JP2009051152A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer using an organic EL element (electroluminescent element) as a light source of a light emission unit part, wherein dispersion of a line or an expanse of a width of one line in a main scanning direction is eliminated by especially performing control such that an exposure spot from the EL element becomes uniform. <P>SOLUTION: A large number of the organic EL elements are disposed as 16 organic EL element groups, output of power source voltage (Vsource) and a selection signal (Vselect) is controlled in each the EL element group, supply of the power source voltage (Vsource) is stopped in set timing so as to adjust light emission of the organic EL element group selected by the selection signal (Vselect) to previous measured optimum light intensity in a non-selection period, and the dispersion of the light intensity between the organic EL elements disposed in each head unit is eliminated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printing apparatus using an electrophotographic printing process (hereinafter referred to as an electrophotographic process), and more particularly to a printing apparatus using an EL element (electroluminescence element) as a light source of a light emitting unit.

  The printing apparatus using the electrophotographic process emits light according to the print data from the light emitting unit on the photosensitive surface charged with a uniform charge, and forms a latent image corresponding to the light intensity on the photosensitive surface. Printing is performed on a recording medium through a series of processes including development, transfer, and fixing with toner. As a light source of the light emitting unit, a laser or an LED (light emitting diode) is generally used. When an organic EL element studied as a light emitting pixel application such as a display is used as a light source, an active matrix driving method is used. This method is effective because it has an advantage that the drive switch circuit is built in the panel and can be driven with low power consumption. Further, by adopting the active matrix method, it is possible to reduce the number of driving ICs, and it is also possible to reduce the number of wire bondings connected to each LED element.

  Patent Document 1 discloses an invention of a drive circuit using the organic EL element. The basic configuration of this drive circuit is as shown in FIG. 55, and includes an organic EL element E, three transistors T1 to T3, and a capacitor C. FIG. 56 is a time chart showing a signal supplied to this circuit and driving of a current flowing through this circuit. A selection signal (Vselect) inputted from terminal A in FIG. 55 and a signal inputted from terminal B in FIG. 5 is a time chart for explaining a power supply voltage (Vsource), a current (Idata) flowing into a current source F, a current (IT3) flowing through a transistor T3, and a current (IE) flowing through an organic EL element E.

  First, in the selection period (Tse) of FIG. 56, the selection signal (Vselect) is supplied to the circuit shown in FIG. 55, and the supply of the power supply voltage (Vsource) is stopped. By this processing, the transistors T1 and T2 are turned on. Further, when the transistor T1 is turned on, a voltage is applied to the gate G and the capacitor C of the transistor T3, and the transistor T3 is turned on. At this time, a current (Idata, (current (IT)) according to the light emission amount flows into the current source F, and the capacitor C is charged.

This charge is an amount of charge that allows the same current (Idata) to flow through the transistor T3 in the next non-selection period (Tnse). The supply of the selection signal (Vselect) is stopped and the supply voltage (Vsource) When the supply is started (non-selection period), when the transistor T2 is turned off, a current (IE) flows through the organic EL element E. The organic EL element E emits light by this current (IE).
JP 2003-195810 A

  However, when the EL element drive circuit is used in an electrophotographic process printing apparatus, the current (IE) continues to flow during the non-selection period, and the exposure size of one dot exposed on the photosensitive surface is sub-scanned. It will stretch in the direction. FIG. 57A shows an ideal beam spot. However, in the conventional process, the beam spot moves in the sub-scanning direction and the exposure dots spread in the sub-scanning direction as shown in FIG. Further, since the amount of emitted light of the EL element itself also varies, the width of one line in the main scanning direction becomes wide, and the line density is not uniform.

  Therefore, the present invention provides a printing apparatus that controls the exposure spots from the EL elements to be uniform, and eliminates the width expansion of one line and the line variation in the main scanning direction.

  According to the first aspect of the present invention, the photosensitive surface is irradiated with light from an organic EL head in which a plurality of EL elements are arranged in an array in the main scanning direction, and an image formed on the photosensitive surface is developed. In a printing apparatus that prints on a recording medium, a selection signal supply unit that supplies a selection signal to the EL unit for each EL unit, and a light emission power source for the EL elements in the EL head unit after the selection signal is output. This is achieved by providing a printing apparatus having a light emission power supply means to be supplied and a control means for stopping the supply of the light emission power based on information on a driving period of the EL element for each EL head unit that is set in advance. it can.

  According to the second aspect of the present invention, information on the driving period of the EL array for each head unit can be achieved by providing a printing apparatus that is set based on a result measured in advance for each head unit.

  According to a third aspect of the present invention, there is provided, according to a third aspect of the present invention, that a charge is charged in a capacitor means formed in a drive circuit by the output of the selection signal, the switching means is switched by the charged charge, and the light emitting power source is connected to the EL array. This can be achieved by providing a printing apparatus that emits light from each organic EL array.

According to a fourth aspect of the present invention, the object can be achieved by providing a printing apparatus in which the EL element is an organic EL element, and a plurality of organic EL element groups are arranged in the EL array.
According to a fifth aspect of the present invention, there is provided a selection signal supply means for supplying a selection signal to the EL array for each EL array in which a plurality of EL elements are formed, and after the selection signal is output, Information on the driving period of the EL element for each EL head unit preset in the light emitting power supply means for supplying light emission power to the EL elements and the storage means provided for each head unit incorporating the EL array. This can be achieved by providing an EL unit driving device having control means for stopping the supply of the light emitting power source.

  According to the means for solving the above problems, current does not continue to flow through the EL element in the non-selection period, the length of the non-selection period can be adjusted according to the characteristics of each head unit, and the amount of emitted light varies between the head units. Can be adjusted.

  Accordingly, it is possible to provide a printing apparatus with excellent print quality by eliminating the width of one line in the main scanning direction and the line variation.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 2 is a diagram illustrating a main part of a printing apparatus illustrating an embodiment of the present invention. In the vicinity of the peripheral surface of the photosensitive drum 1, a charging roller 2, an organic EL head 3, a developing device 4, and a transfer roller 5 are illustrated. A cleaning unit 6 and an eraser 7 are provided. A uniform charge is applied by the charging roller 2 to the photosensitive surface of the photosensitive drum 1 from which the charge has been removed by the eraser 7. The photosensitive drum 1 rotates in the direction of the arrow, and the photosensitive surface to which a uniform charge is applied is exposed according to the print data from the organic EL head 3 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive surface in this manner is converted into a toner image by the developing device 4 and is transferred to the paper (recording medium) 8 by the transfer roller 5. Further, the paper 8 is transported in the direction of the arrow by a transport mechanism (not shown), and the toner image transferred to the paper 8 is thermally fixed by the fixing roller 9 and discharged outside the apparatus.

  In the above configuration, FIG. 3 is a diagram showing the arrangement of the photosensitive drum 1 and the organic EL head 3. The organic EL head 3 includes an organic EL array 10 and an SLA (selfoc lens array) 11, and the organic EL array 10 has a large number of organic EL elements arranged in an array in the main scanning direction.

  FIG. 1 is a diagram showing a circuit configuration of the organic EL array 10 having the above configuration. In the figure, the organic EL array 10 is provided with a large number of organic EL elements in the main scanning direction. For example, when the organic EL array 10 having 1200 dpi, 40 ppm, a distance between sheets of 50 mm, and an A4 horizontal size is used, the required number of pixels. Assuming that A4 width = 297 mm or more, for example, 320 mm and 1 dataDrv output number = 960, (320 mm / (25.4 mm / 1200 dpi)) / 960 = 15.75 / mm. The time 1LineTime allowed for forming one line in the main scanning direction is ((25.4 mm / 1200 dpi) / (210 mm × 40 sheets + 50 mm × 40 sheets)) / 60≈122 μsec.

  The selection period (Tse) includes the data transfer to the current driver 1dataDrv1, and the current is supplied to each pixel at the end of the transfer. The required 1dastaDrv1 depends on how many times the selection period is put in this 1LineTime. The quantity is determined. If the selection period can be set 16 times for 1 LineTime from 15.75 of the above calculation result, the required number of 1 dataDrv is 1.

  That is, if data transfer and charge charging to the capacitor C can be completed within 122 μsec / 16 = 7.625 μsec, a configuration as shown in FIG. 1 is possible. In this example, one output of 1 dataDrv1 is distributed 16 times every 960 outputs, and wiring to pixels is performed.

  Here, when the 16 distributed organic ELs are shown in a group format, the organic EL groups “1” to “16” constitute the organic EL array 10, and the organic EL groups “1” to “16” are arranged in a line. It is installed. Further, as described above, 960 organic EL elements are formed in each of the organic EL groups “1” to “16”, and each organic EL element is driven by the drive circuit shown in FIG.

  That is, the selection signal (Vselect) is supplied to the gates (G) of the transistors T11 and T12 via the terminal A. The selection signal (Vselect) is supplied from the selection signal driver 20 shown in FIG. To be supplied. Further, the power supply voltage (Vsource) is supplied to the drain (D) of the transistor T13 via the terminal B, and this power supply voltage (Vsource) is supplied to the terminal B of each drive circuit from the power supply voltage driver 21 shown in FIG. The The driver 22 having the current source F is connected to each drive circuit, and the current (Idata) output from each drive circuit is input to the driver 22.

  The source (S) of the transistor T11 is connected to the gate (G) of the transistor T13. By turning on the transistor T11, the transistor T13 is driven (turned on), and a current (IT13) flows. A capacitor C1 is connected between the gate (G) and the source (S) of the transistor T13, and a current (Idata) is supplied to the current source F to charge the electric charge. The current (IE1) is a current flowing through the organic EL element E1, emits light from the organic EL element E1, and forms an electrostatic latent image on the photosensitive surface of the photosensitive drum 1 described above.

  In the case of the organic EL element E1, since it is manufactured by forming a light emitting element of a pixel size by patterning on a planar base substrate, the variation between elements in the same head unit is, for example, a head using LED elements. Very small compared to. Therefore, when an organic EL element is used for the organic EL head 3, in order to obtain a uniform light quantity characteristic, it is desirable to correct the variation generated for each organic EL head unit rather than correcting the variation between elements. This will be specifically described below.

  FIG. 5 is a time chart for explaining the processing of this example. As described above, 1 lineTime = 122 μsec, which is the time from a selection period of an arbitrary 960 pixel unit to the next selection period. Sixteen organic EL elements are arranged as 960 pixel units as organic EL groups “1” to “16”, and the selection signal (Vselect1) is controlled to a high level during the selection period of 960 pixel units (one group unit). Then, the power supply voltage (Vsource) is controlled to a low level, and charges are charged according to the required current value for each pixel (timing a shown in FIG. 5). Thereafter, the selection signal (Vselect1) is controlled to a low level, the power supply voltage (Vsource1) is controlled to a high level, and a transition to a non-selection period is made (timing b shown in FIG. 5).

  At this time, the selection signal (Vselect2) supplied to the 960 pixels (group 2) adjacent to the group “1” is controlled to a high level and the power supply voltage (Vsource2) is controlled to a low level. Is charged (timing c shown in FIG. 5). Hereinafter, similarly, the organic EL groups “1” to “16” are sequentially processed.

  In this case, the power supply voltage (Vsource) is at a high level during the non-selection period. In this example, the current supply to the organic EL element E1 is controlled by controlling the non-selection period and controlling it to a low level at an arbitrary time. The light quantity control for each organic EL element group is performed.

  Therefore, first, the light amount of the entire head unit is measured in advance, and the supply period of all the power supply voltages (Vsource) is controlled with the same length based on a certain value. That is, the amount of light energy is controlled by the exposure area received on the photosensitive surface, and the light emission in the entire head unit is uniformly changed.

  First, the light emission duty at 1 LineTime is set to, for example, 50% so that one line width is not increased more than necessary at a certain arbitrary value, and the light quantity is measured by causing the organic EL element E1 to emit light. Then, using this measurement value as a reference value, the head unit to be corrected emits light at the reference duty value and measures the amount of light, detects the difference from the reference value, and emits light at each head unit to match the reference value. Determine the time. This time is set as the non-selection period of the corresponding head unit, and is stored in the memory as each eigenvalue of the corresponding head unit.

  FIG. 6 shows a non-selection period memory 31 that stores the fixed value, a counter 32 that counts the selection period of the head unit, and a shift register 33. FIG. 7 is a time chart for explaining the circuit operation of the above configuration.

  The horizontal synchronization signal (HSYNC) is a signal for instructing writing of one line, the horizontal synchronization signal (HSYNC) is output (timing a shown in FIG. 7), the selection signal (Vselect1) is output, and the organic EL group “ “1” is the selection period. Thereafter, the output of the selection signal (Vselect1) to the organic EL group “1” is stopped, and the power supply voltage (Vsource1) is supplied to each organic EL element E1 of the organic EL group “1” (timing b shown in FIG. 7). ).

  Next, the counter 32 reads a fixed value stored in advance from the non-selection period memory 31 and performs a counting process in synchronization with the input of the clock signal (CLK). This counting process is performed up to N corresponding to the fixed value shown in FIG. During this time, the selection signal (Vselect2) is supplied to the next organic EL group “2”, and after the organic EL group “2” is selected, the power supply voltage (Vsource2) is supplied to enter the non-selection period. The organic EL element E1 arranged in “” emits light according to the print data (timing c shown in FIG. 7). Also in this case, the counter 32 reads the corresponding fixed value stored in advance from the non-selection period memory 31, and performs the counting process in synchronization with the input of the clock signal (CLK). This counting process is also performed up to M (not shown) corresponding to the fixed value.

  Thereafter, the organic EL groups “3” → “4” → “5” →... → “16” are similarly executed, and light emission according to the fixed value of the head unit is performed in the non-selection period. Therefore, as described above, the length of the non-selection period can be adjusted according to the characteristics of each head unit, and variations in the amount of light emitted between the head units can be suppressed.

  As described above, according to the present embodiment, the non-selection period, which is the light emission period in each head unit, can be adjusted, variation between head units can be suppressed, and the width of one line in the main scanning direction can be eliminated. Thus, a printing process with a uniform line density can be performed.

  In the description of the present embodiment, the example of the organic EL head 3 composed of 16 organic EL groups has been described, but the present embodiment is not limited to this example. Further, the number of organic EL elements disposed in each organic EL group is not limited to 960.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described.
In the above-described embodiment, when an electrostatic latent image is formed on the photosensitive surface of the photosensitive drum 1 from the organic EL head 3 via the SLA (selfoc lens array) 11, a large amount of energy is required for light emission of the organic EL element. However, the present embodiment provides a printing apparatus in which the above-described problem does not occur. This will be specifically described below.

  As shown in FIG. 2, the organic EL head 3 is disposed in the vicinity of the photosensitive drum 1, and the organic EL array 10 constituting the organic EL head 3 as shown in FIG. ) 11 is irradiated with light on the photosensitive surface.

  In this configuration, the structure of the organic EL array 10 (organic EL element) is the configuration shown in FIG. That is, an anode electrode (anode) 42, a hole injection layer (HTL) 43, a light emitting layer (EL) 44, an electron injection layer (ETL) 45, and a cathode electrode (cathode) 46 are sequentially formed on a glass substrate 41. It is configured. Then, by applying a voltage between the anode electrode (anode) 42 and the cathode electrode (cathode) 46, the light emitted from the light emitting layer (EL) 44 is completely diffused and emitted toward the glass substrate 41.

  Here, when the organic EL head 3 has the above-described 1200 dpi, the interval between the organic EL elements is about 21 μm, and when the organic EL head 3 is completely diffused in the glass substrate 41, the light beams interfere with each other and do not form an image on the glass surface. In this regard, in the present embodiment, the glass substrate 41 is provided with a fiber function for each organic EL element, and a pseudo-luminous body is formed on the surface of the glass substrate 41. This fiber function is a well-known technique, for example, by arranging air holes in an orderly manner like crystals other than the part that hits the core part, while changing the refractive index of the central part and the peripheral part while using the same material, glass A method of directly forming a fiber inside the substrate 41 is used.

  For example, as shown in FIG. 9, a surface light emitting unit array panel 47 that emits light in a planar shape and a light guide unit 49 that faces the surface light emitting unit 48 that is a light emitting unit of the surface light emitting unit array panel 47 are provided. An exposure head is conceivable in which light from the light emitting section 48 is reflected and collected by the light guide section 49 and can be irradiated with an increased intensity per unit area.

  Since this exposure head is in the form of a fiber or a waveguide, it has a certain degree of directivity, but a small-diameter light spot is formed on the photosensitive surface separated by a distance on the order of millimeters, and each dot is resolved. It is difficult to produce a light beam that can be used (eg, about 21 μm pitch for 1200 dpi).

  Therefore, in this example, the light spot is realized by combining the photosensitive drum 1 and the SLA (selfoc lens array) 11 shown in FIG. Specifically, the SLA (Selfoc Lens Array) 11 has a self-aligned lens having a parabolic refractive index distribution from the center to the periphery, and is regularly and precisely arranged in one or two rows, and is sandwiched between two frame plates. It has a dented structure. There are various types of SLA depending on each optical parameter (working distance Io, incident angle θo, conjugate length TC, etc.), but a normal SLA has a lens diameter of 0, 5 to 1 mm, an incident angle of about 20 °, and a working distance of 2 About 5 mm. Here, a simulation was performed using the SLA (Selfoc Lens Array) 11 having the above values, which is a representative optical parameter.

  In this case, the light that can be captured by the SLA (Selfoc lens array) 11 is collected by about 3.5 Selfoc lenses as shown in FIGS. That is, when the light emitter has a circular directivity (the same directivity in the vertical and horizontal directions), an area outside the range of the lens incident angle occurs in the Y direction (sub-scanning direction) with respect to the lens array. Therefore, in order to efficiently use the effective area, if the directivity of the light emitter is an ellipse in the X direction (main scanning direction), the light capturing efficiency is improved for the SLA (selfoc lens array) 11, and as a result. The load on the light emitter can be reduced.

  Hereinafter, the structure of an exposure apparatus for allowing the light emitter to have an X-direction ellipse directivity will be described. That is, by adding the reflector 50 shown in FIG. 12 to the irradiation surface of the organic EL head of this example, the end face irradiation type EL element of FIG. 13 is obtained, and the directivity of the X-direction ellipse can be provided. Here, the emission end face of the organic EL element is set to 10 × 10 μm by simulation software, and the light receiving surface profile and directivity with and without the reflector are shown.

  FIG. 14 shows this example, and the light receiving surface profile is a graph in which the light receiving surface (lens surface) separated by 2500 μm from the tip of the reflector is irradiated with light, and the light intensity distribution and the XY cross section of the peak point are graphed. In the case of no reflector, a distribution with almost the same XY ratio is shown.

  On the other hand, when the reflector 50 is added to the tip, it can be seen that the light intensity distribution in the Y direction is narrowed, resulting in narrow directivity. At this time, the amount of light applied to the surface corresponding to 3.5 SLA (1800 × 900 μm) is about twice as large as the relative value when the reflector is present and without the reflector.

  Here, the X direction shape of the reflector 50 is narrower in directivity, but the X direction aperture width is 50% of the resolution pitch in order to secure MTF (Modulation Transfer Function) on the surface of the photoreceptor. It needs to be about. In this way, the reflector is expanded in the Y direction and the X direction is substantially perpendicular so that the light irradiated through the SLA (Selfoc Lens Array) 11 can be irradiated without impairing the resolution and MTF on the photosensitive surface. Efficiency can be increased.

  As described above, according to this example, the organic EL light source having complete diffusion or wide directivity is condensed by the reflector 50 while giving the elliptical directivity in the main scanning direction, and thereby the SLA (Selfoc Lens Array) 11. As a result, the transmission rate of the light amount to the photosensitive surface is increased, the current supplied to the organic EL element can be reduced, and the life of the organic EL head 3 can be extended.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
This embodiment is also an invention of a printing apparatus that prevents deterioration of the EL element and extends the life of the organic EL element. This will be specifically described below.

  FIG. 15 is an overall configuration diagram of a printing apparatus used in this example. In the vicinity of the photosensitive belt 52, a charging roller 51, an organic EL head 53, a developing device 54, a transfer roller 55, a cleaning unit 56, and an eraser light source 57 are disposed. A uniform charge is applied by the charging roller 51 to the photosensitive surface of the photosensitive belt 52 from which the charge has been removed by the eraser light source 57. Then, the photosensitive belt 52 rotates in the direction of the arrow, and light emission according to the print data is irradiated from the organic EL head 53 to the photosensitive surface to which a uniform charge is applied, and an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive surface in this manner is converted into a toner image by the developing device 54 and is transferred to the paper (recording medium) 58 by the transfer roller 55. Further, the sheet 58 is conveyed in the direction of the arrow by the conveyance mechanism 59, and the toner image transferred to the sheet 8 is thermally fixed by a fixing roller (not shown) and discharged outside the apparatus.

The photoreceptor belt 52 is a photoreceptor comprising a seamless belt-like translucent substrate, a translucent conductive layer, a charge generation layer, a charge transfer layer, and a surface protective layer.
FIG. 16 is a diagram showing the structure of the organic EL array 10 (organic EL element E1). Similar to FIG. 8, the anode electrode (anode) 42 and the hole injection layer (HTL) 43 are formed on the glass substrate 41. A light emitting layer (EL) 44, an electron injection layer (ETL) 45, and a cathode electrode (cathode) 46 are sequentially formed.

  FIG. 17 is a view showing the arrangement configuration of the photosensitive belt 52 and the organic EL head 53. The photosensitive belt 52 is disposed at a certain distance from the light emitting portion of the organic EL head 53, and the organic EL head 53 is moved upward by the belt tension roller 60 even when the photosensitive belt 52 is extended due to temperature or the like. By moving, the positional relationship between the organic EL head 53 and the photosensitive belt 52 is kept constant.

  In this example, the parabolic reflector 61 shown in FIG. 18 is formed on the organic EL light emitting end face (see FIG. 19). As is well known, the parabolic reflector 61 has a function of radiating parallel light with a parabolic aperture from a point light source. If an ideal point light source, the reflection loss and attenuation are ignored, a light beam with an output aperture is provided. Is the same at any distance in the irradiation direction. However, in reality, a point light source is impossible, and even in the micro order, surface light emission occurs.

  FIG. 20 shows a light receiving surface (photosensitive) separated by 100 μm from the tip of the reflector when the emission end face of the organic EL element is set to 3 × 3 μm by the simulation software (light ray tracing), and the parabolic reflector 61 is turned on at intervals of 1 dot at a pitch of 600 dpi. A light spot is irradiated onto the surface), and the light reception profile and the XY cross section of the peak point are graphed. At this time, when calculated from the value obtained from the graph, the MTF on the light receiving surface was about 70%, and a good resolution was obtained.

  However, when the light receiving surface distance is 150 μm, the MTF is reduced to about 60%. On the other hand, by adding a convex reflector at the center of the reflector as shown in FIG. 21, the MTF can be improved although the peak light quantity is reduced.

  FIG. 22 shows a diagram in which this reflector is added under the same conditions as the simulation of the parabolic reflector 61 described above. In this case, the MTF is about 80% and 70% at the light receiving surface distances of 100 μm and 150 μm, respectively, and it can be seen that the MTF was improved by adding a reflector.

Here, the characteristic of the emitted light by the shape of the parabolic reflector 61 and the parabolic reflector with a reflector is shown below (see FIG. 23). Note that the smaller the light source area (the higher the light density), the larger the output peak light quantity, the more stable the beam diameter depending on the distance, and the ideal shape if the shape is circular but the aspect ratio is similar. '
-Light source position: The focal position of the parabolic reflector 61 or the direction of both ends is desirable.
Reflector diameter: Set to a desired irradiation length according to the array pitch.
-Reflector length: Basically, the longer the light distribution, the narrower the light distribution.
Convex reflector diameter: The smaller the diameter, the larger the peak scene, but the larger the beam diameter.
-Convex reflector curvature: The smaller the radius of curvature, the higher the amount of emitted light.

Convex reflector position: the curvature end face is located inside the reflector end.
Here, as an effect of the convex reflector added to the reflector 61, as shown in FIG. 23, the light I emitted at an angle from the surface light source reaches outside the desired irradiation range of the light receiving surface. On the other hand, if there is a reflecting plate, the reflected light II is irradiated again within the irradiation range via the reflector 61.

  As described above, according to this example, by condensing the organic EL light source, which is completely diffused light, by the parabolic reflector, the light amount transmission rate to the photosensitive surface is increased, and the current supply of the organic EL element can be reduced. Therefore, the lifetime of the organic EL element can be extended.

In addition, the light collecting efficiency can be improved by reflecting light again to the reflector by the reflector of the parabolic reflector.
FIG. 24 shows the structure of the photoreceptor belt 52. A light-transmitting conductive layer 52b, a charge generation layer (CGL) 52c, a charge transfer layer (CTL) 52d, And a surface protective layer (OCL) 52e are formed in this order. The reason why the belt-shaped photoconductor is employed in this example is to contact the organic EL head whose surface is formed of a glass substrate, and a seamless belt of the seamless belt 52 is employed.

The photosensitive belt 52 is made of a transparent resin base material such as polycarbonate, polyethylene terephthalate, polyimide, a light-transmitting conductive material such as indium tin oxide film (ITO), and a binder resin is formed by a dipping method. CGL, CTL, and OCL contained are sequentially applied and formed. This CTL is composed of hydrazone (CTM) and a polycarbonate resin, CGL is a belt composed of a trisazo pigment and a polyvinyl propylal resin, and OCL is composed of a polyester resin, and forms a conductive layer and a photosensitive layer.
(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.

  25 and 26 are overall configuration diagrams of a waveguide type top emission organic EL array exposure head (hereinafter simply referred to as an organic EL array exposure head) in the present embodiment. FIG. 25 is a top view thereof, and FIG. Indicates that country.

  The organic EL array exposure head 65 is roughly composed of the following three parts. That is, the light-emitting body includes a light-emitting transparent substrate portion 66, a waveguide forming substrate portion 67, and a lens transparent substrate portion 68 that form a light-emitting body.

  The light emitter transparent substrate portion 66 includes a lighting control circuit for controlling the lighting of the organic EL light emitter and each layer of the organic EL light emitter in an array in the main scanning direction. In the case of this example, the lower electrode of the organic EL light emitter also functions as a light reflecting plate, and is patterned other than the organic EL light emitter forming portion as shown in FIG.

  Further, a light reflection condensing part 70 is also formed on the light emitter transparent substrate part 66. The light reflection condensing unit 70 is a part where the reflection process is removed or the reflection process is not performed so that light can be transmitted in the thickness direction of the light emitter transparent substrate 66.

  In the waveguide forming substrate portion 67, a waveguide 67a having a wedge-shaped structure as shown in the figure is formed. Due to this wedge-shaped structure, the light generated from the organic EL light-emitting layer 63 travels in the direction of spreading of the light every time it reflects off the waveguide wall surface. The wall surface of the waveguide 67a has a structure having a wall surface formed with a high reflectivity by depositing a metal foil film such as Ag (silver) or Al (aluminum). The inside of the waveguide 67a may be an air layer.

  The lens transparent substrate 68 for realizing erecting equal-magnification imaging is a lens optical system for erecting equal-magnification imaging with two lenses in which flat lenses are formed on the same optical axis on both opposing surfaces of the lens transparent substrate 68. Are arranged in at least a one-dimensional array on both surfaces of the lens transparent substrate 68.

  The flat lens is obtained by forming a refractive index distribution type lens on a glass substrate or the like by ion exchange technology. Openings are formed in the metal film (metal mask that prevents the diffusion of ions) deposited on the glass substrate by photolithography, and in this example, mask openings are formed on both sides, and ions to be diffused are formed. A substantially hemispherical refractive index distribution region is created by immersing ions in the molten salt and diffusing ions in the molten salt into the mask opening.

  Therefore, it has an erecting equal-magnification imaging function capable of adjusting lens parameters according to the thickness of the lens transparent substrate 68, the opening size, and the molten salt immersion time. The working distance on the illuminant side for erecting equal-magnification imaging on this lens substrate is matched to the thickness of the illuminator transparent substrate 66 and is configured to focus on the light reflecting / condensing unit 70.

  The light emitted from the light emitter of the light emitter transparent substrate portion 66 is formed by stacking the light emitter transparent substrate portion 66, the waveguide forming substrate portion 67, and the lens transparent substrate portion 68, which are the three parts, as shown in FIG. The light is reflected and propagated in the waveguide 67 a and reflected by the direction changing mirror unit 71, thereby gathering in the light reflecting and condensing unit 70 and propagating in the thickness direction of the light emitter transparent substrate 66.

  At this time, a latent image in the electrophotographic system is formed by forming the image of the light reflection condensing unit 70 on the image carrier side at the erecting equal magnification by the lens transparent substrate 68 having the erecting equal magnification imaging function. Is possible.

  In order to improve the crosstalk of erecting equal magnification imaging by the double-sided gradient index lens 64, a light absorption layer 69 is disposed in addition to the effective lens area of the lens transparent substrate 68. The light absorbing layer 69 having a light shielding function is for blocking unnecessary light from the outside and preventing reflection of extra light inside the base material. It is formed by non-reflective coating in which the reflectance is reduced to several percent by stacking a book film, or by applying or printing a black paint.

By laminating the waveguide forming substrate 67 and the lens transparent substrate 68 on the light emitter transparent substrate 66, the light emission of the light emitter whose lighting is controlled can be condensed to form an exposure image on the photosensitive surface.
Next, a modification of this embodiment will be described. 27 and 28 are diagrams showing an example of the entire configuration of an organic EL array exposure head for explaining a modification of the present embodiment. FIG. 27 shows a top view thereof, and FIG. 28 shows a side country thereof.

  The organic EL array exposure head 75 is roughly composed of the following three parts. That is, it is composed of a light emitter / waveguide forming transparent substrate portion 76 forming a waveguide and a light emitter, a cover glass 77, and a lens transparent substrate portion 78. The light emitter / waveguide forming transparent substrate 76 is formed with a waveguide 76a having a wedge-shaped structure as shown in FIG. Because of this wedge-shaped structure, the light generated from the organic EL light-emitting layer 79 travels in the wedge-shaped spreading direction every time it reflects off the waveguide wall surface. As described above, the wall surface of the waveguide 76a has a structure having a wall surface formed with a high reflectance by depositing a metal foil film such as Ag (silver) or Al (aluminum). The inside of the waveguide may be an air layer.

  The light emitter / waveguide forming transparent substrate 76 in which the waveguide 76a is formed is flattened by an insulating layer, and then a bottom emission type organic EL light emitting layer is formed on the organic EL control circuit and the waveguide. The predetermined lighting control circuit for controlling the lighting of the organic EL light emitter and each layer of the organic EL light emitter are formed in an array in the main scanning direction. In the case of this example, the lower electrode of the organic EL light emitter also functions as a light reflector, and is patterned other than the organic EL light emitter forming portion as shown in FIG.

  The light emitter / waveguide forming transparent substrate portion 76 is also formed with a light reflecting / condensing portion. In this light reflection condensing part, the light propagated in the waveguide is reflected by the direction changing mirror 80, and the reflection processing is removed or the reflection processing is performed so that the light can be transmitted in the thickness direction of the cover glass 77. This is not the part.

  The cover glass 77 completely seals the upper part where the light emitter is formed, and propagates through the waveguide 76 a and is reflected by the direction changing mirror 80, and transmits the collected light in the thickness direction of the cover glass 77. It is also a propagation medium that enters the lens transparent substrate portion 78.

  The lens transparent substrate 78 that realizes erecting equal-magnification imaging is a lens optical for erecting equal-magnification imaging using two lenses in which flat lenses are formed on the same light beam on both opposing surfaces of the lens transparent substrate 78. It has a structure in which a plurality of systems are arranged in at least a one-dimensional array on both surfaces of the lens transparent substrate 78. This flat lens is obtained by forming a refractive index distribution type lens on a glass substrate or the like by ion exchange technology.

  With such a configuration, a structure in which the light of the light-emitting body whose lighting is controlled can be condensed and focused on the photosensitive surface by laminating the waveguide forming substrate and the lens transparent substrate on the light-emitting body transparent substrate. An organic EL array exposure head having can be realized.

As described above, according to the present embodiment, the light emission area can be increased by using the waveguide reflection method, and the light emission luminance and the life can be extended.
(Embodiment 5)
Next, a fifth embodiment of the present invention will be described.

  FIG. 29 is a diagram illustrating a configuration example of the organic EL head according to the present embodiment. The organic EL head of this example has a bottom emission light emitting structure in which at least one row of organic EL light emitter arrays 82 is formed on a light emitter transparent substrate 81 and irradiates light to the light emitter transparent substrate 81 side. The lens transparent substrate 83 having an erecting equal-magnification imaging function is provided on both surfaces of the lens transparent substrate 83 on the same optical axis in order to collect the emitted light and to form an image on the photosensitive surface. Is laminated below the light emitter transparent substrate 81.

  FIG. 30 is a side cross-sectional view of one organic EL element of this example. This example shows an example in which a bottom emission type single organic polymer organic EL light emitter is formed on a light emitter transparent substrate 81. Specifically, the anode 84 is patterned on the light emitter transparent substrate 81 with a transparent electrode such as ITO, and the hole transport layer 86 and the laminated light emission are disposed between the cathode 85 (for example, Ca, Ba, Ag, etc.). Two layers 87 a are formed, and the upper part of the laminated light emitting layer 87 a is sealed with a sealing material 88.

  The light-absorbing layer 89 around the light-emitting body 87 is configured to block unnecessary light from the outside and prevent reflection inside the base material, and an oxide thin film is stacked on a metal vapor-deposited film. Thus, it is formed by non-reflective coating with a reflectance of about several percent, or by applying or printing a black paint.

  The lens transparent substrate 83 that realizes the erecting equal-magnification imaging shown in FIG. 29 described above is an erecting or the like by two lenses in which flat lenses are formed on the same optical axis on both opposing surfaces of the lens transparent substrate 83. It has a structure in which a plurality of lens optical systems for double imaging are arranged in at least a one-dimensional array on both surfaces of the lens transparent substrate 83.

  This flat lens is obtained by forming a gradient index lens 83a on a glass substrate or the like by ion exchange technology. Openings are formed in the metal film (metal mask that prevents the diffusion of ions) deposited on the glass substrate by photolithography, and in this case, mask openings are formed on both sides, and ions that should diffuse In this case, the ions in the molten salt are diffused from the mask opening to form a substantially hemispherical refractive index distribution region. Therefore, the lens parameter can be adjusted by the thickness of the lens transparent substrate 83, the opening size, and the molten salt immersion time, and has a function of erecting equal magnification imaging.

  FIG. 31 is a diagram for explaining a modification, and shows a configuration of an organic EL head of the modification. This organic EL head has a top emission light-emitting structure in which at least one organic EL light-emitting array is formed on a light-emitting transparent substrate 91 and irradiates light toward the sealing material 93 side of the light-emitting body information. In this structure, a gradient index lens 94 is provided on the same light beam on both surfaces of the lens transparent substrate 95 in order to condense light emitted from the lens and form an image on the photosensitive surface.

  FIG. 32 is a side cross-sectional view of one organic EL element according to the modification. In this example, an example in which a polymer organic EL light emitter having a top emission type single hetero structure is formed on the light emitter transparent substrate 91 is shown. A cathode (Ca, Ba, etc.) 96 is patterned on the light emitter transparent substrate 91 to form a light absorption layer 98, and two layers of a hole transport layer 99 and a laminated light emitter 90a are laminated between the cathode 96 and the anode 97. The upper part of the laminated light emitting body 90 a is sealed with a sealing material 93.

With this configuration, the lens parameters can be adjusted by the thickness of the lens transparent substrate 95, the aperture size, and the molten salt immersion time, and an erecting equal-magnification imaging function can be realized.
(Embodiment 6)
Next, a sixth embodiment of the present invention will be described.

This example relates to the electrophotographic process type printing apparatus used in the first and second embodiments, and FIG. 33 shows the basic configuration thereof.
A charging roller 2, an organic EL head 3, a developing device 4, a transfer roller 5, a cleaning unit 6, and an eraser 7 are disposed in the vicinity of the peripheral surface of the photosensitive drum 1. A uniform charge is applied by the charging roller 2 to the photosensitive surface of the photosensitive drum 1 from which the charge has been removed by the eraser 7. The photosensitive drum 1 rotates in the direction of the arrow, and light emission according to print data is emitted from the organic EL head 3 to the photosensitive surface to which a uniform charge is applied, and an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive surface in this manner is converted into a toner image by the developing device 4 and is transferred to the paper (recording medium) 8 by the transfer roller 5. Further, the paper 8 is transported in the direction of the arrow by a transport mechanism (not shown), and the toner image transferred to the paper 8 is thermally fixed by the fixing roller 9 and discharged outside the apparatus.

  FIG. 34 is a circuit block diagram of an organic EL head according to this embodiment. FIGS. 35 and 36 are diagrams for specifically explaining the system controller of FIG. FIG. 37 is a time chart for explaining the processing of this example.

  In the organic EL head shown in FIG. 34, in the exposure process in accordance with normal image data, first, the system controller 101 receives a horizontal synchronization signal in accordance with print data, paper size information, and conveyance speed from a raster image processor (not shown). (HSYNC) and the vertical synchronization signal (VSYNC) are received, and the data driver 102 and the scan driver 103 are driven based on the on / off and gradation of each pixel in accordance with these control signals.

  The horizontal synchronization signal (HSYNC) and the vertical synchronization signal (VSYNC) are synchronization signals in the main scanning direction, and set a dot formation processing time during which an active to active period is allowed for one line. For example, the data driver 102 drives eight pixels with one Vdata.

  In this example, the supply line to the organic EL panel 104 is set to the gradation signal voltages Vdatal to Vdata6, but this is not restrictive. Similarly, the scan lines supplied from the scan driver 103 to the organic EL panel 104 are Vscan1 to Vscan8, and are connected in common to the pixel groups a to h connected to Vdata1 to Vdata6. Therefore, in the organic EL panel 104, 6 × 8 = 48 (pixels) pixels are formed in a row in the horizontal direction.

  As shown in FIGS. 37 and 38, the data driver 102 generates and applies the grayscale signal voltage Vdata corresponding to the data line of each pixel while the horizontal synchronization signal (HSYNC) is active. At this time, although not shown, control is performed so that power is supplied to the power supply line. Next, at the same time when Vdata is supplied, Vdata1 to Vscan8 are set to H (high) level, processing is performed sequentially, and the selection transistor 105 of each pixel shown in FIG. A gate voltage based on the gradation voltage (gradation signal) Vdata applied to each data line is applied, and an ON operation is performed in a conductive state corresponding to the gate voltage.

  By this processing, a light emission drive current having a current value based on Vdata is supplied to the light emission drive transistor 106 and the organic EL element E1 of the pixel group to which Vscan in the pixel groups a to h is supplied via the power line. The organic EL element E1 emits light with a predetermined light emission luminance.

  At this time, Vdata is supplied to the holding capacitor 107 via the selection transistor 105. Therefore, each holding capacitor 107 is charged with a charge amount having a value corresponding to the level of Vdata. Next, the scanning signal Vscan becomes L (low) level after the selection period described above, and even if the selection transistor 105 is turned off, the storage capacitor 107 holds the charge amount corresponding to Vdata.

  That is, when the amount of charge corresponding to Vdata is held, the light emission drive transistor 106 becomes conductive according to the amount of charge, and the light emission operation is continued (non-selection period). Thereafter, light emission is performed during the active period corresponding to the number of lines.

  Next, a process for adjusting Vdata according to the deterioration state of the organic EL panel 104 will be described. FIG. 35 is a detailed block diagram of the system controller 101 of FIG. 34 as described above, and FIG. 36 is a detailed block diagram of the panel output comparator 108 of FIG.

  39 and 40 are diagrams for explaining the cross-sectional structure of the organic EL panel 104 of this example. FIG. 39 shows the bottom emission type, and FIG. 40 shows the top emission type. Use a pyroelectric substrate. In the bottom emission type shown in FIG. 39, the pyroelectric substrate 110 and the substrate transparent electrodes 111 and 112 must be transparent, and for example, lithium niobate subjected to polarization treatment is suitable. Further, the top emission format shown in FIG. 40 does not need to be transparent, and lead titanate, lead zirconate titanate, lead metaniobate, and the like are suitable. Moreover, when the heat processing in the manufacturing process of an organic EL element are required, it is necessary to pay attention to the curie point of the pyroelectric material so as not to exceed this.

  39 includes a transparent electrode 101b and an insulating layer 101c formed on a TFT 101a, a light-emitting layer 101d formed on the transparent electrode 101b, and a cathode 101e formed on the light-emitting layer 101d. The light emitted from 101d is guided downward. On the other hand, in the light emitting unit 100 shown in FIG. 40, the transparent cathode 101g and the insulating layer 101h are formed on the TFT 101f, the anode 101j is formed on the insulating layer 101h, the light emitting layer 101k is formed on the anode 101j, and the light emitting layer 101k is formed. The light emission from is guided upward.

  First, when the printing apparatus is turned on, an arbitrary organic EL element is caused to emit light with a constant Vdata value. For example, in the time chart shown in FIG. 37, they are Vscanl and Vdatal. FIG. 41 shows the spontaneous polarization change of the pyroelectric substrates 110 and 113 at that time. Due to the spontaneous polarization of the pyroelectric substrates 110 and 113, a charge appears on the surface of the pyroelectric substrate. However, in a steady state, the charge is combined with ions and electrons of opposite signs to maintain electrical neutralization. . However, it absorbs the heat energy generated by the light emission of any element of the organic EL panel 104, and the internal spontaneous polarization changes greatly as shown in FIG. A charge is excited on the surface in proportion to the amount of change, and this charge is taken out as an output voltage through the substrate transparent electrodes 111 and 112 and the load R connected between the substrate electrodes 114 and 115.

  As shown in FIG. 35, the system controller 101 has a panel output comparator 108 for inputting the output voltage of the pyroelectric substrates 110 and 113 with respect to the temperature change amount, a correction value table 117 for correcting the Vdata value, and the Vdata signal. A Vdata signal control unit 118, a Vscan signal control unit 119, and these control units 120 are provided. The correction value table 117 shows the difference between the system initial value of the output voltage value and the value after time and the corresponding Vdata correction value so as to increase the Vdata value as the luminance decreases due to deterioration with time. Are stored in advance.

  FIG. 42 is a flowchart for explaining this process. First, the power is turned on (step (hereinafter referred to as S) 1), and the output voltage due to the temperature change accompanying the light emission at the first system startup is set to the initial value a (S2 is Y (yes), S3). The value a is converted from analog to digital and recorded in the initial value memory 120 (S4). The initial value memory 120 is a non-volatile memory, and retains this state even after normal printing is performed and the power is turned off (S5, S6).

  Next, each time the system is started up when the power is turned on, the output voltage from the pyroelectric substrates 110 and 113 is measured in the same manner as described above before actual printing is performed (for example, measured value b) (S7). ) After analog-digital conversion, the measured value b and the above-mentioned initial value a are compared by the comparator 121 (S8). As a result, for example, if b = a, there is no change in the amount of heat generation, and no correction of Vdata is performed because there is no decrease in luminance due to deterioration with time (S8 is Y, S9, S10).

  On the other hand, if b = a is not satisfied (S8 is N (no)), the value of ba is calculated, and the Vdata correction amount corresponding to the ba value is read from the correction value table 117 during printing (S11). The signal is sent to the signal control unit 118, and correction is made to Vdata from the data driver 102 to the organic EL panel 104 (S12, S13).

As described above, according to this example, the correction value is applied at the time of printing only when the initial value a is different from the measured value b every time the system is started. With this configuration, when the power is turned on, light is emitted separately from the printing process, so that the temperature change amount of the organic EL element is captured and power is generated by the pyroelectric substrates 110 and 113 which are constituent materials of the organic EL element. By performing correction control, it is possible to reduce a decrease in luminance.
(Embodiment 7)
Next, a seventh embodiment of the present invention will be described.

This example is an invention of a printing apparatus that uses an edge-emitting organic EL array light-emitting device as an organic EL head. This will be specifically described below.
43 is a diagram for explaining the configuration of the organic EL array light-emitting device 130. FIG. 43A is a top view of the organic EL array light-emitting device 130, and FIG. (C) is a cross-sectional view taken along the line BB in FIG.

  The organic EL array light emitting device 130 has a structure in which an organic EL light emitter forming layer 131 and a waveguide forming layer 132 are stacked. The organic EL light emitter forming layer 131 functions as a light emitter substrate 133, a lower electrode 134, and a cladding layer. The insulating layer 135 that also serves as the organic light emitting layer 136, and the upper transparent electrode 137 formed of a transparent conductive material are sequentially laminated.

  The organic EL light emitting unit 138 has a plurality of long light emitting units formed in an array as shown in FIG. In order to control individual lighting of the organic EL light emitting unit 138, the lower electrode 134 is also patterned in a long shape with a photoresist, and the organic EL light emitting unit 138 is formed in a long shape by patterning an opening in the insulating layer 135. is doing.

The lower electrode 134 is formed of a metal film having a high light reflectance in order to return the light emitted from the organic light emitting layer 136 to the waveguide side.
On the other hand, the waveguide forming layer 132 is formed by the role of the cladding layer, the waveguide substrate 139 for forming the waveguide, and the core layer 140. The core layer 140 through which light is propagated includes a first layer 140a and a second layer 140b having different refractive indexes, and a diffraction grating 141 is formed in a boundary region between the first core layer 140a and the second core layer 140b. And an optically isolated photonic crystal 142 are formed.

  The diffraction grating 141 and the optically isolated photonic crystal 142 formed on the core layer 140 are arranged as shown in FIG. In other words, the optical waveguide diffraction grating 143 having a diffraction grating with a Bragg condition in which the phase of the light generated in the long organic EL light emitting unit 138 propagates toward the end face is matched and returned is changed to the organic EL light emitting unit 138. It is arranged at a position directly above the top so that it can be paired with a light emitter.

  In the photonic crystal, an optically isolated photonic crystal 142 is disposed immediately above the space between adjacent organic EL light emitting portions 138. The optically isolated photonic crystal 142 is formed in a two-dimensional three-lattice structure, each lattice is formed in a cylindrical shape, and each interstitial pitch is shorter than the wavelength and is about λ / 2.

  The optical waveguide diffraction grating 143 is a distributed feedback diffraction grating. By forming a distributed feedback diffraction grating under Bragg conditions, light is resonated in the optical waveguide, and is excellent in wavelength selectivity and directivity. Light with a narrow spectral width can be obtained. Furthermore, the optical waveguide diffraction grating 143 has a λ / 4 phase shift structure (not shown) or a gain coupling structure.

  Thus, by having a λ / 4 phase shift structure or a gain coupling type structure, the emitted light can be made into a single mode. The diffraction grating structure of the waveguide forming layer 132 is a thin layer resin for forming the first layer 140a of the core layer 140, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), and other optical components. Created by transferring and forming the above-mentioned diffraction grating shape and photonic crystal by thermal nanoimprint method on a base material that is coated with a thin layer on a waveguide substrate 139 made of glass material, for example, with excellent characteristics can do.

  In this manner, the waveguide forming layer 132 is generated by applying the second layer 140b having a different refractive index on the diffraction grating shape and the photonic crystal shape formed on the first layer 140a and flattening them. be able to.

Since the waveguide forming layer 132 forms a shape with respect to the thin film resin layer coated on the glass substrate, distortion and dimensional variation due to thermal contraction of the resin portion can be suppressed to a low level.
When the light emitting substrate 133 of the organic EL light emitting layer 131 is selected from the same material as that of the waveguide substrate 139, the dimensional accuracy and the thermal expansion become the same level, the bonding becomes easy, and particularly when an array having a detailed pitch is formed. The yield is improved.

  In addition, since the organic light emitting layer 136 of the organic EL light emitter forming layer 131 generally has a significantly reduced lifetime due to moisture absorption such as moisture, the organic EL light emitting unit 138 is disposed at a sufficient inner position capable of gas barrier with respect to the end face of the substrate. The organic EL can be sealed by laminating the waveguide forming layer 132 of the waveguide substrate 139 made of a glass material, and light can be guided to the end face of the substrate by the optical waveguide diffraction grating 143.

  By configuring in this way, the spectral width of the emission wavelength is narrower than that of conventional organic EL light emitting devices, and a structure that emits light with excellent wavelength selectivity and directivity is formed in an array. It can be applied, and is applicable not only to printing apparatuses and display bodies but also to optical communications and the like.

Next, a modification of this embodiment will be described.
FIG. 44 is a view for explaining a configuration of a modified example of the organic EL array light emitting device 130. FIG. 44A is a top view of the organic EL array light emitting device 130, and FIG. FIG. 4C is a cross-sectional view taken along the line BB in FIG. The organic EL array light emitting device 130 has a structure in which an organic EL light emitter forming layer 131 and a waveguide forming layer 132 are stacked. The organic EL light emitter forming layer 131 includes a light emitter substrate 133, a lower electrode 134, and a cladding layer. An insulating layer 135 that also serves as a role, an organic light emitting layer 136, and an upper transparent electrode 137 formed of a transparent conductive material are sequentially stacked.

  The difference between this modified example and the above embodiment is that the role of the cladding layer constituting the waveguide forming layer 132 and the reflection mirror 145 between the waveguide layer 139 for forming the waveguide and the core layer 140 are provided. It is forming. For example, Al (aluminum), silver (Ag), or the like is deposited on the waveguide substrate 137 by vapor deposition to form a reflective surface having a light reflectance.

With such a configuration, the confinement ratio of light emitted from the organic EL light emitting unit 138 can be improved by the lower electrode 134 and the reflection mirror 145. Therefore, by improving the light confinement rate, a more efficient organic EL array light-emitting device can be provided.
(Embodiment 8)
Next, an eighth embodiment of the present invention will be described.

  In the present embodiment, an optical waveguide is formed in a base substrate and a glass substrate of an organic EL head, and the light collecting effect on the photosensitive surface is improved. For this reason, in this embodiment, in order to form an optical waveguide, a light-induced refractive index change phenomenon is used. This will be specifically described below.

  FIG. 45 is a conceptual diagram of optical waveguide formation according to the present embodiment. As shown in the figure, the refractive index of the condensing portion 152 is permanently increased by irradiating the femtosecond laser light 150 into the glass substrate 151 in a concentrated manner. As a result, an optical waveguide having an arbitrary shape can be formed at an arbitrary position by continuous scanning.

  Specifically, a pulsed laser beam having a peak intensity of 105 w / cm or more and a repetition frequency of 10 kHz or more is continuously focused on the glass substrate 151 to form an optical waveguide inside the glass substrate 151.

  FIG. 46 shows a schematic view of the structure of this example. FIG. 46A shows a perspective view thereof, and FIG. 46B shows a sectional view thereof. That is, the optical waveguide 153 is formed in the glass base material 151 which becomes the base of the EL head array having the back emission structure. At this time, a condensing part 154 having a tapered side surface of the optical waveguide 153 and a radiating part 155 having a parabolic surface or an ellipsoidal surface are provided. This can be realized by controlling the intensity of the laser in accordance with the scanning.

  By the above processing, light from the organic EL is condensed at one point in the condensing unit 152, and light is incident on the radiating unit from this one point. That is, by emitting light from a point light source placed at the focal point of the paraboloid of revolution, light can be emitted from a parallel light source and from a point light source placed at the focal point of the spheroid surface. Obtainable.

  In this example, since the incident light to the radiation unit 155 is not the focal position, the effect of collimating and converging the light is slightly reduced, but light having a spread from the organic EL is not used as a point light source. Compared with the effect. FIG. 47 shows the relationship between the point light source position of the concave reflecting mirror such as a rectangular plane or an ellipsoid and the light irradiation intensity on the front irradiation surface.

By comprising in this way, the light emitted from the organic EL which has an area can be made into a point light source, and light emission can be collimated and focused.
(Embodiment 9)
Next, a ninth embodiment of the present invention will be described.

This example is an invention of a printing apparatus using a top emission structure organic EL head as the organic EL head. This will be specifically described below.
48A and 48B are diagrams for explaining the configuration of the organic EL head of this example. FIG. 48A shows a plan view thereof, and FIG. 48B shows a sectional view thereof. As shown in FIGS. 4A and 4B, the organic EL head 160 is a planar light emitting body having a top emission structure arranged in a line in the main scanning direction on a long substrate 161. 162 is formed in an array, and a waveguide 163 is formed above the planar light emitter 162 so as to face the planar light emitter 162 for each light emitter. The waveguide 163 emits light emitted from the light emitting element. It is a structure that propagates to the exit surface 165 of the waveguide end face while reflecting.

  In the organic EL planar light emitter 162, the light emitter lower electrode 166, the hole transport layer 167, and the light emitting layer 168 are separated and formed for each planar light emitter by an insulating film 169. An optical sensor unit 170 for detecting light propagated in the waveguide is disposed on the substrate near the exit surface of the waveguide end face 165, and detects the intensity of the light propagated in the waveguide near the exit surface. It is a configuration.

  In addition, since the optical sensor 170 is disposed in the vicinity of the exit surface of the waveguide 163, the light intensity as a result of driving the organic EL light emitter 162 and including the light variation due to the waveguide variation including the light emitter and the light emitter is obtained. It is possible to measure, and a value close to the light intensity emitted from the waveguide exit surface 165 can be measured.

  In the above embodiment, the entire waveguide group is described as being detected by one long optical sensor. However, a structure in which one optical sensor is detected per waveguide, and several waveguides are used. You may form an optical sensor in a unit. However, the common use of photosensors and the small number of photosensors indicate that the same-path wiring to the photosensors and the control logic can be simplified.

FIG. 49 is a diagram illustrating a basic structure of the optical sensor 170 and a function of generating power by receiving light. This structure is the same as the basic structure of the light emitter.
FIG. 50 is a circuit block diagram for controlling the driving of the organic EL light emitter 162 of this example. In the case of this example, since one light sensor is arranged for a plurality of light emitters, a feedback signal of the light sensor is acquired while lighting each light emitter. That is, the light emission scanning control circuit 173 is operated by an output signal from the head control circuit 172, and an arbitrary light emitter is turned on with a reference or correction value current.

  The generated light propagates in the waveguide 163, travels to the exit surface, and enters the optical sensor 170 in the vicinity of the exit surface, thereby generating a terminal voltage of the photosensor. And is converted into a re-digital signal by the A / D conversion unit 174 of the head control circuit 172, and obtained as an optical sensor reading value.

  For example, as an organic EL exposure unit, the brightness of the light beam is measured by an external sensor device at the final imaging position through the imaging optical system, and the driving flow of each light emitter is adjusted so that the value becomes uniform. decide. This value is defined as an initial current correction value A. This current correction value A is a value that can make the luminance uniform with respect to all luminance variation factors such as the organic EL, the waveguide, the imaging optical system, and in some cases the TFT circuit in the initial stage of the organic EL exposure unit.

  Further, when the light sensor reading value in the unit when each light emitter is driven with the initial current correction value A is the initial luminance data B, the initial luminance data B is correlated with the uniform luminance at the final imaging point. Value. Therefore, when the difference between the initial luminance data B and the reading value from the optical sensor occurs, feedback is applied to the driving current to control the optical sensor reading value to be the initial luminance data B, thereby obtaining the final image formation. The brightness uniformity and invariance at the position can be maintained.

  In addition, initially, a current correction value C storing the same value as the initial current correction value A is provided, and control is performed so that the drive current updated by feedback control is stored in the current correction value C when a difference in luminance occurs. By doing so, the life can be estimated.

  For example, the route I shown in FIG. 50 is a route having the above-described feedback control function incorporated in the head control circuit 172. The detected optical sensor reading value is compared with a preset reference value of initial desired luminance (initial luminance data B), and if a difference occurs, the driving current is changed to change the optical sensor reading value to the initial luminance data. A drive current that matches B is found, and the value is updated as current correction data C.

  The path II is configured to provide feedback data by command designation of a higher-level controller such as a controller on the printing apparatus side. By implementing the above feedback control by the host controller, the correction control structure of the head control circuit 172 can be simplified or omitted, and the cost of the apparatus can be reduced.

  FIG. 51 is a diagram showing lifetime characteristics when the organic EL light-emitting body 162 is driven at a constant voltage, a constant current, and a constant luminance. 2A shows the case of constant voltage driving, FIG. 2B shows the case of constant current driving, and FIG. 2C shows the case of constant luminance driving.

  As shown in FIGS. 4A to 4C, the lifetime can be extended in the order of constant voltage driving / constant current driving / constant luminance driving. Can be used with uniform brightness up to the current / voltage limit. Therefore, the problem of the lifetime which is a big problem in the organic EL element is greatly improved.

  In addition, it is possible to prevent luminance reduction and luminance unevenness due to the difference in usage frequency of each light emitter generated by using the printing apparatus for a long period of time, and it is possible to maintain high quality printing until the end of its life. .

Next, a modification of this embodiment will be described.
FIG. 52 is a view for explaining a modification of the present embodiment. FIG. 52 (a) shows a plan view thereof, and FIG. 52 (b) shows a sectional view thereof. Further, as in the above-described embodiment, the organic EL head 160 forms the organic EL element planar light emitters 162 having a top emission structure arranged in a line in the main scanning direction on an elongated substrate 161 in an array. A waveguide 163 is formed above the planar light emitter 162 so as to face the planar light emitter 162 for each light emitter.

The configuration in which this modification is different from that of the above embodiment is that the arrangement of the optical sensor unit 170 is arranged in the vicinity of the end surface of the waveguide 163 opposite to the end surface on the emission surface side 177. With this configuration, the influence on the propagation of the generated light can be minimized. Therefore, the light intensity and light profile emitted from the waveguide exit surface can be made ideal.
(Embodiment 10)
Next, a tenth embodiment of the present invention will be described.

  This example is also an invention of a printing apparatus using an organic EL head having a top emission structure, as in the ninth embodiment. FIGS. 53A and 53B are diagrams for explaining the configuration of the organic EL head of this example. FIG. 53A shows a plan view and FIG. 53B shows a cross-sectional view thereof. FIGS. 4A and 4B are basically the same as those in FIG. 48 described above, and only the configuration different from that in FIG. 48 will be described.

  In the case of this example, on a long substrate 161, organic EL element planar light emitters 180 having TFT drive active matrix type top emission structure arranged in a line in the main scanning direction are formed in an array. A waveguide 181 is formed on the upper side of the light emitter so as to face the planar light emitter for each light emitter, and this waveguide propagates to the emission surface 165 at the end face of the waveguide while reflecting the light emitted from the light emitting element. It is.

  The TFT circuit 190 is made of a semiconductor such as amorphous silicon and forms a lighting circuit for each planar light emitter. The TFT circuit 190 is disposed under the planar light emitter and is planarized by a planarization film 184. The organic EL planar light emitter 180 is formed on the flattening film 184, and the light emitter lower electrode 186, the hole transport layer 187, and the light emitting layer 188 are separated and formed for each planar light emitter by the insulating film 188. is doing.

  In addition, an optical sensor unit 189 that can detect light propagating in the waveguide is disposed on the substrate near the exit surface on the side surface of the waveguide, and the intensity of the light propagated in the waveguide is detected in the vicinity of the exit surface. It is the structure to do.

  Therefore, according to the present embodiment, the drive control can be performed for each organic EL light emitter 180, and the optical sensor can be formed by the same process simultaneously with the TFT formation process, so that a new process for forming the optical sensor is not required.

Next, a modification of this embodiment will be described.
FIGS. 54A and 54B are configuration diagrams of a photosensitive belt for explaining a modified example. FIG. 54A shows a plan view thereof, and FIG. 54B shows a sectional view thereof. This modification is the same as that of FIG. 52 described above, and is that the optical sensor unit 189 is disposed in the vicinity of the end surface on the opposite side to the end surface on the exit surface side 177 of the waveguide. With this configuration, the influence on the propagation of the generated light can be minimized. Therefore, the light intensity and light profile emitted from the waveguide exit surface can be made ideal.

FIG. 3 is a diagram illustrating a circuit configuration of the organic EL head according to the first embodiment. FIG. 3 is a diagram illustrating a main part of the printing apparatus according to the first embodiment. It is a figure which shows the arrangement configuration of a photosensitive drum and an organic EL head. It is a figure which shows the structure of the drive circuit of each organic EL element. 3 is a time chart for explaining processing of the first embodiment. FIG. 5 is a circuit diagram illustrating a control circuit including a non-selection period memory that stores a fixed value, a counter, and a shift register. It is a time chart explaining operation | movement of a control circuit. It is a figure explaining the structure of the organic electroluminescent array of Embodiment 2. FIG. It is an external view of the surface emitting part array panel explaining the principle of Embodiment 2. It is a figure explaining the condensing of a Selfoc lens. It is a figure explaining the condensing of a Selfoc lens. It is a figure which shows the perspective view of a reflector. It is a figure which shows the structure of an end surface irradiation type EL element & reflector. It is a figure which shows the light-receiving surface profile in the case with a reflector, and a case without a reflector, and directivity. FIG. 10 is a diagram illustrating an overall configuration of a printing apparatus used in a third embodiment. It is a figure which shows the structure of an organic electroluminescent array. It is a figure which shows the arrangement configuration of a photoreceptor belt and an organic EL head. It is a figure which shows the example which forms a parabolic reflector in organic electroluminescent light emission end surface. It is a figure which shows the example which forms a parabolic reflector in organic electroluminescent light emission end surface. (A), (b) is a figure explaining the light-receiving surface profile of the parabolic reflector corresponding to light-receiving surface distance. It is a figure which shows the example which adds a convex-shaped reflecting plate to the center part of a reflector. (A), (b) is a figure explaining the light-receiving surface profile of the parabolic reflector corresponding to light-receiving surface distance. It is a figure explaining the characteristic of the emitted light by the shape of a parabolic reflector with a reflecting plate. It is a figure explaining the structure of a photoreceptor belt and an organic EL head. FIG. 6 is a top view of an organic EL head according to a fourth embodiment. 6 is a side view of an organic EL head according to Embodiment 4. FIG. FIG. 10 is a diagram illustrating a top view of an organic EL head according to a modification of the fourth embodiment. FIG. 10 is a side view of an organic EL head according to a modification of the fourth embodiment. FIG. 6 is a top view of an organic EL head according to Embodiment 5. 6 is a side sectional view of an organic EL head according to Embodiment 5. FIG. FIG. 10 is a diagram illustrating a top view of an organic EL head described as a modification of the fifth embodiment. It is a figure which shows the side sectional drawing of the organic electroluminescent head which the modification of Embodiment 5 demonstrates. FIG. 10 is a diagram illustrating an overall configuration of a printing apparatus used in a sixth embodiment. 10 is a diagram showing a circuit configuration of an organic EL head used in Embodiment 6. FIG. It is a figure explaining a system controller concretely. It is a figure explaining the structure of a panel output comparator concretely. 10 is a time chart for explaining the processing of the sixth embodiment. It is a figure explaining the structure of a data driver. It is a figure explaining the cross-section of an organic electroluminescent panel. It is a figure explaining the cross-section of an organic electroluminescent panel. It is a figure explaining the spontaneous polarization change of a pyroelectric board. 14 is a flowchart for explaining processing of the sixth embodiment. It is a figure explaining the structure of the organic electroluminescent array light-emitting device used in Embodiment 7, (a) is a top view of an organic electroluminescent array light-emitting device, (b) is the AA sectional drawing, (c ) Is a cross-sectional view taken along the line B-B. It is a figure explaining the structure of the organic electroluminescent array light-emitting device which shows a modification, (a) is a top view of an organic electroluminescent array light-emitting device, (b) is the AA sectional drawing, (c) is It is the BB sectional drawing. It is a figure which shows the conceptual diagram of optical waveguide formation. (A) shows the perspective view of optical waveguide formation, (b) shows sectional drawing of optical waveguide formation. It is a figure which shows the relationship between the point light source position of concave shape reflective mirrors, such as a rectangular parallelepiped surface or an elliptical surface, and the light irradiation intensity | strength to a front irradiation surface. It is a figure explaining the structure of the organic electroluminescent head of Embodiment 9, (a) shows the top view, (b) shows the sectional drawing. It is a figure explaining the basic structure of an optical sensor. It is a circuit block diagram which performs drive control of an organic electroluminescent light-emitting body. It is a figure which shows the lifetime characteristic at the time of driving an organic electroluminescent light-emitting body by constant voltage drive, constant current drive, and constant brightness, (a) is a case of constant voltage drive, (b) is a case of constant current drive. , (C) shows the case of constant luminance driving. It is a figure explaining the structure of the organic electroluminescent head of a modification, (a) shows the top view, (b) shows the sectional drawing. It is a figure explaining the structure of the organic electroluminescent head of Embodiment 10, (a) shows the top view, (b) shows the sectional drawing. It is a figure explaining the structure of the organic electroluminescent head of a modification, (a) shows the top view, (b) shows the sectional drawing. It is a figure explaining the drive circuit of an organic EL element. It is a time chart explaining the drive process of the organic EL element of a prior art example. (A) is a figure which shows the example of an ideal beam spot, (b) is a figure which shows the state which the beam spot moved to the subscanning direction, and the exposure dot spread in the subscanning direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Charging roller 3 ... Organic EL head 4 ... Developing device 5 ... Transfer roller 6 ... Cleaning part 7 ... Eraser 8 ... Paper 9 ..Fixing roller 10 ..Organic EL array 11 ..SLA (Selfoc lens array)
20. .. selection signal driver 21 .. power supply voltage driver 22 .. driver 31 .. non-selection period memory 32 .. counter 41 .. glass substrate 42 .. anode electrode (anode)
43..Hole injection layer (HTL)
44 .. Light emitting layer (EL)
45 .. Electron injection layer (ETL)
46 .. Cathode electrode (cathode)
47..Surface emitting unit array panel 48.Surface emitting unit 49..Light guide unit 50..Reflector 51..Charging roller 52..Photosensitive belt 52a..Seamless belt-like translucent substrate 52b. Conductive layer 52c .. Charge generation layer (CGL)
52d .. Charge transfer layer (CTL)
52e .. Surface protective layer (OCL)
53..Organic EL head 54.Developer 55.Transfer roller 56.Cleaning unit 57.Eraser light source 58. Paper 59.Conveying mechanism 60. Belt tension roller 61. Parabolic reflector 65. Organic EL array exposure head 66... Light emitter transparent substrate part 67.. Waveguide forming substrate part 68.. Lens transparent substrate part 75.. Organic EL array exposure head 76. · Cover glass 78 · · Lens transparent substrate portion 80 · · Directional change mirror 81 · · Light emitter transparent substrate 82 · · Organic EL light emitter array 83 · · Lens transparent substrate 84 · · Anode 85 · · Cathode 86 · · Hole Transport layer 87 .. Laminated light emitting layer 88.. Sealing material 89... Light absorption layer 90.. Organic EL array exposure head 91. Type lens 95, lens transparent substrate 96, cathode 100, light emitting unit 101, system controller 102, data driver 103, scan driver 104, organic EL panel 105, selection transistor 106, light emission drive transistor 107 ··· Holding capacitor 108 ··· Output comparators 110 and 113 · · Pyroelectric substrates 111 and 112 · · Substrate transparent electrode 117 · · Correction value table 118 · · Vdata signal controller 119 · · Vscan signal controller 120 · · Initial Value memory 121 ..Comparator 123..Control unit 130.Organic EL array light emitting device 131.Organic EL emitter forming layer 133.Light emitter substrate 134.Lower electrode 135.Insulating layer 136.Organic light emission Layer 137 .. Upper transparent electrode 138 .. Organic EL light emitting unit 140 .. Core layer 140 a... First layer 14 b. Second layer 141 Diffraction grating 142 Optical isolated photonic crystal 143 Organic EL light emitting unit 150 Femtosecond laser light 151 Glass substrate 152 Condensing portion 153 Optical waveguide 154... Condensing part 155... Radiation part 160.. Organic EL head 161... Substrate 162 .. Organic EL element planar light emitter 163. 167..Hole transport layer 168..Light emitting layer 169..Insulating film 170..Optical sensor unit 172..Head control circuit 173..Light emission scanning control circuit 174..A / D converter 180..Organic EL element Planar light emitter 181... Waveguide 184.. Flattened film 186.. Light emitter lower electrode 187... Hole transport layer 188.

Claims (5)

In a printing apparatus that irradiates a photosensitive surface with light from an EL array in which a plurality of EL elements are arranged in an array in the main scanning direction, develops a latent image formed on the photosensitive surface, and prints on a recording medium.
Selection signal supply means for supplying a selection signal to the EL array;
A light emission power supply means for supplying light emission power to the EL elements in the EL array after outputting the selection signal;
Control means for stopping the supply of the light emission power based on information of the driving period of the EL array set in advance in the storage means provided for each head unit incorporating the EL array;
A printing apparatus comprising:   The printing apparatus according to claim 1, wherein the information on the driving period of the EL array is set based on a result measured in advance for each EL head unit.   In response to the output of the selection signal, the capacitor means formed in the drive circuit is charged with electric charge, the switching means is switched by the charged electric charge, and the light emitting power is supplied to the EL array to emit light from each EL array. The printing apparatus according to claim 1 or 2.   The printing apparatus according to claim 1, wherein the EL element is an organic EL element, and a plurality of organic EL element groups are arranged in the EL array. Selection signal supply means for supplying a selection signal to each EL array in which a plurality of EL elements are formed;
A light emission power supply means for supplying light emission power to the EL elements in the EL array after outputting the selection signal;
Control means for stopping the supply of the light emission power based on information on the driving period of the EL element for each EL head unit preset in a storage means provided for each head unit incorporating the EL array;
A drive device for an EL head unit, comprising: