JP2007025550A - Driving method of print head, printer using the same, and semiconductor integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving method of a print head which can miniaturize the print head. <P>SOLUTION: The print head 10 comprises a red organic EL element 16, a green organic EL element 18, and a blue organic EL element 20. By selecting one of the scanning lines S1, S2 and S3, and it makes the organic EL elements emit light of the respective colors, and exposes printing pixels in opposing relation. Non-selection periods by dummy signals Sdm1-Sdm3 are provided between the scanning lines S by selection signals Ssl1-Ssl3. The non-selection periods are calculated by a drive control circuit 56, based on the distance of the organic EL elements included in a single column. Based on the result, a scanning line drive timing control circuit 62 performs control so as to select a corresponding scanning line, only when any one of the rows of the organic EL elements is located immediately above any one of the rows of the printing pixels. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a print head drive technique, and more particularly to a print head drive method for operating a print head with respect to an object to be printed, a printer using the same, and a semiconductor integrated circuit.

  An LED (Light Emitting Diode) printer has been developed as a printer having a relatively simple mechanism and a relatively low cost. The LED printer includes a plurality of LEDs, and each of the plurality of LEDs emits light in a predetermined pattern, thereby forming a latent image on the rotating drum. Furthermore, toner is attached to the latent image formed on the rotating drum, and printing or printing is executed with the toner (see, for example, Patent Document 1). Such an LED printer has relatively large power consumption and a large amount of heat generation.

On the other hand, in recent years, mobile phones and digital cameras with an imaging function have become widespread, and users have taken pictures easily in various places. Accordingly, if still images taken with a digital camera or the like can be printed at various places, the usage of the digital camera becomes diverse. For the user, since the captured still image can be exchanged by hand immediately, convenience and entertainment are improved. For manufacturers of digital cameras and the like, this leads to an increase in the number of digital cameras sold. For this purpose, printers are generally required to be small in size and operate with low power consumption assuming battery operation.
JP-A-8-142403

  As a printer that operates with lower power consumption than an LED printer, there is an organic EL printer that uses an organic EL (Electro Luminescence) as a light source. In an organic EL printer, generally, organic EL elements that emit red light are arranged in one direction, and each of an organic EL element that emits green light and an organic EL element that emits blue light emits red light. It is arranged in parallel with the column. An organic EL printer prints a still image on a photosensitive paper when a print head having a plurality of organic EL elements scans the photosensitive paper. However, since the print head has a plurality of organic EL elements, it becomes a certain size. Therefore, in order to reduce the size of such an organic EL printer, it is desirable to reduce the size of the print head.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a print head driving method for miniaturizing a print head, a printer using the same, and a semiconductor integrated circuit.

  One embodiment of the present invention relates to a method for driving a print head. In this method, a plurality of lines formed in the scanning line direction are provided with light emitting elements having emission colors of 1 to n, and each pixel region on the printing object is subjected to relative movement in the sub scanning direction with respect to the printing object. A print head driving method for forming a color image in units of lines on a print object by sequentially causing 1 to n light emitting elements to face each other and causing each color to emit light according to a pixel value. The distance d between the light emitting elements in the upper sub-scanning direction is set to be shorter than the length p in the sub-scanning direction of the pixels on the print object, and any line on the print head is on the print object. When facing a certain line of interest, the pixels included in the line of interest are printed, and then the printing dummy time is set until another line on the print head faces another line of interest on the object to be printed. Special To.

  The “scanning line direction” corresponds to the direction of the scanning line for selecting a row of the light emitting elements when a general matrix type light emitting element display device is taken as an example, and the “sub scanning direction” is, for example, perpendicular to the scanning line direction. This corresponds to the direction, that is, the direction of the row of light emitting elements. “Pixel” is generally the smallest unit that constitutes an image. However, if the color components are the three primary colors of RGB, each of RGB contained in the smallest unit that constitutes an image, for example, an RGB display Each light emitting element may be referred to as a pixel. Hereinafter, pixels printed on a film or the like are particularly referred to as “printed pixels”. The RGB pixels are collectively referred to as “picture elements”, but “picture elements” are referred to as “pixels” unless otherwise specified.

  According to this aspect, even if the interval between the light emitting elements in the sub-scanning direction on the print head is reduced, it is possible to print at an appropriate position without causing a shift from the pixel area on the print object. .

  Another aspect of the present invention relates to a printer. This printer generates a relative movement in the sub-scanning direction between a print head having light emitting elements having emission colors 1 to n on a plurality of lines formed in the scanning line direction, and the print head and an object to be printed. 1 to n color light-emitting elements are sequentially opposed to each pixel region on the print object via the driving unit and a drive unit, and each color is emitted according to the pixel value, and a color image is displayed in line units on the print object. And a control unit that controls the print head. Here, when any line on the print head faces a certain target line on the print target, the control unit causes the organic EL element included in the line on the print head facing the target line to emit light. In addition, control is performed so that a dummy time is provided until another line on the print head faces another line of interest on the print object.

  Yet another embodiment of the present invention relates to a semiconductor integrated circuit. This semiconductor integrated circuit includes a scanning line driving circuit for driving a plurality of scanning lines corresponding to a plurality of lines including light emitting elements having emission colors 1 to n on the print head, and a sub head of the print head and the printing object. When any line on the print head faces a certain line of interest on the object to be printed due to relative movement in the scanning direction, the scanning line corresponding to the line on the print head is driven, and then on the print head. A control circuit for controlling the scanning line driving circuit is integrated on one semiconductor substrate so that a dummy time is provided until another line faces another line of interest on the object to be printed.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between methods, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, a device such as a printer can be downsized.

  Before describing the present invention in detail, an outline will be described. Embodiments described herein relate generally to an organic EL printer including an organic EL element as a light source. The organic EL printer according to the present embodiment includes a print head having organic EL elements arranged in a matrix, scanning lines corresponding to the rows of the matrix, and data lines corresponding to the columns. An image is printed on the photosensitive paper by exposing the photosensitive paper while moving the print head.

  In this embodiment, the print head is moved in the sub-scanning direction perpendicular to the scanning lines corresponding to the rows of the matrix, and the print head is not moved in the scanning line direction (hereinafter referred to as “scanning direction”). In the scanning direction, a plurality of organic EL elements emitting red light (hereinafter referred to as “red organic EL elements”) are arranged. Further, a plurality of organic EL elements that emit green light (hereinafter referred to as “green organic EL elements”) and a plurality of organic EL elements that emit blue light (hereinafter referred to as “blue organic EL elements”) are rows of red organic EL elements. Arranged in parallel. By one light emission of one organic EL element, one print pixel area is exposed with the light emission color of the organic EL element.

  Since the print head does not move in the scanning direction, the size and number of organic EL elements arranged in one scanning direction are defined based on the size of the print pixels and the number contained in one line. In this embodiment, the interval between the organic EL elements in the sub-scanning direction is narrowed to reduce the size of the print head. Specifically, when the row of each organic EL element is located immediately above the row of printing pixels on the photosensitive paper, the organic EL element is caused to emit light appropriately, and the row of organic EL elements straddles the row of two printing pixels. The light emission timing of the organic EL element is controlled in units of rows so that the organic EL element does not emit light when the light is on. By controlling the light emission timing in accordance with the interval between the organic EL elements, an image can be printed without causing any shift in the print pixels regardless of the pitch of the organic EL elements in the sub-scanning direction. Can do.

  FIG. 1 shows a configuration of a printer 100 according to the present embodiment. The printer 100 includes a print head 10, a lens array 12, a first support 24 a and a second support 24 b that are collectively referred to as a support 24. The print head 10 is generally referred to as a first red organic EL element 16 a, a second red organic EL element 16 b, an Nth red organic EL element 16 n, and a green organic EL element 18 that are collectively referred to as a red organic EL element 16. First green organic EL element 18a, second green organic EL element 18b, Nth green organic EL element 18n, first blue organic EL element 20a, second blue organic EL element 20b, Nth green organic EL element 20 A blue organic EL element 20 n is included, and these organic EL elements are opposed to the lens array 12. The lens array 12 includes a first gradient index lens 22a, a second gradient index lens 22b, and an Nth gradient index lens 22n. Also, in the figure, photosensitive paper 14 is shown as an object to which the printer 100 should print a predetermined image. Although FIG. 1 shows the print head 10 and the lens array 12 which are components for directly executing printing in the printer 100, the printer 100 includes other components.

  The print head 10 receives data of an image to be printed on the photosensitive paper 14 from a control unit (not shown), and causes the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 to emit light according to the data. The direction of the arrow in the drawing, that is, the direction in which the first red organic EL element 16a, the first green organic EL element 18a, and the first blue organic EL element 20a are arranged corresponds to the sub-scanning direction described above. The direction perpendicular to the sub-scanning direction, that is, the direction in which the organic EL elements having the same color are arranged corresponds to the above-described scanning direction.

  The print head 10 moves in the sub-scanning direction but does not move in the scanning direction. In the print head 10, red organic EL elements 16 of the same color are arranged in a row in the scanning direction, and the red organic EL elements 16, green organic EL elements 18, and blue organic EL elements 20 of different colors in the sub-scanning direction are arranged. It is arranged. In the case of a VGA (Video Graphics Array), for example, an image to be printed on the photosensitive paper 14 is composed of 480 print pixels in the scanning direction and 640 print pixels in the sub-scanning direction. In this case, 480 red organic EL elements 16 are arranged in the scanning direction. Details of the arrangement of the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 in the print head 10 will be described later.

  The lens array 12 includes a plurality of gradient index lenses 22. The gradient index lens 22 images each color emitted from the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 and prints them on the photosensitive paper 14 as print pixels. The lens array 12 also moves with the print head 10 in the sub-scanning direction.

  The columns 24 support the print head 10 and the lens array 12 so that a predetermined distance from the photosensitive paper 14 can be maintained. Further, it moves in the sub-scanning direction while supporting the print head 10 and the lens array 12. Here, the support 24 is shown to support the print head 10 and the lens array 12, but the present invention is not limited to this. For example, a guide (not shown) is provided along each of the print head 10 and the lens array 12, and each of the print head 10 and the lens array 12 moves in the sub-scanning direction along the guide while being supported by the guide. May be.

  FIG. 2 is a side view of the printer 100. The print head 10 and the lens array 12 are arranged above the photosensitive paper 14 while maintaining a predetermined distance from the photosensitive paper 14 by the support 24. The direction indicated by the arrow is the aforementioned sub-scanning direction, and the print head 10 and the lens array 12 move in the sub-scanning direction. FIG. 3 is a top view of the printer 100. The lens array 12 is not shown in FIG. 3 because it is located below the print head 10. The direction indicated by the arrow is the sub-scanning direction described above. As described above, a plurality of organic EL elements facing the photosensitive paper 14 are arranged in the print head 10 in a lattice pattern.

  FIG. 4 shows an outline in which light emission of each color by the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 is imaged by the gradient index lens 22 and printed on the photosensitive paper 14. . Here, the (I-1) red organic EL element 16i-1, the I red organic EL element 16i, the (I + 1) red organic EL element 16i + 1, and the (I-1) green organic EL in the print head 10 are included. Element 18i-1, I green organic EL element 18i, (I + 1) green organic EL element 18i + 1, (I-1) blue organic EL element 20i-1, I blue organic EL element 20i, (I + 1) blue It is assumed that each of the organic EL elements 20i + 1 emits light with a predetermined luminance. The J-th gradient index lens 22j in the lens array 12 has a predetermined field of view. Therefore, the light of each color emitted from the plurality of red organic EL elements 16, green organic EL elements 18, and blue organic EL elements 20 forms an image on the photosensitive paper 14 as illustrated. A plurality of gradient index lenses 22 are provided, and the images projected on the photosensitive paper 14 by the adjacent gradient index lenses 22 overlap.

  FIG. 5 shows a functional configuration of the printer 100. The printer 100 includes a print head 10, a motor 52, a control unit 50, an image data input unit 54, and an array data input unit 55. The print head 10 corresponds to the print head 10 shown in FIG. The image data input unit 54 inputs image data to be printed by the printer 100 via an interface (not shown). Here, it is assumed that the image data is input in a form corresponding to each of the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20.

  The array data input unit 55 inputs the size of the organic EL element in the print head 10 and the interval between adjacent organic EL elements in the sub-scanning direction. For the input, a value corresponding to the print head 10 may be set in advance and stored in a register (not shown), or may be set by software executed by an external processor (not shown).

  The control unit 50 sends the print head 10 in the sub scanning direction via the motor 52. Further, the control unit 50 outputs data for causing the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 to emit light at an appropriate gradation corresponding to the position of the print head 10 based on the image data. Further, the control unit 50 controls the light emission timing so that the organic EL element in the row emits light when the row of the organic EL element is positioned immediately above the pixel area of 640 rows in the case of a print pixel row, for example, VGA. Take control. The light emission timing is controlled based on the size of the organic EL element input from the array data input unit 55 and the interval in the sub-scanning direction. A specific method will be described later.

  FIG. 6 shows the configuration of the print head 10 and the control unit 50 in more detail. The control unit 50 includes a drive control circuit 56, a scanning line drive circuit 58, and a data line drive circuit 60. The print head 10 includes a red organic EL element 16, a green organic EL element 18, a blue organic EL element 20, scanning lines S1 to S3, and data lines Da to Dn. This figure shows the arrangement of the print head 10 as viewed from the photosensitive paper 14 side. Three scanning lines S1 to S3 (hereinafter collectively referred to as scanning lines S) and N data lines Da to Dn (hereinafter collectively referred to as data lines D) are arranged in a grid pattern. Yes. The red organic EL element 16 is at the intersection of the scanning line S1 and the data line D, the green organic EL element 18 is at the intersection of the scanning line S2 and the data line D, and the intersection of the scanning line S3 and the data line D is at the intersection. A blue organic EL element 20 is disposed. In this figure, the interval between the organic EL elements is appropriately enlarged or reduced for ease of viewing.

  When the potential of the corresponding scanning line S is set to a low level and the potential of the corresponding data line D is set to a high level, the red organic EL element 16 or the like emits light and corresponds to a period during which this current flows. The emission gradation is controlled. In this embodiment, the low-level potential of the scanning line S is set to 0 V, which is the ground potential.

  The drive control circuit 56 outputs a scan control signal Scnt to the scan line drive circuit 58 and a data control signal Dcnt to the data line drive circuit 60, respectively. The print head 10 sequentially switches the rows that emit light in synchronization with the scan control signal Scnt. Further, the data control signal Dcnt is synchronized with the scanning control signal Scnt, and includes data of light emission gradations of the red organic EL element 16, the green organic EL element 18, or the blue organic EL element 20 in all of the first to n columns. Signal.

  A scanning line driving circuit 58 is connected to the scanning lines S1 to S3. The scanning line driving circuit 58 includes a scanning line driving timing control circuit 62. The scanning line drive timing control circuit 62 outputs selection signals Ssl1, Ssl2, and Ssl3 based on the scanning control signal Scnt input from the drive control circuit 56. By these selection signals, the scanning line S1, S2, or S3 is switched to whether the potential of the scanning line S1, S2, or S3 is set to the low level and the scanning line is selected to emit light or not selected as the high level Vcom. Specifically, the red organic EL element 16, the green organic EL element 18, or the blue organic EL element 20 connected to the corresponding scanning line S 1, S 2, or S 3 is positioned immediately above the print pixel and emits light. Each scanning line is selected only when the image on the photosensitive paper 14 is not shifted from the pixel to be printed. During a period in which all the organic EL elements are displaced from the print pixel area due to the movement of the print head 10, the scanning lines S1, S2, and S3 are not selected by the selection signals Ssl1, Ssl2, and Ssl3.

  In order to accurately control the non-selection period, the scanning line drive timing control circuit 62 outputs to the ground potential in addition to the selection signals Ssl1 to Ssl3 output to the scanning lines S1 to S3 as shown in FIG. Dummy signals Sdm1 to Sdm3 are generated. In the present embodiment, the scanning line drive timing control circuit 62 includes a shift register circuit (not shown). The first selection signal Ssl1 for selecting the scanning line S1, the first dummy signal Sdm1, the second selection signal Ssl2 for selecting the scanning line S2, the second dummy signal Sdm2, and the third for selecting the scanning line S3. The selection signal Ssl3 and the third dummy signal Sdm3 are sequentially sent to the respective outputs in order of the selection state. No organic EL element emits light during the period when the selected state is on the dummy signals Sdm1 to Sdm3.

  A data line driving circuit 60 is connected to the data lines Da to Dn. The data line driving circuit 60 includes a PWM current source 66, a precharge voltage source 68, and a pulse control circuit 64 provided for each of the data lines Da to Dn. The pulse control circuit 64 generates pulse width modulated PWM control signals Spwma to Spwmn for controlling the PWM current source 66 based on the data control signal Dcnt output from the drive control circuit 56. Further, the pulse control circuit 64 generates a switching signal Ssw for controlling the switches connected to the data lines Da to Dn, respectively.

  The PWM current source 66 generates PWM data signals Ipwma to Ipwmn, which are constant current signals pulse-modulated based on the PWM control signal Spwm, and supplies them to the data lines Da to Dn. The precharge voltage source 68 is a voltage source for supplying a precharge voltage Vpc for charging the parasitic capacitance of the organic EL element to each data line as a constant voltage signal. Since the precharge voltage Vpc may have the same voltage value for all the data lines D, the data lines Da to Dn may be connected by wiring from one constant voltage source.

  Each of the data lines Da to Dn is supplied with a pulse width modulated data signal Ipwm whose period of high level changes corresponding to each light emission gradation, thereby controlling the light emission gradation of the organic EL element. . Prior to this, a precharge voltage is applied to each of the data lines Da to Dn. For example, when the potential of the scanning line S2 in the second row becomes a low level, each of the green organic EL elements 18a to 18n is first applied with a precharge voltage for a predetermined period, and then supplied with PWM data signals Ipwma to Ipwmn. Is done. First, the organic EL element quickly charges the parasitic capacitance of the element with a precharge voltage, and then emits light with a gradation corresponding to a high level period of the PWM data signals Ipwma to Ipwmn.

  In this way, the scanning lines connected to the organic EL elements are selected by the selection signals Ssl1 to Ssl3 during a period in which the row composed of the organic EL elements of the same color is at an appropriate position, A data signal of a pixel printed by the EL element is supplied. By repeating this operation, for example, each of the 640 rows of print pixels is exposed with each color having luminance based on the image data, thereby completing the print image.

  The above configuration can be realized in hardware by a CPU, memory, or other LSI of any computer, and in software it is realized by a program loaded in memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  Hereinafter, the operation of the above configuration will be specifically described. FIG. 7 shows the arrangement of organic EL elements in the print head 10 to be compared with the present embodiment. In the figure, the horizontal direction is the scanning direction, and the vertical direction is the sub-scanning direction. Each organic EL element has a size necessary for printing one print pixel. In the scanning direction, they are arranged so that the distance from the left end of one red organic EL element 16 to the left end of the adjacent red organic EL element 16 is 100 μm. The same applies to the green organic EL element 18 and the blue organic EL element 20. In the sub-scanning direction, the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20 are arranged so that the size and interval are both 100 μm.

  FIG. 8 schematically shows the operation of the print head 10 having the arrangement shown in FIG. Here, for the sake of easy understanding, attention is focused on only three organic EL elements belonging to one column of the array, that is, the red organic EL element 16, the green organic EL element 18, and the blue organic EL element 20. The plurality of organic EL elements included in each row perform the same movement. In the present embodiment, it is assumed that the light emitted from each organic EL element forms an image on the photosensitive paper 14 at an equal magnification through the gradient index lens 22, and the position of the image formed by these three organic EL elements is that each organic EL element. The position of the EL element itself. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the position of the organic EL element at each time, that is, the imaging position. In the display, the width of each period on the time axis is appropriately enlarged or reduced. Further, at the left end of the figure, the arrangement of the printing pixels p1 to p7 to be originally printed on the photosensitive paper 14 is one row corresponding to the red organic EL element 16, the green organic EL element 18 and the blue organic EL element 20 shown on the right side. Only shows. In the above-described VGA printing, the printing pixels p1 to p640 are arranged. In order to move the print head 10 in the sub-scanning direction so that the surface on which the organic EL elements in FIG. 7 are arranged is opposed to the photosensitive paper 14, the organic EL element is moved while moving the red organic EL element 16 to the lower side in the figure. Exposure by the element is performed.

  In the arrangement shown in FIG. 7, the organic EL elements of the respective colors are arranged so as to have an interval of just one pixel. Therefore, when the red organic EL element 16 is located immediately above the print pixel p3, that is, when the image of the red organic EL element 16 is just overlapped with the print pixel p3, the green organic EL element 18 is located on the print pixel p1, The image of light emission overlaps with the print pixel p1. Therefore, in this state, the red organic EL element 16 and the green organic EL element 18 are controlled by the PWM signal Ipwm controlled by the red gradation of the image data of the printing pixel p3 and the green gradation of the image data of the printing pixel p1, respectively. What is necessary is just to make it light-emit continuously. Since the exposure requires a finite time, the total of these continuous exposure times is defined as a period t1. Strictly speaking, since the print head 10 continues to move during this period, the image formation on the photosensitive paper 14 by the red organic EL element 16 and the green organic EL element 18 is shifted from the print pixel p3 or the print pixel p1. Go.

  After the exposure in the period t1, the print head 10 moves to the position where the image formed by the red organic EL element 16 overlaps with the next print pixel p4 without emitting light. In FIG. 8, this time is shown as Δt. As shown in the figure, the image formed by the red organic EL element 16 overlaps with the next print pixel p4, and at the same time, the image formed by the green organic EL element 18 overlaps with the print pixel p2. Then, during the period t2, among the image data of the print pixel p4 and the print pixel p2, the print pixel p4 and the print pixel p2 are continuously exposed and printed with red and green gradations, respectively. When the exposure time is finished, a period Δt is provided in which only the print head 10 is moved again. When the above operation is repeated, for example, when the printing pixel p3 is exposed by the red organic EL element 16 in the period t1, exposed by the green organic EL element 18 in the period t3, and exposed by the blue organic EL element 20 in the period t5, the printing is performed. A printed image of the pixel p3 is completed. In each of the periods t1, t2, t3, t4, and t5, the scanning lines S1 to S3 are sequentially selected in order to cause each color organic EL element to emit light continuously. This operation is the same as when an image is displayed by sequentially selecting scanning lines on a display device or the like.

  FIG. 9 shows an arrangement of organic EL elements in the print head 10 for effectively realizing the present embodiment. The size and interval of the red organic EL element 16 and the like in the scanning direction and the size in the sub-scanning direction are the same as the comparative array shown in FIG. On the other hand, in the arrangement shown in the figure, the distance between the red organic EL element 16 and the green organic EL element 18 and the distance between the green organic EL element 18 and the blue organic EL element 20 are both 40 μm in the sub-scanning direction. Therefore, the size of the print head 10 shown in FIG. 9 in the sub-scanning direction is smaller than the size of the print head 10 shown in FIG. 7 in the sub-scanning direction. Note that the sizes and intervals of the organic EL elements in this figure are examples, and the print head 10 is prepared by appropriately determining them according to the desired size of the print head 10, the accuracy of the moving mechanism of the print head 10, the standard, and the like. It's okay. As described above, the design rule of the print head 10 can be reflected in the control described later by inputting it to the array data input unit 55 in the functional configuration of the printer 100 shown in FIG.

  FIG. 10 schematically shows the operation of the print head 10 having the arrangement shown in FIG. The display method is the same as that shown in FIG. 8 for the operation of the print head 10 having the array to be compared. Therefore, the width of each period on the time axis is appropriately enlarged or reduced.

  In the figure, for example, in a period T2, the image formed by the red organic EL element 16 overlaps with the print pixel p4. However, unlike the case shown in FIG. 8, the image formation by other organic EL elements, that is, the green organic EL element 18 and the blue organic EL element 20, does not overlap any print pixel. This is because, as shown in FIG. 9, the interval between the organic EL elements adjacent in the sub-scanning direction is 40 μm. Therefore, in the period T2, only the red organic EL element 16 is caused to emit light, and only the red gradation exposure of the image data of the print pixel p4 is performed. This is realized by outputting the first selection signal Ssl1 for selecting the scanning line S1 from the scanning line drive timing control circuit 62 in the configuration shown in FIG. When the period T1, which is the exposure period of the red organic EL element 16, ends, the print head 10 is moved until the image formed by the green organic EL element 18 overlaps the print pixel p3. During this period ΔT, none of the organic EL elements emits light. The value of the period ΔT is calculated in the drive control circuit 56 based on the moving speed of the print head 10 and the interval between the organic EL elements, and is included in the scan control signal Scnt and output to the scan line drive circuit 58. Based on the result, the first dummy signal Sdm1 is selected from the outputs from the scanning line drive timing control circuit 62, so that no scanning line S is selected during the period ΔT.

  When the image formation by the green organic EL element 18 overlaps with the print pixel p3 after the period ΔT, green gradation exposure is performed by causing the green organic EL element 18 to emit light in the image data of the print pixel p3 in the period T3. . When the exposure of the green organic EL element 18 to the print pixel p3 is completed, the image formation by the blue organic EL element 20 is overlapped with the print pixel p2 after a period ΔT during which light emission is not performed again. Then, a period T4 in which only blue gradation exposure is performed in the image data of the print pixel p2 by the blue organic EL element 20 is started. After the period T4, as described with reference to FIG. 8, all the organic EL elements emit light during the period ΔT ′, which is a period until the image formed by the red organic EL element 16 overlaps the next print pixel p5. Without moving the print head 10.

  FIG. 11 is a time chart showing the waveform of a signal output from the scanning line drive timing control circuit 62 in order to perform the drive control of the scanning lines S1 to S3 of the print head 10 having the arrangement shown in FIG. It is a chart. The figure controls the first selection signal Ssl1 for selecting the scanning line S1 corresponding to the red organic EL element 16 from the top, and the non-selection period from the end of light emission of the red organic EL element 16 to the start of light emission of the green organic EL element 18. First dummy signal Sdm1 to be performed, second selection signal Ssl2 for selecting the scanning line S2 corresponding to the green organic EL element 18, non-selection from the end of light emission of the green organic EL element 18 to the start of light emission of the blue organic EL element 20 From the second dummy signal Sdm2 for controlling the period, the third selection signal Ssl3 for selecting the scanning line S3 corresponding to the blue organic EL element 20, and from the light emission end of the blue organic EL element 20 to the light emission start of the red organic EL element 16 The output waveforms of the third dummy signal Sdm3 for controlling the non-selection period are respectively shown. Here, it is assumed that the selection signals Ssl1 to Ssl3 are in a low state, the corresponding scanning lines S1 to S3 are selected, and the potential becomes 0V. The reference numerals of the respective periods correspond to those shown in FIG. 10, and the width thereof is appropriately enlarged and reduced for ease of viewing, as in FIG.

  As shown in FIG. 10, since the image formed by the red organic EL element 16 overlaps with the print pixel p4 in the period T2, the pixel is exposed with red gradation. Therefore, the first selection signal Ssl1 becomes low and the corresponding scanning line S1 is selected. When the exposure of the print pixel p4 by the red organic EL element 16 is completed, the first selection signal Ssl1 becomes high, and instead, the first dummy signal Sdm1 becomes low. As shown in FIG. 6, since the dummy signals Sdm1 to Sdm3 are input to the ground potential, no scanning line S is selected as a result. After a period ΔT, when the image formed by the green organic EL element 18 overlaps the print pixel p3, the first dummy signal Sdm1 becomes high, and the second selection is performed to select the scanning line S2 instead. Signal Ssl2 goes low. When the exposure of the period T3 by the green organic EL element 18 is completed, the second dummy signal Sdm2 becomes low instead of the second selection signal Ssl2. As described above, the scanning line S is not selected in the period ΔT. Similarly, when the image formed by the blue organic EL element 20 overlaps the print pixel p2, the third selection signal Ssl3 becomes low instead of the second dummy signal Sdm2, and the scanning line S3 is selected. When the exposure of the blue organic EL element 20 is completed after the period T4, the third dummy signal Sdm3 is low during the period ΔT ′ until the image formation of the red organic EL element 16 overlaps the print pixel p5. The scanning line S is not selected. By repeating the above operation, each print pixel is exposed to three colors with the same efficiency as that of printing with the print head 10 having the wide array of organic EL elements shown in FIG. Can be completed.

  According to the present embodiment described above, even when the interval between the organic EL elements in the print head is different from the length of the side of the print pixel, the scanning lines for emitting light of the organic EL elements of the respective colors are discontinuously selected. By adjusting, exposure can be performed at an appropriate position. This embodiment can be easily realized because the function of the register used for selecting the scanning line can be used as it is for the timing adjustment. Therefore, the size of the print head can be easily reduced. Further, by narrowing the interval between the organic EL elements, the diameter of the gradient index lens can be reduced and the imaging distance can be reduced. This can reduce the distance between the print head and the photosensitive paper. As a result, it is possible to effectively reduce the size of the printer. By reducing the size of the printer, the portability of the printer can be improved. In addition, since the diameter of the gradient index lens can be reduced, unevenness in the exposure amount due to the gradient index lens can be suppressed.

  Furthermore, since the interval between the organic EL elements can be set arbitrarily in this embodiment, it is easy to cope with changes in the print head design rules in consideration of changes in the standard and the size of the mounted equipment. is there. In addition, when the exposure of each color is continuously performed with the arrangement shown in FIG. 7, it takes time until the light emission of the organic EL element for the third color starts, and a shift between the image formation by the organic EL element and the print pixel occurs. Although it is easy to adjust the light emission timing for each color in this embodiment, the shift width is minimized. Moreover, since an organic EL element is used as a light source, power consumption can be reduced. In addition, since an organic EL element is used as a light source, the waiting time until light emission is shortened, and the printing operation can be performed at high speed.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the present embodiment, the print head 10 includes a red organic EL element 16, a green organic EL element 18, and a blue organic EL element 20. However, the present invention is not limited to this, and for example, an LED, a VFD, or an inorganic EL element corresponding to each color may be used as long as the amount of light necessary for printing can be obtained. Thereby, an optimum light emitting element can be selected in view of the object to be printed, cost, and the like, and the same effect as described in the present embodiment can be obtained.

  In this embodiment, the print head 10 is applied to the printer 100. However, the print head 10 may be introduced into an apparatus such as a copier. That is, the print head 10 can be applied to form a latent image on the toner. Even in this case, the same effects as those described in this embodiment, such as downsizing of the apparatus, can be obtained.

  In this embodiment, the non-selection period following the selection period of the scanning line S is controlled by the output of the dummy signals Sdm1 to Sdm3 from the shift register. However, the present invention is not limited to this, and a timer (not shown) may be provided in the control unit 50, and the scanning line selection / non-selection period may be managed by the timer. In this case as well, effects similar to those described in this embodiment, such as downsizing the printer, can be obtained with a relatively low introduction barrier.

1 is a diagram illustrating a configuration of a printer according to an embodiment. 2 is a side view of the printer according to the present embodiment. FIG. It is a top view of the printer according to the present embodiment. It is a figure which shows typically a mode that light emission of an organic EL element forms an image in this Embodiment. FIG. 2 is a block diagram illustrating a configuration of a printer according to the present embodiment. It is a figure which shows the structure of the print head and control part in this Embodiment. It is a figure which shows the arrangement | sequence of the organic EL element in the print head which should become the comparison object of this Embodiment. It is a figure which shows typically operation | movement of the print head which has the arrangement | sequence shown in FIG. It is a figure which shows an example of the arrangement | sequence of the organic EL element with which the print head in this Embodiment was equipped. It is a figure which shows typically operation | movement of the print head which has the arrangement | sequence shown in FIG. It is a figure which shows the time chart of each signal waveform output from the scanning-line drive timing control circuit in this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Print head, 12 Lens array, 14 Photosensitive paper, 16 Red organic EL element, 18 Green organic EL element, 20 Blue organic EL element, 22 Gradient index lens, 24 support | pillar, 50 Control part, 52 Motor, 54 Image data Input unit, 55 array data input unit, 56 drive control circuit, 58 scan line drive circuit, 60 data line drive circuit, 62 scan line drive timing control circuit, 64 pulse control circuit, 100 printer.

Claims (9)

A plurality of lines formed in the scanning line direction are provided with light emitting elements having emission colors of 1 to n, and each pixel region on the printing object is sequentially moved to 1 to n by relative movement in the sub scanning direction with respect to the printing object. A print head driving method for forming a color image in units of lines on the object to be printed by causing light emitting elements of colors to face each other and causing each color to emit light according to a pixel value,
The distance d between the light emitting elements in the sub-scanning direction on the print head is set shorter than the length p in the sub-scanning direction of the pixels on the print object, and any line on the print head is When a certain line of interest on the print object is opposed, the pixels included in the line of interest are printed, and then printing is performed until another line on the print head faces another line of interest on the print object. A method of driving a print head, wherein a dummy time is set.   The method of driving a print head according to claim 1, wherein the light emission colors of the light emitting elements included in one line on the print head are the same.   The printing dummy time is a time from the end of the selection period for driving the organic EL element having the same emission color to the start of the selection period for driving the organic EL element having another emission color. The method of driving a print head according to claim 2. A print head including light emitting elements having emission colors of 1 to n in a plurality of lines formed in the scanning line direction;
A drive unit for generating a relative movement in the sub-scanning direction between the print head and the printing object;
1 to n color light emitting elements are sequentially opposed to each pixel area on the print object via the driving unit, and each color is emitted according to a pixel value, and a color image is displayed in line units on the print object. A control unit for controlling the drive unit and the print head so as to form,
The control unit, when any line on the print head faces a certain line of interest on the print object, causes the organic EL elements included in the line on the print head facing the line of interest to emit light, Next, a dummy time is provided until another line on the print head faces another line of interest on the print object.     The printer according to claim 4, wherein a distance d between the light emitting elements in the sub-scanning direction of the print head is shorter than a length p of the pixel on the print object in the sub-scanning direction.   The printer according to claim 4, wherein the light emitting elements included in one line on the print head have the same light emission color.   The dummy time is a time from the end of the selection period for driving the organic EL elements having the same emission color to the start of the selection period for driving the organic EL element having another emission color. The printer according to claim 6. An array data input unit for inputting a distance d between light emitting elements in the sub-scanning direction of the print head;
The printer according to claim 4, wherein the control unit determines the dummy time based on data input by the array data input unit. A scanning line driving circuit for driving a plurality of scanning lines corresponding to a plurality of lines including light emitting elements having 1 to n emission colors on the print head;
Scanning corresponding to a line on the print head when any line on the print head faces a certain target line on the print object due to the relative movement of the print head and the print object in the sub-scanning direction A control circuit for controlling the scanning line driving circuit to drive a line and then to provide a dummy time until another line on the print head faces another line of interest on the print object;
Is integrated on a single semiconductor substrate.

Images