Printer head, printing device

Abstract

This printer head (10) comprises a first light-emitting element (21), a second light-emitting element (22), a first control circuit (31), a second control circuit (32), and a power supply unit (40). The first control circuit controls the light emission of the first light-emitting element and operates at a first power supply voltage. The second control circuit controls the light emission of the second light-emitting element and operates at a second power supply voltage. The power supply unit generates the first power supply voltage and the second power supply voltage and individually controls the respective voltage values of the first power supply voltage and the second power supply voltage.

Description

Technical Field

[0001] The present disclosure relates to a printer head for forming a latent image on a photoconductor, and a printing apparatus that performs printing using the photoconductor and the printer head.

Background Art

[0002] Patent Document 1 describes an image forming apparatus such as a printing apparatus that forms an image on a sheet by attaching toner to a latent image formed on a photoconductor and transferring the toner onto the sheet. In particular, Patent Document 1 describes a technique of using a light emitting element such as an OLED (organic EL element) in an optical writing device such as a printer head that irradiates a photoconductor with light.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] All the light emitting elements of the optical writing device described in Patent Document 1 are driven by a power supply voltage from a common power supply. For this reason, a circuit for driving the light emitting elements requires a compensation circuit for compensating for a difference in power supply voltage between the light emitting elements, which may cause complication of the apparatus or an increase in power consumption.

Means for Solving the Problem

[0005] A printer head according to one aspect of the present disclosure includes: a first light-emitting element that irradiates a first region of a photoreceptor with light; a second light-emitting element that irradiates a second region of the photoreceptor with light; a first control circuit that controls the emission of light from the first light-emitting element and operates at a first power supply voltage; a second control circuit that controls the emission of light from the second light-emitting element and operates at a second power supply voltage; and a power supply unit that generates the first power supply voltage and the second power supply voltage and individually controls the voltage values ​​of the first power supply voltage and the second power supply voltage. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, a compensation circuit is not required in the drive circuit of each light-emitting element in the printer head of a printing device, thereby simplifying the printer head or reducing the power consumption of the printer head. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of a printer head according to Embodiment 1. [Figure 2] This is a schematic side cross-sectional view of the printing apparatus according to Embodiment 1. [Figure 3] This is a schematic enlarged view of the inside of the printing apparatus according to Embodiment 1. [Figure 4] This is a schematic plan view of the light-emitting unit according to Embodiment 1. [Figure 5] This is an equivalent circuit diagram of the first control circuit and the first light-emitting element according to Embodiment 1. [Figure 6] This is a schematic diagram of a printer head according to Embodiment 2. [Figure 7] This is a schematic diagram of a printer head according to Embodiment 3. [Figure 8] This is an equivalent circuit diagram of the first control circuit and the first light-emitting element according to Embodiment 3. [Figure 9] This is a schematic diagram of a printer head according to Embodiment 4. [Figure 10] This is an equivalent circuit diagram of the first control circuit and the first light-emitting element according to Embodiment 4. [Figure 11]This is a schematic plan view of the light-emitting unit according to Embodiment 5. [Modes for carrying out the invention]

[0008] [Embodiment 1] <Printing device: Overview> The embodiments of this disclosure will be described below with reference to the drawings. In each drawing, similar components are denoted by the same reference numerals and their descriptions are omitted.

[0009] Figure 2 is a schematic side cross-sectional view of the printing apparatus 1 according to this embodiment. Figure 2 shows the external shape of the printing apparatus 1 and the main parts of the printing apparatus 1 that are relevant to this disclosure. As shown in Figure 2, the printing apparatus 1 comprises a printing unit 2 that supplies toner to a recording medium, such as paper, to perform printing, and a transport unit 3 that transports the recording medium.

[0010] The printing device 1 is, for example, a device that transports paper supplied from an external source using a transport unit 3, prints on the paper using a printing unit 2, and discharges the paper to the outside. Multiple printing units 2 may be provided along the direction of travel of the paper transported by the transport unit 3. Each of the printing units 2 may supply toner of a different color to the paper. In this way, the printing device 1 may perform full-color printing on the paper.

[0011] <Printing device: Details> The printing unit 2 and transport unit 3 of the printing device 1 will be explained in detail by describing the printing method on paper P with reference to Figure 3. Figure 3 is a schematic enlarged view of the printing device 1, showing an enlarged view of one of the printing units 2 and a part of the transport unit 3 inside the printing device 1. Figure 3 also shows paper P that is transported by the transport unit 3 and toner supplied by the printing unit 2.

[0012] The printing unit 2 comprises a printer head 10, a photoreceptor 11, a charging unit 12, a head drive unit 13, a toner supply unit 14, and a toner transfer unit 15. The printing unit 2 may further include a cleaner 16 and a static elimination unit 17.

[0013] The printer head 10 is driven by a head driving unit 13 described later, and irradiates light onto the outer surface of the photoreceptor 11. Details of the printer head 10 will be described later.

[0014] The photoreceptor 11 has, for example, a substantially cylindrical shape, and is rotated around a cylindrical axis by a driving unit (not shown). The photoreceptor 11 can be charged at least on the curved surface of the outer surface, and is discharged when irradiated with light.

[0015] The charging unit 12 is disposed to face the curved surface of the photoreceptor 11. The charging unit 12 charges the opposing portion of the curved surface of the photoreceptor 11 by, for example, a method of generating an electric field, thereby forming a charged region 11E on the curved surface of the photoreceptor 11. As the photoreceptor 11 rotates around the rotation axis, the charging unit 12 charges the curved surface of the photoreceptor 11, so that the charging unit 12 sequentially charges the curved surface of the photoreceptor 11.

[0016] The head driving unit 13 drives light from the printer head 10 to expose at least a part of the curved surface of the photoreceptor 11. For example, the printer head 10 extends along the rotation axis of the photoreceptor 11, and includes a light emitting unit 20 facing the curved surface of the photoreceptor 11. The head driving unit 13 controls light from the light emitting unit 20 to select a portion to be irradiated with light among the curved surface of the photoreceptor 11 facing the light emitting unit 20. Of the charged curved surface of the photoreceptor 11, the portion irradiated with light from the printer head 10 is discharged to form a latent image 11L. By irradiating the curved surface of the photoreceptor 11 rotating around the rotation axis with light from the printer head 10, the head driving unit 13 sequentially forms the latent image 11L on the curved surface of the photoreceptor 11.

[0017] The toner supply unit 14 includes a toner source 14M and a toner supply roller 14R. The toner source 14M contains multiple toners 14T, and the toner supply roller 14R supplies the toners 14T from the toner source 14M to the curved surfaces of the opposing photoreceptor 11. Here, a repulsive force due to electrostatic force acts between the toners 14T and the charged region 11E of the curved surface of the photoreceptor 11. Therefore, the toners 14T adhere only to the latent image 11L on the curved surface of the photoreceptor 11. For this reason, the toner supply unit 14 supplies toners 14T to the photoreceptor 11 according to the latent image 11L. The toner supply unit 14 may have a mechanism for adding a developer to the toners 14T, or it may have a mechanism for adhering only the toners 14T to the curved surface of the photoreceptor 11 from the toners 14T and the developer.

[0018] The toner transfer unit 15 includes a transfer roller 15R. The transfer roller 15R faces the photoreceptor 11, which has toner 14T supplied to its latent image 11L, via the paper P transported by the drive roller 3D provided by the transport unit 3. The toner transfer unit 15 transfers the toner 14T from the photoreceptor 11 to the paper P by adhering the toner 14T on the latent image 11L of the photoreceptor 11 to the portion of the paper surface of the paper P that faces the transfer roller 15R.

[0019] The paper P to which toner 14T is supplied is supplied between two fixing rollers 3F provided in the transport unit 3. The toner 14T on the paper P is pressed onto the paper P by the fixing rollers 3F and fixed to the surface of the paper P. Since the paper P is supplied with toner 14T supplied to the photoreceptor 11 in accordance with the latent image 11L of the photoreceptor 11, the toner 14T fixed to the surface of the paper P has a shape corresponding to the latent image 11L. With this, printing on the paper P is completed.

[0020] The cleaner 16 may include a cleaner board 16B that contacts the curved surface of the photoreceptor 11, and a cleaner roller 16R that faces the cleaner board 16B. The cleaner 16 may scrape off any toner 14T remaining on the curved surface of the photoreceptor 11 after it has passed through the toner transfer section 15 using the cleaner board 16B, and remove it with the cleaner roller 16R. The static elimination section 17 may remove static electricity from the curved surface of the photoreceptor 11 that has passed through the cleaner 16, for example by grounding it or exposing the entire surface to light, and remove the charged area 11E from the photoreceptor 11.

[0021] <Printer Head: Overview> The printer head 10 according to this embodiment will be described in more detail with reference to Figure 1. Figure 1 is a schematic diagram of the printer head 10 according to this embodiment. The printer head 10 comprises the light-emitting unit 20 described above, the light-emitting control circuit unit 30, the power supply unit 40, and the signal generation unit 50.

[0022] <Printer head: Light-emitting part> The light-emitting unit 20 includes multiple light-emitting elements and irradiates light onto the curved surface of the photoreceptor 11. The light-emitting unit 20 according to this embodiment will be described in more detail with reference to Figure 4. Figure 4 is a schematic plan view of the light-emitting unit 20.

[0023] As shown in Figure 4, the light-emitting unit 20 includes a first light-emitting element 21, a second light-emitting element 22, a third light-emitting element 23, and a fourth light-emitting element 24, and may have more light-emitting elements. Each light-emitting element illuminates different regions of the curved surface of the photoreceptor 11 that the light-emitting unit 20 faces. For example, each of the first light-emitting element 21, second light-emitting element 22, third light-emitting element 23, and fourth light-emitting element 24 illuminates a first region, a second region, a third region, and a fourth region of the curved surface of the photoreceptor 11.

[0024] The light-emitting unit 20 is provided with light-emitting elements arranged two-dimensionally along a first direction D1 and a second direction D2. The first direction D1 is parallel to the rotation axis of the photoreceptor 11 opposite the light-emitting unit 20, and the second direction D2 is a direction that intersects both the first direction D1 and the third direction D3, which is the direction of movement of the outer surface of the opposing photoreceptor 11. For example, the first light-emitting element 21 and the third light-emitting element 23 are adjacent to each other in the first direction.

[0025] Therefore, the light-emitting unit 20 has multiple light-emitting elements arranged along the second direction D2, or in other words, multiple light-emitting elements are arranged offset in the first direction D1 with respect to the third direction D3. For example, the light-emitting unit 20 may include a first light-emitting element 21 and a fifth light-emitting element 25 adjacent to it in the second direction D2.

[0026] <Printer head: Light emission control circuit> Returning to Figure 1, the light emission control circuit unit 30 includes control circuits corresponding to each of the light-emitting elements, for example, a first control circuit 31, a second control circuit 32, a third control circuit 33, and a fourth control circuit 34. Each of the first control circuit 31, second control circuit 32, third control circuit 33, and fourth control circuit 34 controls the light emission of the first light-emitting element 21, second light-emitting element 22, third light-emitting element 23, and fourth light-emitting element 24. Details of each control circuit included in the light emission control circuit unit 30 will be described later.

[0027] <Printer head: Power supply unit> The power supply unit 40 includes a plurality of power supply circuits, each of which generates a power supply voltage, for example, a first power supply circuit 41 and a second power supply circuit 42. Each of the first power supply circuit 41 and the second power supply circuit 42 generates a first power supply voltage and a second power supply voltage, and individually controls the voltage values ​​of the first power supply voltage and the second power supply voltage, respectively.

[0028] The first power supply voltage generated by the first power supply circuit 41 is supplied to the first control circuit 31 and the third control circuit 33 via the first power line PL1. Therefore, the first control circuit 31 and the third control circuit 33 each operate at the first power supply voltage. The second power supply voltage generated by the second power supply circuit 42 is supplied to the second control circuit 32 and the fourth control circuit 34 via the second power line PL2. Therefore, the second control circuit 32 and the fourth control circuit 34 each operate at the second power supply voltage.

[0029] <Printer head: Signal generation unit> The signal generation unit 50 generates signals to be supplied to each control circuit of the light emission control circuit unit 30, for example, generating a first signal, a second signal, a third signal, and a fourth signal. The first signal is supplied to the first control circuit 31 via the first signal line SL1. Similarly, the second signal, the third signal, and the fourth signal are supplied to the second control circuit 32, the third control circuit 33, and the fourth control circuit 34, respectively, via the second signal line SL2, the third signal line SL3, and the fourth signal line SL4.

[0030] For example, the potential of the first signal is selected from either a first low potential or a first high potential higher than the first low potential, and the potential of the second signal is selected from either a second low potential or a second high potential higher than the second low potential. From the viewpoint of simplifying the configuration of the signal generation unit 50, the first low potential and the second low potential may be the same, and the first high potential and the second high potential may be the same.

[0031] Each control circuit in the light emission control circuit unit 30 controls the emission of light from each light-emitting element in the light emission unit 20 based on signals supplied from the signal generation unit 50. For example, the first control circuit 31 controls the emission of light from the first light-emitting element 21 based on the first signal. Similarly, the second control circuit 32, the third control circuit 33, and the fourth control circuit 34 each control the emission of light from the second, third, and fourth light-emitting elements 22, 33, and 4, respectively, based on the second, third, and fourth signals.

[0032] <Control circuit details> Each control circuit included in the light emission control circuit unit 30 will be described in detail with reference to Figure 5, using the first control circuit 31 as an example. Figure 5 is an equivalent circuit diagram of the first control circuit 31. Figure 5 also shows the first light-emitting element 21 whose light emission is controlled by the first control circuit 31.

[0033] The first control circuit 31 includes a first light-emitting control transistor LT1, a first capacitor C1, and a first reset transistor RT1. While this disclosure describes an example where each transistor is a field-effect transistor, the invention is not limited to this.

[0034] The first light-emitting control transistor LT1 has its source electrode connected to the first power line PL1, its drain electrode connected to one electrode of the first light-emitting element 21, and its gate electrode connected to the first signal line SL1. The first capacitor C1 is formed between the first power line PL1 and the first signal line SL1. The first reset transistor RT1 has its source electrode connected to the drain electrode side of the first light-emitting control transistor LT1, and its gate electrode connected to the first signal line SL1. The other electrode of the first light-emitting element 21 and the drain electrode of the first reset transistor RT1 are connected to the low-voltage lines LL included in each control circuit of the light-emitting control circuit unit 30, which includes the first control circuit 31. The low-voltage lines LL have a potential lower than each power supply voltage generated by the power supply unit 40 and may be connected to an auxiliary power supply (not shown) or to ground.

[0035] The first light-emitting control transistor LT1 generates a drain current when, for example, a first signal having a first high potential is supplied to the gate electrode via the first signal line SL1. In other words, current flows from the first power line PL1 to the first light-emitting element 21. The first light-emitting element 21, to which current is supplied, emits light, in other words, the first light-emitting element 21 irradiates a first region of the photoreceptor 11 with light. On the other hand, this drain current stops when a first signal having a first low potential is supplied to the gate electrode. Therefore, the first light-emitting control transistor LT1 controls the current applied to the first light-emitting element 21 based on the first signal applied to the gate electrode via the first signal line SL1, thereby controlling the emission of light from the first light-emitting element 21.

[0036] As described above, the first light-emitting control transistor LT1 drives the first light-emitting element 21 based on a first signal that takes two values: a first high potential and a first low potential. For example, the first light-emitting control transistor LT1 is driven in the linear region, where the presence or absence of drain current is controlled by the gate voltage.

[0037] When a first signal having a first high potential is supplied to the first signal line SL1, charge may be accumulated in the first capacitor C1. The first light-emitting control transistor may control the first light-emitting element 21 based on the charge accumulated in the first capacitor C1.

[0038] The first reset transistor RT1 generates a drain current when, for example, a first signal having a first low potential is supplied to its gate electrode via the first signal line SL1. In other words, the first light-emitting control transistor LT1 is short-circuited with the low-voltage line LL. As a result, the first reset transistor RT1 releases the charge accumulated in the first light-emitting element 21 to the low-voltage line LL. On the other hand, this drain current stops when a first signal having a first high potential is supplied to its gate electrode.

[0039] Therefore, the first reset transistor RT1 controls the release of the charge accumulated in the first light-emitting element 21 based on the first signal applied to the gate electrode via the first signal line SL1. As a result, the first control circuit 31 can reduce the possibility of the first light-emitting element 21 emitting light when it is not intended to do so, due to residual charge in the first light-emitting element 21.

[0040] The polarity of the first light-emitting control transistor LT1 and the polarity of the first reset transistor RT1 may be different. This allows the first control circuit 31 to control the light emission of the first light-emitting element 21 and release the charge accumulated in the first light-emitting element 21 simply by supplying the same first signal to the first light-emitting control transistor LT1 and the first reset transistor RT1. In other words, the first control circuit 31 does not require a mechanism to apply separate signals to the first light-emitting control transistor LT1 and the first reset transistor RT1 in order to control the light emission of the first light-emitting element 21 and release the charge accumulated in the first light-emitting element 21.

[0041] In this embodiment, except for the applied power supply voltage and the supplied signal, the control circuits included in the light emission control circuit unit 30 may have the same configuration as the first control circuit 31. For example, in this embodiment, the second control circuit 32 includes a second light emission control transistor, a second capacitor, and a second reset transistor. In particular, the second light emission control transistor controls the current applied to the second light-emitting element 22 based on the second signal.

[0042] <Summary of Embodiments> Generally, when operating the control circuits of multiple light-emitting elements using the same power supply voltage, unintended differences in the power supply voltage supplied to each control circuit may occur due to voltage reduction in the power supply line, etc. In this case, to reduce the influence of the power supply voltage difference on the light emission control of each light-emitting element, it is advisable to form a compensation circuit in each control circuit.

[0043] In this embodiment, each control circuit of the light-emitting control circuit unit 30 that drives each light-emitting element of the light-emitting unit 20 operates by a power supply voltage generated by the power supply unit 40 and whose voltage value is individually controlled. For example, the first control circuit 31 operates at the first power supply voltage, and the second control circuit 32 operates at the second power supply voltage. The power supply unit 40 individually controls the voltage values ​​of the first power supply voltage and the second power supply voltage.

[0044] Therefore, by individually controlling the operating voltage of each control circuit, the printer head 10 can more precisely control the light emission of each light-emitting element, even if each control circuit does not have a compensation circuit. The printing device 1 equipped with the printer head 10 can achieve both simplification of the printer head 10 and improvement of print quality.

[0045] The power supply unit 40 according to this embodiment includes individual power supply circuits corresponding to each control circuit. Therefore, the printer head 10 according to this embodiment can control the operating voltage of each control circuit by directly controlling the power supply voltage generated by each power supply circuit.

[0046] In this embodiment, both the first control circuit 31 and the third control circuit 33 operate at the first power supply voltage. Therefore, since the printer head 10 operates multiple control circuits at the same power supply voltage, the number of power lines connected from the power supply unit 40 to each control circuit can be reduced, simplifying the configuration. In addition, the printer head 10 can simplify the control of the operating voltage of each control circuit by the power supply unit 40.

[0047] In this embodiment, the printer head 10 controls the emission of light from each light-emitting element of the light-emitting unit 20 by driving a control circuit included in the light-emitting control circuit unit 30 with a signal generated by the signal generation unit 50. In particular, the printer head 10 controls the emission of light from each light-emitting element of the light-emitting unit 20 by driving the light-emitting control transistors of each control circuit with the above signal. Therefore, the printer head 10 can control the emission of light from each light-emitting element with a simpler configuration than directly controlling the current or voltage values ​​applied to each light-emitting element.

[0048] In particular, the light emission control transistors included in each control circuit are driven in the linear region, or in other words, driven by signals that take a binary potential. Therefore, the printer head 10 according to this embodiment realizes the generation of signals for driving each control circuit with a simpler configuration.

[0049] In this embodiment, the first control circuit 31 and the third control circuit 33 are adjacent to each other in the first direction D1. Therefore, the printer head 10 can place multiple control circuits that operate at the same power supply voltage close together, shortening the distance over which power lines need to be routed. This makes it easier to form power lines in the printer head 10 and simplifies the configuration of the power lines.

[0050] [Embodiment 2] <Main power supply circuit and conversion circuit> Figure 6 is a schematic diagram of the printer head 10 according to this embodiment. The printer head 10 of the printing apparatus 1 according to this embodiment differs from the printer head 10 according to the previous embodiment only in that it is equipped with a power supply unit 60 instead of a power supply unit 40.

[0051] The power supply unit 60 includes a main power supply circuit 61 and a plurality of conversion circuits, including a first conversion circuit 62 and a second conversion circuit 63. The main power supply circuit 61 generates a main power supply voltage and supplies it to each conversion circuit, including the first conversion circuit 62 and the second conversion circuit 63. Each conversion circuit converts the main power supply voltage into a power supply voltage supplied to each control circuit. For example, the first conversion circuit 62 converts the main power supply voltage into a first power supply voltage, and the second conversion circuit 63 converts the main power supply voltage into a second power supply voltage.

[0052] The power supply voltage converted by each conversion circuit is supplied to each control circuit of the light emission control circuit unit 30. For example, the first power supply voltage from the first conversion circuit 62 is supplied to the first control circuit 31 and the third control circuit 33 via the first power line PL1. Also, the second power supply voltage from the second conversion circuit 63 is supplied to the second control circuit 32 and the fourth control circuit 34 via the second power line PL2.

[0053] In this embodiment, the power supply unit 60 is equipped with only a main power supply circuit 61 as a power supply circuit for generating multiple power supply voltages to be supplied to each control circuit; in other words, it is not equipped with multiple power supply circuits. Therefore, the printer head 10 can be simplified in configuration by reducing the number of power supply circuits equipped in the power supply unit 60.

[0054] Furthermore, the power supply unit 60 can adjust the power supply voltage supplied to each control circuit using each conversion circuit, meaning that the main power supply circuit 61 does not require a mechanism to adjust the voltage value of the main power supply voltage it generates. Therefore, the printer head 10 can simplify the control of the operating voltage of each control circuit by the power supply unit 60.

[0055] [Embodiment 3] <Reset signal> Figure 7 is a schematic diagram of the printer head 10 according to this embodiment. Compared to the printer head 10 according to each of the above embodiments, the printer head 10 of the printing apparatus 1 according to this embodiment includes a light emission control unit 70 instead of a light emission control unit 30. Compared to the light emission control unit 30, the light emission control unit 70 according to this embodiment includes a first control circuit 71, a second control circuit 72, a third control circuit 73, and a fourth control circuit 74 instead of a first control circuit 31, a second control circuit 32, a third control circuit 33, and a fourth control circuit 34.

[0056] Furthermore, the signal generation unit 50 according to this embodiment generates reset signals corresponding to each control circuit included in the light emission control circuit unit 70. For example, the signal generation unit 50 generates a first reset signal corresponding to the first control circuit 71, and also generates a second reset signal corresponding to the second control circuit 72. For example, the potential of the first reset signal may be selected from, for example, a first low potential and a first high potential that is higher than the first low potential. Similarly, the potential of the second reset signal may be selected from, for example, a second low potential and a second high potential that is higher than the second low potential. Each reset signal generated by the signal generation unit 50 is supplied to each control circuit via, for example, the first reset signal line RL1, the second reset signal line RL2, the third reset signal line RL3, and the fourth reset signal line RL4.

[0057] Figure 8 is an equivalent circuit diagram of the first control circuit 71 and the first light-emitting element 21 according to this embodiment. Compared to the first control circuit 31, the first reset transistor RT1 in the first control circuit 71 is not connected to the first signal line SL1; in other words, the first signal is not applied to the first reset transistor RT1. In this embodiment, the first reset signal is applied to the gate electrode of the first reset transistor RT1 from the signal generation unit 50 via the first reset signal line RL1. Therefore, the first reset transistor RT1 releases the charge accumulated in the first light-emitting element 21 based on the first reset signal.

[0058] In this embodiment, the polarity of the first light-emitting control transistor LT1 and the polarity of the first reset transistor RT1 may be the same. For example, in this embodiment, the first reset transistor RT1 may release the charge accumulated in the first light-emitting element 21 to the low-voltage line LL when a first reset signal having a first high potential is supplied to the gate electrode via the first signal line SL1. With the above configuration, the polarity of the transistors included in the first control circuit 71 can be unified, simplifying the configuration.

[0059] The supply of a first reset signal having a first high potential to the first reset transistor RT1 may occur before the supply of a first signal having a first low potential to the first light emission control transistor LT1. Conversely, the supply of a first reset signal having a first low potential to the first reset transistor RT1 may occur after the supply of a first signal having a first high potential to the first light emission control transistor LT1. With the above configuration, the first control circuit 71 prevents the potential changes of the first signal and the first reset signal from occurring simultaneously, thereby preventing a short circuit between the first power line PL1 and the low voltage line LL.

[0060] In this embodiment, except for the applied power supply voltage and the supplied signal, the control circuits included in the light emission control circuit unit 70 may have the same configuration as the first control circuit 71. For example, in this embodiment, the second control circuit 72 includes a second light emission control transistor, a second capacitor, and a second reset transistor. In particular, the second reset transistor releases the charge accumulated in the second light-emitting element based on the second reset signal.

[0061] Each control circuit in the light emission control circuit unit 70 according to this embodiment has a reset transistor that releases the charge accumulated in the light-emitting element based on a reset signal. Therefore, the printer head 10 can individually control the light emission of each light-emitting element and the release of the charge accumulated in each light-emitting element. Consequently, the printer head 10 can more appropriately control the light emission of each light-emitting element.

[0062] [Embodiment 4] <Write signal> Figure 9 is a schematic diagram of the printer head 10 according to this embodiment. Compared to the printer head 10 according to the previous embodiment, the printer head 10 of the printing apparatus 1 includes a light emission control unit 80 instead of a light emission control unit 70. Compared to the light emission control unit 70, the light emission control unit 80 according to this embodiment includes a first control circuit 81, a second control circuit 82, a third control circuit 83, and a fourth control circuit 84 instead of a first control circuit 71, a second control circuit 72, a third control circuit 73, and a fourth control circuit 74.

[0063] Furthermore, the signal generation unit 50 according to this embodiment generates a reset signal and a write signal. The reset signal is supplied to each control circuit of the light emission control circuit unit 80 via the reset signal line RL, and the write signal is supplied to each control circuit of the light emission control circuit unit 80 via the write signal line WL. In other words, in this embodiment, a reset signal of the same potential is supplied simultaneously to multiple control circuits, and a write signal of the same potential is supplied simultaneously to multiple control circuits. The potentials of the reset signal and the write signal may be selected from, for example, a first low potential and a first high potential higher than the first low potential.

[0064] Figure 10 is an equivalent circuit diagram of the first control circuit 81 and the first light-emitting element 21 according to this embodiment. Compared to the first control circuit 71, the first control circuit 81 further includes a first writing transistor WT1. The source electrode of the first writing transistor WT1 is connected to the first signal line SL1, and the drain electrode of the first writing transistor WT1 is connected to the first light-emitting control transistor LT1. In addition, the gate electrode of the first writing transistor WT1 is connected to the writing signal line WL.

[0065] In the first control circuit 81 according to this embodiment, the first capacitor C1 is formed between the first power line PL1 and the drain electrode of the first writing transistor WT1. The first control circuit 81 further includes a first reset transistor RT1, the source electrode of which is connected to the first power line PL1 and the drain electrode of which is connected to the drain electrode of the first writing transistor WT1. In the first control circuit 81, the gate electrodes of the two first reset transistors RT1 are connected to the reset signal line RL.

[0066] As a result, in the first control circuit 81, when a first high-potential write signal is supplied to the first write transistor WT1, a first signal is supplied to the first capacitor C1 via the first signal line SL1, and charge is accumulated in the first capacitor C1. The first light emission control transistor LT1 is driven by the charge accumulated in the first capacitor C1 and controls the light emission of the first light-emitting element 21. In addition, in the first control circuit 81, when a first high-potential reset signal is supplied to the two first reset transistors RT1 via the reset signal line RL, the charge accumulated in the first capacitor C1 and the first light-emitting element 21 is released.

[0067] In other words, in the first control circuit 81, the first write transistor WT1 supplies a first signal to the first capacitor C1 based on the write signal, and the first control circuit 81 controls the light emission of the first light-emitting element 21 based on the charge stored in the first capacitor C1. Also, in the first control circuit 81, the two first reset transistors RT1 release the charge stored in the first capacitor C1 and the first light-emitting element 21 based on the reset signal.

[0068] In this embodiment, except for the applied power supply voltage and the supplied signal, the control circuits included in the light emission control circuit unit 80 may have the same configuration as the first control circuit 81. For example, in this embodiment, the second control circuit 82 includes a second light emission control transistor, a second capacitor, two second reset transistors, and a second write transistor. In particular, the second control circuit 82 controls the light emission of the second light-emitting element 22 based on the write signal and releases the charge accumulated in the second capacitor and the second light-emitting element 22 based on the reset signal.

[0069] In this embodiment, the printer head 10 can perform light emission of the light-emitting elements and release of the charge accumulated in the light-emitting elements based on a common write signal and reset signal for each control circuit. Therefore, the printer head 10 can reduce the number of reset signal lines corresponding to each light-emitting element, simplifying the configuration and the control content of each control circuit.

[0070] [Embodiment 5] <Variations in the arrangement of light-emitting elements> The printer head 10 of the printing apparatus 1 according to this embodiment differs from the printer head 10 according to the previous embodiments in that it has a light-emitting unit 90 instead of a light-emitting unit 20. Figure 11 is a schematic plan view of the light-emitting unit 90 according to this embodiment.

[0071] The light-emitting unit 90 differs from the light-emitting unit 20 only in the arrangement of each light-emitting element. In other words, each light-emitting element of the light-emitting unit 90 illuminates different regions of the curved surface of the photoreceptor 11 that the light-emitting unit 90 faces. The light-emitting unit 90 is equipped with light-emitting elements arranged two-dimensionally along a first direction D1 and a second direction D2.

[0072] In this embodiment, the first light-emitting element 21 and the third light-emitting element 23 are adjacent to each other in the second direction. Therefore, in this embodiment as well, the printer head 10 can place multiple control circuits that operate at the same power supply voltage close together, shortening the distance over which power lines need to be routed. This makes it easier to form power lines in the printer head 10 and simplifies the configuration of the power lines.

[0073] In the light-emitting unit 90, the second light-emitting element 22 may be adjacent to the first light-emitting element 21 in the first direction D1. This allows the light-emitting unit 90 to irradiate, for example, a third region of the curved surface of the photoreceptor 11, located between the first and second regions, with light from the third light-emitting element 23. In this embodiment, the first, second, and third regions may be aligned along the first direction D1. In this case, the light-emitting unit 90 can further shorten the spacing in the first direction D1 between the regions irradiated with light from each light-emitting element. Therefore, the printing apparatus 1 equipped with the printer head 10 according to this embodiment enables higher resolution printing.

[0074] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of Symbols]

[0075] 1 Printing device 10 Printer heads 11 Photoreceptor 11L latent image 12 Charged parts 13. Head drive unit 14. Toner supply unit 14T Toner 15 Toner transfer section 20 Light-emitting part 21 First light-emitting element 22 Second light-emitting element 31 First Control Circuit 32 Second Control Circuit 40 Power supply section 50 Signal generation unit

Claims

1. A first light-emitting element that illuminates the first region of the photoreceptor with light, A second light-emitting element that irradiates light onto the second region of the photoreceptor, A first control circuit that controls the light emission of the first light-emitting element and operates at a first power supply voltage, A second control circuit that controls the light emission of the second light-emitting element and operates at the second power supply voltage, A printer head comprising a power supply unit that generates the first power supply voltage and the second power supply voltage and individually controls the voltage values ​​of the first power supply voltage and the second power supply voltage.

2. The printer head according to claim 1, wherein the power supply unit includes a first power supply circuit that generates the first power supply voltage and a second power supply circuit that generates the second power supply voltage.

3. The printer head according to claim 1, wherein the power supply unit includes a main power supply circuit that generates a main power supply voltage, a first conversion circuit that converts the main power supply voltage to the first power supply voltage, and a second conversion circuit that converts the main power supply voltage to the second power supply voltage.

4. It includes a signal generation unit that generates a first signal and a second signal, The printer head according to any one of claims 1 to 3, wherein the first control circuit controls the emission of light from the first light-emitting element based on the first signal, and the second control circuit controls the emission of light from the second light-emitting element based on the second signal.

5. The first control circuit includes a first light-emitting control transistor that controls the current applied to the first light-emitting element based on the first signal, The printer head according to claim 4, wherein the second control circuit includes a second light-emitting control transistor that controls the current applied to the second light-emitting element based on the second signal.

6. The printer head according to claim 5, wherein the first light emission control transistor and the second light emission control transistor are driven in the linear region.

7. The potential of the first signal is selected from either a first low potential or a first high potential that is higher than the first low potential. The printer head according to claim 5, wherein the potential of the second signal is selected from either a second low potential or a second high potential that is higher than the second low potential.

8. The printer head according to claim 7, wherein the first low potential and the second low potential are the same, and the first high potential and the second high potential are the same.

9. The first control circuit includes a first capacitor that stores charge when the first signal is supplied, and controls the light emission of the first light-emitting element based on the charge stored in the first capacitor. The printer head according to claim 5, wherein the second control circuit includes a second capacitor that stores charge when the second signal is supplied, and controls the emission of light from the second light-emitting element based on the charge stored in the second capacitor.

10. The signal generation unit generates a write signal, The first control circuit includes a first writing transistor that supplies a first signal to the first capacitor based on the writing signal, The printer head according to claim 9, wherein the second control circuit includes a second writing transistor that supplies a second signal to the second capacitor based on the writing signal.

11. The first control circuit includes a first reset transistor that releases the charge accumulated in the first light-emitting element based on the first signal. The printer head according to claim 5, wherein the second control circuit includes a second reset transistor that releases the charge accumulated in the second light-emitting element based on the second signal.

12. The printer head according to claim 11, wherein the polarity of the first light-emitting control transistor and the polarity of the first reset transistor are different, and the polarity of the second light-emitting control transistor and the polarity of the second reset transistor are different.

13. The signal generation unit generates a first reset signal and a second reset signal. The first control circuit includes a first reset transistor that releases the charge accumulated in the first light-emitting element based on the first reset signal. The printer head according to claim 4, wherein the second control circuit includes a second reset transistor that releases the charge accumulated in the second light-emitting element based on the second reset signal.

14. The signal generation unit generates a reset signal, The first control circuit includes a first reset transistor that releases the charge accumulated in the first light-emitting element based on the reset signal. The printer head according to claim 4, wherein the second control circuit includes a second reset transistor that releases the charge accumulated in the second light-emitting element based on the reset signal.

15. The printer head according to claim 13, wherein the polarity of the first light-emitting control transistor and the polarity of the first reset transistor are the same, and the polarity of the second light-emitting control transistor and the polarity of the second reset transistor are the same.

16. A third light-emitting element that irradiates light onto the third region of the photoreceptor, The system comprises a third control circuit for controlling the light emission of the third light-emitting element, The printer head according to any one of claims 1 to 3, wherein the third control circuit operates at the first power supply voltage.

17. A third light-emitting element that irradiates light onto the third region of the photoreceptor, The system comprises a third control circuit for controlling the light emission of the third light-emitting element, The third control circuit operates at the first power supply voltage, The signal generation unit generates a third signal, The printer head according to claim 4, wherein the third control circuit controls the emission of light from the third light-emitting element based on the third signal.

18. The printer head according to claim 16, wherein the first light-emitting element and the third light-emitting element are adjacent to each other in a first direction parallel to the rotation axis of the photoreceptor.

19. The direction parallel to the rotation axis of the photoreceptor is taken as the first direction, The printer head according to claim 16, wherein the first light-emitting element and the third light-emitting element are adjacent to each other in a second direction intersecting the first direction.

20. A printing apparatus comprising a printer head according to any one of claims 1 to 3.

21. The aforementioned photoreceptor, A charging unit for charging the photoreceptor, A head drive unit that controls the light from the printer head to remove static electricity from at least a portion of the photoreceptor, thereby forming a latent image on the photoreceptor, A toner supply unit that supplies toner to the photoreceptor according to the latent image, The printing apparatus according to claim 20, further comprising a toner transfer unit for transferring the toner of the photoreceptor to a recording medium.

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