JPS61176272A - Picture recorder - Google Patents

Abstract

PURPOSE:To keep the fine visual properties of recorded pictures and at the CONSTITUTION:A timer is started and increases its count value from the first set value of a timer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image recording device in a facsimile communication device or the like, and particularly to an image recording device using thermal recording means.

[Prior art] Conventionally, this type of device attaches a temperature detection element such as a thermocouple or thermistor to an appropriate position on the heat-sensitive head in order to keep the temperature of the heating element constant, and then detects the heating element based on the measured temperature data. However, due to various factors, the temperature of the heating element was not constant, and the reproduced image showed differences in density depending on the mode. A relatively large factor among these factors is that the recording cycle of one line differs depending on the mode of the image to be reproduced.

For example, considering the case of a received image and an image reproduced by a copy operation, in the case of a received image, MH (Modified
Haffnian): +-do and MR (Modifier)
Depending on the device, it generally takes time to decode the dRead) code, or to convert raw data from RL (Run Length):+- to other codes depending on the device. Furthermore, in the case of received images, due to restrictions on transmission speed and transmission time itself, the more complex the image pattern is, the longer the recording time for each line exceeds the shortest recording time capability of the recording device, resulting in heat generation. It takes longer for the element to cool down, so its temperature does not rise.

On the other hand, in the case of a copy operation, there is no need to decode the code or convert data, so the recording device performs recording in the shortest recording time. Therefore, the temperature rises due to the heat storage effect of the heating element, and the reproduced image becomes darker than the reproduced image at the time of reception. This is because if the way in which the energy is applied to the heating element is matched to the copying operation from the beginning, the reproduced image will become lighter than expected upon reception. At that time, the temperature of the heating element is instantly detected,
The applied energy can be controlled based on this data, but it is difficult to create such an ideal temperature detection element due to the structure of the thermal head.

Furthermore, when creating gradations using the dithering method, image recording with an applied energy higher than necessary increases the heating area, causing fogging between adjacent heating elements, resulting in a reduction in the aesthetic appearance and resolution of the reproduced image. . On the other hand, in normal binary image recording, the physical area of the heating element itself is reduced to some extent to provide a gap between adjacent elements. For this reason, it is better to fill in the gaps by recording with a certain amount of high applied energy, so that the reproduced image looks more beautiful.

However, in conventional recording devices, the applied energy is controlled regularly regardless of the type of reproduced image, so if the applied energy is adjusted to match the gradation image, the recording of the normal binary image will become thinner. Furthermore, if this is applied to a normal binary image, there is a drawback that the gradation image becomes too dark.

[Objective] The object of the present invention is to eliminate the above-mentioned conventional drawbacks, maintain the visual beauty of recorded images regardless of the image type or operation mode, and increase the resolution. An object of the present invention is to provide an image recording device.

[Example] Figures 1 to 4 show examples of the present invention. Although the present invention generally relates to a facsimile communication device, in order to avoid complication, the following description will focus on the characteristic part of the present invention, that is, the control of applied energy to a thermal head.

One of the features of the present invention is that in addition to temperature control, the energy applied to the thermal head is controlled depending on the type of image to be reproduced or the operating state of the device. How to control the pulse width of a signal! shall be.

FIG. 1 is an internal wiring diagram of the thermal head. In the figure, l is a heating resistor, there are 2048 in total, and they are deposited adjacent to each other on a substrate such as alumina.
By passing current through this, ohmic heat is generated. 2 is a Nant gate, W as one input, 5TB (
By setting the voltage of either write strobe signal line) 0 to W or 5TB7 to 0 (hereinafter, the voltage level will be expressed as l and 0, respectively), if the other input line is 0, its output will be 1, If the other input line is 1, its output is 0
, and only the heating resistor connected to the 0 output generates heat.

On the other hand, image data is serially input to a plurality of shift registers 4. Here, each shift register is composed of 25[theta] flip-flops, and as shown in the figure, the serial output of the shift register of each block is the input to the next stage. Therefore, all 8 block shift registers have 2048 parallel outputs in total.
It constitutes a 48-bit shift register, and image data from the DATA line is sequentially transferred from left to right in the 8-block shift register.

When the transfer of 2048 pieces of serial data is completed, voltages of 0 and 1 representing black and white are output from the parallel outputs of the 8 block shift registers, and these are latched by a plurality of latch circuits 3.

The latch is performed by inputting a relatch signal to each latch circuit 3 through a latch input line. The input of each latch circuit 3 corresponds one-to-one to the output line of the shift register 4, and the output line of the same circuit 3 is connected to the other input of the Nandt gate 2.

Therefore, the image data has now been serially transferred to the 2048-bit shift register, and the latch signal is transferred to the latch circuit 3.
For example, if the second parallel output line of the first shift register 4 is 1, the second output line of the first latch circuit 3 also becomes 1, and then W, 5TBO
When the line is set to 0, the output of the second Nant gate 2 is 0.
When a certain voltage is applied to the recording voltage Pv, a current flows through the resistor R2, generating heat, and as a result, 2 of the thermal recording paper
A black dot is recorded at the bit. If the parallel output line of the shift register is 0, the output line of the corresponding latch circuit will also be 0, and even if the write strobe signal line is set to 0, the output line of Nant gate 2 will remain 1. No current flows through the heating resistor and is not recorded on the thermal recording paper.

Through the process described above, the image data transferred to the shift register 4 is latched by the latch circuit 3, and then, by setting the write strobe signal lines to 0 one by one or several at a time, 1947 worth of data is recorded. be done.

The thermistor 5 is installed at an appropriate position where it can easily detect the temperature of the substrate of the thermal head or the heating element, but since this thermistor 5 has the characteristic that its resistance value changes depending on the temperature, the voltage across the resistor 2 changes depending on the temperature. Change. Therefore, by measuring the voltage value across the resistor R, the temperature of the substrate or heating element of the thermal head can be determined.

Also, the TCLK (clock) signal line is connected to shift register 4.
This is to synchronize when transferring data.

FIG. 2 is a block diagram of a circuit that controls the aforementioned thermal head, where 6 is a thermal head, and 7 is a 1-chip microcomputer (in this example, a 1-chip I10 control chip manufactured by Intel, which is generally available on the market) is used. An example using the CPU 8041 will be described.
41 is the CPU, RAM, ROM, and 8 registers O~
7, and has an accumulator. Hereinafter, this will be abbreviated as anus. ), 8 is A/D (analog/digital)
It is a converter. ) The LC7 performs control according to the procedure shown in FIG. 4, which is stored in the built-in ROM. To explain the operation in Fig. 2, in order to record 1947 minutes of image data on thermal recording paper, the main or slave CPU (not shown in the figure) synchronizes with the clock of the TCLK line through the DATA line. Image data is serially input to the thermal head 6. 1 line (20
After inputting the data (48 bits), the latch signal from the main or slave CPU becomes LATC.
The image data is input to the thermal head 8 via the H line, and the input image data is latched within the head 6. Next, the main or slave CPU gives a recording command to the MC 7 through the data bus line. Upon receiving the recording command, the MC 7 controls the A/D converter 8 and reads the output voltage THERM of the thermistor in the thermal head 6.
Based on the result, the write strobe signal lines W connected to port 1 of MC 7, 5TBO to 7, are sequentially set to 0 with a reduced pulse width, and recording of one line is completed. Here, MC? CLK input to MC7 is a clock signal to operate MC7, RESET is a reset signal at start, and C8 is a main or slave CP input to MC7.
U is a chip select signal when passing data.

Next Me? The control procedure will be explained below. The MC7 receives commands from the main or slave CPU, and performs operations based on the results.Three types of commands will be considered here. That is, i) Recording start command (print 5tart comm
and).

ii) Record command (print cmmand) and 1
ii) a stop command;
The bit patterns are shown in Figure 3 (A), (B) and (C).
) as shown. Here, as shown in Figure 3 (A), counting from the LSB of the recording start command (hereinafter, bits are LS
counting from B) 1st bitO and 2nd bit
l has a special meaning, and each bit is used to determine whether bit is copied or received (copy is set to 1), and
Let bitl be a bit for determining whether the image is a normal binary image or a halftone (halftone is set to 1). The roles of the above three directives are roughly as follows. In other words, the recording start command is
The register specified by the contents is set and preparations for recording are made. Also, the recording command outputs a signal to the write strobe signal line while controlling the pulse width of the write strobe based on the contents of the register set above and the temperature information detected by the thermistor, and records one line. . A stop command stops the operation and returns to the initial state.

The role of each command has been described above. Next, the operation of the MC 7 when receiving the command will be explained with reference to FIG. 4. M
When the C7 is powered on, in step S1, a reset signal is applied to the MC7 for a certain period of time from the main or slave CPU or by other means, and then released. starts from address zero and is INITIAL
The IZE routine clears each register and sets port 1 to FF. Then, in step S2,
It waits for a command to be sent by determining whether or not DBB FULL. When a command is input, it is determined in step S3 what kind of command it is, and a processing routine for that command is entered. To determine what command it is, the upper 3 of the command bits
This is done by determining in which position of the bit the 1 is located. If the current command is a print start command, PRINT 5T
Program control is transferred to ART ROUTINE, and the process proceeds to step S4. In step S4, it is determined whether the command bit bit is 1 or not, and if it is 0, step S5
Proceed to MC7 and set the built-in REGO (register 0) to 0.
If bito is 1, proceed to step S6 and set an appropriate number in REGO (here, 5 is set).

Next, proceed to step S7 and similarly determine whether or not the command bit bitl is 1, and if it is 0, step S8
Me? Set the built-in REG 1 to 0,
If it is 1, proceed to step S8, set an appropriate number (10 in this case), and return to the routine of waiting for the first command.

In step S3, if the captured data (command) is a print command, Mm routine
T ROU'rlNE 4. : Transfer, stay/paste S10
Proceed to. In step SIO, a conversion start signal is given to the A/D converter to start temperature measurement (SENSE
TEMP), import the data converted in step Sll through PORT2 of MC7 (
TAKEIN TEMP, DATA). Next, in step S12, the temperature data is converted into a pulse width data format convenient for pulse width control (CONVE
RT TOP, W, DATA). This is done by preparing a table in advance, for example, in the ROM of the MC7, in which temperature data and data for pulse width control are correlated one-to-one, and converting based on that table.
The method is quick and hassle-free. Next, pulse width data (P, W, DATA) converted to narrow the pulse width in step S13 and step 314
The contents of REGO and RECI set in the recording start command routine are added to.゛If the recording mode is communication reception (COMMUNIC:ATION) and normal binary image (CONVENTrONAL), then
EGO, t: Since t and REGI are set to zero, the pulse width data (P, W, DATA) remains unchanged. In other cases, since a value other than zero is set in REGO or REGI, the pulse width data (P, W, DATA) will increase by that amount. Next, in step S15, 8 is put in REG2, and in step S1B, P, W, IIATA are put in the internal timer of MC7 via accumulator A (TIMER4-P, W, DATA). After So (7), step At S17, set the tabulated data to PORTI (Boat 1) of MC7 (PORTI
←TABLE DATA). The data tabulated here is the numerical value of the bit pattern that becomes zero in order from the LSB of the 8-bit data that constitutes the recording command, and as described later, it is sequentially written into the accumulator A. Set up the import boat 1.

That is, first, FE of the 8-bit data is set in port 1. Then, in step S1B, when a timer is started (START TIMERE), a register within the timer is incremented at a certain time interval. Next, in step S19, it is determined whether or not the timer register has overflowed and become zero, and a routine is entered to wait until it becomes zero, and when it becomes zero, step S2
0, the timer is stopped, and then step S21
decrements REG2 by 1 (DCR
REG2). Next, in step S22, it is determined whether or not REG2 is zero, and if it is not zero, the process returns to step 5113 and P, W, and DATA are set in the timer again, and then in step St? - In S21, the next FD of the 8-bit data is set in port 1, a timer is started, and when the register of the timer reaches zero, the timer is stopped, and REG2 is decremented by 1. Below, the value in the 8-bit data set to boat 1 is F.
By repeating the same procedure while changing B and F7 until reaching the final 7F, the signal of the light strobe (W, 5TB) connected to boat 1 will become 0 in order from 0 to 7 at regular intervals. , recording is performed on thermal recording paper.

When the last 7F of the 8-bit data is set to port 1 in this loop, REG2 is set to 0 in step S22 (at the end of the loop), so the process proceeds to step S23 and port 2 is set to FF. and returns to the routine waiting for the first command. In this routine, once the timer is started, the timer is set at regular intervals (MC7 is clocked at flMHz) from the initial setting value of the timer register.
When activated with C1, K), the timer register is incremented by 139 g5ec), so the larger the initial setting value is, the sooner the timer register becomes zero. As a result, the light strobe (
W, 5TB) will be reduced to zero for a shorter time. That is, the energy applied to the thermal head becomes smaller. Therefore, by determining the contents of the print start command sent from the main or slave CPU, it is possible to control the pressure applied to the thermal head. For example, during a copy operation, the applied energy is smaller than during a reception operation. Ordinary binary images can be recorded with less applied energy than gradation images, and can be recorded visually with an average density regardless of the operating status of the device or the type of image. Beautiful recorded images can be obtained.

Next, if the command taken into the MC7 is a stop f4 command, the process returns to step Sl and all initialization is performed. Naoki This was omitted in the program flow to avoid complexity, but when the command processing routine is entered, a busy flag is set, and while this busy flag is set, data is not sent to the main or slave CPULDBB (7"-Tabas/\Tsfa). However, for the stop command, this busy flag is ignored and the data is input to DBH, and in each processing routine, I) BB is set to F.
Determine whether it is ULL or not. If FULL then BEGI
By returning to N, an urgent stop command can be executed immediately.

This embodiment is just one example, and various other embodiments are possible. That is, in order to change the amount of applied energy, the recording voltage P can be changed without changing the pulse width of the write strobe.
A method of controlling v, or a method of repeatedly overwriting one line at a constant period and changing the number of repetitions may be used. Furthermore, although a method of controlling the energy applied to the thermal head by controlling the CPU has been described here, a method of realizing it by hardware without relying on such control of the CPU can be considered. Furthermore, a wide variety of CPU control algorithms can be considered. Further, the present invention is not limited to facsimile communication devices, but can be applied to any device equipped with a printer using a thermal recording means, including a thermal transfer method or an inkjet recording method that uses a heating element to eject droplets. can. In this example, as examples of image types and device operation modes, only normal binary images, halftones, copying operations, and receiving operations are listed, but there are also other types of images such as complex figures, fine characters, G2 mode, etc. Various image types and device operation modes are possible, such as low-speed operation, using only MH, or using MR in combination. Further, as a thermal head, it is applicable not only to full-multi one-time writing and two-time writing thermal heads, but also to all types of thermal heads including shuttle type thermal heads.

[Effects] As described above, according to the present invention, regardless of the operating state of the device such as copying or receiving, and regardless of the type of image such as a normal binary image or halftone image, uniform It is possible to reproduce visually beautiful images with high density and resolution.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a thermal head. FIG. 2 is a diagram showing the main parts of the electric circuit of the recording device, FIG. 3 is a diagram showing the bit arrangement of commands, and FIG. 4 is a diagram showing the control procedure of the CPU. l... Heat generating resistor, 2... Nant gate, 3... Latch circuit, 4... Shift register, 5... Thermistor, 8... Thermal head, 7... CPU for I10 control (8041), 8
...Analog-digital converter. Figure 4

Claims (1)

[Claims] An image recording apparatus comprising means for controlling energy applied to a heating element of a thermal recording means in accordance with at least one of the type of image to be reproduced and the operating state.