JPS63268365A - Thermosensing recorder - Google Patents

Abstract

PURPOSE:To prevent large capacity of a buffer storage means and a recording power supply by measuring a transfer interval of picture information in the unit of lines to a thermal head from a buffer storage means, varying the recording tine of picture information and inhibiting the transfer to the thermal head by the time in response to the transfer interval. CONSTITUTION:A transfer interval measuring section 16 measures the elapsed time from a point of time when a signal G outputted from a buffer storage section 13 is reset till a point of time when the signal is reset next. The buffer storage section 13 transfers the picture information of one line to the thermal head 14 as soon as the information reaches the transfer enable state. A recording control section 15 controls the width of a recording pulse I, that is, the recording time to Tp2 and a transfer inhibition section 17 sets a signal K by the time Ti2. While the signal K given from a transfer inhibition section 17 is set, the buffer storage section 13 does not transfer the picture information. Thus, the buffer storage section 13 has only to have the storage capacity to store the picture information by 2 lines at a minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal recording device that records image information line by line, and particularly to a thermal recording device that records image information line by line. The present invention relates to a thermal recording device suitable for applications in which the temperature varies from line to line.

Conventional technology Figure 3 shows a schematic configuration of a thermal recording device used in the recording section of a conventional 7-axis IJ device, where 1 is an input terminal for image information, and 2 is a terminal for temporarily storing input image information. 3 is a recording control section; 4 is a thermal head for thermally recording image information line by line; and 5 is an AND gate for controlling transfer lock.

The thermal head 4 includes a large number of heating elements 6 corresponding to one line arranged in a negative column, and a driver 7 for driving each heating element 6.
, an AND gate 8 for input control of each driver 7, a latch circuit 9 for reporting one line of image information, and a shift register 10 for serial/parallel conversion of image information.
It consists of

Each heating element 6 is connected in parallel to a terminal 11, and this terminal is connected to a recording power source (not shown).

The operation of the thermal recording apparatus configured as above will be described below. FIG. 4 is a time chart of signals related to the recording operation.

The buffer storage unit 2 continuously sends out a transfer lock at a constant period, and this transfer lock is inputted to the shift register 10 as a shift clock via the gate 5. When it becomes possible to transfer one line of image information, the buffer storage unit 2 turns on the signal B, opens the AND gate 5, transfers the image information A to the thermal head 4 in synchronization with the transfer lock, and transfers the image information of that line. When the transfer is completed, signal B is turned off.

In response to the transition of signal B from on to off, the recording control unit 3
generates a latch pulse C to cause the latch circuit 9 to latch the image information in the shift register 10, and immediately thereafter generates a recording pulse D to open the AND gate 8 and activate the driver 7 corresponding to the black pixel of the line. By turning it on, the heating element 6 corresponding to the black pixel is energized to generate heat, thereby recording image information on recording paper (not shown).

The buffer storage unit 2 starts transferring the image information of the next line to the thermal head 4 as soon as the image information of the next line becomes transferable.

Thereafter, image information is recorded on the recording paper line by line by repeating the same operation.

Here, one of the characteristics of thermosensitive recording is shown in FIG.

This diagram shows the relationship between the recording cycle (the time interval from the start of recording on one line to the start of recording on the next line) and the recording energy that is required to be applied to the heating element of the thermal head in order to record at a constant density. It shows. As is clear from this figure, in order to record at a constant density, it is necessary to increase the recording energy as the recording cycle becomes longer. This is due to the heat storage effect of the thermal head or recording paper. Since recording energy is proportional to the product of applied power and recording time (width of recording pulse D), if applied power is constant, recording energy is proportional to recording time.

Now, in the case of group 3 facsimile machines, the transmission speed of image information on each line fluctuates because the image information is encoded and transmitted, and therefore the input interval of image information on each line to the buffer storage section 2 is also 1. It fluctuates significantly within a range greater than or equal to the line minimum transmission time. Since the buffer storage unit 2 transfers one line of image information to the thermal head 4 as soon as it becomes transferable, the image information transfer interval to the thermal head 4 also changes, and as a result, the recording of each line The period also fluctuates.

In order to prevent changes in recording density due to fluctuations in the recording cycle, also in the above-mentioned thermal recording apparatus, the recording control section 3 changes the recording time (recording pulse width) in accordance with the recording cycle. However, in order to prevent the buffer storage unit 2 from overflowing, the recording time is controlled so that the time from when one line of image information is transferred until the end of recording of that line does not exceed the minimum transmission time for one line. It had become.

Problems to be Solved by the Invention However, with the above-mentioned configuration, uneven recording density tends to occur;
Another problem is that an expensive recording power source is required.

The above problem arises for the following reasons. In other words, even if the recording time is changed according to the recording cycle, the range is within the range that does not exceed the minimum transmission time of one line, so it is necessary to maintain the recording density constant over a wide range of changes in the recording cycle. This is because recording density tends to decrease, especially when the recording interval becomes long. Further, in order to obtain a predetermined recording density even when the recording cycle is long, a large amount of recording energy must be supplied to the thermal head in a short period of time, which requires a large-capacity recording power source.

In order to solve these problems, a configuration can be considered in which the capacity of the recording power source is further increased so that when the recording cycle is long, the necessary recording energy can be applied to the heating element within the minimum transmission time of one line.

Alternatively, a large-capacity buffer storage section may be provided, and, for example, after one page's worth of image information is temporarily stored in the buffer storage section,
A configuration in which image information is transferred to a thermal head and recorded at a speed that can maintain a constant density may also be considered. However, in either case, the cost of the thermal recording device increases considerably and is not practical.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a thermal recording device that enables recording without density unevenness at a recording speed equal to or higher than that of the conventional technology without increasing the cost of the device. purpose.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention measures the transfer interval of image information in line units from the buffer storage means to the thermal head, and transfers the image information to the thermal head according to the measured transfer interval. In addition to changing the recording time of image information by
The apparatus is configured to prohibit the transfer of image information from the buffer storage means to the thermal head for a time corresponding to the transfer interval.

As described above, the present invention increases the capacity of the buffer storage means in order to change not only the recording time but also the prohibition time for transmitting the next line of image information to the thermal head depending on the length of the image information transfer interval. When the recording cycle is long, it is possible to record for a longer recording time than the minimum input interval of external image information without overflowing the buffer storage means, and as a result, the recording power source is It is possible to prevent a decrease in recording density even when the recording cycle is long without increasing the capacity, and to record with uniform density. In addition, when the recording cycle is short instead of prohibiting the transfer of image information for a certain period of time, not only the recording time but also the transfer prohibition time of the image information is shortened, thereby achieving a recording speed equal to or higher than that of the conventional technique.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a thermal recording apparatus according to an embodiment of the present invention, in which 12 is an image information input terminal;
3 is a buffer storage unit that can temporarily store image information for at least two lines; 14 is a thermal head that thermally records image information line by line; 15 is a recording control unit that controls recording by the thermal head 14; is thermal head 1
a transfer interval measurement unit that measures the transfer interval of image information to 4;
Reference numeral 17 designates a transfer prohibition unit for prohibiting the transfer of image information in the buffer storage unit 13, and reference numeral 18 represents an AND gate for controlling transmission of a transfer lock for image information.

The thermal head 14 is the thermal head 4 shown in FIG.
3, its components are given the same reference numerals as the corresponding elements in FIG.

The transfer interval measurement section 16 measures the elapsed time (i.e., transfer interval) from the time when the signal G output from the buffer storage section 13 is turned off to the time when the signal G is turned off next time, and when the elapsed time exceeds a predetermined time Th, This is a type of timer that turns on the output signal J. If the signal J is on when the signal G is turned off, the transfer inhibiting unit 17 turns on the output signal K for a predetermined time Ti1, and if the signal J is off, the transfer inhibiting unit 17 turns on the output signal K for a predetermined time Ti2 (<' The output signal K only during T'i + )
It is a kind of timer that turns on the .

The recording control unit 15 outputs a latch pulse H when the signal G is turned off.
is generated, and immediately after that, a recording pulse is generated. The time width of this recording pulse is TPI if the signal J is on when the signal G is off, and the time width of the recording pulse is TPI if the signal J is off when the signal G is off.
(<TPI).

Note that the minimum input interval for image information from outside (group 3
- Corresponds to the minimum transmission time for one line in facsimile. (see FIG. 2) is T, there is the following relationship.

T h > T P+ > T > T P2
(1) The buffer storage section 13 does not transfer image information while the signal K (transfer prohibition signal) given from the transfer prohibition section 17 is in the on state (transfer prohibition state).

During the period when the signal K is in the off state (transfer inhibition released state), the buffer storage unit 13 transfers the image information of one line as image information F as soon as it becomes possible to transfer the image information of one line and synchronizes it with the lock L. Transfer to the thermal head 14. Signal G is turned on during the transfer period of image information F.

The transfer lock L is always sent out from the buffer storage section 13, and is input to the shift register 10 as a shift clock via the AND gate 18 only during the ON period of the signal G.

The operation of the thermal recording apparatus configured as above will be described below. FIG. 2 is a time chart for explaining the operation. Note that X indicates a time series of image information transferred from the buffer storage unit 13 when the transfer prohibition unit 17 does not prohibit the transfer.

For example, when the transfer of the image information G of line ■ is completed and the signal G is turned off, a latch pulse H is output from the recording control unit 15, and the image information of the line ■ in the shift register 10 is latched by the latch circuit 9. .

Immediately after that, a recording signal is output from the recording control unit 15,
The heating element 6 corresponding to the black pixel generates heat, and the image information of the line (2) is recorded on the recording paper.

Here, since the interval from the end of the transfer of the immediately preceding line (2) to the end of the transfer of the line (2), that is, the transfer interval, is shorter than Th, the signal J is in the OFF state at the time of the end of the transfer of the line (2). Therefore, the recording control unit 15 controls the width of the recording pulse I, that is, the recording time, to Tp2, and the transfer inhibiting unit 17 turns on the signal K for a time Ti2. Note that the signal J is reset (turned off) after the recording pulse E and the signal K are turned on.

More than Th time elapses after the transfer of line ■ is completed and before the transfer of the next line ■ is completed (the transfer interval is Th
No, the signal J turns on when Th has elapsed. Therefore, the width of the bar sequence for the next line (■), that is, the recording time, is controlled to Tp+, and the signal has Ti7
For the first line of one page, the recording time is unconditionally controlled by Tpo, and the signal ON time is controlled by Ti.

In this way, depending on the length of the image information transfer interval, the formula (
In order to control the recording time and the transfer prohibition time of the next line of image information according to the condition of 1), if the buffer storage unit 13 has a storage capacity that can store at least two lines of image information, the buffer storage unit 13 can be Image information can be recorded without causing overflow. If the image information transfer interval is long (in other words, the recording cycle is long),
Since the recording time can be set to Tp+, which is longer than the minimum input interval T, even if the power capacity of the recording power supply is the same as before,
A decrease in recording density can be prevented. In addition, when the recording cycle is short instead of prohibiting the transfer of image information for a certain period of time, not only the recording time but also the transfer prohibition time of the image information is shortened, thereby achieving a recording speed equal to or higher than that of the conventional technique. - In this embodiment, it was measured whether the transfer time exceeded a predetermined time, and the recording time and transfer prohibition time were switched to two stages depending on the measurement result.
By measuring the transfer time in multiple stages and switching the recording time and transfer inhibition time in multiple stages according to the measurement results, it is possible to make the recording density more uniform.

Furthermore, in this embodiment, the recording pulse is simultaneously applied to all the AND gates 8 corresponding to all the heating elements 6 to record one line at the same time. However, for the purpose of reducing the capacity of the recording power source, etc. One line may be divided into a plurality of blocks, and recording may be performed for each block.

Note that the transfer time control section 16, transfer prohibition section 17, and recording control section 15 may be realized by program control.

Effects of the Invention As is clear from the above description, the present invention measures the transfer interval of image information in line units from the buffer storage means to the thermal head, and records the image information by the thermal head in accordance with the measured transfer interval. Since the time is changed and the transfer of image information from the buffer storage means to the thermal head is prohibited for a time corresponding to the transfer interval, the recording cycle can be extended without increasing the capacity of the buffer storage means and recording power source. This has the effect of preventing the recording density from decreasing in the case of printing, and making it possible to record without density unevenness at a speed equal to or higher than that of the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a thermal recording device according to an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the thermal recording device, FIG. 3 is a schematic block diagram of a conventional thermal recording device, and FIG. The figure is a time chart for explaining the operation of the conventional device.
FIG. 5 is a characteristic diagram showing the relationship between recording period and recording energy in thermal recording. 13... Buffer storage section, 14... Thermal head, 15... Recording control section, 16... Transfer interval measurement section,
17...Transfer prohibited section. Name of agent: Patent attorney Toshio Nakao and 1 other person
Tsutsumi 0 ヱ - hx ward shi -!

Claims (1)

[Claims] A thermal head that thermally records image information line by line, a buffer storage means that temporarily stores image information input from the outside and transfers it to the thermal head, and a line from this buffer storage means to the thermal head. A measuring means for measuring a transfer interval of unit image information and a recording operation of the thermal head, the recording time of image information by the thermal head being changed according to the transfer interval measured by the measuring means. recording control means; and transfer prohibition means for prohibiting the transfer of image information from the buffer storage means for a time period corresponding to a transfer interval measured by the measuring means after one line of image information is transferred to the thermal head. , wherein the buffer storage means transfers the image information of the line to the thermal head as soon as the prohibition by the transfer prohibition means is lifted and the image information of the line to be transferred becomes transferable. Recording device.