Printing apparatus

Abstract

To provide a printing apparatus that can improve heat dissipation within a fire-resistant enclosure while reducing the risk of fire spreading due to element ignition. [Solution] A printing apparatus comprising: a transport unit for transporting a medium; a discharge unit for discharging liquid onto the medium; and a substrate equipped with a first element having a power supply of 100W or more and a second element having a power supply of less than 100W, wherein the first element is covered by a fireproof enclosure, the second element is not covered by the fireproof enclosure, the fireproof enclosure comprises a wall portion and a top plate portion, the wall portion is made of a flame-retardant resin material of V-1 grade or higher, surrounds the four sides of the first element, the first surface of the wall portion is in contact with the substrate, the second surface of the wall portion opposite the first surface is in contact with the top plate portion, and the top plate portion is made of aluminum and has a series of bumps for heat dissipation.

Description

Technical Field

[0001] The present invention relates to a printing apparatus.

Background Art

[0002] In recent years, various electrical appliances have been used, and electrical appliances continue to undergo technical evolution to improve the quality of human life. Technological evolution has led to the creation of electrical appliances equipped with new technologies, and safety standards have been established globally to ensure that electrical appliances equipped with new technologies never threaten human safety. For example, as an international safety standard, the safety standard IEC62368-1 for information and communication equipment has been enacted. Along with technological evolution, IEC62368-1 has also been updated, and the 4th edition of IEC62368-1 was enacted in 2023. IEC62368-1 is also related to fireproof enclosures provided to prevent fire spread when an overheated electronic component catches fire, as described in Patent Document 1. Furthermore, as described in Patent Document 2, an invention that takes fireproof enclosures into consideration has also been made in the field of image forming apparatuses.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there are few inventions concerning fire-resistant enclosures for image forming and printing apparatuses. Furthermore, because the enclosure covers high-temperature electronic components, the inside of the enclosure tends to become very hot, making the electronic components inside the fire-resistant enclosure prone to overheating and ignition. Therefore, there was room for improvement in methods for dissipating heat from inside the enclosure while preventing the spread of fire in printing apparatuses. [Means for solving the problem]

[0005] One aspect of the printing apparatus according to the present invention is: A transport unit that transports the media, A dispensing unit for dispensing liquid into the aforementioned medium, The substrate comprises a first element that supplies 100W or more of power and a second element that supplies less than 100W of power, The first element is covered with a fire-resistant enclosure. The second element is not covered by the fire-resistant enclosure. The aforementioned fire-resistant enclosure comprises a wall section and a top section, The wall portion is made of a flame-retardant resin material of V-1 grade or higher, and surrounds the four sides of the first element. The first surface of the wall portion is in contact with the substrate. The second surface of the wall portion opposite to the first surface is in contact with the top plate portion. The aforementioned top panel is made of aluminum and has a series of bumps and grooves for heat dissipation. [Brief explanation of the drawing]

[0006] [Figure 1] This is a diagram illustrating the schematic configuration of a printing apparatus. [Figure 2] This diagram shows the functional configuration of a printing device. [Figure 3] This is a diagram showing the circuit configuration of the power supply circuit. [Figure 4] This is a diagram showing the circuit configuration of the drive circuit. [Figure 5] This is a diagram illustrating the general configuration of the discharge section. [Figure 6]This figure shows an example of a signal waveform for a drive signal. [Figure 7] This figure shows an example of the relationship between the size of the dots formed on the medium and the signal waveform of the drive voltage VOUT. [Figure 8] This figure shows an example of the functional configuration of a drive signal selection circuit. [Figure 9] This figure shows an example of the decoding content of the decoder in the selection control circuit. [Figure 10] This figure shows an example of the configuration of a selection circuit corresponding to the discharge section. [Figure 11] This diagram illustrates specific examples of latch signals, change signals, clock signals, and print data signals. [Figure 12] This is a perspective view of a circuit board with a fire-resistant enclosure. [Figure 13] Figure 12 is a side view of the circuit board after the fire-resistant enclosure shown has been cut open. [Figure 14] This diagram shows the wall section viewed from the tip of the arrow indicating the Z-axis direction. [Modes for carrying out the invention]

[0007] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings used are for illustrative purposes only. The embodiments described below are not intended to unduly limit the scope of the present invention as described in the claims. Furthermore, not all of the configurations described below are essential components of the present invention.

[0008] In the following description, an inkjet printer is used as an example of a printing apparatus according to the present invention.

[0009] 1. Overview of the printing equipment FIG. 1 is a diagram illustrating an example of a schematic configuration of a printing apparatus 1. The printing apparatus 1 of the present embodiment is a so-called serial-type inkjet printer that forms a desired image on a medium P by reciprocating a carriage 21 carrying print heads 22-1 to 22-n along a scanning axis, and causing the print heads 22-1 to 22-n to eject ink, which is an example of liquid, onto the medium P conveyed along a conveyance direction. As the medium P used in such a printing apparatus 1, in addition to printing paper such as plain paper, any arbitrary printing medium such as a resin film or fabric can be used. Further, the medium P may have a size equal to or smaller than the short side width of A3.

[0010] As shown in FIG. 1, the printing apparatus 1 includes a control circuit board 10, a power supply circuit board 11, a drive circuit board 12, print heads 22-1 to 22-n, a moving unit 30, a conveyance unit 40, and an ink container 90.

[0011] The ink container 90 stores a plurality of types of ink to be ejected onto the medium P. As such an ink container 90, an ink cartridge, a bag-shaped ink pack formed of a flexible film, an ink tank capable of being refilled with ink, or the like can be used.

[0012] A control circuit including processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory is mounted on the control circuit board 10. The control circuit controls each component of the printing apparatus 1, and controls ink ejection from ejection units 600[1] to 600[p] which will be described later.

[0013] A power supply circuit is mounted on the power supply circuit board 11. For example, the power supply circuit generates a power supply voltage VDC, which is a constant DC voltage with a voltage value of, for example, 48V, from an AC voltage signal such as commercial power supplied to the printing apparatus 1, and outputs the power supply voltage VDC to each part of the printing apparatus 1. The power supply circuit includes, for example, an AC / DC converter such as a flyback converter, and further includes a DC / DC converter .

[0014] The drive circuit board 12 is equipped with a drive circuit that generates a drive signal COM based on data supplied from the control circuit. The drive signal COM is a signal that causes ink to be ejected to the ejection units 600[1] to 600[p], which will be described later.

[0015] The print heads 22-1 to 22-n are mounted on the carriage 21. The print heads 22-1 to 22-n are supplied with a control signal Ctrl-H from the control circuit board 10 and a drive signal COM from the drive circuit board 12. Ink stored in the ink container 90 is also supplied to the print heads 22-1 to 22-n via tubes or the like (not shown). Each of the print heads 22-1 to 22-n ejects the supplied ink onto the medium P based on the control signal Ctrl-H and the drive signal COM.

[0016] The moving unit 30 includes a carriage motor 31 and an endless belt 32. The carriage motor 31 operates based on a control signal Ctrl-C supplied from the control circuit board 10. A carriage 21, on which print heads 22-1 to 22-n are mounted, is fixed to the endless belt 32. The endless belt 32 rotates in accordance with the operation of the carriage motor 31. As a result of the rotation of the endless belt 32, the carriage 21 fixed to the endless belt 32 moves along the scanning direction. In other words, the moving unit 30 controls the movement of the print heads 22-1 to 22-n mounted on the carriage 21.

[0017] The transport unit 40 includes a transport motor 41 and transport rollers 42. The transport motor 41 operates based on a control signal Ctrl-T supplied from the control circuit board 10. The transport rollers 42 rotate in accordance with the operation of the transport motor 41 while holding the medium P. This rotation of the transport rollers 42 transports the medium P held by the transport rollers 42 along the transport direction. In other words, the transport unit 40 transports the medium P.

[0018] In the printing apparatus 1 configured as described above, the moving unit 30 controls the reciprocating motion of the carriage 21 along the scanning direction, and the transport unit 40 controls the transport of the medium P along the transport direction. Then, in conjunction with the reciprocating motion of the carriage 21 and the transport of the medium P, each of the print heads 22-1 to 22-n mounted on the carriage 21 ejects ink onto the medium P. As a result, the ink ejected from each of the print heads 22-1 to 22-n lands on any surface of the medium P, and a desired image is formed on the medium P.

[0019] 2. Functional configuration of the printing device Next, the functional configuration of the printing device 1 will be described. Figure 2 is a diagram showing the functional configuration of the printing device 1. As shown in Figure 2, the printing device 1 comprises a control circuit board 10, a power supply circuit board 11, a drive circuit board 12, a head unit 20, and a transport unit 40.

[0020] The control circuit board 10 and the head unit 20 are connected by cable 71. The drive circuit board 12 and the head unit 20 are connected by cable 72. Cables 71 and 72 are cables that have sliding properties that can follow the movement of the carriage 21, and may be, for example, flexible flat cables (FFC).

[0021] The power supply circuit board 11 has a power supply circuit 110 mounted on it. The power supply circuit 110 includes a voltage conversion circuit 111 and a smoothing circuit 112. The voltage conversion circuit 111 transforms an AC voltage signal such as a commercial power supply and outputs the transformed AC voltage to the smoothing circuit 112. The smoothing circuit 112 smooths the AC voltage output from the voltage conversion circuit 111 and outputs a DC power supply voltage VDC.

[0022] Figure 3 is a schematic circuit diagram showing the configuration of the voltage conversion circuit 111 and the smoothing circuit 112. As shown in Figure 3, the voltage conversion circuit 111 includes a transformer 121. For example, the transformer 121 transforms the AC voltage of a 100V commercial power supply 2 and outputs the transformed AC voltage to the smoothing circuit 112. As shown in Figure 3, the smoothing circuit 112 includes a rectifier circuit 122 and a capacitor 123. The rectifier circuit 122 is, for example, a diode bridge circuit composed of multiple diodes, and rectifies the AC voltage converted by the voltage conversion circuit 111. The capacitor 123 is a smoothing capacitor that smooths the voltage after it has been rectified by the rectifier circuit 122, converts it to a DC voltage of, for example, 48V, and outputs the power supply voltage VDC of that DC voltage.

[0023] Returning to the explanation of Figure 2, the control circuit board 10 has the DC / DC converter 80 and the control circuit 100 mounted on it.

[0024] The DC / DC converter 80 steps down the power supply voltage VDC output from the smoothing circuit 112 of the power supply circuit 110 to generate a power supply voltage VDD, for example, a constant DC voltage with a voltage value of 3.3V, which is output to the control circuit 100 and the drive circuit 50, and also to the head unit 20 via cable 71. The DC / DC converter 80 also steps down the power supply voltage VDC to generate a power supply voltage VHV, for example, a constant DC voltage with a voltage value of 42V, which is output to the drive circuit 50, and also to the head unit 20 via cable 71.

[0025] The control circuit 100 includes, for example, a processor such as a microcontroller, and is communicatively connected to an external device, such as a host computer (not shown), located outside the printing device 1. The control circuit 100 receives an image information signal from the external device, which includes image data formed on the medium P. The control circuit 100 generates various data for controlling the printing device 1 and signals corresponding to that data by applying predetermined image processing to the input image information signal.

[0026] The control circuit 100 generates a control signal Ctrl-T for controlling the transport of the medium P and outputs it to the transport unit 40. This causes the transport motor 41 of the transport unit 40 to rotate, controlling the transport of the medium P along the transport direction. Here, the control signal Ctrl-T output by the control circuit 100 may be converted into a signal in a driver circuit (not shown) before being input to the transport motor 41.

[0027] Furthermore, based on the input image information signal, the control circuit 100 generates a latch signal LAT, a change signal CH, a clock signal SCK, and print data signals SI1~SIn as control signals Ctrl-H for controlling the head unit 20, and outputs them to the head unit 20 via cable 71. Details of the latch signal LAT, change signal CH, clock signal SCK, and print data signals SI1~SIn will be described later.

[0028] The drive circuit board 12 has a drive circuit 50 mounted on it. The control circuit 100 outputs a base drive signal dA, which is a digital signal, to the drive circuit 50. The drive circuit board 12 may also be mounted on the head unit 20.

[0029] The drive circuit 50 converts the base drive signal dA of the input digital signal from digital to analog, and then generates a drive signal COM containing one or more signal waveforms by class D amplification of the converted analog signal. The drive circuit 50 may generate multiple drive signals COM. The drive circuit 50 then outputs the generated drive signals COM to the head unit 20 via cable 72. Here, the base drive signal dA defines the signal waveform of the drive signal COM. The drive circuit 50 generates the drive signal COM, which is an analog signal, by performing a Class D amplification of the signal waveform defined by the base drive signal dA. In other words, the base drive signal dA is the digital signal that forms the basis of the drive signal COM output from the drive circuit 50. However, the base drive signal dA only needs to be able to define the signal waveform of the drive signal COM and may be an analog signal. Furthermore, the drive circuit 50 only needs to be able to amplify the signal waveform defined by the base drive signal dA and output it as the drive signal COM. Therefore, the drive circuit 50 may generate the drive signal COM by performing a Class A, Class B, or Class AB amplification of the signal waveform defined by the base drive signal dA.

[0030] Furthermore, the drive circuit 50 generates a reference voltage VBS, which serves as the reference potential for driving the piezoelectric element 60 of the head unit 20, which will be described later. The drive circuit 50 then outputs the generated reference voltage VBS to the head unit 20 via the cable 72. Such a reference voltage VBS may be, for example, a ground potential with a voltage value of 0V, or it may be a DC voltage such as 5.5V or 6V.

[0031] The head unit 20 has print heads 22-1 to 22-n. The print head 22-i also includes a drive signal selection circuit 200 and p ejection units 600[1] to 600[p], where i is an integer between 1 and n.

[0032] The drive signal selection circuit 200 is configured to include one or more integrated circuit devices. The drive signal selection circuit 200 receives a latch signal LAT, a change signal CH, a clock signal SCK, a print data signal SIi, and a drive signal COM as inputs. Based on the input latch signal LAT, change signal CH, clock signal SCK, and print data signal SIi, the drive signal selection circuit 200 selects or deselects the signal waveform of the drive signal COM, thereby generating and outputting drive voltages VOUT[1] to VOUT[p] that correspond individually to each of the ejection units 600[1] to 600[p]. In other words, the drive signal selection circuit 200 functions as a drive control unit that controls the application of the drive signal COM to the ejection units 600[1] to 600[p]. Details of the configuration and operation of the drive signal selection circuit 200 will be described later.

[0033] Each of the ejection units 600[1] to 600[p] contains a piezoelectric element 60. A drive voltage VOUT[j] output by the drive signal selection circuit 200 is supplied to one end of the piezoelectric element 60 included in ejection unit 600[j]. j is an integer between 1 and p. A reference voltage VBS is supplied in common to the other ends of the p piezoelectric elements 60 included in ejection units 600[1] to 600[p]. The piezoelectric element 60 included in ejection unit 600[j] is displaced by the potential difference between the drive voltage VOUT[j] and the reference voltage VBS. An amount of ink corresponding to the displacement of the piezoelectric element 60 is ejected from the corresponding ejection unit 600[j]. The drive voltage VOUT[j] is generated by selecting or deselecting the signal waveform of the drive signal COM; in other words, the ejection unit 600[j] ejects ink when the drive signal COM is applied. Then, ink ejected from the ejection units 600[1] to 600[p] contained in the print heads 22-1 to 22-n, respectively, lands on the medium P, forming an image on the medium P.

[0034] Thus, the ejection unit 600[j] included in the print head 22-i is subjected to a drive voltage VOUT[j] generated based on the latch signal LAT, change signal CH, clock signal SCK, and print data signal SIi, and ejects ink onto the medium P. In other words, the latch signal LAT, change signal CH, clock signal SCK, and print data signals SI1 to SIn are ejection control signals that control the ejection of ink from the ejection unit 600[j] to the medium P, and the ejection unit 600[j] ejects ink onto the medium P based on the ejection control signals.

[0035] Here, print heads 22-1 to 22-n all have the same configuration, and there is no need to distinguish between them. When not necessary, it may be referred to as the print head 22. In this case, it will be explained that the print head 22 is input with print data signals SI as print data signals SI1 to SIn. Also, the ejection units 600[1] to 600[p] of the print head 22 all have the same configuration and when there is no need to distinguish them, they may be simply referred to as the ejection unit 600. In this case, it will be explained that the ejection unit 600 is supplied with a drive voltage VOUT as drive voltage VOUT[1] to VOUT[p].

[0036] 3. Drive Circuit Configuration Figure 4 shows the circuit configuration of the drive circuit 50. As shown in Figure 4, the drive circuit 50 includes an integrated circuit 500, transistors 551 and 552, a coil 553, and a capacitor 554. The integrated circuit 500 includes a voltage generation circuit 510, a DAC 520, a modulation unit 530, and a gate drive unit 540. DAC is an abbreviation for Digital to Analog Converter.

[0037] The voltage generation circuit 510 generates a voltage GVDD based on the power supply voltage VHV. Voltage GVDD is a DC voltage with a voltage value of, for example, 7.5V, and is input to the gate drive unit 540. The voltage generation circuit 510 also generates a reference voltage VBS based on the power supply voltage VHV.

[0038] The DAC520 receives a base drive signal dA as input. The DAC520 converts the input base drive signal dA into an analog base drive signal aA. This base drive signal aA is the target signal before amplification of the drive signal COM. The modulation unit 530 receives the base drive signal aA as input. The modulation unit 530 outputs a modulated signal Ms obtained by applying pulse width modulation to the base drive signal aA. The gate drive unit 540 receives voltages VHV and GVDD and the modulated signal Ms as input. The gate drive unit 540 amplifies the input modulated signal Ms based on the voltage GVDD and generates an amplification control signal Hgd, which is level-shifted to high amplitude logic based on the voltage VHV, and an amplification control signal Lgd, which inverts the logic level of the input modulated signal Ms and amplifies it based on the voltage GVDD. That is, the amplification control signal Hgd and the amplification control signal Lgd are mutually exclusive to the high level.

[0039] A voltage VHV is supplied to the drain terminal of transistor 551. An amplification control signal Hgd is supplied to the gate terminal of transistor 551. The source terminal of transistor 551 is electrically connected to the drain terminal of transistor 552. An amplification control signal Lgd is supplied to the gate terminal of transistor 552. The source terminal of transistor 552 is connected to ground. Transistor 551, connected in this manner, operates according to the amplification control signal Hgd, and transistor 552 operates according to the amplification control signal Lgd. In other words, transistors 551 and 552 are exclusively turned on. As a result, an amplified modulated signal is generated at the connection point between the source terminal of transistor 551 and the drain terminal of transistor 552, which is obtained by amplifying the modulation signal Ms based on the voltage VHV. Note that each of transistors 551 and 552 is, for example, an N-channel type FET. FET is an abbreviation for Field Effect Transistor.

[0040] One end of coil 553 is connected to the source terminal of transistor 551 and the drain terminal of transistor 552. The other end of coil 553 is connected to one end of capacitor 554. The other end of capacitor 554 is connected to ground. In other words, coil 553 and capacitor 554 constitute a low-pass filter. When an amplified and modulated signal is supplied to this low-pass filter, the amplified and modulated signal is demodulated, and a drive signal COM is generated. The drive circuit 50 outputs the drive signal COM generated as described above.

[0041] Thus, the drive circuit 50 generates the drive signal COM by performing a digital / analog conversion on the base drive signal dA and then performing a Class D amplification. That is, DAC 520, modulation unit 530, gate drive The moving part 540, transistors 551 and 552, coil 553, and capacitor 554 constitute an amplification circuit 501, which is a Class D amplifier. However, the drive circuit 50 may generate the drive signal COM by amplifying the signal waveform defined by the base drive signal dA in Class A, Class B, or Class AB.

[0042] 4. Structure of the discharge section Next, the structure of the discharge section 600 will be described. Figure 5 is a diagram illustrating the schematic configuration of the discharge section 600. In addition to the discharge section 600, Figure 5 also shows the nozzle plate 632, reservoir 641, and supply port 661.

[0043] As shown in Figure 5, the discharge section 600 includes a piezoelectric element 60, a diaphragm 621, a cavity 631, and a nozzle 651. The piezoelectric element 60 includes a piezoelectric body 601 and electrodes 611 and 612. The piezoelectric element 60 is configured such that electrodes 611 and 612 are positioned to sandwich the piezoelectric body 601. Such a piezoelectric element 60 is driven so that its central portion is displaced vertically in accordance with the potential difference between the voltage supplied to electrode 611 and the voltage supplied to electrode 612. Specifically, electrode 611 is supplied with a drive voltage VOUT based on a drive signal COM, and electrode 612 is supplied with a reference voltage VBS. When the voltage value of the drive voltage VOUT supplied to electrode 611 changes, the potential difference between the drive voltage VOUT supplied to electrode 611 and the reference voltage VBS supplied to electrode 612 changes. As a result, the piezoelectric element 60 is driven so that its central portion is displaced vertically.

[0044] The diaphragm 621 is located below the piezoelectric element 60 in Figure 5. In other words, the piezoelectric element 60 is formed on the upper surface of the diaphragm 621 in Figure 5. Such a diaphragm 621 is displaced vertically as the piezoelectric element 60 is driven vertically.

[0045] Below the diaphragm 621 in Figure 5, there is a cavity 631. Ink is supplied to the cavity 631 from the reservoir 641. In addition, ink stored in the ink container 90 is introduced into the reservoir 641 via the supply port 661. In other words, the inside of the cavity 631 is filled with ink stored in the ink container 90. The internal volume of this cavity 631 expands or contracts with the vertical displacement of the diaphragm 621. That is, the diaphragm 621 functions as a diaphragm that changes the internal volume of the cavity 631, and the cavity 631 functions as a pressure chamber whose pressure changes with the vertical displacement of the diaphragm 621.

[0046] The nozzle 651 is an opening provided in the nozzle plate 632 and communicates with the cavity 631. When the internal volume of the cavity 631 changes, the ink filled inside the cavity 631 is ejected from the nozzle 651 in accordance with the change in internal volume.

[0047] In the ejection unit 600 configured as described above, when the piezoelectric element 60 is driven to bend upward, the diaphragm 621 is displaced upward. This expands the internal volume of the cavity 631, and as a result, the ink stored in the reservoir 641 is drawn into the cavity 631. On the other hand, when the piezoelectric element 60 is driven to bend downward, the diaphragm 621 is displaced downward. This reduces the internal volume of the cavity 631, and as a result, an amount of ink corresponding to the degree of reduction in the internal volume of the cavity 631 is ejected from the nozzle 651.

[0048] Furthermore, the piezoelectric element 60 is driven by a drive voltage VOUT corresponding to the drive signal COM, and the structure is not limited to the structure shown in Figure 5, as long as it is driven in a way that allows ink to be ejected from the nozzle 651.

[0049] 5. Functional configuration of the drive signal selection circuit Next, the configuration and operation of the drive signal selection circuit 200 will be described. In describing the configuration and operation of the drive signal selection circuit 200, an example of the signal waveform of the drive signal COM input to the drive signal selection circuit 200 and an example of the signal waveform of the drive voltage VOUT output from the drive signal selection circuit 200 will be described.

[0050] Figure 6 shows an example of the signal waveform of the drive signal COM. In Figure 6, two drive signals COMA and COMB are shown as examples of drive signals COM.

[0051] The drive signal COMA is a signal waveform formed by continuously combining a trapezoidal waveform Adp1, which is positioned during the period t1 from when the latch signal LAT rises until when the change signal CH rises, and a trapezoidal waveform Adp2, which is positioned during the period t2 from when the change signal CH rises until when the latch signal LAT rises. Furthermore, the trapezoidal waveform Adp1 is a signal waveform that, when supplied to the piezoelectric element 60 contained in the ejection unit 600, causes the ejection unit 600 to eject a predetermined amount of ink, and the trapezoidal waveform Adp2 is a signal waveform that, when supplied to the piezoelectric element 60 contained in the ejection unit 600, causes the ejection unit 600 to eject an amount of ink greater than the predetermined amount. Hereinafter, in the following description, the amount of ink ejected from the ejection unit 600 when the trapezoidal waveform Adp1 is supplied to the piezoelectric element 60 contained in the ejection unit 600 may be referred to as a small amount, and the amount of ink ejected from the ejection unit 600 when the trapezoidal waveform Adp2 is supplied to the piezoelectric element 60 contained in the ejection unit 600 may be referred to as a medium amount.

[0052] Furthermore, as shown in Figure 6, the drive signal COMB is a signal waveform formed by continuously combining a trapezoidal waveform Bdp1 positioned during period t1 and a trapezoidal waveform Bdp2 positioned during period t2. The trapezoidal waveform Bdp1, when supplied to the piezoelectric element 60 included in the ejection unit 600, is a signal waveform that prevents ink from being ejected from the ejection unit 600, while the trapezoidal waveform Bdp2, when supplied to the piezoelectric element 60 included in the ejection unit 600, is a signal waveform that causes a small amount of ink to be ejected from the ejection unit 600. Here, the trapezoidal waveform Bdp1 is a signal waveform that prevents an increase in ink viscosity by vibrating the ink near the nozzle opening in the ejection unit 600 to the extent that ink is not ejected. In the following description, the operation of vibrating the ink near the nozzle opening when the trapezoidal waveform Bdp1 is supplied to the piezoelectric element 60 of the ejection unit 600 may be referred to as micro-vibration.

[0053] Here, as shown in Figure 6, the voltage values ​​at the start and end timings of each trapezoidal waveform Adp1, Adp2, Bdp1, and Bdp2 are all the same, at voltage Vc. That is, each trapezoidal waveform Adp1, Adp2, Bdp1, and Bdp2 starts and ends at voltage Vc. The period tp, consisting of periods t1 and t2, corresponds to the printing cycle that forms new dots on the medium P.

[0054] In Figure 6, the case where the trapezoidal waveform Adp1 and the trapezoidal waveform Bdp2 are the same signal waveform is shown, but the trapezoidal waveform Adp1 and the trapezoidal waveform Bdp2 may be different signal waveforms. Furthermore, in the explanation, it is assumed that a small amount of ink is ejected from the ejection unit 600 in both cases where the trapezoidal waveform Adp1 is supplied to the piezoelectric element 60 included in the ejection unit 600 and where the trapezoidal waveform Bdp2 is supplied to the piezoelectric element 60 included in the ejection unit 600, but this is not the only case. In other words, the signal waveforms of the drive signals COMA and COMB are not limited to the signal waveforms shown in Figure 6, and various combinations of signal waveforms may be used depending on the properties of the ink ejected from the ejection unit 600 and the material of the medium P to which the ejected ink lands.

[0055] Furthermore, in Figure 6, the trapezoidal waveforms Adp1 and Adp2 included in the drive signal COMA are The example shows a case where the timing of the switching between the two trapezoidal waveforms, and the timing of the switching between trapezoidal waveforms Bdp1 and Bdp2 included in the drive signal COMB, are defined by a single change signal CH. However, the change signal CH that defines the timing of the switching between trapezoidal waveforms Adp1 and Adp2 included in the drive signal COMA, and the change signal CH that defines the timing of the switching between trapezoidal waveforms Bdp1 and Bdp2 included in the drive signal COMB, may be different signals.

[0056] Figure 7 shows an example of the signal waveform of the drive voltage VOUT for each case where the size of the dots formed on the medium P is large dot LD, medium dot MD, small dot SD, and non-recorded ND.

[0057] As shown in Figure 7, when a large dot LD is formed on the medium P, the drive voltage VOUT is a continuous signal waveform consisting of a trapezoidal waveform Adp1 positioned during period t1 of the period tp and a trapezoidal waveform Adp2 positioned during period t2 of the period tp. When this drive voltage VOUT is supplied to the piezoelectric element 60 included in the ejection unit 600, a small amount of ink and a medium amount of ink are ejected from the corresponding ejection unit 600. Then, each ink lands on the medium P and combines, forming a large dot LD on the medium P during period tp.

[0058] When a medium dot MD is formed on the medium P, the drive voltage VOUT is a continuous signal waveform consisting of a trapezoidal waveform Adp1 positioned during period t1 of the period tp and a trapezoidal waveform Bdp2 positioned during period t2 of the period tp. When this drive voltage VOUT is supplied to the piezoelectric element 60 included in the ejection unit 600, a small amount of ink is ejected twice from the corresponding ejection unit 600. Then, each ink droplet lands on the medium P and combines, forming a medium dot MD on the medium P during period tp.

[0059] When small dots SD are formed on the medium P, the drive voltage VOUT is a continuous signal waveform consisting of a trapezoidal waveform Adp1 positioned during period t1 of the period tp, and a constant signal waveform of voltage Vc positioned during period t2 of the period tp. When this drive voltage VOUT is supplied to the piezoelectric element 60 included in the ejection unit 600, a small amount of ink is ejected once from the corresponding ejection unit 600. When this ink lands on the medium P, small dots SD are formed on the medium P during period tp.

[0060] The drive voltage VOUT corresponding to non-recording ND, which does not form dots on the medium P, is a continuous signal waveform consisting of a trapezoidal waveform Bdp1 positioned during period t1 of the period tp, and a constant signal waveform with voltage Vc positioned during period t2 of the period tp. When this drive voltage VOUT is supplied to the piezoelectric element 60 included in the ejection unit 600, only the ink near the nozzle opening of the corresponding ejection unit 600 vibrates slightly, and no ink is ejected from the ejection unit 600. Therefore, no dots are formed on the medium P during period tp.

[0061] Here, a constant signal waveform with a voltage Vc in the drive voltage VOUT refers to the case where none of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are selected as the drive voltage VOUT, and the voltage Vc immediately preceding the trapezoidal waveform Adp1, Adp2, Bdp1, and Bdp2 corresponds to the voltage value held by the capacitive component of the piezoelectric element 60 included in the discharge unit 600. In other words, when none of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are selected as the drive voltage VOUT, the piezoelectric element 60 included in the discharge unit 600 is supplied with the voltage Vc that was supplied immediately before as the drive voltage VOUT.

[0062] Here, the drive signal selection circuit 200 selects or deselects the trapezoidal waveforms Adp1 and Adp2 included in the drive signal COMA and the trapezoidal waveforms Bdp1 and Bdp2 included in the drive signal COMB, thereby individually selecting the drive signals for each of the multiple discharge units 600, as shown in Figure 7. A dynamic voltage VOUT is generated and output to the piezoelectric element 60 included in the corresponding discharge unit 600.

[0063] Figure 8 shows the functional configuration of the drive signal selection circuit 200. As shown in Figure 8, the drive signal selection circuit 200 includes a selection control circuit 210 and a plurality of selection circuits 230. Figure 8 also shows the discharge sections 600[1] to 600[p] to which the drive voltages VOUT[1] to VOUT[p] output from the drive signal selection circuit 200 are supplied.

[0064] The selection control circuit 210 receives the print data signal SI, the clock signal SCK, the latch signal LAT, and the change signal CH. The selection control circuit 210 is provided with a set of register 212, latch circuit 214, and decoder 216 corresponding to each of the ejection units 600[1] to 600[p]. That is, the selection control circuit 210 includes at least the same number of sets of register 212, latch circuit 214, and decoder 216 as there are ejection units 600[1] to 600[p].

[0065] The print data signal SI is a signal synchronized with the clock signal SCK, and is a 2p-bit signal that serially includes 2 bits of print data [SIH,SIL] for each of the ejection units 600[1] to 600[p] to select one of the following: large dot LD, medium dot MD, small dot SD, or no-recording ND. The print data signal SI is held in register 212 for each piece of print data [SIH,SIL] contained in the print data signal SI, corresponding to each of the ejection units 600[1] to 600[p].

[0066] Specifically, in the selection control circuit 210, the registers 212 are connected in cascading order to form a p-stage shift register. The print data [SIH,SIL] input serially as the print data signal SI is then sequentially transferred to the subsequent registers 212 according to the clock signal SCK. When the supply of the clock signal SCK stops, the print data [SIH,SIL] corresponding to each of the ejection units 600[1] to 600[p] is held in the registers 212 corresponding to each of the ejection units 600[1] to 600[p]. In the following explanation, to distinguish the p registers 212 that constitute the shift register, they may be referred to as stages 1, 2, ..., p, from the upstream side to the downstream side where the print data signal SI is propagated.

[0067] Each of the p latch circuits 214 corresponds to one of the p registers 212. Each latch circuit 214 simultaneously latches the print data [SIH,SIL] held in each of the p registers 212 on the rising edge of the latch signal LAT and outputs it to the corresponding decoder 216.

[0068] Figure 9 shows an example of the decoding content in decoder 216. Decoder 216 generates and outputs selection signals S1 and S2 by decoding the print data [SIH,SIL] latched by latch circuit 214 with the content shown in Figure 9. For example, if the input print data [SIH,SIL] is [1,0], decoder 216 outputs the logic level of selection signal S1 as H and L levels for periods t1 and t2 to selection circuit 230, and the logic level of selection signal S2 as L and H levels for periods t1 and t2 to selection circuit 230.

[0069] The selection circuit 230 is provided in correspondence to each of the p discharge units 600. That is, the drive signal selection circuit 200 has at least p selection circuits 230, the same number as the p discharge units 600. Figure 10 shows the configuration of the selection circuit 230 corresponding to one discharge unit 600. As shown in Figure 10, the selection circuit 230 includes inverters 232a, 232b and transfer gates 234a, 234b, which are NOT circuits.

[0070] The selection signal S1 is input to the unmarked positive control terminal of transfer gate 234a, while being logically inverted by inverter 232a and input to the marked negative control terminal of transfer gate 234a. A drive signal COMA is also supplied to the input terminal of transfer gate 234a. The selection signal S2 is input to the unmarked positive control terminal of transfer gate 234b, while being logically inverted by inverter 232b and input to the marked negative control terminal of transfer gate 234b. A drive signal COMB is also supplied to the input terminal of transfer gate 234b. The output terminals of transfer gate 234a and transfer gate 234b are then connected in common. The signal at this connection terminal, where the output terminals of transfer gate 234a and transfer gate 234b are connected in common, is output as the drive voltage VOUT.

[0071] Specifically, when the selection signal S1 is at a high level, the input and output terminals of the transfer gate 234a become conductive, and when the selection signal S1 is at a low level, the input and output terminals of the transfer gate 234a become non-conductive. Similarly, when the selection signal S2 is at a high level, the input and output terminals of the transfer gate 234b become conductive, and when the selection signal S2 is at a low level, the input and output terminals of the transfer gate 234b become non-conductive. In other words, the selection circuit 230 selects or deselects the signal waveforms of the drive signals COMA and COMB supplied to the input terminals of the transfer gates 234a and 234b by switching the conduction state between the input and output terminals of the transfer gates 234a and 234b based on the selection signals S1 and S2, and outputs a drive voltage VOUT to the connection terminal where the output terminals of the transfer gate 234a and the output terminals of the transfer gate 234b are commonly connected.

[0072] The operation of the drive signal selection circuit 200 will be explained using Figure 11. Figure 11 is a diagram illustrating the operation of the drive signal selection circuit 200. The print data [SIH,SIL] included in the print data signal SI is input serially in synchronization with the clock signal SCK. The print data [SIH,SIL] is then sequentially transferred in the registers 212 that constitute the shift register, corresponding to the p ejection units 600, in synchronization with the clock signal SCK. Subsequently, when the supply of the clock signal SCK is stopped, each of the registers 212 holds the print data [SIH,SIL] corresponding to each of the p ejection units 600. The print data [SIH,SIL] included in the print data signal SI is input in the order corresponding to the p, ..., 2, and 1 stage ejection units 600 of the registers 212 that constitute the shift register.

[0073] Then, when the latch signal LAT rises, each of the latch circuits 214 simultaneously latches the print data [SIH,SIL] held in the register 212. In Figure 11, LS1, LS2, ..., LSp represent the print data [SIH,SIL] latched by the latch circuits 214 corresponding to the 1st, 2nd, ..., pth stage registers 212.

[0074] The decoder 216 outputs the logic levels of the selection signals S1 and S2 in the manner shown in Figure 9, for each of the periods t1 and t2, according to the size of the dots defined by the latched print data [SIH, SIL].

[0075] Specifically, when the input print data [SIH,SIL] is [1,1], the decoder 216 sets the logic level of selection signal S1 to H,H level during periods t1 and t2, and the logic level of selection signal S2 to L,L level during periods t1 and t2. In this case, the selection circuit 230 selects trapezoidal waveform Adp1 during period t1 and trapezoidal waveform Adp2 during period t2. As a result, a drive voltage VOUT corresponding to the large dot LD shown in Figure 7 is generated at the output terminal of the selection circuit 230.

[0076] Furthermore, when the input print data [SIH,SIL] is [1,0], the decoder 216 sets the logic level of selection signal S1 to H and L levels during periods t1 and t2, and the logic level of selection signal S2 to L and H levels during periods t1 and t2. In this case, the selection circuit 230 selects trapezoidal waveform Adp1 during period t1 and trapezoidal waveform Bdp2 during period t2. As a result, a drive voltage VOUT corresponding to the middle dot MD shown in Figure 7 is generated at the output terminal of the selection circuit 230.

[0077] Furthermore, when the input print data [SIH,SIL] is [0,1], the decoder 216 sets the logic level of selection signal S1 to H,L level during periods t1 and t2, and the logic level of selection signal S2 to L,L level during periods t1 and t2. In this case, the selection circuit 230 selects trapezoidal waveform Adp1 during period t1, and does not select either trapezoidal waveform Adp2 or Bdp2 during period t2. As a result, a drive voltage VOUT corresponding to the small dot SD shown in Figure 7 is generated at the output terminal of the selection circuit 230.

[0078] Furthermore, when the input print data [SIH,SIL] is [0,0], the decoder 216 sets the logic level of selection signal S1 to L,L level during periods t1 and t2, and the logic level of selection signal S2 to H,L level during periods t1 and t2. In this case, the selection circuit 230 selects trapezoidal waveform Bdp1 during period t1, and does not select either trapezoidal waveform Adp2 or Bdp2 during period t2. As a result, a drive voltage VOUT corresponding to the non-recorded ND shown in Figure 7 is generated at the output terminal of the selection circuit 230.

[0079] As described above, the drive signal selection circuit 200 generates and outputs drive voltages VOUT[1] to VOUT[p] by selecting the signal waveforms of drive signals COMA and COMB based on the print data signal SI, clock signal SCK, latch signal LAT, and change signal CH.

[0080] 6. Fire-resistant enclosure According to IEC 62368-1, 4th edition, circuits are classified into three types based on their power supply capacity: PS1, PS2, and PS3. PS1 circuits are those whose power is always 15W or less after 3 seconds. PS2 circuits are those whose power exceeds that of PS1 and are always 100W or less after 5 seconds. PS3 circuits are those whose power exceeds 100W. Electronic components classified as PS1 or PS2 do not need to be enclosed in a fireproof enclosure, but electronic components classified as PS3 do.

[0081] Examples of electronic components with a power consumption of 100W or more include CPUs, chip capacitors, and electrolytic capacitors, while examples of electronic components with a power consumption of less than 100W include fuses, switches, and LEDs. LED stands for Light Emitting Diode. Electronic components with a power consumption of less than 100W may be enclosed in a fireproof enclosure along with electronic components with a power consumption of 100W or more, but switches and LEDs are not suitable for being enclosed in a fireproof enclosure because it would make them difficult to access or obscure their light.

[0082] In the printing apparatus 1, for example, some of the electronic components mounted on the control circuit board 10, some of the electronic components mounted on the power supply circuit board 11, and some of the electronic components mounted on the drive circuit board 12 may have a power consumption exceeding 100W and therefore need to be covered with a fire-resistant enclosure.

[0083] Figure 12 is a perspective view of a circuit board with a fire-resistant enclosure. Figure 13 is a side view of the circuit board with the fire-resistant enclosure shown in Figure 12 cut away. Figure 13 also shows the mutually orthogonal X, Y, and Z axes for the purpose of illustrating the directional correspondence between the two figures. Figure 13 is a view from the starting point of the arrow indicating the direction of the Y axis.

[0084] As shown in Figures 12 and 13, the substrate 300 is, for example, a printed circuit board and comprises a plurality of electronic components, including electronic components 311, 312, 313, 314, 321, 322, 323, and 324. The substrate 300 is, for example, a drive circuit board 12, a control circuit board 10, or a power supply circuit board 11. For example, electronic component 311 is an electronic component that supplies 100W or more of power and is covered by a fire-resistant enclosure 400 together with electronic components 312, 313, and 314. Electronic component 311 may be, for example, a capacitor, a transistor, or a processor. Each of electronic components 312, 313, and 314 may be an electronic component that supplies 100W or more of power, or an electronic component that supplies less than 100W of power. Furthermore, electronic components 321, 322, 323, and 324 are electronic components that supply less than 100W of power and are not covered by the fire-resistant enclosure 400. Each of the electronic components 321, 322, 323, and 324 may be, for example, a fuse, a switch, or an LED.

[0085] The fire-resistant enclosure 400 comprises a wall section 401 and a top plate section 402. Figure 14 shows the wall section 401 viewed from the tip of the arrow indicating the Z-axis direction. As shown in Figures 13 and 14, in order to suppress the spread of fire, the wall section 401 is made of a flame-retardant resin material of UL94 V-1 grade or higher, which is a standard for evaluating the flammability of materials, and surrounds the electronic components 311, 312, 313, and 314 on all four sides. UL94 specifies three grades for vertical combustion testing: V-0, V-1, and V-2. V-0 grade materials have the highest flame retardancy, followed by V-1 grade materials. For example, V-0 grade materials have a burning time of 10 seconds or less, while V-1 grade or V2- grade materials have a burning time of 30 seconds or less. Furthermore, with V-0 grade or V-1 grade materials, the cotton fuss does not ignite due to molten material dripping during combustion, while with V-2 grade materials, the cotton fuss does ignite due to molten material dripping during combustion. Flame-retardant resins of V-1 grade or higher are V-0 grade or V-1 grade flame-retardant resins, such as polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyetherimide (PEI), polyamideimide (PAI), polyphenylsulfone (PPSU), polyimide (PI), and modified polyphenylene ether (PPE).

[0086] Furthermore, as shown in Figure 13, the bottom surface 401a of the wall portion 401 is in contact with the substrate 300, and the top surface 401b of the wall portion 401 opposite to the bottom surface 401a is in contact with the top plate portion 402. Note that when the bottom surface 401a of the wall portion 401 is in contact with the substrate 300, it includes not only the state in which the two are in direct contact, but also the state in which adhesive or the like is provided between them. Similarly, when the top surface 401b of the wall portion 401 is in contact with the top plate portion 402, it includes not only the state in which the two are in direct contact, but also the state in which adhesive or the like is provided between them. For example, the wall portion 401 is fixed to the substrate 300 with adhesive, or with bolts and nuts.

[0087] Since the flame-retardant resin material of the wall portion 401 has high insulating properties, the contact surface between the wall portion 401 and the substrate 300 is insulated, reducing the risk of leakage current and short circuits. An insulating material may also be attached to the contact surface between the wall portion 401 and the substrate 300.

[0088] As shown in Figures 13 and 14, the wall portion 401 has a rectangular parallelepiped-shaped cavity extending from the bottom surface 401a to the top surface 401b, and the electronic components 311, 312, 313, and 314 are housed in this cavity.

[0089] As shown in Figure 13, the top plate portion 402 is made of a metal plate 403 and a heat sink 404. The structure is as follows: The lower surface 403a of the metal plate 403 is in contact with the upper surface 401b of the wall portion 401, and the upper surface 403b of the metal plate 403 is in contact with the bottom surface 404a of the heat sink 404. For example, the metal plate 403 of the top plate portion 402 is fixed to the wall portion 401 by adhesive, screws, or a fit. The wall portion 401 and the metal plate 403 of the top plate portion 402 may be fixed with screws using helicoils, or they may be fixed with bolts and nuts.

[0090] Furthermore, for example, the heat sink 404 is fixed to the metal plate 403 by adhesive, screws, or a press fit. In the case of press fit fixing, either the heat sink 404 or the metal plate 403 may have a protrusion. The metal plate 403 and the heat sink 404 may also be fixed to each other by screws using helicoils, or by bolts and nuts.

[0091] The heat sink 404 is a heat dissipation component, and to enhance heat dissipation, multiple prismatic protrusions 405 are provided on the upper surface 404b of the heat sink 404. For weight reduction, the metal plate 403 and the heat sink 404 are made of aluminum.

[0092] Furthermore, when fixing the wall portion 401 and the metal plate 403 with an adhesive, it is preferable that the adhesive is one with high thermal conductivity in order to improve heat dissipation. Similarly, when fixing the metal plate 403 and the heat sink 404 with an adhesive, it is preferable that the adhesive is one with high thermal conductivity in order to improve heat dissipation.

[0093] Due to the structure of the fire-resistant enclosure 400, the hollow portion of the wall 401 forms a sealed space 410, and the electronic components 311, 312, 313, and 314 mounted on the substrate 300 are placed in the sealed space 410. In other words, the electronic components 311, 312, 313, and 314 are surrounded on all sides by the fire-resistant enclosure 400, which consists of the wall 401 made of flame-retardant resin material of V-1 grade or higher and a flame-retardant metal plate 403, so even if any of the electronic components 311, 312, 313, or 314 ignite, the spread of fire is prevented. Note that the hollow portion of the wall 401 does not necessarily have to form a completely sealed space; there may be small gaps as permitted in IEC 62368-1 4th edition.

[0094] Furthermore, the heat generated by the electronic components 311, 312, 313, and 314 is conducted to the heat sink 404 via the metal plate 403 and efficiently dissipated from the heat sink 404, which is provided with multiple protrusions 405.

[0095] The metal plate 403 is optional, and the heatsink 404 may constitute the top plate portion 402 on its own. In this case, the bottom surface 404a of the heatsink 404 contacts the top surface 401b of the wall portion 401. For example, the heatsink 404, which is the top plate portion 402, is fixed to the wall portion 401 by adhesive, screws, or a press fit. Alternatively, the wall portion 401 and the heatsink 404, which is the top plate portion 402, may be fixed together with screws using helicoil inserts.

[0096] Thus, regardless of the presence or absence of the metal plate 403, the top plate portion 402 is made of aluminum and has heat dissipation bumps arranged in accordance with the multiple protrusions 405. When the metal plate 403 is present, the top plate portion 402 has a surface 403a that is in contact with the wall portion 401 and a surface 404b opposite to surface 403a, and the surface 404b is provided with multiple prismatic protrusions 405. When the metal plate 403 is absent, the top plate portion 402 has a surface 404a that is in contact with the wall portion 401 and a surface 404b opposite to surface 404a, and the surface 404b is provided with multiple prismatic protrusions 405.

[0097] Note that the transport mechanism 4 is an example of a "transport section". Also, the electronic component 311 is the "first element". This is just one example, and electronic component 321 is an example of a "second element". Also, the bottom surface 401a of the wall portion 401 is an example of a "first surface", and the top surface 401b of the wall portion 401 is an example of a "second surface". Furthermore, the surface 403a or surface 404a of the top plate portion 402 that is in contact with the wall portion 401 is an example of a "third surface", and the surface 404b of the top plate portion 402 is an example of a "fourth surface".

[0098] 7. Effects As described above, in the printing apparatus 1 of this embodiment, the electronic components 311, which are relatively prone to ignition because the supplied power is 100W or more, are covered by a fire-resistant enclosure 400 composed of a wall portion 401 made of flame-retardant resin material of V-1 grade or higher and a top portion 402 made of flame-retardant aluminum material, thereby reducing the risk of fire spreading due to ignition of the electronic components 311. In addition, since the wall portion 401 made of flame-retardant resin material with high insulating properties is provided at the contact surface between the fire-resistant enclosure 400 and the substrate 300, the risk of leakage current and short circuits is reduced.

[0099] Furthermore, according to the printing apparatus 1 of this embodiment, the top plate portion 402 is made of aluminum instead of a flame-retardant resin material, and the top plate portion 402 has a series of heat-dissipating bumps, which improves the heat dissipation performance within the fire-resistant enclosure 400. Also, according to the printing apparatus 1 of this embodiment, the wall portion 401 is made of a flame-retardant resin material that is lighter than metal, thus achieving a lighter fire-resistant enclosure 400. Therefore, according to the printing apparatus 1 of this embodiment, both improved heat dissipation and weight reduction of the fire-resistant enclosure 400 can be achieved.

[0100] Furthermore, according to the printing apparatus 1 of this embodiment, some of the ink ejected from the print heads 22-1 to 22-n becomes mist and floats in the air before it lands on the medium P, and the liquid that lands on the medium P also floats back into the air and becomes mist before it is absorbed by the medium P and solidifies. However, since the relatively flammable electronic components 311 are covered by the fire-resistant enclosure 400, the risk of leakage or short circuits caused by the ink mist and subsequent ignition of the electronic components 311 is reduced.

[0101] In particular, in relatively small printing devices 1 where the medium P is A3 or smaller in size, the inside of the enclosure tends to become hot, and ink mist tends to adhere to the circuit board 300, but the fire-resistant enclosure 400 reduces the risk of electronic components 311 catching fire.

[0102] The present invention is not limited to this embodiment, and various modifications can be implemented within the scope of the gist of the present invention.

[0103] The present invention includes configurations substantially identical to those described in this embodiment, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configuration described in this embodiment are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configuration described in this embodiment. Finally, the present invention includes configurations that add known technology to the configuration described in this embodiment.

[0104] The embodiments and variations described above are merely examples and are not limited thereto. For example, each embodiment and each variation can be combined as appropriate.

[0105] The following can be derived from the embodiments and modifications described above.

[0106] One aspect of a printing apparatus is: A transport unit that transports the media, A dispensing unit for dispensing liquid into the aforementioned medium, The substrate comprises a first element that supplies 100W or more of power and a second element that supplies less than 100W of power, The first element is covered with a fire-resistant enclosure. The second element is not covered by the fire-resistant enclosure. The aforementioned fire-resistant enclosure comprises a wall section and a top section, The wall portion is made of a flame-retardant resin material of V-1 grade or higher, and surrounds the four sides of the first element. The first surface of the wall portion is in contact with the substrate. The second surface of the wall portion opposite to the first surface is in contact with the top plate portion. The aforementioned top panel is made of aluminum and has a series of bumps and grooves for heat dissipation.

[0107] In this printing apparatus, the first element, which is relatively prone to ignition due to the power supplied (100W or more), is covered with a fire-resistant enclosure made of flame-retardant resin material of V-1 grade or higher and flame-retardant aluminum, thereby reducing the risk of fire spreading due to ignition of the first element. In addition, a wall made of highly insulating flame-retardant resin material is provided at the contact surface between the fire-resistant enclosure and the substrate, reducing the risk of electrical leakage and short circuits.

[0108] Furthermore, this printing device allows the top plate to be made of aluminum instead of flame-retardant resin, and the top plate has a series of heat-dissipating protrusions, thus improving heat dissipation within the fire-resistant enclosure. In addition, this printing device allows the walls to be made of flame-retardant resin, which is lighter than metal, thus achieving a lighter fire-resistant enclosure. Therefore, this printing device achieves both improved heat dissipation and weight reduction of the fire-resistant enclosure.

[0109] Furthermore, with this printing device, some of the liquid ejected from the ejection section becomes mist and floats in the air before impact, and the liquid that lands on the medium also floats again as mist before being absorbed by the medium and solidifying. However, since the first element, which is relatively prone to ignition, is covered with a fire-resistant enclosure, the risk of electrical leakage or short circuits caused by the mist and subsequent ignition of the first element is reduced.

[0110] In one embodiment of the printing apparatus, The wall portion may be fixed to the substrate with adhesive or with bolts and nuts.

[0111] In one embodiment of the printing apparatus, The top plate portion may be fixed to the wall portion by adhesive, screws, or a press fit.

[0112] In one embodiment of the printing apparatus, The wall portion and the top plate portion may be fixed together with screws using helicoil inserts.

[0113] In one embodiment of the printing apparatus, The wall portion has a rectangular parallelepiped-shaped cavity extending from the first surface to the second surface. The first element may be housed in the cavity.

[0114] In one embodiment of the printing apparatus, The first element may be a capacitor, a transistor, or a processor.

[0115] In one embodiment of the printing apparatus, The second element may be a fuse, a switch, or an LED.

[0116] In one embodiment of the printing apparatus, The aforementioned circuit board may be a printed circuit board.

[0117] In one embodiment of the printing apparatus, The discharge section may include a piezoelectric element.

[0118] In one embodiment of the printing apparatus, The substrate may be a drive circuit board on which a drive circuit that generates a drive signal to discharge the liquid from the discharge unit is mounted, a control circuit board on which a control circuit that controls the discharge of the liquid from the discharge unit is mounted, or a power supply circuit board on which a power supply circuit is mounted.

[0119] This printing device reduces the risk of fire in the drive circuit board, control circuit board, or power supply circuit board on which the first element, which supplies 100W or more of power, is mounted.

[0120] In one embodiment of the printing apparatus, The aforementioned drive circuit may include a Class D amplifier, which is an amplification circuit.

[0121] In one embodiment of the printing apparatus, The drive signal output from the drive circuit may be an analog signal.

[0122] In one embodiment of the printing apparatus, The control circuit may output a base drive signal, which is a digital signal that forms the basis of the drive signal output from the drive circuit.

[0123] In one embodiment of the printing apparatus, The power supply circuit may also include a voltage conversion circuit and a smoothing circuit.

[0124] In one embodiment of the printing apparatus, The voltage conversion circuit may include a transformer that transforms the AC voltage of the commercial power supply.

[0125] In one embodiment of the printing apparatus, The smoothing circuit may include a rectifier circuit and a capacitor.

[0126] In one embodiment of the printing apparatus, The rectifier circuit may be a diode bridge circuit, which rectifies the AC voltage converted by the voltage conversion circuit.

[0127] In one embodiment of the printing apparatus, The aforementioned medium may be no larger than the width of the shorter side of A3 paper.

[0128] With this printing device, although the enclosure tends to get hot due to its relatively small size and mist is likely to adhere to the circuit board, the fire-resistant enclosure reduces the risk of the first element igniting.

[0129] In one embodiment of the printing apparatus, The top plate portion has a third surface that is in contact with the wall portion, and a fourth surface opposite to the third surface. The fourth surface may be provided with a plurality of prismatic protrusions.

[0130] This printing device has multiple prismatic protrusions on the top plate, which improves heat dissipation within the fire-resistant enclosure. [Explanation of symbols]

[0131] 1…Printing device, 2…Commercial power supply, 10…Control circuit board, 11…Power supply circuit board, 12…Drive circuit board, 20…Head unit, 21…Carriage, 22,22-1~22-n…Print head, 30…Movement unit, 31…Carriage motor, 32…Endless belt, 40…Conveyor unit, 41…Conveyor motor, 42…Conveyor roller, 50…Drive circuit, 60…Piezoelectric element, 71,72…Cable, 80…DC / DC converter 90...Ink container, 100...Control circuit, 110...Power supply circuit, 111...Voltage conversion circuit, 112...Smoothing circuit, 121...Transformer, 122...Rectifier circuit, 123...Capacitor, 200...Drive signal selection circuit, 210...Selection control circuit, 212...Register, 214...Latch circuit, 216...Decoder, 230...Selection circuit, 232a,232b...Inverter, 234a,234b...Transfer gate, 300...Circuit board, 31 1,312,313,314…Electronic components, 321,322,323,324…Electronic components, 400…Fireproof enclosure, 401…Wall section, 401a…Bottom surface of wall section, 401b…Top surface of wall section, 402…Top plate section, 403…Metal plate, 403a…Bottom surface of metal plate, 403b…Top surface of metal plate, 404…Heat sink, 404a…Bottom surface of heat sink, 404b…Top surface of heat sink, 405…Protrusion, 410…Sealed space, 50 0...integrated circuit, 501...amplifier circuit, 510...voltage generation circuit, 520...DAC, 530...modulation unit, 540...gate drive unit, 551, 552...transistor, 553...coil, 554...capacitor, 600, 600-1~600-p...discharge unit, 601...piezoelectric element, 611, 612...electrode, 621...diaphragm, 631...cavity, 632...nozzle plate, 641...reservoir, 651...nozzle, 661...supply port, P...medium

Claims

1. A transport unit that transports the media, A dispensing unit for dispensing liquid into the aforementioned medium, The substrate comprises a first element that supplies 100W or more of power and a second element that supplies less than 100W of power, The first element is covered with a fire-resistant enclosure. The second element is not covered by the fire-resistant enclosure. The aforementioned fire-resistant enclosure comprises a wall section and a top section, The wall portion is made of a flame-retardant resin material of V-1 grade or higher, and surrounds the four sides of the first element. The first surface of the wall portion is in contact with the substrate. The second surface of the wall portion opposite to the first surface is in contact with the top plate portion. The aforementioned top panel is made of aluminum and has a series of bumps and grooves for heat dissipation. A printing apparatus characterized by the following features.

2. The wall portion is fixed to the substrate with adhesive or bolts and nuts. The printing apparatus according to feature 1.

3. The top plate is fixed to the wall by adhesive, screws, or a press-fit. The printing apparatus according to feature 1.

4. The wall portion and the top plate portion are fixed together with screws using helicoil inserts. The printing apparatus according to feature 1.

5. The wall portion has a rectangular parallelepiped-shaped cavity extending from the first surface to the second surface. The first element is housed in the cavity. The printing apparatus according to feature 1.

6. The first element is a capacitor, a transistor, or a processor. The printing apparatus according to feature 1.

7. The second element is a fuse, a switch, or an LED. The printing apparatus according to feature 1.

8. The aforementioned substrate is a printed circuit board. The printing apparatus according to feature 1.

9. The discharge section includes a piezoelectric element. The printing apparatus according to feature 1.

10. The substrate is a drive circuit board on which a drive circuit that generates a drive signal to discharge the liquid from the discharge unit is mounted, a control circuit board on which a control circuit that controls the discharge of the liquid from the discharge unit is mounted, or a power supply circuit board on which a power supply circuit is mounted. The printing apparatus according to feature 1.

11. The aforementioned drive circuit includes a Class D amplifier, which is an amplification circuit. The printing apparatus according to feature 10.

12. The drive signal output from the aforementioned drive circuit is an analog signal. The printing apparatus according to feature 10.

13. The control circuit outputs a base drive signal, which is a digital signal that forms the basis of the drive signal output from the drive circuit. The printing apparatus according to feature 10.

14. The power supply circuit comprises a voltage conversion circuit and a smoothing circuit. The printing apparatus according to feature 10.

15. The voltage conversion circuit includes a transformer that transforms the AC voltage of the commercial power supply. The printing apparatus according to feature 14.

16. The smoothing circuit includes a rectifier circuit and a capacitor. The printing apparatus according to feature 14.

17. The rectifier circuit is a diode bridge circuit, which rectifies the AC voltage converted by the voltage conversion circuit. The printing apparatus according to feature 16.

18. The aforementioned medium is no larger than the width of the short side of A3 paper. The printing apparatus according to feature 1.

19. The top plate portion has a third surface that is in contact with the wall portion, and a fourth surface opposite to the third surface. The fourth surface is provided with a plurality of prismatic protrusions. The printing apparatus according to any one of claims 1 to 18.

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