Image forming apparatus

Abstract

An image forming apparatus according to an embodiment includes a print head, a detection unit, and a controller. The print head includes one or more arrays of light emitting elements each of which is composed of a plurality of light emitting elements. The detection unit detects a light emitting time of the print head in accordance with image data. The controller controls a time interval until a start of printing corresponding to second image data following first image data, based on a detection result of the light emitting time corresponding to the first image data.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to an image forming apparatus. BACKGROUND

[0002] Electronic photograph printing machines (hereinafter referred to as printers) equipped with print heads are widely spread. The print head includes a plurality of light emitting elements such as LEDs (Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes). For example, light emitting elements corresponding to 15,400 pixels are provided on the print head, the arrangement of the light emitting elements corresponds to a main scanning direction, and a direction orthogonal to the main scanning direction corresponds to a sub scanning direction. The printer exposes a photosensitive drum with light emitted from the plurality of light emitting elements, and prints an image corresponding to a latent image formed on the photosensitive drum on a sheet as a recording paper. SUMMARY

[0003] Embodiments relate to an image forming apparatus including: a print head including one or more light emitting element arrays each composed of a plurality of light emitting elements; a detection section that detects a light emitting time of the print head that emits light in accordance with image data; and a controller that controls a time interval until printing starts in accordance with second image data after first image data based on a detection result of the light emitting time corresponding to the first image data.

[0004] Embodiments relate to an image forming apparatus including: a plurality of print heads corresponding to respective colors, each print head including one or more light emitting element arrays each composed of a plurality of light emitting elements; a detection section that detects a light emitting time of the print head that emits light in accordance with image data; and a controller that controls a time interval until printing starts in accordance with second image data after first image data corresponding to each color based on a detection result of the light emitting time corresponding to the first image data corresponding to each color. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 is a view showing an example of a positional relationship between a photosensitive drum and a print head applied in the image forming apparatuses according to the first and second embodiments.

[0006] Figure 2 is a view showing an example of a transparent substrate constituting the print head according to the first and second embodiments.

[0007] Figure 3 is a view showing an example of a layout of a light emitting element and a drive circuit of the print head according to the first and second embodiments.

[0008] Figure 4This is a diagram showing an example of a cross-section of the transparent substrate of the printhead according to the first and second embodiments.

[0009] Figure 5 This is a diagram illustrating an example of the connection between the control board and the printhead according to the first and second embodiments.

[0010] Figure 6 This is a diagram illustrating an example of the structure of the light-emitting element of the printhead according to the first and second embodiments.

[0011] Figure 7 This is a diagram illustrating an example of the circuit structure involved in the first and second embodiments, which includes a DRV circuit for driving a light-emitting element, a light-emitting element that emits light through the DRV circuit, and a switch for switching the supply of current to the light-emitting element.

[0012] Figure 8 This is a diagram illustrating an example of the head circuit block of the printhead according to the first and second embodiments.

[0013] Figure 9 This is a diagram illustrating an example of an image forming apparatus employing a printhead according to the first and second embodiments.

[0014] Figure 10 This is a block diagram illustrating an example of a control system for an image forming apparatus according to the first embodiment.

[0015] Figure 11 This is a flowchart illustrating an example of controlling the time interval from the start of printing by the image forming apparatus according to the first embodiment.

[0016] Figure 12 This is a block diagram illustrating an example of a control system for an image forming apparatus according to the second embodiment.

[0017] Figure 13 This is a diagram illustrating an example of a time setting table applied during the time interval from the start of printing to the control of the image forming apparatus according to the second embodiment.

[0018] Figure 14 This is a flowchart illustrating an example of controlling the time interval from the start of printing by the image forming apparatus according to the second embodiment.

[0019] Figure 15 It is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the light emission time of the light emission element of the printhead, and it is a graph illustrating a longer light emission time and its recovery time.

[0020] Figure 16It is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the light emission time of the light emission element of the printhead, and it is a graph illustrating a shorter light emission time and its recovery time.

[0021] Figure 17 This is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the light emission time and current value of the light-emitting element of the printhead.

[0022] Figure 18 This is a diagram illustrating an example of the effect of reduced light emission time and light intensity of the light-emitting element when the time interval control up to the start of printing involved in the first or second embodiment is not applied.

[0023] Figure 19 This is a diagram illustrating an example of the effect of the decrease in the emission time and light intensity of the light-emitting element when the time interval control up to the start of printing involved in the first or second embodiment is applied.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1…Print head; 10…Light-emitting unit; 11…Transparent substrate; 12…Bar lens array; 13…Light-emitting element array; 14…Circuit array; 16…Connector; 17…Photosensitive drum; 100…Image forming apparatus; 101…Control board; 102…Power supply unit; 103…Transfer belt; 104…Wire harness; 118…Transfer roller pair; 119…Fixing unit; 120…Fixing roller; 121…Gap spacer; 131…Light-emitting element; 140…Drive circuit; 142…Capacitor; 144…Switch; 145…Wiring; 151…Light-emitting element address counter; 152… Decoder; 153… Conversion circuit; 154… Light intensity correction memory; 155… Indicator circuit; 171… Image reading unit; 172… Image processing unit; 173… Image forming unit; 174… Controller; 177… Non-volatile memory; 178… Communication interface; 179… Control panel; 181… Color offset sensor; 182… Mechanical control driver; 183… Light emission controller; 184… Image data bus; 201, 202… Paper; 1001, 1002, 1003, 1004… Printhead; 1011, 1012, 1013… 1014…Light-emitting unit; 1021, 1022, 1023, 1024…Image forming unit; 1101…Reference plane; 1102…Sealing glass; 1121, 1122, 1123, 1124…Charger; 1131, 1132, 1133, 1134…Developer; 1141, 1142, 1143, 1144…Transfer roller; 1161, 1162, 1163, 1164…Cleaner; 1171, 1172…Paper tray; 1201, 1202, 1203, 1204…Rod lens array; 1301… First light-emitting element array; 1302…Second light-emitting element array; 1311…Hole transport layer; 1312…Light-emitting layer; 1313…Electron transport layer; 1321…Electrode (+); 1322…Insulating layer; 1323…Electrode (-); 1401…First drive circuit array; 1402…Second drive circuit array; 1701, 1702, 1703, 1704…Photosensitive drum; 1741…Time setting unit; 1742…Current (voltage) setting unit; 1801, 1802, 1803, 1804…Page memory; 1831…Light emission time detection unit. Detailed Implementation

[0026] Hereinafter, an example of an image forming apparatus according to the first and second embodiments will be described using the accompanying drawings. In each drawing, the same reference numerals are used to denote the same structures. The image forming apparatus is a printer, copier, or multi-function device (MFP). In the first and second embodiments, an image forming apparatus equivalent to an MFP will be described.

[0027] First and second embodiments: Structure of the print head

[0028] Reference Figures 1-8 An example of the structure of the printhead used in the image forming apparatus according to the first and second embodiments will be described.

[0029] Figure 1 This is a diagram illustrating an example of the positional relationship between the photosensitive drum and the printhead used in the image forming apparatus according to the first and second embodiments.

[0030] Image forming apparatus includes Figure 1 The photosensitive drum 17 and printhead 1 are shown. The printhead 1 is configured opposite to the photosensitive drum 17.

[0031] Photosensitive drum 17 edge Figure 1 The direction of rotation is indicated by the arrow. The rotation direction of the photosensitive drum 17 is called the sub-scanning direction, and the direction orthogonal to the sub-scanning direction is called the main scanning direction. The photosensitive drum 17 is uniformly charged by a charge carrier and exposed to light from the printhead 1, thereby lowering the potential of its exposed portion. In other words, the image forming apparatus controls the light emission of the printhead 1 to form an electrostatic latent image on the photosensitive drum 17. Controlling the light emission of the printhead 1 refers to controlling the timing of the light emission and extinguishing (non-light emission) of the printhead 1.

[0032] The printhead 1 includes a light-emitting part 10 and a rod-shaped lens array 12. The light-emitting part 10 includes a transparent substrate 11. For example, the transparent substrate 11 is a light-transmitting glass substrate. A plurality of light-emitting element arrays 13, consisting of a plurality of light-emitting elements of LEDs or OLEDs, are formed on the transparent substrate 11.

[0033] like Figure 1 As shown, the first light-emitting element array 1301 and the second light-emitting element array 1302 are arranged in parallel columns. The rod lens array 12 converges the light from each light-emitting element 131 in both columns onto the photosensitive drum 17. Thus, image lines corresponding to the emission of the light-emitting elements 131 are formed on the photosensitive drum 17. It should be noted that although the first and second embodiments describe the case where the print head 1 includes multiple light-emitting element arrays 13, it can also be assumed that the print head 1 includes a single light-emitting element array 13. Furthermore, the print head 1 includes a gap spacer 121. The gap spacer 121 maintains a predetermined distance between the transparent substrate 11 and the photosensitive drum 17.

[0034] Figure 2 This is a diagram illustrating an example of a transparent substrate constituting a printhead according to the first and second embodiments.

[0035] like Figure 2As shown, two light-emitting element arrays 13 (a first light-emitting element array 1301 and a second light-emitting element array 1302) are formed in the central portion of the transparent substrate 11 along the length direction of the transparent substrate 11. Near the light-emitting element arrays 13, drive circuit arrays 14 (a first drive circuit array 1401 and a second drive circuit array 1402) are formed for driving each light-emitting element (making it emit light). Hereinafter, "drive" will be denoted as "DRV". Figure 2 In this configuration, DRV circuit columns 14 for driving the light-emitting elements (making them emit light) are arranged on both sides of the two light-emitting element arrays 13, but the DRV circuit columns 14 can also be arranged on one side.

[0036] An IC (Integrated Circuit) 15 is disposed at one end of the transparent substrate 11. Additionally, the transparent substrate 11 includes a connector 16. The connector 16 is electrically connected to the printhead 1 and the control system of a printer, copier, or multifunction device. This connection enables power supply, printhead control, and image data transmission. A substrate is mounted on the transparent substrate 11 to seal the light-emitting element array 13, DRV circuit array 14, etc., preventing them from contacting the outside air. Furthermore, when it is difficult to mount the connector onto the transparent substrate, an FPC (Flexible Printed Circuit) can be connected to the transparent substrate and electrically connected to the control system.

[0037] Figure 3 This is a diagram illustrating an example of the layout of the light-emitting element and driving circuit of the printhead according to the first and second embodiments.

[0038] like Figure 3 As shown, the light-emitting part 10 of the printhead 1 includes a light-emitting element array 13 in which a plurality of light-emitting elements 131 are arranged, and a drive circuit column 14 in which a plurality of drive circuits 140 are arranged. The drive circuits 140 cause the light-emitting elements 131 connected to each other to emit light based on signals from wiring 145 (equivalent to the sample / hold signal 21, light emission level signal 22, light emission on signal 26 and light emission off signal 27 described later).

[0039] Figure 4 This is a diagram showing an example of a cross-section of the transparent substrate of the printhead according to the first and second embodiments.

[0040] like Figure 4As shown, the light-emitting portion 10 of the printhead 1 includes a plurality of light-emitting elements 131, a plurality of driving circuits 140, and wiring 145 arranged opposite to the reference surface 1101 of the transparent substrate 11. Additionally, the light-emitting portion 10 includes a sealing glass 1102. The plurality of light-emitting elements 131, the plurality of driving circuits 140, and the wiring 145 are arranged within the space surrounded by the transparent substrate 11 and the sealing glass 1102. Light from the light-emitting elements 131 passes through the transparent substrate 11 and illuminates the photosensitive drum 17.

[0041] Figure 5 This is a diagram illustrating an example of the connection between the control board and the printhead according to the first and second embodiments.

[0042] like Figure 5 As shown, the image forming apparatus includes a control board 101, which includes a power supply unit 102. The power supply unit 102 supplies a power supply voltage VDDa to both ends of the print head 1 via a wiring harness 104. The relationship between the number of light-emitting elements 131 and the light intensity reduction rate will be explained later.

[0043] Figure 6 This is a diagram illustrating an example of the structure of the light-emitting element of the printhead according to the first and second embodiments. It should be noted that, in Figure 6 In the original text, the sealing glass 1102 was omitted.

[0044] For example, the light-emitting element 131 is an organic EL (Organic Electroluminescence). Figure 6 As shown, the light-emitting element 131 includes a hole transport layer 1311, a light-emitting layer 1312, and an electron transport layer 1313, and is in contact with and sandwiched between electrodes (+) 1321 and (-) 1323, which are insulated by an insulating layer 1322. For example, the light-emitting layer 1312 is an organic EL. The electrode (-) 1323 has a structure that reflects the light emitted by the light-emitting layer 1312. Through this structure, the light emitted by the light-emitting layer 1312 is output to the transparent substrate 11 side.

[0045] Figure 7 This is a diagram illustrating an example of the circuit structure involved in the first and second embodiments, which includes a DRV circuit for driving a light-emitting element, a light-emitting element that emits light through the DRV circuit, and a switch for switching the supply of current to the light-emitting element.

[0046] The DRV circuit is constructed using low-temperature polycrystalline silicon thin-film transistors (TFTs). When the light intensity of the light-emitting element 131 connected to the DRV circuit 140 changes, the sample / hold signal 21 becomes "L" level (low level). When the sample / hold signal 21 becomes "L", the voltage of the capacitor 142 changes according to the voltage of the light-emitting level signal 22. That is, the capacitor 142 maintains a potential that changes according to the correction data described later.

[0047] When the sample / hold signal 21 becomes "H" (high level), the voltage of capacitor 142 is maintained. Even if the voltage of the light emission level signal 22 changes, the voltage level of capacitor 142 remains unchanged. A current corresponding to the voltage maintained in capacitor 142 flows through the light-emitting element 131, which is connected to signal line I of the DRV circuit 140. That is, the light-emitting element 131 emits light according to the potential of the capacitor. A predetermined light-emitting element 131 can be selected from the plurality of light-emitting elements 131 included in the light-emitting element array 13 based on the sample / hold signal 21, and the light emission intensity can be determined and maintained based on the light emission level signal 22.

[0048] Additionally, switch 144 is connected to DRV circuit 140. Switch 144 toggles the supply of current to the light-emitting element 131 (current supply on or off). When switch 144 is closed via the light-on signal 26, current flows through the light-emitting element 131, and the light-emitting element 131 emits light. When switch 144 is open via the light-off signal 27, current does not flow through the light-emitting element 131, and the light-emitting element 131 is off.

[0049] Figure 8 This is a diagram illustrating an example of the head circuit block of the printhead according to the first and second embodiments.

[0050] like Figure 8 As shown, the light-emitting unit 10 has a head circuit block including IC 15. IC 15 includes a light-emitting element address counter 151, a decoder 152, a D / A (digital-to-analog) conversion circuit 153, a light intensity correction memory 154, and a light emission on / off indicator circuit 155, etc. These light-emitting element address counter 151, decoder 152, D / A conversion circuit 153, light intensity correction memory 154, and light emission on / off indicator circuit 155 supply the aforementioned sample / hold signal 21, light emission level signal 22, light emission on signal 26, and light emission off signal 27 to the DRV circuit 140, etc.

[0051] like Figure 8As shown, light-emitting elements 131 are connected to each of the DRV circuits 140. Each individual DRV circuit 140 supplies a separate current to each individual light-emitting element 131. A D / A conversion circuit 153 is connected to a first DRV circuit column 1401 connected to the first light-emitting element array 1301. Similarly, the D / A conversion circuit 153 is connected to a second DRV circuit column 1402 connected to the second light-emitting element array 1302.

[0052] The light intensity correction memory 154 stores correction data corresponding to the current flowing through each light-emitting element 131. The horizontal synchronization signal 24 and the image data write clock C are input to the light-emitting element address counter 151 via connector 16. The horizontal synchronization signal 24 resets the count value of the light-emitting element address counter 151. The light-emitting element address counter 151 outputs a light-emitting element address signal 25 synchronized with the image data write clock C.

[0053] Image data 31 and the light-emitting element address signal 25 output from the light-emitting element address counter 151 are input to the light intensity correction memory 154. The light-emitting element address signal 25 output from the light-emitting element address counter 151 is input to the decoder 152. The decoder 152 outputs a sample / hold signal 21 corresponding to the light-emitting element 131 specified by the light-emitting element address signal 25. The light intensity correction memory 154 outputs correction data 33 corresponding to the light-emitting element 131 specified by the light-emitting element address signal 25. The correction data 33 output from the light intensity correction memory 154 is input to the D / A conversion circuit 153. The D / A conversion circuit 153 outputs a voltage of the light emission level signal 22 based on the correction data 33. The voltage of the light emission level signal 22 is sampled and held in capacitor 142 of the DRV circuit 140. Sample and hold are performed periodically on capacitor 142.

[0054] First and second embodiments: Structure of the image forming apparatus

[0055] Figure 9 This is a diagram illustrating an example of an image forming apparatus employing a printhead according to the first and second embodiments. Figure 9 This is an example of a quadruple tandem color image forming apparatus, but printhead 1 can also be applied to monochrome image forming apparatuses.

[0056] like Figure 9As shown, for example, the image forming apparatus 100 includes an image forming unit 1021 for forming a yellow (Y) image, an image forming unit 1022 for forming a magenta (M) image, an image forming unit 1023 for forming a cyan (C) image, and an image forming unit 1024 for forming a black (K) image. The image forming units 1021, 1022, 1023, and 1024 form yellow, cyan, magenta, and black images, respectively, and transfer them onto a transfer belt 103. Thus, a full-color image is formed on the transfer belt 103.

[0057] The image forming unit 1021, which forms a yellow (Y) image, includes a printhead 1001, which includes a light-emitting unit 1011 and a rod lens array 1201. Furthermore, the image forming unit 1021 includes a charged charger 1121, the printhead 1001, a developer 1131, a transfer roller 1141, and a cleaner 1161 around the photosensitive drum 1701. The printhead 1001 corresponds to printhead 1, the light-emitting unit 1011 corresponds to light-emitting unit 10, the rod lens array 1201 corresponds to rod lens array 12, and the photosensitive drum 1701 corresponds to photosensitive drum 17; further descriptions of these components are omitted.

[0058] The image forming unit 1022, which forms a magenta (M) image, includes a printhead 1002, which includes a light-emitting unit 1012 and a rod lens array 1202. Furthermore, the image forming unit 1022 includes a charged charger 1122, a printhead 1002, a developer 1132, a transfer roller 1142, and a cleaner 1162 around a photosensitive drum 1702. The printhead 1002 corresponds to the printhead 1, the light-emitting unit 1012 corresponds to the light-emitting unit 10, the rod lens array 1202 corresponds to the rod lens array 12, and the photosensitive drum 1702 corresponds to the photosensitive drum 17; further descriptions of these components are omitted.

[0059] The image forming unit 1023, which forms a cyan (C) image, includes a printhead 1003, which includes a light-emitting unit 1013 and a rod lens array 1203. Furthermore, the image forming unit 1023 includes a charged charger 1123, the printhead 1003, a developer 1133, a transfer roller 1143, and a cleaner 1163 around the photosensitive drum 1703. The printhead 1003 corresponds to the printhead 1, the light-emitting unit 1013 corresponds to the light-emitting unit 10, the rod lens array 1203 corresponds to the rod lens array 12, and the photosensitive drum 1703 corresponds to the photosensitive drum 17; further descriptions of these components are omitted.

[0060] The image forming unit 1024, which forms a black (K) image, includes a printhead 1004, which includes a light-emitting unit 1014 and a rod lens array 1204. Furthermore, the image forming unit 1024 includes a charged charger 1124, the printhead 1004, a developer 1134, a transfer roller 1144, and a cleaner 1164 around a photosensitive drum 1704. The printhead 1004 corresponds to printhead 1, the light-emitting unit 1014 corresponds to light-emitting unit 10, the rod lens array 1204 corresponds to rod lens array 12, and the photosensitive drum 1704 corresponds to photosensitive drum 17; further descriptions of these components are omitted.

[0061] Chargers 1121, 1122, 1123, and 1124 uniformly charge photosensitive drums 1701, 1112, 1113, and 1114, respectively. Printheads 1001, 1002, 1003, and 1004 expose photosensitive drums 1701, 1702, 1703, and 1704 by the light emission of light-emitting elements 131 in the first light-emitting element array 1301 and the second light-emitting element array 1302, forming electrostatic latent images on the photosensitive drums 1701, 1702, 1703, and 1704. Developers 1131, 1132, 1133, and 1134 attach (develop) yellow toner, magenta toner, cyan toner, and black toner to the electrostatic latent image portions of the photosensitive drums 1701, 1702, 1703, and 1704, respectively.

[0062] Transfer rollers 1141, 1142, 1143, and 1144 transfer the toner image developed on photosensitive drums 1701, 1702, 1703, and 1704 onto transfer belt 103. Cleaners 1161, 1162, 1163, and 1164 clean any remaining toner that was not transferred by photosensitive drums 1701, 1702, 1703, and 1704, and prepare the system for the next image formation.

[0063] The first-size (small-size) paper (recording medium) 201 is housed in the paper tray 1171, which serves as a paper supply unit. The second-size (large-size) paper (recording medium) 202 is housed in the paper tray 1172, which serves as a paper supply unit.

[0064] The toner image is transferred from the transfer belt 103 to the paper 201 or 202 taken from the paper tray 1171 or 1172 via the transfer roller pair 118, which serves as a transfer unit. The paper 201 or 202 with the toner image transferred is heated and pressed by the fixing roller 120 of the fixing unit 119. The toner image is firmly fixed onto the paper 201 or 202 by the heating and pressing of the fixing roller 120. The image forming operation is performed continuously by repeating the above processing steps.

[0065] First Implementation Method: Structure of the Control System

[0066] Figure 10 This is a block diagram illustrating an example of a control system for an image forming apparatus according to the first embodiment.

[0067] like Figure 10 As shown, the image forming apparatus 100 includes a control board 101. The control board 101 includes a power supply unit 102, an image reading unit 171, an image processing unit 172, an image forming unit 173, a controller 174, a ROM (Read Only Memory) 175, a RAM (Random Access Memory) 176, a non-volatile memory 177, a communication I / F 178, a control panel 179, page memories 1801, 1802, 1803, and 1804, a light-emitting controller 183, and an image data bus 184. Furthermore, the image forming apparatus 100 includes a color shift sensor 181 and a mechanical control driver 182. Additionally, the image forming unit 173 includes image forming units 1021, 1022, 1023, and 1024. The power supply unit 102 supplies driving voltage to both ends of the printheads 1001, 1002, 1003, and 1004 of the image forming unit 173 via the wiring harness 104.

[0068] ROM175, RAM176, non-volatile memory177, communication I / F (communication interface)178, control panel179, color offset sensor181, mechanical control driver182, and light-emitting controller183 are connected to controller174.

[0069] Image reading unit 171, image processing unit 172, controller 174, and page memories 1801, 1802, 1803, and 1804 are connected to image data bus 184. Page memories 1801, 1802, 1803, and 1804 output Y, M, C, or K image data 31, respectively. Page memories 1801, 1802, 1803, and 1804 are connected to light-emitting controller 183 and input Y image data 31 from page memory 1801, M image data 31 from page memory 1802, C image data 31 from page memory 1803, and K image data 31 from page memory 1804. Corresponding to each image data 31, printheads 1001, 1002, 1003, and 1004 are connected to light-emitting controller 183. The light-emitting controller 183 inputs each image data 31 into the print head 1001, 1002, 1003 or 1004 corresponding to each image data 31.

[0070] The controller 174 consists of one or more processors and controls actions such as image reading, image processing, and image formation according to various programs stored in at least one of the ROM 175 and non-volatile memory 177.

[0071] Additionally, the controller 174 inputs image data of the test pattern into page memories 1801, 1802, 1803, and 1804, and forms the test pattern. The color offset sensor 181 detects the test pattern formed on the transfer belt 103 and outputs a detection signal to the controller 174. The controller 174 can identify the positional relationship of each color in the test pattern from the input of the color offset sensor 181. Furthermore, the controller 174 selects the paper tray 1171 or 1172 for feeding the paper used to form the image via the mechanical control driver 182.

[0072] Additionally, the controller 174 includes a time setting unit 1741. The time setting unit 1741 controls the number of pages printed per unit time based on the detection results of the emission time according to the image data. For example, the time setting unit 1741 controls the time interval from the end of printing corresponding to the first image data to the start of printing corresponding to the second image data following the first image data, based on the detection results of the emission time corresponding to the first image data. When the light-emitting element 131 emits light based on the first image data, the time setting unit 1741 controls the time interval up to the start of printing corresponding to the second image data based on the longest emission time detected for each light-emitting element 131. In the case of color printing, the time setting unit 1741 controls the time interval up to the start of printing corresponding to the second image data based on the longest emission time detected for each light-emitting element 131 included in the printheads 1001, 1002, 1003, and 1004.

[0073] The light intensity of the light-emitting element 131 decreases according to the light emission time (controlled by the characteristics of the TFT (thin-film transistor) 143 built into the DRV circuit 140), and the decrease in light intensity during light emission recovers according to the non-light emission time. That is, with respect to the light-emitting element 131, the light intensity decreases as the light emission time increases, and the decrease in light intensity during light emission is recovered as the non-light emission time increases. By providing the light-emitting element 131 with a non-light emission time of a certain duration, the decrease in light intensity during light emission can be sufficiently recovered. To prevent image quality degradation due to the characteristics of the light-emitting element 131 and the DRV circuit 140, the controller 174 controls the number of prints per unit time based on the light emission time. In other words, if the light emission time based on the first image data is long, the controller 174 delays the start of printing based on the second image data to recover the decrease in light intensity of the light-emitting element 131.

[0074] The ROM175 stores various programs required for controlling the controller 174. These programs include a printhead illumination control program. This program controls the timing of illumination and de-illumination (non-illumination) based on image data. Additionally, the programs include a timing control program that controls the number of pages printed per unit time. For example, the timing control program controls the time interval from the end of printing corresponding to the first image data to the start of printing corresponding to the second image data following the first image data, based on the detection result of the illumination time corresponding to the first image data.

[0075] RAM 176 temporarily stores data required for control of controller 174. Non-volatile memory 177 stores part or all of various programs and various parameters.

[0076] The mechanical control drive 182 controls the operation of motors and other components required for printing, according to the instructions of the controller 174. The communication I / F 178 outputs various information to the outside and inputs various information from the outside. For example, the communication I / F 178 acquires image data including multiple image lines. The image forming apparatus 100 prints the image data acquired via the communication I / F 178 using its printing function. The control panel 179 accepts operation input from users and service personnel.

[0077] Image reading unit 171 optically reads the image of the original document, acquires image data including multiple image lines, and outputs it to image processing unit 172. Image processing unit 172 performs various image processing operations, such as correction, on image data input via communication I / F 178 or image data from image reading unit 171. Page memories 1801, 1802, 1803, and 1804 store the image data processed by image processing unit 172. Controller 174 edits the image data in page memories 1801, 1802, 1803, and 1804 to match the print position and print head. Image forming unit 173 forms an image based on the image data stored in page memories 1801, 1802, 1803, and 1804. That is, image forming unit 173 forms an image based on the emission (emitting and extinguishing states) of each light-emitting element 131 corresponding to the image data.

[0078] The light-emitting controller 183 is composed of one or more processors, and controls the light emission of the light-emitting element 131 based on image data according to various programs stored in at least one of the ROM 175 and the non-volatile memory 177. The light-emitting controller 183 includes a light emission time detection unit 1831.

[0079] The emission time detection unit 1831 detects the emission time of the print head 1 that emits light based on image data and notifies the controller 174 of the emission time information 28. In other words, the emission time detection unit 1831 detects the emission time of the print head 1 that emits light for printing a first image (one page image) based on image data. For example, the emission time detection unit 1831 detects the emission time of each light-emitting element 131 based on image data and outputs the longest emission time as the detection result. In the case of color printing, the emission time detection unit 1831 detects the emission time of each light-emitting element 131 contained in print heads 1001, 1002, 1003, and 1004 based on image data and outputs the longest emission time as the detection result.

[0080] First implementation method: Controlling the time interval until printing begins

[0081] Figure 11 This is a flowchart illustrating an example of controlling the time interval from the start of printing by the image forming apparatus according to the first embodiment.

[0082] Communication interface 178 receives first image data and second image data following the first image data, and outputs the received first and second image data. Alternatively, image reading unit 171 reads the first original image and the second original image following the first original image, and outputs the read first and second image data. In the case of continuous printing or continuous copying, sometimes the first image data and the second image data are the same.

[0083] The controller 174 begins feeding paper 201 or 202, which is the transfer destination of the first image based on the first image data, at a predetermined timing instruction. Additionally, the controller 174 sets a reference current value (voltage value) 29 supplied from the power supply unit 102 to the printheads 1001, 1002, 1003, and 1004. The paper 201 or 202 contained in the paper trays 1171 or 1172 is fed toward the image forming units 1021, 1022, 1023, and 1024. The image forming units 1021, 1022, 1023, and 1024 detect the fed paper and, based on the timing of the paper detection, print the first image based on the first image data onto the fed paper 201 or 202 (ACT 101, Yes).

[0084] For example, when receiving first image data corresponding to each color (i.e., during color printing), the image processing unit 172 converts the first image data corresponding to each color into raster data and expands the converted raster data into page memories 1801, 1802, 1803, and 1804. Page memories 1801, 1802, 1803, and 1804 output the first image data. Printheads 1001, 1002, 1003, and 1004 emit light based on the first image data and print the first image based on the first image data onto paper 201 or 202.

[0085] The luminescence timing detection unit 1831 detects the luminescence timing of the printheads 1001, 1002, 1003 and 1004 that emit light according to the first image data, and notifies the controller 174 of the luminescence timing information 28 (ACT102).

[0086] The light emission time detection unit 1831 detects the light emission time of each light-emitting element 131 included in the print head 1001 based on the first image data, and detects the longest light emission time as the light emission time of the print head 1001. Similarly, the light emission time detection unit 1831 also detects the light emission time of each light-emitting element 131 included in each of the print heads 1002, 1003, and 1004, and detects the longest light emission time as the light emission time of each print head. Furthermore, the light emission time detection unit 1831 detects the longest light emission time among the light emission times of print heads 1001, 1002, 1003, and 1004 as the light emission time corresponding to the first image data.

[0087] The light-emitting element 131 emits light according to the first image data, and the emission time during which it emits light in all periods of the sub-scanning direction according to the first image data (image data of one page) is defined as 100%. That is, if the emission time of at least one light-emitting element included in printheads 1001, 1002, 1003, and 1004 is 100%, the emission time detection unit 1831 will detect the emission time corresponding to the first image data as 100%. In addition, if the emission time of the light-emitting element with the longest emission time among all the light-emitting elements included in printheads 1001, 1002, 1003, and 1004 is 80%, the emission time detection unit 1831 will detect the emission time corresponding to the first image data as 80%.

[0088] Furthermore, the timing setting unit 1741 of the controller 174 controls the time interval (inter-page time) (ACT103 to ACT111) from the end of the light emission time corresponding to the first image data to the start of printing corresponding to the second image data following the first image data, based on the detection result of the light emission time corresponding to the first image data. For example, if the light emission time corresponding to the first image data exceeds the reference time, the timing setting unit 1741 extends the time interval from the start of printing corresponding to the second image data. For example, if the light emission time corresponding to the first image data exceeds the reference time, the controller 174 delays the timing of starting the delivery of the recording medium for printing the second image corresponding to the second image data compared to the reference timing. It should be noted that the timing setting unit 1741 can control the time interval from the end of the light emission corresponding to the first image data to the start of the light emission corresponding to the second image data based on the detection result of the light emission time corresponding to the first image data.

[0089] For example, when the illumination time corresponding to the first image data is 20% (first proportion) or less (ACT103, yes), the time setting unit 1741 sets (maintains) the reference time without changing the time between the first image printing based on the first image data and the second image printing based on the second image data (ACT104).

[0090] When the emission time corresponding to the first image data exceeds 20% (ACT103, No) and is less than 40% (second ratio) (ACT105, Yes), the time setting unit 1741 sets the time between pages to a first time interval that is 5% longer than the reference time (ACT106).

[0091] When the emission time corresponding to the first image data exceeds 40% (ACT105, No) and is less than 60% (third ratio) (ACT107, Yes), the time setting unit 1741 sets the time between pages to a second time interval that is 10% longer than the reference time (ACT108).

[0092] When the emission time corresponding to the first image data exceeds 60% (ACT107, No) and is below 80% (fourth ratio) (ACT109, Yes), the time setting unit 1741 sets the time between pages to a third time interval (ACT110) that is 15% longer than the reference time.

[0093] When the emission time corresponding to the first image data exceeds 80% (ACT109, No), the time setting unit 1741 sets the time between pages to a fourth time interval (ACT111) that is 20% longer than the reference time.

[0094] The controller 174 monitors a set time interval and, when it detects that the set time interval has been reached or has elapsed (ACT112, Yes), begins printing based on the second image data (ACT101). The controller 174 controls the timing of starting the feeding of paper 201 or 202 based on the set time interval. That is, the controller 174 instructs the feeding of paper 201 or 202, which is the transfer destination of the image based on the image data, to begin at a predetermined time based on the set time interval. The paper 201 or 202 contained in the paper trays 1171 or 1172 is fed toward the image forming unit 173. The image forming units 1021, 1022, 1023, and 1024 detect the fed paper and, based on the paper detection timing, print a second image based on the second image data onto the fed paper 201 or 202 (ACT101, Yes). In other words, printheads 1001, 1002, 1003 and 1004 emit light based on the second image data and print the second image corresponding to the second image data onto paper 201 or 202.

[0095] Second implementation method: Structure of the control system

[0096] Figure 12 This is a block diagram illustrating an example of a control system for an image forming apparatus according to a second embodiment. The control system for the image forming apparatus according to the second embodiment is designed to be compatible with... Figure 10 The description will focus on the differences in the control system of the image forming apparatus according to the first embodiment shown, while the commonalities will be omitted as appropriate.

[0097] like Figure 12 As shown, the image forming apparatus 100 includes a controller 174. The controller 174 includes a time setting unit 1741 and a current (voltage) setting unit 1742.

[0098] The current (voltage) setting unit 1742 sets the current (voltage) value 29 supplied from the power supply unit 102 to the print heads 1001, 1002, 1003, and 1004. For example, the current setting unit 1742 selects any one of a reference current value, a first current value 5% higher than the reference current value, and a second current value 10% higher than the reference current value, and sets the selected current value. For example, the current setting unit 1742 sets the current value based on the printing results of a test pattern. For example, the light intensity of the light-emitting element 131 decreases as the light emission time accumulates. The current setting unit 1742 detects or predicts such a decrease in light intensity and changes the reference current value to the first or second current value to suppress the effect of the decrease in light intensity.

[0099] The timing unit 1741 controls the number of pages printed per unit time based on the detection result of the light emission time corresponding to the image data and a set current value (or voltage value). For example, the timing unit 1741 controls the time interval from the end of printing corresponding to the first image data to the start of printing corresponding to the second image data following the first image data, based on the detection result of the light emission time corresponding to the first image data and a set current value. Furthermore, the timing unit 1741 controls the time interval up to the start of printing corresponding to the second image data based on the longest light emission time detected for each light-emitting element and a set current value. In the case of color printing, the timing unit 1741 controls the time interval up to the start of printing corresponding to the second image data based on the longest light emission time detected for each light-emitting element included in the printheads 1001, 1002, 1003, and 1004 and a set current value.

[0100] The light intensity of the light-emitting element 131 decreases with the duration of emission; however, the higher the current value, the higher the rate of decrease in light intensity corresponding to the emission time. Furthermore, the light-emitting element 131 recovers the light intensity during the non-emission period, but again, the higher the current value, the higher the rate of decrease in light intensity corresponding to the emission time. Therefore, the higher the current value, the longer the non-emission period required to recover the light intensity. By allowing the light-emitting element 131 to have a non-emission period of a certain duration after emission, the light intensity during emission can be fully recovered. To prevent image quality degradation due to these characteristics of the light-emitting element 131, the controller 174 controls the number of prints per unit time based on the emission time and current value.

[0101] Non-volatile memory 177 stores a time setting table used in the control of the time interval up to the start of printing. Controller 174 controls the number of pages printed per unit time based on data representing the relationship between the emission time and current value registered in the time setting table.

[0102] Figure 13 This is a diagram illustrating an example of a time setting table applied during the time interval from the start of printing to the control of the image forming apparatus according to the second embodiment.

[0103] like Figure 13As shown, the time setting table includes data representing the relationship between emission time and current value. The emission time during all periods in the sub-scanning direction based on image data corresponding to one page is defined as 100%. When a reference current is supplied and the maximum emission time is 20% or less, the time setting unit 1741 sets (maintains) the reference time based on the time setting table without changing the time setting. Furthermore, when a first current 5% higher than the reference current is supplied and the maximum emission time is 20% or less, the time setting unit 1741 sets the time to a time interval 5% longer than the reference time based on the time setting table. Additionally, when a second current 10% higher than the reference current is supplied and the maximum emission time is 20% or less, the time setting unit 1741 sets the time to a time interval 10% longer than the reference time based on the time setting table.

[0104] Furthermore, when a reference current is supplied and the maximum light emission time exceeds 20% but is less than 40%, the time setting unit 1741 sets the time to a time interval 5% longer than the reference time based on the time setting table. Additionally, when a first current is supplied and the maximum light emission time exceeds 20% but is less than 40%, the time setting unit 1741 sets the time to a time interval 10% longer than the reference time based on the time setting table. Furthermore, when a second current is supplied and the maximum light emission time exceeds 20% but is less than 40%, the time setting unit 1741 sets the time to a time interval 15% longer than the reference time based on the time setting table.

[0105] In addition, when the reference current, the first current or the second current is supplied and the maximum light emission time exceeds 40% and is less than 60%, exceeds 60% and is less than 80%, or exceeds 80%, the time setting unit 1741 also sets a predetermined time interval based on the time setting table.

[0106] Second implementation method: Controlling the time interval until printing begins

[0107] Figure 14 This is a flowchart illustrating an example of the image forming apparatus according to the second embodiment controlling the time interval until the start of printing. Regarding the control of the time interval until the start of printing by the image forming apparatus according to the second embodiment, in conjunction with... Figure 12 The explanation focuses on the differences in time control during the shown time intervals, while omitting explanations of the commonalities as appropriate.

[0108] The controller 174 begins feeding paper 201 or 202, which is the transfer destination of the first image based on the first image data, at a predetermined timing instruction. Additionally, the current setting unit 1742 of the controller 174 sets a reference current value (reference voltage value) 29 supplied from the power supply unit 102 to the printheads 1001, 1002, 1003, and 1004. The paper 201 or 202 contained in the paper trays 1171 or 1172 is fed toward the image forming units 1021, 1022, 1023, and 1024. The image forming units 1021, 1022, 1023, and 1024 detect the fed paper and, based on the timing of the paper detection, print the first image based on the first image data onto the fed paper 201 or 202 (ACT 201, Yes).

[0109] The light emission time detection unit 1831 detects the light emission time of printheads 1001, 1002, 1003, and 1004 that emit light according to the first image data, and notifies the controller 174 of the light emission time information 28 (ACT202). For example, the light emission time detection unit 1831 detects the light emission time of each light-emitting element 131 included in printheads 1001, 1002, 1003, and 1004 based on the first image data, and detects the longest light emission time as the light emission time corresponding to the first image data.

[0110] In addition, the current setting unit 1742 detects the set current value (reference current value) (ACT203).

[0111] Time Setting Department 1741 Reference Figure 13 The time setting table shown contains the data (ACT204). Based on the data contained in the time setting table and the detection results of the emission time and current value corresponding to the first image data, the time setting unit 1741 controls the time interval (time between pages) from the start of printing corresponding to the second image data after the first image data (ACT205).

[0112] For example, when a reference current is supplied and the maximum light emission time is 20% or less, the timing setting unit 1741 sets (maintains) the reference time without changing the time setting (ACT205). Furthermore, when a first current 5% higher than the reference current is supplied and the maximum light emission time is 20% or less, the timing setting unit 1741 sets the time to a time interval 5% longer than the reference time (ACT205). Additionally, when a second current 10% higher than the reference current is supplied and the maximum light emission time is 20% or less, the timing setting unit 1741 sets the time to a time interval 10% longer than the reference time (ACT205).

[0113] The controller 174 monitors a set time interval and, when it detects that the set time interval has been reached or has elapsed (ACT206, Yes), begins printing based on the second image data (ACT201). The controller 174 instructs the start of feeding paper 201 or 202, which is the transfer destination of the image based on the image data, at a predetermined time based on the set time interval. The paper 201 or 202 contained in the paper trays 1171 or 1172 is fed toward the image forming unit 173. The image forming units 1021, 1022, 1023, and 1024 detect the fed paper and, based on the paper detection timing, print a second image based on the second image data onto the fed paper 201 or 202 (ACT201, Yes).

[0114] Figure 15 This is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the emission time of the printhead's light-emitting element. It is also a graph illustrating an example of a longer emission time (e.g., 100% of the time for one page in the sub-scanning direction) and its recovery time. Additionally, Figure 16 It is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the light emission time of the light emission element of the printhead, and it is a graph of an example of a shorter light emission time (e.g., 60% of the time for a page in the sub-scanning direction) and its recovery time.

[0115] like Figure 15 and Figure 16 As shown, the amount of light emitted by the light-emitting element 131 decreases according to the light emission time and recovers to the amount of light emitted during the non-light emission time. Figure 15 and Figure 16 The dashed line diagram illustrates the recovery process. For example, as... Figure 15 As shown, regarding the light-emitting element 131, if the light emission time is long, the light intensity decreases significantly, and it takes a long time for the light intensity to recover. Additionally, as... Figure 16 As shown, regarding the light-emitting element 131, if the light emission time is short, the light intensity will decrease slightly, and it will take a short time for the light intensity to recover.

[0116] Figure 17 This is a graph showing the relationship between the light intensity decrease and the light intensity decrease recovery characteristics corresponding to the light emission time and current value of the light-emitting element of the printhead. Figure 17 The vertical axis represents the light intensity ratio. The light intensity varies depending on the current flowing through the light-emitting element 131, but... Figure 17 In this example, the light intensity ratio at the start of printing is set to 100%, and the ratio is used to represent how the light intensity changes over time.

[0117] like Figure 17As shown in curve A, if the current supplied to the light-emitting element 131 is current IA, and the emission time is long (e.g., one page in the sub-scanning direction corresponds to 100% of the time), the light intensity decreases by approximately 3% (light intensity ratio is 97%). Furthermore, the recovery time required during standard emission is needed to restore the light intensity to the level at the start of emission (100%). In contrast, as... Figure 17 As shown in curve B, for example, if the current supplied to the light-emitting element 131 is the current IB, which is 10% higher than the current IA, and the emission time is longer (e.g., one page in the sub-scanning direction is equivalent to 100% of the time), then the light intensity decreases by about 5% (the light intensity ratio is 95%). Moreover, the recovery time required for the light intensity UP (e.g., 10% longer than the recovery time during standard emission) is needed to recover to the light intensity at the start of emission (100%).

[0118] As described above, if the current supplied to the light-emitting element 131 is increased, the amount of light emitted by the light-emitting element 131 increases, and the rate of decrease in light amount also increases. If the rate of decrease in light amount increases, the recovery time becomes longer. By increasing the current and extending the recovery time, image quality degradation can be prevented.

[0119] Figure 18 This is a diagram illustrating an example of the effect of reduced emission time and light intensity of the light-emitting element when the time interval control up to the start of printing involved in the first or second embodiment is not applied. Figure 18 For example, the light intensity at the start of printing the first image is set to 100%, and the allowable light intensity drop level is set to 3% (light intensity ratio 97%). In the following description, the allowable light intensity drop level (light intensity ratio 97%) is sometimes referred to as the baseline (97%).

[0120] like Figure 18 As shown, two intervals corresponding to a predetermined number of light-emitting elements 131 among the plurality of light-emitting elements 131 included in the printhead 1 are respectively referred to as block A and block B. For example, the light emission time of block A is set to 100% (when light emission occurs throughout all periods in the sub-scanning direction), and the light emission time of block B is set to 20%. The light emission time of the light-emitting elements 131 corresponding to block A is long, and the light intensity decreases significantly. On the other hand, the light emission time of the light-emitting elements 131 corresponding to block B is short, and the light intensity decreases slightly.

[0121] When the first image is started to be printed, the light intensity of the light-emitting element 131 corresponding to block A is sufficient (100%). At the end of the printing of the first image, the light intensity of the light-emitting element 131 corresponding to block A is also sufficient, meeting the benchmark (97%). In addition, at both the start and end of the printing of the first image, the light intensity of the light-emitting element 131 corresponding to block B is sufficient (above 97%).

[0122] After printing the first image, even with a given time interval between pages (non-light emission time) as a reference, the light intensity of the light-emitting element 131 corresponding to block A sometimes does not recover to sufficient levels (100%). When printing the second image after the first image begins, the light intensity of the light-emitting element 131 corresponding to block A meets the reference level (above 97%), but in the later stages of printing the second image, the light intensity of the light-emitting element 131 corresponding to block A is sometimes slightly insufficient (less than 97%). It should be noted that the light intensity of the light-emitting element 131 corresponding to block B is sufficient (above 97%) both at the beginning of printing the second image and in the later stages of printing the second image.

[0123] After printing the second image, even with a given time interval between pages as a reference, the light intensity of the light-emitting element 131 corresponding to block A sometimes does not recover to a sufficient level (100%). When printing the third image after the second image begins, the light intensity of the light-emitting element 131 corresponding to block A meets the reference level (above 97%), but during the printing of the third image, the light intensity of the light-emitting element 131 corresponding to block A is sometimes insufficient (less than 97%) in the early stages (refer to the insufficient light intensity area Eb). It should be noted that at any time during the printing of the third image, the light intensity of the light-emitting element 131 corresponding to block B is sufficient (above 97%).

[0124] Figure 19 This is a diagram illustrating an example of the effect of the decrease in the emission time and light intensity of the light-emitting element when the time interval control up to the start of printing involved in the first or second embodiment is applied.

[0125] When the first image is started to be printed, the light intensity of the light-emitting element 131 corresponding to block A is sufficient (100%). Even at the end of the printing of the first image, the light intensity of the light-emitting element 131 corresponding to block A is not insufficient, meeting the benchmark (more than 97%). In addition, at both the start and end of the printing of the first image, the light intensity of the light-emitting element 131 corresponding to block B is sufficient (more than 97%).

[0126] After printing the first image, if an extended time interval between pages is given, the light intensity of the light-emitting element 131 corresponding to block A recovers to sufficient (100%). When printing the second image after the first image begins, the light intensity of the light-emitting element 131 corresponding to block A is sufficient (100%), and even in the later stages of printing the second image, the light intensity of the light-emitting element 131 corresponding to block A is not insufficient, meeting the benchmark (above 97%).

[0127] After printing the second image, if an extended time interval between pages is given, the light intensity of the light-emitting element 131 corresponding to block A is restored to sufficient (100%). When printing the third image after the second image begins, the light intensity of the light-emitting element 131 corresponding to block A is sufficient (100%), and then the light intensity of the light-emitting element 131 corresponding to block A is also not insufficient, meeting the benchmark (above 97%).

[0128] As described above, by applying the time interval control up to the start of printing involved in the first or second embodiment, the amount of light from the light-emitting element 131 is restored, thus preventing image quality degradation due to a decrease in the amount of light.

[0129] For example, control panel 179 can set whether time interval control is applied or not based on input. Non-volatile memory 177 stores the setting for applying or not applying time interval control. When time interval control is applied, controller 174 extends the time interval until printing begins based on the detection result of the light emission time. This prevents image quality degradation due to decreased light intensity. Conversely, when time interval control is not applied, controller 174 fixes the time interval until printing begins as a reference time. This prevents printing time delays.

[0130] It should be noted that the time interval control described in the first and second embodiments can be applied to a monochrome image forming apparatus based on a single printhead or a color image forming apparatus based on printheads corresponding to each color. Furthermore, although the case where the emission time of the optical element 131 and the detection of the current value for emitting light from the optical element 131 are implemented in software has been described, it can also be implemented in hardware. Additionally, as a method for extending the time interval between pages, the case where the timing of starting to feed paper 201 or 202 is delayed has been described, but the time interval between pages can also be extended by reducing the feed speed.

[0131] As described above, the image forming apparatus according to the embodiment extends the time interval until the start of the next printing cycle by extending the emission time, thereby restoring the light amount of the light-emitting element 131 and preventing image quality degradation. Furthermore, by variably setting the current value (voltage value) of the light-emitting element 131, changing the time interval until the start of the next printing cycle according to the emission time and current value, thereby restoring the light amount of the light-emitting element 131, can also prevent image quality degradation.

[0132] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. An image forming apparatus, characterized in that, include: A printhead, comprising one or more light-emitting element arrays consisting of multiple light-emitting elements; The detection unit detects the emission time of the printhead that emits light based on image data; as well as The controller, based on the detection result of the emission time corresponding to the first image data, controls the time interval up to the start of printing corresponding to the second image data after the first image data.

2. The image forming apparatus according to claim 1, characterized in that, The controller controls the time interval from the end of printing corresponding to the first image data to the start of printing corresponding to the second image data, based on the detection result of the emission time corresponding to the first image data.

3. The image forming apparatus according to claim 1, characterized in that, The detection unit detects the emission time of each light-emitting element based on the first image data. The controller controls the time interval up to the start of printing corresponding to the second image data, based on the longest detected emission time.

4. The image forming apparatus according to claim 1, characterized in that, The controller controls the timing of starting the delivery of the recording medium for printing the second image corresponding to the second image data, based on the detection result of the emission time corresponding to the first image data.

5. The image forming apparatus according to claim 1, characterized in that, When the emission time corresponding to the first image data exceeds the reference time, the controller extends the time interval until the printing start corresponding to the second image data.

6. The image forming apparatus according to claim 1, characterized in that, When the emission time corresponding to the first image data exceeds the reference time, the controller causes the timing for starting the delivery of the recording medium for printing the second image corresponding to the second image data to be delayed compared to the reference timing.

7. The image forming apparatus according to claim 5, characterized in that, When the emission time corresponding to the first image data is less than the reference time, the controller sets the time interval up to the start of printing corresponding to the second image data as the reference time.

8. An image forming apparatus, characterized in that, include: Multiple printheads, corresponding to each color, each printhead including one or more light-emitting element arrays consisting of multiple light-emitting elements; The detection unit detects the emission time of the printhead that emits light based on image data; as well as The controller, based on the detection results of the emission time corresponding to the first image data corresponding to each color, controls the time interval up to the start of printing corresponding to the second image data corresponding to each color after the first image data.

9. The image forming apparatus according to claim 8, characterized in that, The detection unit detects the emission time of each light-emitting element in multiple printheads corresponding to each color, based on the first image data. The controller controls the time interval up to the start of printing corresponding to the second image data, based on the longest detected emission time.

Images