JPH09118472A - Printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load to monitor the charged condition of printing papers by a CPU, and to improve the judging accuracy of the charged condition. SOLUTION: The output signal of a PE sensor 30 is successively latched by latches 21, 22 every time a counter 24 is overflown. When the PE signal is on the low level in two overflows of the counter 24, both output signals of the latches 21, 22 are on the low level, the low level signal is outputted from an XOR gate 25, and when the output of the latch 21 is on the low level, the low level signal (the interrupt signal) is outputted from a latch 23. The interruption to judge the charged condition is performed by a CPU 10 when the level of the output signal of the PE sensor 30 to be held by the latches 21, 22 is same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device such as a printer, and to an improvement in a function of detecting a loading state of printing paper such as paper empty or paper jam.

[0002]

2. Description of the Related Art Conventionally, as the above-mentioned printing apparatus, those shown in FIGS. 3 and 4 have been known. What is shown in FIG.
The output of the PE (paper empty) sensor 30 is a port 52 of the CPU 50 provided in the printer.
Directly connected to. Then, the change of the voltage level appearing at the port (Port) 52 of the CPU 50 is monitored at regular intervals by an interval timer or the like, and when there is a change in the level, the CPU 50 causes the CPU 50 to load the printing paper such as paper empty or paper jam. To judge.

Further, FIG. 4 shows an ASIC (Application Specific Integrated) connected to the CPU 60.
Circuit) port 72, a level change of the detection signal 32 output from the PE sensor 30 is monitored at regular intervals by an interval timer or the like, and when there is a level change, the CPU 60 causes the paper empty, paper jam, etc. Determine the loading status of printing paper.

[0004]

However, in both of the above-mentioned conventional devices, the CPU must be provided with a function of monitoring the level change of the port at regular intervals. Therefore, since the monitoring function is provided, the arithmetic processing of the CPU becomes complicated, and there is a problem that the load of the CPU becomes large.

In both of the above-mentioned conventional systems, the CPU determines the loading state of the printing paper when the level of the port changes once, so that when external noise enters the detection signal, There is a risk of erroneously determining that the level has changed. That is, there is also a problem that the determination accuracy is low.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to simplify the processing for determining the loading state of the printing paper of the CPU. Accordingly, it is an object of the present invention to provide a printing device that can reduce the load on the CPU and can improve the accuracy of determining the loading state of printing paper.

[0007]

In order to achieve the above object, the present invention provides a loading state detecting means for detecting a loading state of printing paper, and an output from the loading state detecting means. In the printing apparatus including an arithmetic processing device that inputs the generated detection signal and performs the arithmetic processing including the loading state determination that determines the loading state of the printing paper, the detection signal output from the loading state detection unit is included. A command signal output means is provided for detecting the level at least twice and outputting a command signal for executing the loaded state determination to the arithmetic processing device when the detected levels are the same predetermined level. Adopt technical means.

According to a second aspect of the present invention, in the printing apparatus according to the first aspect, the command signal output means includes a first holding circuit for holding the detection signal output from the loading state detection means. A second holding circuit for inputting and holding the detection signal of the first holding circuit after the detection signal is held in the first holding circuit, and the first and second holding circuits. An output circuit that outputs the command signal when the held detection signals have the same predetermined level,
The technical means of being equipped is adopted.

According to a third aspect of the present invention, in the printing apparatus according to the second aspect, when the detection signals held by the first and second holding circuits are at the same level, the output circuit has the same level. A first output circuit that outputs a signal, and a second output circuit that outputs the signal detected by the first holding circuit as the command signal based on a change in the level of the signal output from the first output circuit. And an output circuit is provided.

According to a fourth aspect of the present invention, in the ink jet printer according to any one of the first to third aspects, a technical means is provided with a print head that ejects ink onto the printing paper to perform printing. To adopt. In addition,
The printing device includes printers such as an inkjet printer, a wire dot printer, and a thermal printer, as well as devices such as a facsimile machine and a copying machine having a function of determining a loading state of printing paper by a CPU.

[0011]

According to the present invention, the level of the detection signal output from the loading state detecting means is detected at least twice, and when the detected levels are the same predetermined level, A command signal for executing the loaded state determination can be output to the arithmetic processing device. Therefore, erroneous determination is less than that in the case where the loaded state determination is executed by only one detection, and the determination accuracy can be improved. Moreover, since the command signal for executing the loaded state determination can be output to the arithmetic processing device, it is not necessary to provide the arithmetic processing device with a function of monitoring the loaded state at regular intervals. The burden on the arithmetic processing device can be reduced.

Particularly, in the invention described in claim 2 or 3, the first holding circuit can detect and hold the detection signal output from the loading state detecting means, and the second holding circuit can hold the detection signal. After the first level is held in the first holding circuit, the detection signal of the first holding circuit can be input and held. Then, when the detection signals held by the first and second holding circuits have the same predetermined level, the first output circuit outputs a signal. Based on the signal, the second output circuit outputs the signal detected by the first holding circuit as an instruction signal to the arithmetic processing device, and the arithmetic processing device determines the loaded state. In other words, when one level is caused by the intrusion of external noise or the like, the command signal is not output to the arithmetic processing device, so that the erroneous determination of the arithmetic processing device can be prevented.

Further, in the invention described in claim 4, an ink jet printer having a print head for ejecting ink onto the printing paper to perform printing is also described in any one of claims 1 to 3. The invention can be applied.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, as a printing apparatus according to the present invention, a serial printer such as an inkjet printer, a wire dot printer, a thermal printer will be described as a representative. FIG. 1 is a block diagram showing the configuration of a control system for detecting the paper empty of the printer.

As shown in FIG. 1, an arithmetic processing unit built in the printer, that is, a CPU 10, has a well-known printing mechanism (not shown), a paper feeding mechanism, and a command signal output circuit 20 as command signal output means according to the present invention. Is connected to the command signal output circuit 20. The PE sensor 30 for detecting paper empty (the state where there is no printing paper) is connected to the command signal output circuit 20.
Is connected. The command signal output circuit 20 receives the detection signal (PE signal) of the PE sensor 30 and holds it.
The latch 21 is provided as a holding circuit for the. The latch 21 is connected to a latch 22 as a second holding circuit for inputting and holding the signal output from the latch 21. The command signal output circuit 20 is C
It is provided in an ASIC (not shown) connected to the PU 10, and the ASIC is configured by a hardware circuit that performs various operations of the printer under the control of the CPU 10. .

A counter 24 is connected to the latches 21 and 22, and the holding time of the latches 21 and 22 is until the counter 24 overflows. An XOR gate 25 as a first output circuit is connected to the output sides of the latches 21 and 22,
On the output side of the XOR gate 25 and the latch 21,
A latch 23 as a second output circuit is connected.
That is, the output of the XOR gate 25 becomes high level when the outputs of the latches 21 and 22 are not at the same level, and becomes low level when they are at the same level.
The output of the latch 23 outputs the output signal level of the latch 21 when the output of the XOR gate 25 changes from the high level to the low level.

That is, the level change signal output from the latch 23 is an interrupt signal for causing the CPU 10 to execute interrupt processing, and C
When the PU 10 receives the interrupt signal, the PU 10 performs an interrupt process for determining the paper empty, and the processing result controls the printing operation and the paper feeding operation, and the paper empty lamp of the printer is provided. Informed by lighting. The latches 21 to 23 are composed of a gate array or the like, and the XOR gate 25 and the latch 23 correspond to the output circuit according to the present invention.

Next, the operation of the command signal output circuit 20 will be described with reference to FIG. FIG. 2 is a timing chart showing the detection signal (PE signal) output from the PE sensor 30, the count signal of the counter 24, the Q output signals of the latches 21 to 23, and the output signal of the XOR gate 25. In this example, if the printing paper runs out,
That is, in the PE state (t7 to t15 in FIG. 2), the PE signal is assumed to change from the high level to the low level, and in FIG. The part that changes to high level at is the change due to the intrusion of external noise. Further, the counter 24 is assumed to overflow in one cycle (one set of high level and low level).

First, the PE output from the PE sensor 30.
When the signal changes to a low level signal due to intrusion of external noise or the like (t1), the low level signal is held by the latch 21 whose gate is opened due to the overflow of the counter 24 (t2). This holding is carried out until the next overflow of the counter 24 (t4), and is taken over and held by the latch 22 opened next (t4 to t5). Here, when the counter 24 overflows (t4) for the second time from the time t1, the PE signal has already returned to the high level signal, and therefore the latch 21 holds the high level signal. Therefore, in each period (t2 to t4, t4 to t5) after the first and second overflows of the counter 24, the Q outputs of the latch 21 and the latch 22 are not at the same level, so that the latch 21 and the latch 22 have the same Q output. The output of the XOR gate 25 that receives the Q output becomes a high level signal (t2 to t).
5). Then, the counter 24 at the third time from the time t1
In the overflow (t5), the Q outputs of the latch 21 and the latch 22 are at the same level, so the output of the XOR gate 25 becomes a low level signal (t5 to t5).
8), the latch 23 outputs a high level signal which is the Q output of the latch 21. That is, the output signal of the latch 23 is
The interrupt signal is not output because it remains at the high level and does not change. Therefore, even if external noise enters as described above, the CPU 10 does not erroneously determine the paper empty.

Next, at time t8, the PE signal has already become
Since it is a low level signal, that is, a signal indicating paper empty, this low level signal is held by the latch 21. At this time, the latch 22 inherits the high-level signal held by the latch 21 from time t6 to t8 and holds it from time t8 to t9. When the PE signal becomes the low level signal (t7) and the PE signal maintains the low level signal even after the second overflow (t9) of the counter 24,
The latch 21 also holds the low level signal continuously. At this time, the latch 22 inherits and holds the low level signal of the latch 21 after the first overflow (t8 to t9). Therefore, when the counter 24 overflows for the second time, the Q output signals of the latches 21 and 22 both become the same level (low level). And X
Since the output signal of the OR25 also changes from high level to low level, and the Q output signal of the latch 21 is also low level,
The output signal of the latch 23 changes to the low level from time t9.

In the low level state of the output signal from the latch 23, the PE signal changes to a high level signal (t1
5) The state is maintained until the counter 24 overflows twice (from time t9 to t17 in this example). Then, the low level signal output from the latch 23 is interrupted and input to the CPU 10 as an interrupt signal, and the CPU stops other arithmetic processing and executes the paper empty determination program. Subsequently, the processing result of the program is notified by controlling the printing operation and the paper feeding operation and turning on the paper empty lamp provided in the printer.

As described above, according to the printer according to the above-described embodiment, the CPU 10 only has to determine the paper empty state when the interrupt process is applied. Therefore, when the interrupt process is not performed, , Other arithmetic processing can be executed. That is, unlike the conventional case, it is not necessary to monitor the paper empty state at regular time intervals, and thus the function of the CPU can be normally used for other arithmetic processing such as printing operation and paper feeding operation. Therefore, the burden on the CPU can be reduced and the reliability can be improved.

Moreover, the interrupt processing is applied to the CPU only when the level of the PE signal is detected twice and the PE signal level is the same twice, so that the CPU does not erroneously judge the paper empty state. Therefore, it is possible to improve the determination accuracy of the loading state of the printing paper. Further, since the command signal output circuit 20 is a very small amount in view of the circuit scale of the ASIC as a whole, if the command signal output circuit 20 is incorporated at the time of designing the ASIC, the cost is hardly increased. The above printer can be realized.

In the above embodiment, the paper empty state has been described as an example of the loading state of the printing paper, but the present invention can also be applied to the purpose of detecting the paper jam state and the like. Further, in the above-described embodiment, the PE signal level is detected twice. However, when the latches and gate circuits are added to detect three or more times, and the detected levels are all the same. Only, the interrupt signal may be output to the CPU 10. Further, in the above-described embodiment, the case where the present invention is applied to the printer as an example of the printing device has been described, but the present invention may be applied to a device such as a facsimile machine or a copying machine having a function of determining the loading state of the printing paper by the CPU. For example, it can be applied to other devices.

[0025]

As described above, according to the present invention, since the command signal for executing the loaded state determination can be output to the arithmetic processing device, the arithmetic processing device receives the above command signal when it receives the command signal. It suffices to execute the loading state judgment,
Other arithmetic processing can be performed except when the determination is performed. That is, the burden on the arithmetic processing device can be reduced. Moreover, the level of the detection signal output from the loading state detection means of the printing paper is detected at least twice, and when the detected levels are the same predetermined level, the arithmetic processing unit executes the loading state determination. Therefore, it is possible to improve the detection accuracy of the loaded state.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration for determining a loading state of printing paper of a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart of signals output from each block in the block diagram of FIG.

FIG. 3 is a block diagram showing a configuration for determining a loading state of printing paper in a conventional printing device.

FIG. 4 is a block diagram showing a configuration for determining a loading state of printing paper in a conventional printing device.

[Explanation of symbols]

 10 CPU 20 Command signal output circuit 30 PE sensor

Claims (4)

[Claims] 1. An arithmetic process including a loading state detecting means for detecting a loading state of printing paper, and a loading state determination for determining a loading state of the printing paper by inputting a detection signal output from the loading state detecting means. In a printing apparatus including: an arithmetic processing unit that performs the above-mentioned, the level of the detection signal output from the loading state detection unit is detected at least twice, and when the detected levels are the same predetermined level, A printing apparatus comprising: a command signal output means for outputting a command signal for executing the loaded state determination to the arithmetic processing unit. 2. The command signal output means includes a first holding circuit that holds the detection signal output from the loading state detection means, and the first holding circuit holds the detection signal,
A second holding circuit for inputting and holding the detection signal of the first holding circuit, and a detection signal held by the first and second holding circuits,
The printing device according to claim 1, further comprising: an output circuit that outputs the command signal when the predetermined levels are the same. 3. The detection signal held by the first and second holding circuits is supplied to the output circuit,
A first output circuit that outputs a signal when they are at the same level, and a signal detected by the first holding circuit based on a change in the level of the signal output from the first output circuit, the command signal The printer according to claim 2, further comprising: a second output circuit for outputting as. 4. The inkjet printer according to claim 1, further comprising a print head that discharges ink onto the printing paper to print.