveguide 2 that independently guides the light of each organic electroluminescence element described above, the second conductor that guides the light of each organic electroluminescence element in common. Having a waveguide. FIG. 4 is a detailed top view of the exposure apparatus 1 shown in FIG. 1 (however, in order to facilitate the explanation, the common electrode (cathode) 25 and the sealing material 26 are omitted).

  Hereinafter, the configuration and function of the second waveguide 4 will be described in detail with reference to FIGS. 3 and 4.

  As described above, the first waveguide 2 has a structure in which the core 21 made of a so-called high refractive material and the clad 22 made of a material having a lower refractive index than the core 21 are alternately arranged in the arrangement direction of the organic electroluminescence elements. It has become.

  As shown in FIG. 4, the light emitting region 27 of each organic electroluminescence element is divided into a region A (40) and a region B (41). When each organic electroluminescence element is in an ON state by a drive circuit (not shown), the region Both A (40) and region B (41) emit light. Since a predetermined energy is required to form an electrostatic latent image on the photoreceptor, the size of the region A (40) is made larger than the size of the region B (41) in order to form an electrostatic latent image at high speed. As a result, the amount of light incident on the first waveguide 2 is made larger than the amount of light incident on the second waveguide 4.

  Similar to the core material in the first waveguide 2, the second waveguide 4 arranged along the arrangement direction of the organic electroluminescence elements is formed of a high refractive index material. In the 2nd waveguide 4, you may coat with the material which reflects light (or does not permeate | transmit) as needed other than the surface into which the light of each organic electroluminescent element injects, and the light-shielding plate 7. FIG.

  The region A (40) and the region B (41) are separated by a light shielding plate 7 made of, for example, aluminum, which reflects light, and the light on the second waveguide 4 side is allowed to pass through the first waveguide 2 by the light shielding plate 7. This prevents crosstalk between organic electroluminescence elements caused by leakage to the side. When it is difficult to use an independent member as the light shielding plate in the manufacturing process, for example, the clad layer may be formed by using the above-described photo bleaching method to replace the light shielding plate 7.

  The light generated in the region A (40) which is a part of the light emitting region 27 is directly incident on the first waveguide 2 and guided in the direction A (the direction of the photoconductor not shown). The light generated in the area A (40) is also guided in the direction opposite to the direction A, but the light in this direction is reflected in the direction A by the light shielding plate 7. On the other hand, the light generated in the region B (41) which is a part of the light emitting region 27 is directly incident on the second waveguide 4 and guided in both the direction B and the direction C. No leakage in the direction of 2.

A first light receiving sensor 5 and a second light receiving sensor 6 are provided at both ends of the second waveguide 4, and the amount of light emitted from each organic electroluminescence element guided by the second waveguide 4 is It is detected by two light receiving sensors. The first light receiving sensor 5 and the second light receiving sensor 6 convert the received light quantity into a voltage or current value and output it.

  Now, as shown in FIG. 3, in the exposure apparatus 1 of the present invention, since light is irradiated from the end face, a control electrode (anode) 23, a light emitting layer 24, and a common electrode (cathode) 25 for controlling each organic electroluminescence element are provided. It is necessary to form on the first waveguide 2 and the second waveguide 4. For example, since the control electrode (anode) is made of ITO or the like with a thickness of about 0.1 μm or more by sputtering, if the heights of the first waveguide 2 and the second waveguide 4 are different, the control electrode (anode) 23 is formed. Cause trouble. Therefore, it is desirable that the first waveguide 2 and the second waveguide 4 are arranged on the same plane on the smoothing film 20 and have the same height.

  FIG. 5 is a block diagram of an electrophotographic apparatus using the exposure apparatus according to the present invention.

  The electrophotographic apparatus has a configuration in which toner images of four colors of yellow, magenta, cyan, and black are sequentially formed on a photoconductor, and a full color image is formed on the photoconductor 50 and then transferred to a recording sheet. .

  The order of forming colors in full-color image formation is yellow for the first color, magenta for the second color, cyan for the third color, and black for the fourth color. The photoreceptor 50 is a drum-like rotating body in which an inorganic photosensitive layer such as organic or amorphous Si is provided on a conductive substrate. Reference numeral 51 denotes a charger which is a means for charging the photoreceptor 50 to a uniform potential. For example, a well-known corona charger (a corotron charger or a scorotron charger) can be used. Reference numeral 1 denotes an exposure apparatus described above. After the surface of the photoreceptor 50 is charged to a uniform potential by a charger 51, each organic electroluminescence element of the exposure apparatus 1 is made to selectively emit light corresponding to image data. Based on the light guided to the first waveguide (not shown), an electrostatic latent image corresponding to the image data is formed on the surface of the photoreceptor 50. Reference numerals 52 to 55 denote developing units of respective colors, in which 52 is a yellow developing unit, 53 is a magenta developing unit, 54 is a cyan developing unit, and 55 is a black developing unit. Each developing device is a unit that develops the electrostatic latent image formed on the photoconductor 50 with the toner of each color in the developing device and forms a toner image of each color on the photoconductor 50. A transfer unit 56 includes an intermediate transfer roller (intermediate transfer member) 57 and a pressure roller 58 that applies a pressing force to the intermediate transfer roller 57 via a recording paper 59. The toner image on the photoconductor 50 is transferred to the recording paper 59 by the transfer unit 56. A cleaner 60 is a cleaning unit that collects the toner remaining on the photoreceptor 50 after the toner image is transferred onto the recording paper 59 by the transfer unit 56.

  An image forming process of the electrophotographic apparatus having the above configuration will be briefly described. First, the charger 51 charges the surface of the photoconductor 50 to a uniform potential (for example, −700 V). Then, when each organic electroluminescence element of the exposure apparatus 1 is selectively made to emit light corresponding to the yellow image data of the first color, the surface potential of the part where the photoconductor 50 is exposed corresponding to the light emitting point is It decreases (for example, -100V). As a result, an electrostatic latent image having a potential difference of −700 V and −100 V is formed on the photoreceptor 50.

When a predetermined voltage (for example, −300 V) is applied to the developing roller (toner layer forming portion for development) of the yellow developing device 52, the exposure device 1 causes the photosensitive member to be exposed to an electric field acting between the photosensitive member 50 and the developing roller. The toner charged negatively from the developing roller selectively adheres to the exposed portion 50, and a yellow toner image is formed on the photoreceptor 50. Thereafter, magenta for the second color, cyan for the third color, and black toner for the fourth color are sequentially formed on the photoconductor 50 using the developing devices (53 to 55) for the respective colors, and the full color toner is formed on the photoconductor 50. Form an image. Thereafter, the toner image formed on the photoreceptor 50 is collectively transferred onto the recording paper 59 by the transfer means 56. In FIG. 5, the batch transfer is performed on the recording paper 59 via the intermediate transfer roller 57, but the batch transfer may be directly performed on the paper. In the transfer from the photoconductor 50 to the intermediate transfer roller 57 and the transfer from the intermediate transfer roller 57 to the recording paper 59, transfer by electric field or transfer by pressure (offset transfer) can be used.

  The recording paper 59 onto which the toner image has been transferred by the transfer means 56 is heated and fixed by a fixing device (not shown). Thereafter, the residual toner on the photoconductor 50 after the transfer of the full color toner image is removed by the cleaner 60.

  In the above exposure apparatus and an electrophotographic apparatus using the exposure apparatus, a configuration for adjusting the light amount of each organic electroluminescence element of the exposure apparatus will be described with reference to FIGS.

  FIG. 6 is a diagram illustrating the configuration of a control block relating to light amount adjustment. In the present embodiment, it is assumed that the control block of FIG. 6 is configured in the exposure apparatus 1.

  As described above, when each organic electroluminescence element is in the ON state, both the region A (40) and the region B (41) emit light (see FIG. 4). Therefore, the light amount deterioration accompanying the light emission of the organic electroluminescence element proceeds at the same rate in the region A (40) and the region B (41). Therefore, by detecting the amount of light in the region B (41), which is a part of the light-emitting region, and controlling the total light emission luminance and light emission time based on this, the latent image forming conditions in the electrophotographic apparatus are fixed. Can be.

  A part of the light based on the region B enters the first light receiving sensor 5 and the second light receiving sensor 6 through the second waveguide 4. The second waveguide 4 is made of, for example, a resin such as polysilane, and light guided through the second waveguide 4 is gradually attenuated (in the case of a transparent resin material, it is generally set to about 1 dB / cm). The amount of light incident on the first light receiving sensor 5 and the second light receiving sensor 6 is lower than the amount of light incident on the second waveguide 4 from each organic electroluminescence element.

  FIG. 7 is a diagram showing the positional relationship between each organic electroluminescence element position of the exposure apparatus 1 and the second waveguide 4 and the light receiving sensors 5 and 6. In FIG. 7, reference numeral 60 denotes an organic electroluminescence element, and in order to simplify the description, each organic electroluminescence element is given a number corresponding to the element position, such as 60-1, 60-2 to 60 -n. .

  FIG. 8 is a diagram illustrating an output example of the light receiving sensors 5 and 6. FIG. 8A shows an output example of the first light receiving sensor 5, and FIG. 8B shows an output example of the second light receiving sensor 6. In each graph of FIG. 8, the horizontal axis represents the position of each organic electroluminescent element (60-1 to 60-n) from the left end in the exposure apparatus 1 of FIG. 7, and the vertical axis represents each organic electroluminescent element (60- 1 to 60-n) represent outputs (for example, voltage values) of the respective light receiving sensors 5 and 6 when individually turned on. The output of the first light receiving sensor 5 is the highest when the organic electroluminescence element 60-1 is turned on. This is because the distance from the organic electroluminescence element to the first light receiving sensor 5 via the second waveguide 4 is the shortest among all the organic electroluminescence elements (60-1 to 60-n), and the light attenuation is the smallest. Because. On the other hand, the output of the first light receiving sensor 5 is the smallest when the organic electroluminescence element 60-n is turned on. This is opposite to the organic electroluminescence element 60-1, and the distance from the organic electroluminescence element to the first light receiving sensor 5 via the second waveguide 4 is all organic electroluminescence elements (60-1 to 60-). This is because it is the longest of n) and has the largest light attenuation.

Thus, the output when the light of each organic electroluminescent element (60-1 to 60-n) is detected by the light receiving sensor is the distance from the organic electroluminescent element to the light receiving sensor via the second waveguide 4. Varies depending on

  Similarly to the first light receiving sensor 5, the second light receiving sensor 6 also depends on the distance from the organic electroluminescence element to the second light receiving sensor 6 via the second waveguide 4 as shown in FIG. Although the output characteristic is shown, since the distance from the organic electroluminescence element to the second light receiving sensor 6 via the second waveguide 4 is reversed from that of the second light receiving sensor 6, the output of the second light receiving sensor 6 is The output when the organic electroluminescence element 60-n is turned on is the largest, and the output when the organic electroluminescence element 60-1 is turned on is the smallest. Based on such a relationship, the output characteristics of each light receiving sensor are shown in FIG.

  Returning to the description of FIG. 6, a signal processing unit 70 performs signal processing such as amplification and addition on the outputs (analog voltage values in this case) of the first light receiving sensor 5 and the second light receiving sensor 6. It is. For example, the outputs of the first light receiving sensor 5 and the second light receiving sensor 6 shown in FIG. 8 are added, and amplification processing is performed so as to correspond to the signal input range of the A / D conversion unit 71 in the subsequent stage.

  FIG. 9 is a diagram illustrating a processing result of the signal processing unit 70.

  As a result of the analog arithmetic processing in the signal processing unit 70, the light amount detection output of each organic electroluminescence element (60-1 to 60-n) as shown in FIG. 9 can be obtained.

  When only one light receiving sensor is used, an organic electroluminescent element that cannot take a large output of the light receiving sensor is generated due to the distance from the organic electroluminescent element to the light receiving sensor via the second waveguide 4, and the S / N is poor. Therefore, adding two light receiving sensor outputs, as shown in FIG. 9, reduces the potential difference between the maximum output Vx1 and the minimum output Vx2, and the subsequent stage. When the signal is input to the A / D converter 71, the amplification gain in the signal processor 70 can be increased.

  Next, the A / D conversion unit 71 converts the light amount detection output of each organic electroluminescence element (60-1 to 60-n) into a digital value having a predetermined bit length and outputs it. Reference numeral 72 denotes a RAM which is a memory for temporarily storing the light amount detection output of each organic electroluminescence element (60-1 to 60-n) converted into a digital value. Reference numeral 73 denotes a ROM which stores a light amount adjustment program and the like. Reference numeral 74 denotes a non-volatile rewritable memory, which uses an EEPROM in this embodiment. The EEPROM 74 stores control data for equalizing the amount of light of each organic electroluminescence element (60-1 to 60-n). Reference numeral 75 denotes a CPU, which is a microcomputer that controls light amount adjustment.

  In the present embodiment, the light quantity detection results of the respective organic electroluminescence elements (60-1 to 60-n) are temporarily stored in the RAM 72. However, depending on the light quantity adjustment control method, the light quantity detection output may be stored in the RAM 12. You may pass directly to CPU75, without storing in.

  Reference numeral 76 denotes a data setting unit that determines the light emission conditions of each organic electroluminescence element (60-1 to 60-n). In this configuration, each organic electroluminescence element (60-1 to 60-n) can be individually controlled to be turned on, and the data setting unit 76 has a configuration in which data can be set in units of each organic electroluminescence element. Is provided. For example, the current value or the voltage value supplied to each organic electroluminescence element (60-1 to 60-n) is adjusted according to the value set in the data setting unit 76, or the lighting time in one light emission is adjusted. Thereby, the light quantity of each organic electroluminescent element (60-1 to 60-n) is controlled.

  Reference numeral 8 denotes a drive circuit composed of a TFT or the like that performs lighting control (ON / OFF) of each organic electroluminescence element (60-1 to 60-n). Like the data setting unit 76, a driver circuit is provided for each organic electroluminescence element (60-1 to 60-n) in the drive circuit 8. The drive circuit 8 drives each organic electroluminescent element (60-1 to 60-n) based on the data set in the data setting unit 76, and emits light from each organic electroluminescent element (60-1 to 60-n). To control.

  Next, light amount detection and light amount adjustment of each organic electroluminescence element in the configuration of FIG. 6 will be described.

  The CPU 75 sets predetermined data in the data setting unit 76, operates the drive circuit 8, and first selectively emits only the organic electroluminescence element 60-1. As already described, a part of the light emitted from the organic electroluminescence element 60-1 enters the second waveguide 4, and the incident light passes through the second waveguide 4 (in the direction B and the direction C in FIG. 1). Are guided and output from the two ends of the second waveguide 4. This output light is detected by the first light receiving sensor 5 and the second light receiving sensor 6 arranged at the end of the second waveguide 4, and analog signals converted into voltage values by these light receiving sensors are respectively signal processing units. 70.

  The signal processing unit 70 performs addition / amplification processing on the two input analog signals, and outputs the result to the A / D conversion unit 71 as light amount detection data (analog value) of the organic electroluminescence element 60-1. In the A / D conversion unit 71, the light amount detection data (digital value) having a predetermined bit length is converted and stored in the RAM 72.

  Then, the CPU 75 reads out the light amount detection data of the organic electroluminescence element 60-1 from the RAM 72 and compares it with the light amount adjustment reference value corresponding to the target value of the light amount adjustment of the organic electroluminescence element 60-1 stored in the EEPROM 74 in advance. . As for the light quantity adjustment reference value, individual data is stored in the EEPROM 74 for all the organic electroluminescence elements (60-1 to 60-n), and the light quantity adjustment reference value of each organic electroluminescence element is, for example, that of the exposure apparatus. This is data acquired when adjusting the light intensity after assembly.

  When the light quantity adjustment reference value of the organic electroluminescence element 60-1 and the light quantity detection data read from the RAM 72 are different, the CPU 75 calculates a data value for causing the organic electroluminescence element 60-1 to emit light with a target light quantity, and sets the data. This is set in the section 76 and also stored in the EEPROM 74.

  In the same manner, from the organic electroluminescence elements 60-2 to 60-n, the light quantity detection and the light quantity adjustment of all the organic electroluminescence elements are sequentially performed, and the subsequent driving conditions of each organic electroluminescence element are adjusted. Perform image formation. Since the driving conditions of each organic electroluminescence element are stored in the EEPROM 74, even if the exposure apparatus is turned off in conjunction with the electrophotographic apparatus main body, the data set in the data setting unit 76 from the EEPROM 74 after the power is turned on again. , And each organic electroluminescence element can be controlled under the previously adjusted driving conditions to form an image.

  As described above, according to the present embodiment, it is possible to adjust the light quantity of all the organic electroluminescence elements of the exposure apparatus to be uniform with an extremely simple configuration, both initially and over time.

As a result, in the electrophotographic apparatus as shown in FIG. 5, it is possible to stably form an electrostatic latent image on the photoconductor, and to suppress problems such as image density variation and streak unevenness, Thus, a high-quality image can be formed. In addition, since the number of light receiving sensors can be greatly reduced, problems such as an increase in space involved in the wiring of the light receiving sensor and difficulty in connection can be solved. Furthermore, since the arrangement space for the second waveguide and the light receiving sensor can be small, the size (particularly the depth) of the exposure apparatus can be reduced.

  In this embodiment, the light receiving sensors are arranged at both ends of the second waveguide. However, when the length of the second waveguide is short and the influence of light attenuation is small (for example, exposure with a small number of light emitting elements). In the case of a combination of a plurality of devices, the light receiving sensor is arranged only at one end of the second waveguide, and the light amount of all organic electroluminescence elements is detected by one light receiving sensor. May be.

  In this embodiment, the control block for adjusting the amount of light shown in FIG. 6 is configured in the exposure apparatus. However, for example, the CPU 75 is not limited to the control CPU on the electrophotographic apparatus main body side. A configuration may be used in which the output of the light receiving sensor is subjected to signal processing and A / D conversion in the exposure apparatus, and the digitized light amount detection data is transferred to the control CPU on the main body side of the electrophotographic apparatus to adjust the light amount. .

  In this embodiment, as shown in FIG. 5, the electrophotographic apparatus has been described using a so-called multiple development system in which a plurality of color materials are superimposed on a photoreceptor, but the present invention is applied to a multiple development system. However, it goes without saying that it can be applied to any electrophotographic apparatus that forms a latent image by exposing a pre-charged photoconductor, that is, using the Carlson process. Furthermore, it can be easily applied to electrophotographic apparatuses using liquid toner as well as powder toner.

  According to the present invention, it is possible to effectively correct variations and changes with time of each light emitting element while greatly reducing the number of light receiving sensors, and as the number of light receiving sensors decreases, the wiring of the light receiving sensors can be routed. That can effectively solve problems such as an increase in space required for connection and difficulty in connection, and an exposure apparatus including a light emitting element array in which a large number of light emitting elements are arranged in a line, and an exposure apparatus It is suitable for the field of electrophotographic apparatus using

Schematic top view of the exposure apparatus of the present invention The figure which shows the cross section A of the exposure apparatus shown in FIG. The figure which shows the cross section B of the exposure apparatus shown in FIG. The figure which shows the detailed top view of the exposure apparatus shown in FIG. 1 is a block diagram of an electrophotographic apparatus using an exposure apparatus according to the present invention. The figure showing the composition of the control block concerning light quantity adjustment The figure which shows the positional relationship of each organic electroluminescent element position of an exposure apparatus, a 2nd waveguide, and a light receiving sensor Figure showing an output example of the light receiving sensor The figure which shows the processing result of the signal processing section

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 2 1st waveguide 3 Fiber lens array 4 2nd waveguide 5 1st light receiving sensor 6 2nd light receiving sensor 7 Light-shielding plate 8 Drive circuit 9 Base material 21 Core 22 Cladding 23 Control electrode (anode)
24 Light emitting layer 25 Common electrode (cathode)
27 Light Emitting Area 50 Photoconductor 51 Charger 52 to 55 Developer 60-1 to 60-n Element Position 70 Signal Processing Unit 71 A / D Converter 72 RAM
73 ROM
74 EEPROM
75 CPU
76 Data setting part

Claims (11)

A light emitting element array in which a plurality of light emitting elements are arranged in a line, a first waveguide that individually guides light output from each of the light emitting elements in a first direction, and light output from each of the light emitting elements An exposure apparatus comprising: a second waveguide guided in common in the second direction. 2. The exposure apparatus according to claim 1, wherein the first waveguide is an aggregate of a plurality of minute waveguides. 2. The exposure apparatus according to claim 1, wherein the second waveguide is disposed in the same direction as the arrangement direction of the light emitting element rows. 2. The exposure apparatus according to claim 1, wherein the second waveguide is substantially equal to or longer than an arrangement length of the light emitting element rows, and guides light emitted from all the light emitting elements in the same direction. 2. The exposure apparatus according to claim 1, wherein a part of light emitted from the light emitting element is directly incident on the second waveguide. A part of the light emitted from the light emitting element is directly incident on the first waveguide, and the amount of light incident on the first waveguide is larger than the amount of light incident on the second waveguide. The exposure apparatus according to claim 1. The first waveguide and the second waveguide are disposed on the same plane, and the height of the first waveguide from the plane is substantially equal to the height of the second waveguide. The exposure apparatus according to claim 1. 2. An exposure apparatus according to claim 1, further comprising a light shielding unit between the first waveguide and the second waveguide along the second waveguide. 2. An exposure apparatus according to claim 1, further comprising a light amount detecting means for detecting a light amount of the light guided by the second waveguide at an end of the second waveguide. 8. The exposure apparatus according to claim 7, further comprising light amount detection means for detecting a light amount of light guided by the second waveguide at both ends of the second waveguide. A light emitting element array in which a plurality of light emitting elements are arranged in a line, a first waveguide that individually guides light output from each of the light emitting elements in a first direction, and light output from each of the light emitting elements A second waveguide commonly guided in a second direction, exposing the photosensitive member with light guided by the first waveguide, and transmitting the light guided through the second waveguide to the light An electrophotographic apparatus that controls driving conditions of the plurality of light emitting elements based on a result detected by a detecting means.

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