Signal transmission circuit and image processing device

Abstract

To provide a signal transmission circuit and an image processing device capable of achieving reliable signal transmission using simpler circuits.SOLUTION: A signal transmission circuit 3 includes an input terminal 33, an output terminal 34, a filter unit 31, and a waveform shaping unit 32. The filter unit 31 is inserted between the input terminal 33 and the output terminal 34, and passes a signal input from the input terminal 33 toward the output terminal 34. The waveform shaping unit 32 is inserted between the filter unit 31 and the output terminal 34, and shapes the waveform of the signal that has passed through the filter unit 31.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a signal transmission circuit and an image processing device. [Background technology]

[0002] As a related technique, a noise reduction device including a first noise removal unit, a correction unit, a detection unit, and a second noise removal unit is known (see, for example, Patent Document 1).

[0003] The first noise removal means removes edge noise from the video signal. The correction means corrects the rounding of the edge waveform in the output signal by adding a signal obtained by shaping the waveform of the processed signal in the first noise removal means to the output signal of the first noise removal means. The detection means detects edges of the video signal. The second noise removal means removes only low-level high-frequency noise of the video signal from the output signal of the correction means using the detection signal from the detection means. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 1-60065 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of the related art described above, for example, even just to remove the influence of static electricity or the like from a control signal that controls a simple operation of a device, a relatively complicated circuit is required.

[0006] An object of the present invention is to provide a signal transmission circuit and an image processing device that can realize reliable signal transmission with simpler circuitry. [Means for solving the problem]

[0007] A signal transmission circuit according to one aspect of the present invention includes an input terminal, an output terminal, a filter section, and a waveform shaping section. The filter section is inserted between the input terminal and the output terminal and passes a signal input from the input terminal toward the output terminal. The waveform shaping section is inserted between the filter section and the output terminal and shapes the waveform of the signal that has passed through the filter section.

[0008] An image processing device according to another aspect of the present invention includes the signal transmission circuit and a main body having an image processing function. Effect of the Invention

[0009] According to the present invention, it is possible to provide a signal transmission circuit and an image processing device that are capable of realizing reliable signal transmission with a simpler circuit. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic block diagram of an image processing device according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the appearance of the image processing device according to the first embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a transmission state of a control signal in the image processing device according to the first embodiment. [Figure 4] FIG. 4 is a schematic block diagram showing a signal transmission circuit of the image processing device according to the first embodiment. [Diagram 5] FIG. 5 is a schematic circuit diagram showing a specific example of a signal transmission circuit of the image processing device according to the first embodiment. [Figure 6] FIG. 6 is a timing chart showing an example of a control signal transmitted through the signal transmission circuit of the image processing device according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0012] (Embodiment 1) [1] Overall configuration of image processing device First, the overall configuration of an image processing device 10 according to this embodiment will be described with reference to FIGS.

[0013] The image processing device 10 according to the present embodiment is, for example, a multifunction device having multiple functions such as a scanning function for acquiring image data from an original, a printing function for forming an image based on image data, a facsimile function, and a copy function. The image processing device 10 only needs to have an image processing function including at least one of a function for forming an image and a function for acquiring image data, and may be a printer, a scanner, a facsimile machine, a copy machine, or the like.

[0014] As shown in Fig. 1, the image processing device 10 includes an automatic document feeder 11, an image reading unit 12, an image forming unit 13, a paper feed unit 14, a display unit 15, an operation unit 16, a control unit 17, and a power supply unit 18. The automatic document feeder 11 is an ADF (Auto Document Feeder), and is therefore indicated as "ADF" in Fig. 1, and will also be referred to as "ADF 11" in the following description. In this embodiment, as shown in Fig. 2, the image processing device 10 includes a main body 101. The ADF 11, the image reading unit 12, the image forming unit 13, the paper feed unit 14, the display unit 15, the operation unit 16, the control unit 17, and the power supply unit 18 are provided in the main body 101.

[0015] The ADF 11 transports an original document whose image is to be read by the image reading unit 12. The ADF 11 includes an original document setting unit, a plurality of transport rollers, an original document pressing unit, and a paper ejection unit.

[0016] The image reading unit 12 reads an image from a document and outputs image data corresponding to the read image. The image reading unit 12 includes a document table, a light source, a plurality of mirrors, an optical lens, a CCD (Charge Coupled Device), and the like.

[0017] The image forming unit 13 forms an image on a sheet by an electrophotographic method based on image data output from the image reading unit 12. The image forming unit 13 also forms an image on a sheet based on image data input from an information processing device external to the image processing device 10, such as a personal computer. The image forming unit 13 has four image forming units corresponding to four colors, C (cyan), M (magenta), Y (yellow), and K (black), an optical scanning device, an intermediate transfer belt, a secondary transfer roller, a fixing device, and the like. The image forming unit 13 may be configured to form an image on a sheet by an image forming method other than the electrophotographic method, such as an inkjet method, for example.

[0018] The image forming unit 13 forms an image on a sheet using toner as a developer. When the image forming unit 13 forms an image by an inkjet method, ink (another example of a developer) is supplied instead of toner. Examples of toner supplied to the image forming unit 13 include toner of multiple colors, such as C (cyan), M (magenta), Y (yellow), and K (black). After the image is formed in the image forming unit 13, the sheet is discharged (supplied) to an extension device or the like for post-processing.

[0019] The paper feed unit 14 supplies sheets to the image forming unit 13. The paper feed unit 14 has a paper feed cassette, a manual feed tray, a sheet transport path, and multiple transport rollers. In this embodiment, the paper feed unit 14 has multiple paper feed sources (including two or more paper feed cassettes and a manual feed tray). The image forming unit 13 forms an image on the sheet supplied from the paper feed unit 14. The sheet supplied to the image forming unit 13 is paper as an example, but is not limited to paper and may be, for example, a resin film, etc.

[0020] The display unit 15 is a user interface for presenting (displaying) information to a user in the image processing device 10. The display unit 15 displays various information in response to a control instruction from the control unit 17. As an example in the present embodiment, the display unit 15 includes a liquid crystal display, and displays a display screen including various information on the liquid crystal display.

[0021] The operation unit 16 is, for example, a user interface for accepting operation input by a user to a display screen displayed on the display unit 15. The operation unit 16 accepts various operations by a user, for example, by outputting an electrical signal according to the user's operation. As an example in this embodiment, the operation unit 16 has a switch, a touch panel, or the like.

[0022] Furthermore, the image processing device 10 may include, in addition to or instead of the display unit 15 and the operation unit 16, for example, an audio output unit and an audio input unit, etc., as a user interface.

[0023] The control unit 17 mainly comprises a computer system having one or more processors and one or more memories, and performs overall control of the image processing device 10. In the image processing device 10, the one or more processors execute programs to realize the functions of the control unit 17. In this embodiment, as an example, the control unit 17 includes a CPU (Central Processing Unit).

[0024] The program may be pre-recorded in one or more memories, or may be provided via a telecommunication line such as the Internet, or may be provided by recording it in a non-transitory recording medium readable by a computer system, such as a memory card or an optical disk. The one or more processors are composed of one or more electronic circuits including a semiconductor integrated circuit. Furthermore, the computer system referred to here includes a microcontroller having one or more processors and one or more memories. The control unit 17 may be a control unit provided separately from a main control unit that comprehensively controls the image processing device 10.

[0025] Specifically, control unit 17 controls each device, such as ADF 11, image reading unit 12, image forming unit 13, paper feed unit 14, and display unit 15, by transmitting (outputting) a control signal to each device. For example, control unit 17 outputs a PF (Paper Feeder) selection signal and a clock signal to paper feed unit 14 as control signals. The PF selection signal is a control signal for selecting a paper feed source, and the clock signal is a control signal for specifying the timing for paper feed unit 14 to feed a sheet. This allows control unit 17 to feed paper from any of a plurality of paper feed sources (including two or more paper feed cassettes and a manual feed tray) in paper feed unit 14 at any timing.

[0026] The power supply unit 18 is a device that generates (outputs) power for the operation of the image processing device 10. The power supply unit 18 is electrically connected to one or more electric loads and supplies power to the one or more electric loads. In this embodiment, the main body 101 of the image processing device 10 is the "electrical load", and the power supply unit 18 supplies power to each part of the main body 101 as the electric load. In other words, the one or more electric loads to which power is supplied from the power supply unit 18 include the ADF 11, the image reading unit 12, the image forming unit 13, the paper feeding unit 14, the display unit 15, the operation unit 16, and the control unit 17.

[0027] In this embodiment, the power supply unit 18 is electrically connected to an AC plug, and converts an AC voltage of 100V (or 200V) applied to the AC plug into, for example, a DC voltage of 24V and a DC voltage of 3.3V (or 5V). In other words, when the AC plug is connected to an outlet, AC power is applied to the power supply unit 18 from an AC power source such as a system power source, and the power supply unit 18 generates DC power from this AC power.

[0028] The image processing device 10 further includes a storage unit and a communication unit, etc. The storage unit includes one or more non-volatile memories, and stores information such as control programs for causing the control unit 17 to execute various processes in advance. The communication unit is an interface that executes data communication between the image processing device 10 and an external device connected via a communication network such as the Internet or a LAN (Local Area Network).

[0029] [2] Configuration related to the transmission of control signals Next, the configuration relating to the transmission of a control signal will be described in more detail with reference to FIGS.

[0030] As described above, the image processing device 10 according to this embodiment controls devices such as the paper feed unit 14 by transmitting (outputting) control signals such as a PF selection signal and a clock signal from the control unit 17 to the devices. In other words, the paper feed unit 14 is an example of a device controlled by a control signal, and the PF selection signal and the clock signal are examples of a control signal.

[0031] 3, the image processing device 10 according to this embodiment includes a first board (Engine board) 21 which is a transmission source of a control signal Si1, and a second board (PF board) 22 which is a transmission destination of the control signal Si1. A control unit 17 is mounted on the first board 21, and a device control unit 141 included in a device such as a paper feeder 14 is mounted on the second board 22.

[0032] Furthermore, a signal transmission circuit 3 is mounted on the second substrate 22. The first substrate 21 and the second substrate 22 are electrically connected by a signal line 23 which serves as a transmission path for the control signal Si1.

[0033] In this manner, the signal transmission circuit 3 according to this embodiment, together with the main body 101 having an image processing function, constitutes the image processing device 10. In other words, the image processing device 10 includes the signal transmission circuit 3 and the main body 101 having an image processing function.

[0034] According to this configuration, a control signal Si1 such as a clock signal output by the control unit 17 of the first substrate 21 is transmitted to the signal transmission circuit 3 of the second substrate 22 through the signal line 23. The signal transmission circuit 3 transmits the input control signal Si1 to the device control unit 141. As a result, the device control unit 141 operates devices such as the paper feed unit 14 in accordance with the control signal Si1.

[0035] In this type of configuration, for example, static electricity acting on the signal line 23 may cause noise to be superimposed on the control signal Si1 transmitted from the first board 21 to the second board 22. If noise is superimposed on the control signal Si1, the noise may cause an error in communication between the control unit 17 and a device (such as the paper feed unit 14), making it impossible to control the device correctly.

[0036] Therefore, the image processing device 10 according to this embodiment removes such noise in the signal transmission circuit 3, thereby making it less susceptible to the effects of static electricity and the like.

[0037] Meanwhile, as a related technique, a noise reduction device including a first noise removal means, a correction means, a detection means, and a second noise removal means is known.

[0038] The first noise removal means removes edge noise from the video signal. The correction means corrects the rounding of the edge waveform in the output signal by adding a signal obtained by shaping the waveform of the processed signal in the first noise removal means to the output signal of the first noise removal means. The detection means detects edges of the video signal. The second noise removal means removes only low-level high-frequency noise of the video signal from the output signal of the correction means using the detection signal from the detection means.

[0039] In the configuration of the related art described above, for example, even just to remove the influence of static electricity or the like from the control signal Si1 that controls a simple operation of the device, a relatively complicated circuit is required.

[0040] In contrast to this, in this embodiment, the signal transmission circuit 3 and the image processing device 10 that can realize reliable signal transmission with simpler circuits are realized by the configuration described below.

[0041] 4, the signal transmission circuit 3 according to this embodiment includes an input terminal 33, an output terminal 34, a filter section 31, and a waveform shaping section 32. The filter section 31 is inserted between the input terminal 33 and the output terminal 34, and passes a signal (such as a control signal Si1) input from the input terminal 33 toward the output terminal 34. The waveform shaping section 32 is inserted between the filter section 31 and the output terminal 34, and shapes the waveform of the signal that has passed through the filter section 31.

[0042] 4, even if a control signal Si1 on which noise caused by static electricity or the like is superimposed is input from the input terminal 33, the signal transmission circuit 3 can output the control signal Si1 from which the noise components have been removed from the output terminal 34. In other words, the control signal Si1 input from the input terminal 33 passes through the filter section 31, whereby high-frequency noise components are removed.

[0043] Here, when the control signal Si1 passes through the filter section 31, the rise and fall slew rates decrease, causing rounding. The waveform of the control signal Si1 rounded off by the filter section 31 is shaped by the waveform shaping section 32, so that it is possible to output the control signal Si1 from the output terminal 34 with noise components removed and improved rise and fall slew rates. As a result, it is possible to realize a signal transmission circuit 3 and an image processing device 10 that can achieve reliable signal transmission using simpler circuits.

[0044] More specifically, in this embodiment, the filter unit 31 includes an RC filter as shown in Fig. 5. That is, the filter unit 31 is an RC filter including a resistor 311 (R component) and a capacitor 312 (C component), and constitutes a low-pass filter having a predetermined time constant. Therefore, high-frequency noise is removed from the signal (control signal Si11) passing through the filter unit 31. By using such a passive filter for the filter unit 31, the filter unit 31 can be realized with a relatively simple configuration.

[0045] 5, the waveform shaping unit 32 includes an operational amplifier 321. That is, the waveform shaping unit 32 includes an operational amplifier 321, and even if a signal (control signal Si12) is significantly rounded by the filter unit 31, the waveform can be faithfully shaped by the gain of the operational amplifier 321.

[0046] Here, the waveform shaping unit 32 has a comparator using an operational amplifier 321. In other words, the waveform shaping unit 32 configures a comparator using the operational amplifier 321, and compares the output (control signal Si12) of the filter unit 31 with a threshold voltage V1, and outputs a signal (control signal Si13) of an H (High) level or an L (Low) level according to the comparison result. This makes it possible to realize the waveform shaping unit 32 with a relatively simple configuration.

[0047] 5 shows a specific example of the signal transmission circuit 3 according to this embodiment. That is, the signal transmission circuit 3 is a circuit that transmits a control signal Si1 from an input terminal 33 to an output terminal 34. The "terminal" in this disclosure may be, for example, a component having a physical form such as a connector, or may be a part of a conductive film or signal line 23 formed on a substrate.

[0048] 5, the filter section 31 has, as an example, a resistor 311 and a capacitor 312 electrically connected in series between the input terminal 33 and the circuit ground. The resistor 311 and the capacitor 312 are connected such that the resistor 311 is on the input terminal 33 side, and the connection point of the resistor 311 and the capacitor 312 becomes the output point of the filter section 31.

[0049] 5, the waveform shaping unit 32 includes an operational amplifier 321 and a pair of voltage dividing resistors 322 and 323. A constant voltage source Vcc1 supplies power to the operational amplifier 321. The pair of voltage dividing resistors 322 and 323 are electrically connected in series between the constant voltage source Vcc1 and the circuit ground.

[0050] The inverting input terminal of the operational amplifier 321 is electrically connected to the connection point of the pair of voltage dividing resistors 322, 323. As a result, a threshold voltage V1 obtained by dividing the voltage applied from the constant voltage source Vcc1 by the pair of voltage dividing resistors 322, 323 is input to the inverting input terminal of the operational amplifier 321. The non-inverting input terminal of the operational amplifier 321 is electrically connected to the output point of the filter unit 31 (the connection point of the resistor 311 and the capacitor 312). As a result, the control signal Si12 that has passed through the filter unit 31 is input to the non-inverting input terminal of the operational amplifier 321.

[0051] A comparator using operational amplifier 321 compares the output of filter section 31 with threshold voltage V1, and outputs an H-level signal if the output of filter section 31 exceeds threshold voltage V1, and outputs an L-level signal if the output of filter section 31 is equal to or lower than threshold voltage V1.

[0052] With the above-mentioned configuration, the signal transmission circuit 3 acts on the control signal Si1 passing through the signal transmission circuit 3, for example, as shown in Fig. 6. In Fig. 6, the horizontal axis is the time axis, and from the top, a control signal Si11 input to the input terminal 33, a control signal Si12 output from the filter section 31 (i.e., input to the waveform shaping section 32), and a control signal Si13 output from the output terminal 34 are shown in schematic form.

[0053] That is, first, the filter unit 31 uses an RC filter to pass only the components of the control signal Si11 that are equal to or lower than the cutoff frequency, thereby removing the noise components of the control signal Si11 to obtain the control signal Si12. However, the rise and fall slew rates of the control signal Si12 decrease, causing distortion.

[0054] Next, the waveform shaping unit 32 generates a new control signal Si13 in accordance with the result of comparing the control signal Si12 output from the filter unit 31 with the threshold voltage V1. As a result, the control signal Si13 with improved rise and fall slew rates is output from the output terminal 34.

[0055] Here, when the control signal Si11 input to the input terminal 33 is compared with the control signal Si13 output from the output terminal 34, a delay occurs in the timing of the rise and fall. Therefore, it is preferable to set the time constant of the filter unit 31 and / or the threshold voltage V1, etc., so that the delay time falls within the specification range of the device (e.g., the paper feed unit 14) of the control signal Si1.

[0056] [3] Variations The multiple components included in the image processing device 10 may be distributed across multiple housings.

[0057] Furthermore, the signal transmission circuit 3 may be used not only for transmitting the control signal Si1 but also for transmitting various signals (voltage signals) whose voltage levels change. In other words, the control signal Si1 transmitted by the signal transmission circuit 3 is not limited to the PF selection signal and the clock signal.

[0058] Furthermore, the device controlled by the control signal Si1 is not limited to the paper feed unit 14.

[0059] Furthermore, it is not essential that the image processing device 10 has a first substrate 21 which is the source of the control signal Si1 and a second substrate 22 which is the destination of the control signal Si1; for example, the source and destination of the control signal Si1 may be configured on the same substrate.

[0060] Furthermore, the specific configuration of the signal transmission circuit 3 is not limited to the configuration shown in FIG. 5, and can be changed as appropriate as long as the same function can be realized.

[0061] [Appendix to the invention] The following will provide an overview of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0062] <Appendix 1> An input terminal; An output terminal; a filter section inserted between the input terminal and the output terminal, for passing a signal input from the input terminal toward the output terminal; a waveform shaping unit that is inserted between the filter unit and the output terminal and shapes the waveform of a signal that has passed through the filter unit, Signal transmission circuit.

[0063] <Appendix 2> The filter unit includes an RC filter. 2. A signal transmission circuit as described in claim 1.

[0064] <Appendix 3> The waveform shaping unit includes an operational amplifier. 3. The signal transmission circuit according to claim 1 or 2.

[0065] <Appendix 4> The waveform shaping unit has a comparator using the operational amplifier. 4. A signal transmission circuit as described in appended claim 3.

[0066] <Appendix 5> A signal transmission circuit according to any one of appendix 1 to 4; A main body having an image processing function. Image processing device. [Explanation of symbols]

[0067] 3. Signal Transmission Circuit 10 Image processing device 31 Filter section 32 Waveform shaping section 33 Input terminal 34 Output terminal 321 Operational Amplifier 101 Main unit

Claims

1. An input terminal; An output terminal; a filter section inserted between the input terminal and the output terminal, for passing a signal input from the input terminal toward the output terminal; a waveform shaping unit that is inserted between the filter unit and the output terminal and shapes the waveform of a signal that has passed through the filter unit, Signal transmission circuit.

2. The filter unit includes an RC filter.

2. The signal transmission circuit according to claim 1.

3. The waveform shaping unit includes an operational amplifier.

3. The signal transmission circuit according to claim 1 or 2.

4. The waveform shaping unit has a comparator using the operational amplifier.

4. The signal transmission circuit according to claim 3.

5. A signal transmission circuit according to claim 1 or 2; A main body having an image processing function. Image processing device.

Images