JPH0798398B2 - Printer - Google Patents

Description

TECHNICAL FIELD The present invention relates to print control of a dot matrix type printer.

(Prior Art) In a dot matrix printer, while moving a print head in which the dot generation mechanisms such as print pins and heating elements are arranged in the vertical direction in the paper width direction, the dot generation mechanism corresponding to the print pattern is used for the print timing. In a device that also supplies electric power to generate dots for printing, the drive power to be supplied to the print head is proportional to the dot density of the print pattern.

By the way, in normal character printing, it is necessary to drive only about 1/3 to 1/2 of the number of dot generation mechanisms at the same time, so it is equipped with a power supply unit with a capacity of about 1/2 of the power required for 100% drive. Therefore, the cost is reduced.

Therefore, in pattern printing that requires a high dot density such as a solid black pattern, the power supply from the power supply device cannot catch up with the operation of the print head, or the power supply device breaks down. .

In order to solve such a problem, as disclosed in JP-A-57-160657, the print head is moved from the time when the print head reaches the print timing position until the power supply voltage returns to a predetermined range. However, since the actual print timing fluctuates depending on the power supply voltage at all times, the operation of the dot generation mechanism may become unstable and the print quality may deteriorate. Also,
Since the drive of the print head is kept waiting until the power supply voltage is constantly restored within a predetermined range, there is a problem that throughput is reduced.

(Object) The present invention has been made in view of such a problem, and an object of the present invention is to perform printing at a constant speed without lowering the printing speed within the power supply voltage fluctuation range allowed for the print head. The object of the present invention is to provide a printing apparatus in which a stable printing operation is obtained by performing low-speed printing at a predetermined constant speed when the power outage falls below an allowable range, and the decrease in throughput is suppressed to a minimum. To do.

(Example) Therefore, the details of the present invention will be described below based on an illustrated example.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 is a power supply circuit which receives power from a commercial power supply and supplies DC power to a carriage drive motor 2 and a print head 3 which will be described later. Then, the power transformer 1a, the rectifier 1b, and the smoothing capacitor 1c are provided, and are configured to be capable of supplying 1/2 of the electric power required to drive all the dot generation mechanisms. Reference numeral 2 denotes the above-mentioned carriage drive motor which moves the carriage on which the print head 3 is mounted in the axial direction of the platen in synchronization with the signal from the pulse motor drive circuit 10. Three
Is a print head mounted on a carriage (not shown),
It is configured by arranging a plurality of dot generating mechanisms such as printing pins and heating elements in the vertical direction. Reference numeral 4 is an A / D converter that converts the output voltage of the power supply circuit 1 into a digital signal, and 5 is a dot generation mechanism drive circuit, which receives the signal from the line buffer memory 6 and the signal from the A / D converter 4. Then, the dot generating mechanism 3 of the print head 3 is configured to supply a current for a time width inversely proportional to the power supply voltage to generate dots having a constant density regardless of the power supply voltage. A power supply voltage detection circuit 7 has a lower limit rated voltage capable of driving the device as a set level, and outputs a signal when the power supply voltage falls below the set level.
Reference numeral 8 is a printing speed adjusting circuit, which divides the frequency of the timing pulse generating circuit 9 into 1/2 when a signal from the power supply voltage detecting circuit 7 is input, and divides the frequency of the timing pulse generating circuit 9 into 1/2. Configured to output to.

Next, the operation of the apparatus thus configured will be described.

When a character code signal is input from a host device (not shown), the character code signal is converted into a dot pattern by the character generator and stored in the line buffer memory 6. A print command is output when data for one line is stored in this way, and a dot signal is output from the line buffer memory 6 to the dot generation mechanism drive circuit 5.

At this point in time, the power supply circuit 1 is outputting a voltage equal to or higher than the lower limit rated voltage, so the printing speed adjusting circuit 8 outputs the signal from the timing pulse generating circuit 9 as it is to the dot generating mechanism driving circuit 5 and the pulse motor driving circuit. Output to 10 to activate print head 3 and carriage drive motor 2,
Printing is performed at normal printing timing. When the print pattern is changed during such a printing process and a print signal that requires a high dot density is output, the power to be supplied to the print head 3 increases and the output voltage of the power supply circuit 1 decreases. The dot generation mechanism drive circuit 5 supplies a drive signal having a pulse width inversely proportional to the power supply voltage to the dot generation mechanism 3 to prevent a decrease in print density. When the output voltage of the power supply circuit 1 further decreases and falls below the set level (FIG. 2), the power supply voltage detection circuit 7 outputs a signal to the printing speed adjustment circuit 8. In response to this signal, the print speed adjusting circuit 8 divides the timing pulse from the timing pulse generating circuit 9 into 1/2 and outputs it to the dot generating mechanism drive circuit 5 and the pulse motor drive circuit 10, and the print head 3 The dot generating mechanism and the carriage driving motor 2 are driven at a constant speed which is half the printing timing. This allows
The printing mechanism operates at a constant speed that is 1/2 of the printing timing, and continues to print character patterns one after another while consuming power within a range commensurate with the output power of the power supply circuit 1.

FIG. 3 shows a second embodiment of the present invention,
Reference numeral 11 in the figure denotes a power supply voltage detection circuit, which outputs a first signal when the voltage falls below a first set level having a set lower limit rated voltage capable of driving the device, and a voltage slightly higher than the first set level. Is configured to output the second signal when the second set level is exceeded. Reference numeral 12 denotes a printing speed adjusting circuit, which is configured to divide and output a timing pulse signal in response to a signal from the power supply voltage detecting circuit 11.

In this embodiment, the output voltage from the power supply circuit 1 is the first
When the level falls below the set level, the print speed adjustment circuit 12 reduces the print timing to half the frequency and continues printing at a constant speed. While continuing such a state,
When the number of dots printed per unit time decreases and the output voltage of the power supply circuit 1 starts to rise and exceeds the second set level (Fig. 4), the power supply voltage detection circuit 11 causes the printing speed adjustment circuit 12 to operate. The second signal is output. Upon receiving the second signal, the printing speed adjusting circuit 12 outputs a pulse to the dot generating mechanism driving circuit 5 and the pulse motor driving circuit 10 at a normal printing timing to switch to printing by a normal printing dimming. According to this embodiment, it is possible to detect a decrease in the print dot density and automatically switch the print speed to the normal print timing.

In this embodiment, the printing speed when the power supply voltage is reduced is set to 1/2 of the rated speed, but it goes without saying that it may be reduced to a speed that balances the output of the power supply circuit. Nor.

(Effect) As described above, according to the present invention, printing is performed at a constant speed without lowering the printing speed within the power supply voltage fluctuation range allowed for the print head, and when the power supply voltage falls outside the allowable range. Since the low speed printing is performed at the preset speed only, the printing speed is not always influenced by the power supply voltage, the printing operation can be stabilized, and the decrease in throughput can be suppressed to the minimum. Furthermore, breakdown of the power supply circuit can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention,
2 is a timing chart showing the operation of the above apparatus, FIG. 3 is a block diagram of the apparatus showing another embodiment of the present invention, and FIG. 4 is a timing chart showing the operation of the apparatus shown in FIG. is there. 1 ... Power supply circuit, 2 ... Carriage drive motor 3 ... Print head

Claims (1)

[Claims] 1. A carriage having a print head equipped with a plurality of dot generating mechanisms is first moved in a digit direction by a drive motor.
In the printing apparatus that feeds and records at a speed of, a power supply unit that supplies power to at least the print head and the drive motor, a voltage detection unit that detects an output voltage of the power supply unit, and a detection voltage of the voltage detection unit. And controlling the drive pulse width of the print head according to the above, when the detected voltage becomes a voltage that causes the power supply means to be overloaded, the carriage feed speed is slower than the first speed. Second
A printing apparatus, comprising: a control unit for continuously controlling the speed of the printing.