Printer head and 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

Printer head, printing device

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

[0002] Patent Document 1 describes an image forming apparatus such as a printer that forms an image on paper by attaching toner to a latent image formed on a photosensitive member and transferring the toner to the paper. In particular, Patent Document 1 describes a technology that uses a light-emitting element such as an OLED (organic light-emitting diode) in an optical writing device such as a printer head that irradiates light onto the photosensitive member.

[0003] Japanese Patent Application Publication No. 2015-101059

[0004] All of the light-emitting elements in the optical writing device described in Patent Document 1 are driven by a power supply voltage from a common power supply, so the circuit that drives the light-emitting elements requires a compensation circuit to compensate for the difference in power supply voltage between the light-emitting elements, which may lead to the device becoming more complex or increasing power consumption.

[0005] A printer head according to one aspect of the present disclosure includes a first light-emitting element that irradiates light onto a first region of a photosensitive body, a second light-emitting element that irradiates light onto a second region of the photosensitive body, a first control circuit that controls the light emission of the first light-emitting element and operates on a first power supply voltage, a second control circuit that controls the light emission of the second light-emitting element and operates on 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.

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

[0007] 1 is a schematic diagram of a printer head according to embodiment 1. FIG. 2 is a schematic side cross-sectional view of a printing device according to embodiment 1. FIG. 3 is a schematic enlarged view of the interior of a printing device according to embodiment 1. FIG. 4 is a schematic plan view of a light-emitting section according to embodiment 1. FIG. 5 is an equivalent circuit diagram of a first control circuit and a first light-emitting element according to embodiment 1. FIG. 6 is a schematic diagram of a printer head according to embodiment 2. FIG. 7 is a schematic diagram of a printer head according to embodiment 3. FIG. 8 is an equivalent circuit diagram of a first control circuit and a first light-emitting element according to embodiment 3. FIG. 9 is a schematic diagram of a printer head according to embodiment 4. FIG. 10 is an equivalent circuit diagram of a first control circuit and a first light-emitting element according to embodiment 4. FIG. 11 is a schematic plan view of a light-emitting section according to embodiment 5.

[0008] [First Embodiment] <Printing Apparatus: Overview> Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that in each drawing, the same components are denoted by the same reference numerals, and the description thereof will be omitted.

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

[0010] The printing device 1 is, for example, a device that prints on paper supplied from outside using a printing unit 2 while transporting the paper using a transport unit 3 and then ejects the paper to the outside. A plurality of printing units 2 may be provided along the direction in which the paper transported by the transport unit 3 travels. Each printing unit 2 may supply toner of a different color to the paper. This allows the printing device 1 to perform full-color printing on the paper.

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

[0012] The printing unit 2 includes a printer head 10, a photoconductor 11, a charging unit 12, a head driving 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 charge removing unit 17.

[0013] The printer head 10 is driven by a head drive unit 13, which will be 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 its cylindrical axis by a drive unit (not shown). The photoreceptor 11 can be charged at least on the curved surface of its outer surface, and can be discharged by being irradiated with light.

[0015] The charging unit 12 is disposed opposite 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, generating an electric field, thereby forming a charged region 11E on the curved surface of the photoreceptor 11. As the photoreceptor 11 rotates around its rotation axis, the charging unit 12 charges the curved surface of the photoreceptor 11, thereby gradually charging the curved surface of the photoreceptor 11.

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

[0017] The toner supply unit 14 includes a toner source 14M and a toner supply roller 14R. The toner source 14M contains a plurality of toners 14T, and the toner supply roller 14R supplies the toner 14T from the toner source 14M to the curved surface of the photoconductor 11 that faces it. A repulsive force due to electrostatic force acts between the toner 14T and the charged region 11E of the curved surface of the photoconductor 11. Therefore, the toner 14T adheres only to the latent image 11L on the curved surface of the photoconductor 11. Therefore, the toner supply unit 14 supplies the toner 14T to the photoconductor 11 in accordance with the latent image 11L. The toner supply unit 14 may have a mechanism for adding a developer to the toner 14T, or may have a mechanism for adhering only the toner 14T of the toner 14T and the developer to the curved surface of the photoconductor 11.

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

[0019] The paper P to which the toner 14T has been supplied is fed 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 toner 14T supplied to the photoconductor 11 in accordance with the latent image 11L on the photoconductor 11 has been supplied to the paper P, the toner 14T fixed to the surface of the paper P has a shape corresponding to the latent image 11L. This completes printing on the paper P.

[0020] Cleaner 16 may include a cleaner board 16B that contacts the curved surface of photoreceptor 11 and a cleaner roller 16R that faces cleaner board 16B. Cleaner 16 may scrape off toner 14T remaining on the curved surface of photoreceptor 11 even after it has passed through toner transfer unit 15 with cleaner board 16B and remove it with cleaner roller 16R. Discharge unit 17 may discharge the curved surface of photoreceptor 11 that has passed cleaner 16, for example, by grounding it or exposing the entire surface to light, and remove charged region 11E from photoreceptor 11.

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

[0022] <Printer Head: Light Emitting Unit> The light emitting unit 20 includes a plurality of 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 Fig. 4. Fig. 4 is a schematic plan view of the light emitting unit 20.

[0023] 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 include more light-emitting elements. Each light-emitting element irradiates light onto a different region of the curved surface of the photoconductor 11 that the light-emitting unit 20 faces. For example, the first light-emitting element 21, the second light-emitting element 22, the third light-emitting element 23, and the fourth light-emitting element 24 irradiate light onto a first region, a second region, a third region, and a fourth region of the curved surface of the photoconductor 11, respectively.

[0024] The light-emitting unit 20 has light-emitting elements arranged two-dimensionally along a first direction D1 and a second direction D2. The first direction D1 is a direction parallel to the rotation axis of the photoconductor 11 that the light-emitting unit 20 faces, and the second direction D2 is a direction intersecting both the first direction D1 and a third direction D3 that is the direction of movement of the outer surface of the facing photoconductor 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] For this reason, the light-emitting unit 20 has a plurality of light-emitting elements arranged along the second direction D2, in other words, the plurality of 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 fifth light-emitting element 25 adjacent to the first light-emitting element 21 in the second direction D2.

[0026] 1, the light-emission control circuit unit 30 includes control circuits corresponding to the respective light-emitting elements, such as a first control circuit 31, a second control circuit 32, a third control circuit 33, and a fourth control circuit 34. The first control circuit 31, the second control circuit 32, the third control circuit 33, and the fourth control circuit 34 control the light emission of the first light-emitting element 21, the second light-emitting element 22, the third light-emitting element 23, and the fourth light-emitting element 24, respectively. Details of the control circuits included in the light-emission control circuit unit 30 will be explained 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, such as a first power supply circuit 41 and a second power supply circuit 42. The first power supply circuit 41 and the second power supply circuit 42 each generate a first power supply voltage and a second power supply voltage, and individually control the voltage values ​​of the first power supply voltage and the second power supply voltage.

[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 a first power supply line PL1. Therefore, the first control circuit 31 and the third control circuit 33 each operate on 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 a second power supply line PL2. Therefore, the second control circuit 32 and the fourth control circuit 34 each operate on 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 in the light-emission control circuit unit 30, for example, 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 a 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 via a second signal line SL2, a third signal line SL3, and a fourth signal line SL4, respectively.

[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 generating 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 included in the light emission control circuit section 30 controls light emission from each light emitting element included in the light emitting section 20 based on a signal supplied from the signal generating section 50. For example, the first control circuit 31 controls the light emission of the first light emitting element 21 based on a first signal. Similarly, the second control circuit 32, the third control circuit 33, and the fourth control circuit 34 control the light emission of the second light emitting element 22, the third light emitting element 23, and the fourth light emitting element 24 based on a second signal, a third signal, and a fourth signal, respectively.

[0032] <Details of Control Circuit> Each control circuit included in the light emission control circuit unit 30 will be described in detail with reference to Fig. 5, taking the first control circuit 31 as an example. Fig. 5 is an equivalent circuit diagram of the first control circuit 31. Fig. 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. Note that, although an example in which each transistor is a field-effect transistor will be described in this disclosure, the present invention is not limited to this.

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

[0035] The first light-emission control transistor LT1 generates a drain current when, for example, a first signal having a first high potential is supplied to its gate electrode via the first signal line SL1; in other words, a current flows from the first power supply line PL1 to the first light-emitting element 21. The first light-emitting element 21, supplied with a current, emits light; in other words, the first light-emitting element 21 irradiates a first region of the photoconductor 11 with light. On the other hand, the drain current stops when a first signal having a first low potential is supplied to its gate electrode. Therefore, the first light-emission control transistor LT1 controls the current applied to the first light-emitting element 21 based on the first signal applied to its gate electrode via the first signal line SL1, thereby controlling the light emission of 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 the 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 a linear region in which the presence or absence of a drain current is controlled by the level of 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, i.e., the first light-emitting control transistor LT1 and the low-voltage line LL are short-circuited. 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, the 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, so that the first control circuit 31 can reduce the possibility that the charge remaining in the first light-emitting element 21 will cause the first light-emitting element 21 to emit light when it is not intended to do so.

[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 need a mechanism for applying 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 all have the same configuration as the first control circuit 31. For example, in this embodiment, the second control circuit 32 has 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 the embodiment> Generally, when control circuits for a plurality of light-emitting elements are operated by the same power supply voltage, an unintended difference in the power supply voltage supplied to each control circuit may occur due to a drop in the power supply voltage in the power supply line, etc. In this case, in order to reduce the influence of the difference in power supply voltage on the light emission control of each light-emitting element, it may be considered 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 on a power supply voltage that is generated by the power supply unit 40 and whose voltage value is individually controlled. For example, the first control circuit 31 operates on the first power supply voltage, and the second control circuit 32 operates on 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 without each control circuit being equipped with a compensation circuit. A 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 a power supply circuit corresponding to each control circuit, so that 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 on the first power supply voltage. Therefore, the printer head 10 operates multiple control circuits on the same power supply voltage, reducing the number of power supply lines connecting the power supply unit 40 to each control circuit and simplifying the configuration. Furthermore, the printer head 10 can simplify the control of the operating voltage of each control circuit by the power supply unit 40.

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

[0048] In particular, the light-emission control transistors included in each control circuit are driven in a linear region, in other words, by signals that take on two potential values. 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. This allows the printer head 10 to have multiple control circuits that operate on the same power supply voltage close to each other, shortening the distance over which power lines are routed. This makes it easier to form the power lines in the printer head 10 and simplifies the power line configuration.

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

[0051] The power supply unit 60 includes a main power supply circuit 61 and multiple 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 voltages converted by the respective conversion circuits are supplied to the respective control circuits of the light emission control circuit section 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 a first power supply line PL1. Furthermore, 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 a second power supply line PL2.

[0053] In this embodiment, the power supply unit 60 has only the main power supply circuit 61 as a power supply circuit to generate the multiple power supply voltages supplied to each control circuit, in other words, it does not have multiple power supply circuits. Therefore, the printer head 10 can reduce the number of power supply circuits provided in the power supply unit 60 and simplify the configuration.

[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 a printer head 10 according to this embodiment. Compared to the printer head 10 according to each of the previously described embodiments, the printer head 10 of the printing device 1 according to this embodiment includes a light-emitting control circuit section 70 instead of the light-emitting control circuit section 30. Compared to the light-emitting control circuit section 30, the light-emitting control circuit section 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 the first control circuit 31, the second control circuit 32, the third control circuit 33, and the fourth control circuit 34.

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

[0057] 8 is an equivalent circuit diagram of the first control circuit 71 and the first light-emitting element 21 according to this embodiment. In the first control circuit 71, the first reset transistor RT1 is not connected to the first signal line SL1, as compared to the first control circuit 31. In other words, the first signal is not applied to the first reset transistor RT1. In this embodiment, a first reset signal is applied to the gate electrode of the first reset transistor RT1 from the signal generating 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, the first reset transistor RT1 according to this embodiment 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 polarities of the transistors included in the first control circuit 71 can be unified, simplifying the configuration.

[0059] The supply of the first reset signal having the first high potential to the first reset transistor RT1 may be executed before the supply of the first signal having the first low potential to the first light-emitting control transistor LT1. Also, the supply of the first reset signal having the first low potential to the first reset transistor RT1 may be executed after the supply of the first signal having the first high potential to the first light-emitting 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 supply line PL1 and the low-voltage line LL.

[0060] In this embodiment, except for the applied power supply voltage and the supplied signals, 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 has 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 a 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. This allows the printer head 10 to individually control the light emission and release of the charge accumulated in each light-emitting element. This allows the printer head 10 to more appropriately control the light emission of each light-emitting element.

[0062] [Embodiment 4] <Write signal> Figure 9 is a schematic diagram of a 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 device 1 according to this embodiment has a light-emitting control circuit section 80 instead of the light-emitting control circuit section 70. Compared to the light-emitting control circuit section 70, the light-emitting control circuit section 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 the first control circuit 71, the second control circuit 72, the third control circuit 73, and the fourth control circuit 74.

[0063] The signal generating unit 50 according to this embodiment generates a reset signal and a write signal. The reset signal is supplied to each control circuit in the light-emission control circuit unit 80 via a reset signal line RL, and the write signal is supplied to each control circuit in the light-emission control circuit unit 80 via a write signal line WL. In other words, in this embodiment, reset signals of the same potential are supplied simultaneously to multiple control circuits, and write signals of the same potential are 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 or a first high potential higher than the first low potential.

[0064] 10 is an equivalent circuit diagram of a first control circuit 81 and a 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 write transistor WT1. The source electrode of the first write transistor WT1 is connected to a first signal line SL1, and the drain electrode of the first write transistor WT1 is connected to a first light-emitting control transistor LT1. The gate electrode of the first write transistor WT1 is connected to a write signal line WL.

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

[0066] As a result, in the first control circuit 81, when a write signal of a first high potential 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. Furthermore, in the first control circuit 81, when a reset signal of a first high potential 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 signals, the control circuits included in the light-emission control circuit unit 80 may all have the same configuration as the first control circuit 81. For example, in this embodiment, the second control circuit 82 has 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 a write signal, and releases the charge accumulated in the second capacitor and the second light-emitting element 22 based on a reset signal.

[0069] The printer head 10 according to this embodiment can control the light emitting elements to emit light and release the charge accumulated in the light emitting elements based on a write signal and a reset signal that are common to each control circuit. This allows the printer head 10 to 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] Fifth Embodiment <Modification of Arrangement of Light-Emitting Elements> The printer head 10 of the printing device 1 according to this embodiment differs from the printer head 10 according to the above-described embodiments only in that it includes a light-emitting unit 90 instead of the 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 irradiates light onto a different region of the curved surface of the photoconductor 11 that the light-emitting unit 90 faces. The light-emitting unit 90 has light-emitting elements arranged two-dimensionally along the first direction D1 and the 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, the printer head 10 also has multiple control circuits that operate at the same power supply voltage close to each other, which shortens the distance over which the power supply lines are routed. This makes it easier to form the power supply lines in the printer head 10 and simplifies the power supply line configuration.

[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, for example, the light-emitting unit 90 to irradiate a third region of the curved surface of the photoconductor 11, the third region being 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 reduce the distance in the first direction D1 between the regions irradiated with light from each light-emitting element. Therefore, the printing device 1 equipped with the printer head 10 according to this embodiment enables printing with higher resolution.

[0074] The present disclosure is not limited to the above-described embodiments, 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 the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0075] REFERENCE SIGNS LIST 1 Printing device 10 Printer head 11 Photoconductor 11L Latent image 12 Charging section 13 Head driving section 14 Toner supply section 14T Toner 15 Toner transfer section 20 Light emitting section 21 First light emitting element 22 Second light emitting element 31 First control circuit 32 Second control circuit 40 Power supply section 50 Signal generating section

Claims

1. a first light-emitting element that irradiates a first region of the photosensitive member with light; a second light-emitting element that irradiates a second region of the photosensitive member with light; a first control circuit that controls light emission of the first light emitting element and operates on a first power supply voltage; a second control circuit that controls the light emission of the second light emitting element and operates on a second power supply voltage; a power supply unit that generates the first power supply voltage and the second power supply voltage and that controls the voltage values ​​of the first power supply voltage and the second power supply voltage individually.

2. 2. The printer head according to claim 1, wherein the power supply section 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. 2. 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. a signal generating unit that generates a first signal and a second signal; 4. A printer head according to claim 1, wherein the first control circuit controls the light emission of the first light-emitting element based on the first signal, and the second control circuit controls the light emission of the second light-emitting element based on the second signal.

5. the first control circuit includes a first light-emitting control transistor that controls a current applied to the first light-emitting element based on the first signal; 5. 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. 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 a linear region.

7. the potential of the first signal is selected from a first low potential and a first high potential higher than the first low potential; 6. The printer head according to claim 5, wherein the potential of the second signal is selected from a second low potential and a second high potential higher than the second low potential.

8. 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 light emission of the first light-emitting element based on the charge stored in the first capacitor; 6. A printer head as described in 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 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 write transistor that supplies a first signal to the first capacitor based on the write signal; 10. The printer head according to claim 9, wherein the second control circuit includes a second write transistor that supplies a second signal to the second capacitor based on the write signal.

11. the first control circuit includes a first reset transistor that releases charges accumulated in the first light-emitting element based on the first signal; 6. 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. 12. The printer head according to claim 11, wherein the polarity of the first light-emission control transistor is different from the polarity of the first reset transistor, and the polarity of the second light-emission control transistor is different from the polarity of the second reset transistor.

13. the signal generating unit generates a first reset signal and a second reset signal; the first control circuit includes a first reset transistor that releases charges accumulated in the first light-emitting element based on the first reset signal; 5. 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 generating 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; 5. 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. 14. The printer head according to claim 13, wherein the polarity of the first light-emission control transistor and the polarity of the first reset transistor are the same, and the polarity of the second light-emission control transistor and the polarity of the second reset transistor are the same.

16. a third light-emitting element that irradiates a third region of the photosensitive member with light; a third control circuit that controls the light emission of the third light emitting element, 4. A printer head according to claim 1, wherein the third control circuit operates on the first power supply voltage.

17. a third light-emitting element that irradiates a third region of the photosensitive member with light; a third control circuit that controls the light emission of the third light emitting element, the third control circuit operates on the first power supply voltage, the signal generator generates a third signal; 5. The printer head according to claim 4, wherein the third control circuit controls the light emission of 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 photosensitive member.

19. a direction parallel to the rotation axis of the photosensitive member is defined as a first direction, The printer head of 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 device comprising the printer head according to any one of claims 1 to 3.

21. the photoreceptor; a charging unit that charges the photosensitive member; a head driving unit that controls light from the printer head to neutralize at least a portion of the photosensitive member, thereby forming a latent image on the photosensitive member; a toner supply unit that supplies toner to the photosensitive member in accordance with the latent image; 21. The printing apparatus according to claim 20, further comprising a toner transfer unit that transfers the toner on the photosensitive member onto a recording medium.